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Current understanding of ecological and evolutionary processes underlying island biodiversity is heavily shaped by empirical data from plants and birds, although arthropods comprise the overwhelming majority of known animal species, and as such can provide key insights into processes governing biodiversity. Novel high throughput sequencing (HTS) approaches are now emerging as powerful tools to overcome limitations in the availability of arthropod biodiversity data, and hence provide insights into these processes. Here, we explored how these tools might be most effectively exploited for comprehensive and comparable inventory and monitoring of insular arthropod biodiversity. We first reviewed the strengths, limitations and potential synergies among existing approaches of high throughput barcode sequencing. We considered how this could be complemented with deep learning approaches applied to image analysis to study arthropod biodiversity. We then explored how these approaches could be implemented within the framework of an island Genomic Observatories Network (iGON) for the advancement of fundamental and applied understanding of island biodiversity. To this end, we identified seven island biology themes at the interface of ecology, evolution and conservation biology, within which collective and harmonized efforts in HTS arthropod inventory could yield significant advances in island biodiversity research. [ABSTRACT FROM AUTHOR]

Assessing the vulnerability of low-lying coral reef islands is a global concern due to predictions that climate and environmental change will increase reef island instability and cause reef island populations to be among the first environmental refugees. Reef islands in the Pacific and Indian Oceans are highly dynamic environments that morphologically adjust to changing environmental conditions over annual-decadal timescales. However, there is a paucity of reef island shoreline change data from the Caribbean where sea-level rise, ecological and environmental disturbance and hydrodynamic regimes are considerably different than in other oceans globally. Here we present shoreline change analysis of 16 reef islands in northern Honduras, at the southern end of the Mesoamerican Barrier Reef. Satellite imagery from a maximum period of 12.4 years from Utila (2006–2019), and 2.4 years from Cayos Cochinos (2018–2021) was analysed to quantify island shoreline change and planform morphological adjustments. We identified accretion as the dominant island behaviour in Utila, where 5 of 7 islands increased in area and 61.7% of shorelines accreted, contributing to an overall net area increase of 9.4%. Island behaviour was more variable in Cayos Cochinos, where 55.7% of shorelines eroded, 5 of 9 islands remained stable, and net island area change was insignificant (2%). Conversely, the 4 smallest Cayos Cochinos islands (all <1500 m2) experienced significant shoreline change, potentially highlighting a new size threshold for considering reef island evolution. Across both sites, reef islands demonstrated a range of modes of planform change, including lateral accretion and erosion, and migration. Consequently, we provide the first empirical evidence of the dynamic nature of Caribbean reef islands during a period coincident with sea-level rise and highlight the heterogeneous nature of reef island evolution between and within two neighbouring sites at timescales relevant for island adaptation efforts. [ABSTRACT FROM AUTHOR]

Insular gigantism is an evolutionary phenomenon whereby small animals become bigger on islands compared to their mainland relatives. The abundance of insular giant taxa in the fossil record suggests the presence of a universal "giant niche" present on islands, with resource limitation as a potential driver for this process. However, insular habitats are ecologically diverse, suggesting that island taxa adopt different survival strategies, including adaptations for foraging behaviors. Here, we used finite element analysis to evaluate insular feeding niche adaptations in some of the most extreme examples of insular gigantism: Mediterranean giant dormice. We calculated stress, strain, and mechanical advantage during incisor and molar biting for 3 extinct insular giant species (Leithia melitensis , Hypnomys morpheus , and H. onicensis), an extant giant (Eliomys quercinus ophiusae), and their extant non-giant mainland relative, the generalist-feeder Eliomys quercinus. Our results show that dietary adaptations vary between giant taxa on different islands, and can occur relatively rapidly. Furthermore, the functional mandibular morphology in some insular taxa indicate adaptations moving away from a generalist feeding strategy toward greater trophic specialization. We show that the "insular giant niche" varies between islands and across time periods, arguing against a universal ecological driver for insular gigantism in small mammals. [ABSTRACT FROM AUTHOR]

The evolution of behaviour on islands is a pervasive phenomenon that contributed to Darwin's theory of natural selection. Island populations frequently show increased boldness and exploration compared with their mainland counterparts. Despite the generality of this pattern, the genetic basis of island-associated behaviours remains a mystery. To address this gap in knowledge, we genetically dissected behaviour in 613 F2s generated by crossing inbred mouse strains from Gough Island (where they live without predators or human commensals) and a mainland conspecific. We used open field and light/dark box tests to measure seven behaviours related to boldness and exploration in juveniles and adults. Across all assays, we identified a total of 41 quantitative trait loci (QTL) influencing boldness and exploration. QTL have moderate effects and are often unique to specific behaviours or ages. Function-valued trait mapping revealed changes in estimated effects of QTL during assays, providing a rare dynamic window into the genetics of behaviour often missed by standard approaches. The genomic locations of QTL are distinct from those found in laboratory strains of mice, indicating different genetic paths to the evolution of similar behaviours. We combine our mapping results with extensive phenotypic and genetic information available for laboratory mice to nominate candidate genes for the evolution of behaviour on islands. [ABSTRACT FROM AUTHOR]

Recent work in island biogeography has shown that back-colonization (‘boomerang’ events) from islands to continents have occurred more frequently than previously understoodWe report possibly the earliest inference of this pattern, by John Ball and Joseph Dalton Hooker in a book published in 1878.

Female song is ancestral to songbirds and shows considerable phylogenetic signal, but its presence also appears to be labile and correlated with life‐history and ecology. While previous studies have examined the evolution of female song across species‐rich families, here we studied female song in island populations of a recently diverged species‐complex, the chaffinches (genus Fringilla). We show this behaviour has recently evolved in these populations, and probably on two independent occasions. In F. teydea, female song is performed in loose duets with males, while in F. coelebs, female song is produced solo. Populations with singing females showed year‐round territoriality and were found in regions with low seasonality – both factors previously connected with high rates of female singing. To determine the relative saliency of female songs to conspecifics, and the degree to which they instigate territorial defence behaviours, we performed a series of speaker playback experiments. In F. c. canariensis, female song could induce comparable responses to male song, whilst duetting F. teydea playback produced similar responses to solo songs, and therefore may relate to within‐pair communication instead. Our results suggest female song can be a highly labile trait that can evolve over short evolutionary timescales. [ABSTRACT FROM AUTHOR]

The recovery and persistence of rare and endangered species are often threatened by genetic factors, such as the accumulation of deleterious mutations, loss of adaptive potential, and inbreeding depression [1]. Island foxes (Urocyon littoralis), the dwarfed descendants of mainland gray foxes (Urocyon cinereoargenteus), have inhabited Californias Channel Islands for >9,000 years [2-4]. Previous genomic analyses revealed that island foxes have exceptionally low levels of diversity and elevated levels of putatively deleterious variation [5]. Nonetheless, all six populations have persisted for thousands of generations, and several populations rebounded rapidly after recent severe bottlenecks [6, 7]. Here, we combine morphological and genomic data with population-genetic simulations to determine the mechanism underlying the enigmatic persistence of these foxes. First, through analysis of genomes from 1929 to 2009, we show that island foxes have remained at small population sizes with low diversity for many generations. Second, we present morphological data indicating an absence of inbreeding depression in island foxes, confirming that they are not afflicted with congenital defects common to other small and inbred populations. Lastly, our population-genetic simulations suggest that long-term small population size results in a reduced burden of strongly deleterious recessive alleles, providing a mechanism for the absence of inbreeding depression in island foxes. Importantly, the island fox illustrates a scenario in which genetic restoration through human-assisted gene flow could be a counterproductive or even harmful conservation strategy. Our study sheds light on the puzzle of island fox persistence, a unique success story that provides a model for the preservation of small populations.

The recovery and persistence of rare and endangered species are often threatened by genetic factors, such as the accumulation of deleterious mutations, loss of adaptive potential, and inbreeding depression [1]. Island foxes (Urocyon littoralis), the dwarfed descendants of mainland gray foxes (Urocyon cinereoargenteus), have inhabited California's Channel Islands for >9,000 years [2-4]. Previous genomic analyses revealed that island foxes have exceptionally low levels of diversity and elevated levels of putatively deleterious variation [5]. Nonetheless, all six populations have persisted for thousands of generations, and several populations rebounded rapidly after recent severe bottlenecks [6, 7]. Here, we combine morphological and genomic data with population-genetic simulations to determine the mechanism underlying the enigmatic persistence of these foxes. First, through analysis of genomes from 1929 to 2009, we show that island foxes have remained at small population sizes with low diversity for many generations. Second, we present morphological data indicating an absence of inbreeding depression in island foxes, confirming that they are not afflicted with congenital defects common to other small and inbred populations. Lastly, our population-genetic simulations suggest that long-term small population size results in a reduced burden of strongly deleterious recessive alleles, providing a mechanism for the absence of inbreeding depression in island foxes. Importantly, the island fox illustrates a scenario in which genetic restoration through human-assisted gene flow could be a counterproductive or even harmful conservation strategy. Our study sheds light on the puzzle of island fox persistence, a unique success story that provides a model for the preservation of small populations.

We report the rediscovery of Lecocarpus leptolobus at its type locality, and restrict the latter to El Ripioso, San Cristóbal, Galapagos. We compare the morphology of the population at this site with other populations of Lecocarpus on San Cristóbal and other Galapagos islands. We conclude that L. leptolobus is a valid taxon endemic to the south-western half of San Cristóbal and is not synonymous with L. lecocarpoides , whereas populations further north-east on the same island constitute a separate species validly named L. darwinii. These two taxa support the idea of a former biogeographic barrier between the two halves of San Cristóbal. Plants at two of the easternmost localities of the south-western species show some characters intermediate between the two species, possibly representing introgression following easing of the barrier. The three specimens of Lecocarpus collected on San Cristóbal by Charles Darwin, all mounted on a single herbarium sheet, comprise one branch of L. leptolobus and two of L. darwinii. We identify possible sites for Darwin's collections based on information about his explorations. We find grounds for accepting the taxon Acanthospermum brachyceratum as a subspecies of L. lecocarpoides endemic to Gardner-by-Española, Osborn and Xarifa islets, the first of these being the type locality, demonstrating that even narrow sea barriers can contribute to plant radiation in oceanic archipelagos. On the basis of our findings, we provide a new key to the taxa of Lecocarpus. [ABSTRACT FROM AUTHOR]

Oceanic islands are natural laboratories where evolutionary processes can be studied more readily. In the present work we use nuclear microsatellites to quantitatively assess the roles of hybridization, colonization, gene flow and geographical barriers in four Parolinia spp. endemic to Gran Canaria in connection with known geological events throughout the dynamic geological ontogeny of the island. Our genetic analyses show that these Parolinia spp. share 69% of all alleles detected and display low genetic divergence among populations, suggesting a close genetic relationship and recent differentiation. This close relationship is more evident between Parolinia platypetala and Parolinia ornata , which were included in the same genetic pool in the STRUCTURE analysis, and probably represent the early stages of an incipient speciation process, as suggested by the absence of gene flow barriers between them. NEWHYBRIDS, STRUCTURE and MIGRATE analyses unequivocally suggest frequent past migration and hybridization from P. ornata to P. filifolia , but contemporary migration is low overall. Despite the overall genetic closeness among the Parolinia spp. assessed, microsatellites dispelled doubts regarding the appropriate name/s for two taxonomically conflicting populations. In line with the predictions of the surfing syngameon hypothesis, ancestral hybridization, vicariance and dispersal events linked to the complex ontogeny of the island may have been key factors to shape the current genetic diversity and structure of Parolinia in Gran Canaria. [ABSTRACT FROM AUTHOR]

Abstract Background The Caribbean offers a unique opportunity to study evolutionary dynamics in insular mammals. However, the recent extinction of most Caribbean non-volant mammals has obstructed evolutionary studies, and poor DNA preservation associated with tropical environments means that very few ancient DNA sequences are available for extinct vertebrates known from the region’s Holocene subfossil record. The endemic Caribbean eulipotyphlan family Nesophontidae (“island-shrews”) became extinct ~ 500 years ago, and the taxonomic validity of many Nesophontes species and their wider evolutionary dynamics remain unclear. Here we use both morphometric and palaeogenomic methods to clarify the status and evolutionary history of Nesophontes species from Hispaniola, the second-largest Caribbean island. Results Principal component analysis of 65 Nesophontes mandibles from late Quaternary fossil sites across Hispaniola identified three non-overlapping morphometric clusters, providing statistical support for the existence of three size-differentiated Hispaniolan Nesophontes species. We were also able to extract and sequence ancient DNA from a ~ 750-year-old specimen of Nesophontes zamicrus, the smallest non-volant Caribbean mammal, including a whole-mitochondrial genome and partial nuclear genes. Nesophontes paramicrus (39-47 g) and N. zamicrus (~ 10 g) diverged recently during the Middle Pleistocene (mean estimated divergence = 0.699 Ma), comparable to the youngest species splits in Eulipotyphla and other mammal groups. Pairwise genetic distance values for N. paramicrus and N. zamicrus based on mitochondrial and nuclear genes are low, but fall within the range of comparative pairwise data for extant eulipotyphlan species-pairs. Conclusions Our combined morphometric and palaeogenomic analyses provide evidence for multiple co-occurring species and rapid body size evolution in Hispaniolan Nesophontes, in contrast to patterns of genetic and morphometric differentiation seen in Hispaniola’s extant non-volant land mammals. Different components of Hispaniola’s mammal fauna have therefore exhibited drastically different rates of morphological evolution. Morphological evolution in Nesophontes is also rapid compared to patterns across the Eulipotyphla, and our study provides an important new example of rapid body size change in a small-bodied insular vertebrate lineage. The Caribbean was a hotspot for evolutionary diversification as well as preserving ancient biodiversity, and studying the surviving representatives of its mammal fauna is insufficient to reveal the evolutionary patterns and processes that generated regional diversity.

Since the contributions of Charles Darwin and Alfred Russel Wallace, oceanic archipelagos have played a central role in the development of biogeography. However, despite the critical influence of oceanic islands on ecological and evolutionary theory, our focus has remained limited to either the island-level of specific archipelagos or single archipelagos. Recently, it was proposed that oceanic archipelagos qualify as biotic provinces, with diversity primarily reflecting a balance between speciation and extinction, with colonization having a minor role. Here we focus on major attributes of the archipelagic geological dynamics that can affect diversity at both the island and the archipelagic level. We also re-affirm that oceanic archipelagos are appropriate spatiotemporal units to frame analyses in order to understand large scale patterns of biodiversity.

In this paper, a revision is carried out on the dental evolution of the endemic dormouse Hypnomys Bate, 1918 in the late Neogene-Quaternary of the Balearic Islands. In Mallorca, we have reviewed material (upper and lower first and second molars) coming from the localities of Cap Ferrutx, Pedrera de s'Ònix, Cova de Canet, Cova de Llenaire, Cova de son Bauçà, Cova de son Maiol and Cova de sa Bassa Blanca, ranging from the Pliocene to the Holocene. In Menorca, a revision is done of the species H. mahonensis and H. eliomyoides. It is concluded that, while H. eliomyoides corresponds to an endemic lineage from Menorca, H. mahonensis should be considered as a descendant of H. morpheus from Mallorca which probably entered Menorca during the late Pleistocene. Finally, the presence of Hypnomys in Eivissa is not confirmed, since a large lower first molar previously assigned to this genus in the locality of Cova de ca na Reia could belong to a new endemic form. [ABSTRACT FROM AUTHOR]

Harsh and variable environments have been hypothesized to both drive and constrain the evolution towards higher cognitive abilities and behavioural flexibility. In this study, we compared the cognitive abilities of island and mainland Aegean wall lizards (Podarcis erhardii), which were expected to live in respectively a more variable and a more stable habitat. We used four proxies of behavioural flexibility: a neophobia assay, a problem-solving test and a spatial + reversal learning task. Surprisingly, the two populations did not differ in neophobia or problem-solving. Insular lizards, however, outperformed mainland conspecifics in an initial spatial learning task, but were less successful during the subsequent reversal learning. Our results thus seem to indicate that the effect of environmental variability on cognition is complex, as it may favour some, but not all aspects of behavioural flexibility. [ABSTRACT FROM AUTHOR]

Aim: Adaptive radiation, in which successful lineages proliferate by exploiting untapped niche space, provides a popular but potentially misleading characterization of evolution on oceanic islands. Here we analyse the respective roles of members of in situ diversified vs. non‐diversified lineages in shaping the main ecosystems of an archipelago to explore the relationship between evolutionary and ecological 'success'. Location: Canary Islands. Taxon: Vascular plants. Methods: We quantified the abundance/rarity of the native flora according to the geographical range (number of islands where present and geographical extent of the range), habitat breadth (climatic niche) and local abundance (cover) using species distribution data based on 500 × 500 m grid cells and 2000 vegetation inventories located all over the archipelago. Results: Species of diversified lineages have significantly smaller geographic ranges, narrower climatic niches and lower local abundances than those of non‐diversified lineages. Species rarity increased with the degree of diversification. The diversified Canarian flora is mainly comprised by shrubs. At both archipelagic and island level, the four core ecosystems (Euphorbia scrub, thermophilous woodlands, laurel forest and pine forest) were dominated by non‐diversified lineages species, with diversified lineages species providing <25% cover. Species of diversified lineages, although constituting 54% of the archipelagic native flora, were only abundant in two rare ecosystems: high mountain scrub and rock communities. Main conclusions: Radiated species, endemic products of in situ speciation, are mostly rare in all three rarity axes and typically do not play an important role in structuring plant communities on the Canaries. The vegetation of the major ecosystem types is dominated by plants representing non‐diversified lineages (species that derive from immigration and accumulation), while species of evolutionarily successful lineages are abundant only in marginal habitats and could, therefore, be considered ecological losers. Within this particular oceanic archipelago, and we posit within at least some others, evolutionary success in plants is accomplished predominantly at the margins. [ABSTRACT FROM AUTHOR]

Island populations are hallmarks of extreme phenotypic evolution. Radical changes in resource availability and predation risk accompanying island colonization drive changes in behavior, which Darwin likened to tameness in domesticated animals. Although many examples of animal boldness are found on islands, the heritability of observed behaviors, a requirement for evolution, remains largely unknown. To fill this gap, we profiled anxiety and exploration in island and mainland inbred strains of house mice raised in a common laboratory environment. The island strain was descended from mice on Gough Island, the largest wild house mice on record. Experiments utilizing open environments across two ages showed that Gough Island mice are bolder and more exploratory, even when a shelter is provided. Concurrently, Gough Island mice retain an avoidance response to predator urine. F1 offspring from crosses between these two strains behave more similarly to the mainland strain for most traits, suggesting recessive mutations contributed to behavioral evolution on the island. Our results provide a rare example of novel, inherited behaviors in an island population and demonstrate that behavioral evolution can be specific to different forms of perceived danger. Our discoveries pave the way for a genetic understanding of how island populations evolve unusual behaviors. Significance: Organisms on islands are known to behave differently from mainland organisms. An absence of predators and a different set of natural resources are expected to make island organisms less anxious and more exploratory. We raised two groups of house mice, one from Gough Island in the South Atlantic and one from the mainland Eastern USA, in the same laboratory environment to see if behavioral differences between the two groups are heritable. Mice from both groups were placed in novel enclosures that are known to cause anxiety in rodents. We found that mice from the island are bolder and more exploratory in these enclosures but avoid predator odors in the same way as mainland mice. Our results show that boldness and exploration can evolve after island colonization. [ABSTRACT FROM AUTHOR]

In the Pleistocene faunas of the island of Crete, Cervidae was one of the most abundant taxa. Respective species vary in body size, including dwarfs, and skeletal morphology; however, the number of species and the identity of the mainland ancestor(s) are still debated. In this paper, we morphologically and morphometrically describe and analyze eight skulls of Cretan deer from a so far little known fossil site near Gerani, Rethymnon, Greece. The recorded character suite allows for affiliation to dwarfed Candiacervus Kuss, 1975, Candiacervus ropalophorus de Vos, 1984 and C. reumeri van der Geer, 2018. It comprises previously unknown unique traits, some of them hinting to sexual dimorphism. Comparisons of the Candiacervus skulls presented here with those of cervids belonging to Megalocerotini Brooke, 1828, s.s. and s.l. stress certain similarities; yet more material is needed to reconstruct Candiacervus' phylogenetic position. The newly detected craniodental specifics allow for more insights into island adaptation of Candiacervus; at the same time, they blur the morphological heritage of their mainland ancestors. [ABSTRACT FROM AUTHOR]

During the Ceramic Age (500 BCE–1500 CE), Lesser Antilles rice rats (Tribe Oryzomyini) made up a significant portion of the diet of Caribbean islanders. Archaeological excavations across the archipelago resulted to the discovery of large quantities of remains from to these now extinct taxa. It offers a unique opportunity to investigate the past biogeography of this taxon of high cultural and ecological importance. We have studied 1140 first lower molars originating from 40 archaeological sites across eleven islands of the Lesser Antilles archipelago using two-dimensional geometric morphometric approaches to establish spatiotemporal patterns relying on phenotypic variations. This study identified three morphological groups, present in all chrono-cultural periods, that were geographically restricted and consistent with published ancient mitochondrial DNA clusters. These three geographically-separate groups likely represent three distinct genera of rice rats. The first group includes specimens from the North of the archipelago (Saint-Martin, Saba, Saint-Eustatius, Saint-Kitts, and Nevis) and likely referable to as Pennatomys sp.; the second, occurring in the South (Martinique), is assigned to Megalomys desmarestii ; and the third corresponds to specimens from the center of the Lesser Antilles (Antigua, Barbuda, Marie-Galante, and Guadeloupe) and likely corresponds to Antillomys sp. These oryzomyine morphotypes are present during all studied periods and support an older presence of these rodents in the region. Our results are congruent with ancient DNA studies that favor the hypothesis of a natural introduction of the group in the archipelago before settlement of human populations. Moreover, the observed phenotypic homogeneity and stability over the 2000 years of Pre-Columbian occupation suggests that rice rats were not part of long-distance inter-island exchanges by humans. Instead, rice rat human consumption was likely based on in-situ hunting of local populations. [ABSTRACT FROM AUTHOR]

The general dynamic model of oceanic island biogeography integrates temporal changes in ecological circumstances with diversification processes, and has stimulated current research in island biogeography. In the original publication, a set of testable hypotheses was analysed using regression models: specifically, whether island data for four diversity indices are consistent with the ‘B~ATT2’ model, in which B is a diversity index, A is log(area) and T is time. The four indices were species richness, the number and percentage of single‐island endemic species, and a diversification index. Whether the relationships between these indices and time are unimodal (i.e., ‘hump‐shaped’) was a key focus, based on the characteristic ontogeny of a volcanic oceanic island. However, the significance testing unintentionally used zero, rather than the mean of the diversity index, as the null hypothesis, greatly inflating F‐ values and reducing P‐values compared with the standard regression approach. Here we first re‐analyze the data used to evaluate the general dynamic model in the seminal paper, using the standard null hypothesis, to provide an important qualification of its empirical results. This supports the significance of about half the original tests, the rest becoming non‐significant but mostly suggestive of the hypothesized relationship. Then we expand the original analysis by testing additional, theoretically derived functional relationships between the diversity indices, island area and time, within the framework of the ATT2 model and using a mixed‐effects modelling approach. This shows that species richness peaks earlier in island life‐cycles than endemism. Area has a greater effect on species richness and the number of single‐island endemics than on the proportion of single‐island endemics and the diversification index, and was always better fit as a log–log relationship than as a semi‐log one. Finally, the richness–time relationship is positively skewed, the initial rise happening much more quickly than the later decline.

Aim: Mammals on islands often undergo remarkable evolutionary changes. The acquisition of 'low gear' locomotion, namely short and robust limb elements, has been typically associated with the island syndrome in large mammals and, especially, ruminants. Here we provide an investigative framework to examine biotic and abiotic selective factors hypothesized to influence evolution of this peculiar type of gait. Location: Islands worldwide. Taxon: Bovidae. Methods: We calculated response variables associated with 'low gear' locomotion in 21 extinct and extant insular bovids. We assembled data on the physiography of 11 islands and on life history and ecological traits of the focal taxa. We estimated 10 predictors (island area and four topographic indices, body mass, body size divergence, number of predators and competitors, large mammal richness) and used multiple regressions, regression trees, and random forests to assess their contextual importance. Results: The acquisition of 'low gear' locomotion generally happens on islands with a small number of competitors. However, the roughness of the island terrain appears to be also important, without being a main driver. Finally, although the most extreme cases of 'low gear' locomotion occurred on islands with no mammalian predators, our models show a non‐significant relationship with this factor. Main conclusions: The evolution of 'low gear' locomotion in insular ruminants does not simply result from phyletic dwarfing and predatory release. Variation in morphological responses within Bovidae to ecological and topographic traits suggests, instead, a complex interplay of biotic and abiotic factors. Current understanding on the main drivers of species evolutionary pathways and biogeographic patterns are disproportionally based on few taxa, mainly vertebrates, and in some extreme cases (like this one) even on few species. Here we show how adding more data, even within the same taxonomic group, can challenge historically accepted macroevolutionary and macroecological concepts. [ABSTRACT FROM AUTHOR]

Island populations repeatedly evolve extreme body sizes, but the genomic basis of this pattern remains largely unknown. To understand how organisms on islands evolve gigantism, we compared genome-wide patterns of gene expression in Gough Island mice, the largest wild house mice in the world, and mainland mice from the WSB/EiJ wild-derived inbred strain. We used RNA-seq to quantify differential gene expression in three key metabolic organs: gonadal adipose depot, hypothalamus, and liver. Between 4,000 and 8,800 genes were significantly differentially expressed across the evaluated organs, representing between 20% and 50% of detected transcripts, with 20% or more of differentially expressed transcripts in each organ exhibiting expression fold changes of at least 2×. A minimum of 73 candidate genes for extreme size evolution, including Irs1 and Lrp1 , were identified by considering differential expression jointly with other data sets: 1) genomic positions of published quantitative trait loci for body weight and growth rate, 2) whole-genome sequencing of 16 wild-caught Gough Island mice that revealed fixed single-nucleotide differences between the strains, and 3) publicly available tissue-specific regulatory elements. Additionally, patterns of differential expression across three time points in the liver revealed that Arid5b potentially regulates hundreds of genes. Functional enrichment analyses pointed to cell cycling, mitochondrial function, signaling pathways, inflammatory response, and nutrient metabolism as potential causes of weight accumulation in Gough Island mice. Collectively, our results indicate that extensive gene regulatory evolution in metabolic organs accompanied the rapid evolution of gigantism during the short time house mice have inhabited Gough Island. [ABSTRACT FROM AUTHOR]

Animals frequently evolve unique suites of traits on islands, but whether plants evolve comparable island syndromes remains unresolved. Here, we test the prediction on the basis of natural history observations that insect-pollinated plants evolve smaller flowers on islands than on mainland communities. We examined 556 plant species representing 136 phylogenetically independent contrasts between island and mainland sister taxa. We focused on endemic taxa originating from the Americas associated with seven tropical and subtropical islands of the Pacific Ocean. Contrary to conventional wisdom, flowers were not on average smaller on islands than on the mainland. On specific archipelagos (the Galápagos Islands and Revillagigedo Islands), however, island taxa did evolve smaller flowers. Divergence in flower size between island and mainland taxa also varied among taxonomic families, such that some plant families evolved smaller flowers on islands, other families evolved larger flowers on islands, and some families exhibited no divergence in flower size between island and mainland taxa. Overall, our results show that there is no general island syndrome for flower size, but instead that the evolution of floral morphology is complex and context dependent, depending on variation among islands and plant families. Our results also suggest that if island floras are typically dominated by small flowered species, as suggested by natural history observations, then ecological filtering is a more likely explanation of this pattern than evolutionary divergence postcolonization. We propose future studies that could disentangle the relative roles of ecological filtering and evolution in the distribution of floral traits on islands. [ABSTRACT FROM AUTHOR]

Aim: To identify the effect of multiple, temporally close, forcing events (i.e. climate‐driven habitat fragmentations/homogenizations) in shaping current patterns of biodiversity in alpine areas. Given their spatial configuration, alpine areas have been traditionally seen as islands surrounded by an "ocean" of unsuitable lands. A quantitative assessment of the effects of Holocene climate fluctuations on islands area and inter‐island connectivity is crucial to finely reconstruct past biodiversity dynamics and forecast species responses to future changes. Location: Italy. Taxa: Carabidae (Ground beetles), Chrysomelidae (Leaf beetles), Elateridae (Click beetles), Orthoptera (Grasshoppers and Crickets) and Papilionoidea (Butterflies and Skippers). Methods: A total of 1,077 species for 128,093 records were analysed and a classification based on their functional traits allowed identifying groups of good and poor dispersers within each taxon. A dynamic discrete model of ecosystem evolution provided the spatio‐temporal context to test two competing (transient equilibria vs. nonequilibrium) dynamics based on different colonization capabilities. In the transient equilibria dynamic the species are able to respond to island evolution through successful dispersal and colonization events, whereas in the nonequilibrium dynamic ineffective immigration constrains the current species richness to that generated by the strongest island contraction. Results: With the exception of Elateridae, good dispersers (Chrysomelidae and Papilionoidea) responded to environmental changes by establishing a series of transient equilibria. In contrast, the nonequilibrium dynamic better described patterns of species richness in poor dispersers (Carabidae and Orthoptera). Main conclusions: Our approach could be used as the basis for the development of spatially and temporally explicit models of island evolution and could be a valuable tool for quantifying the sensitivity of single taxa to climate‐driven habitat changes. It also represents a further step towards the forecasting of future responses to climate change and the accompanying development of conservation strategies that more effectively respond to the detrimental impacts of climate change on biodiversity. [ABSTRACT FROM AUTHOR]

Aim: The impact of Pleistocene climatic oscillations on tropical biomes is associated with changes in the extent of forest cover. Fruit bats have played a role in woodland dynamics via pollination and seed dispersal. We hypothesized that phylogeographic patterns of Rousettus on continental Africa and adjacent islands should show a signature of pluvial‐drought cycles, involving demographic expansions and contractions. Location: Afrotropical, Malagasy and Saharo‐Arabian biogeographic realms. Taxon: Genus Rousettus (Pteropodidae). Methods: Phylogeographic and population genetic approaches using mitochondrial and microsatellite data were integrated with species distribution modelling of currently suitable habitats and those of the Last Glacial Maximum using climate simulations. Results: Phylogenetic reconstruction yielded an Asian outgroup followed by pectinate branching of the Indian Ocean taxa and Rousettus aegyptiacus. While nuclear microsatellites were homogeneous across the African mainland, two mitochondrial haplogroups were found. Haplogroup I is widespread in regions with extensive tree cover, including tropical rain forests, and has close relationships to isolated lineages in the Middle East and islands in the Gulf of Guinea. Haplogroup II is sister to the rest of the R. aegyptiacus radiation and is found in eastern and southern Africa and the Sudanian savanna in habitats with semi‐open land cover. Main Conclusion: Palaeodistributional modelling ascertained that the Indian Ocean islands provided more extensive areas of suitable habitat in the past relative to conditions today, suggesting stepping stone connectivity between Asia and Africa during Pleistocene interpluvial sea‐level lowstands. Inverse pluvial‐drought demography was detected in lineages ancestral to recent haplogroups, providing evidence of past forest refugia and complex ecogeographic scenarios of haplogroup origins involving allopatry and parapatry connected with the eastern Afromontane biodiversity hotspot, and subsequent admixture of nuclear gene pools. The Middle Eastern lineage probably originated during pluvial green Sahara periods, possibly in co‐evolution with ancestors of tree crop species domesticated later during the Neolithic revolution. The keystone role of rousettine bats for forest regeneration and their ability to pioneer dry and distant habitats emphasize their role in conservation biology and restoration ecology. [ABSTRACT FROM AUTHOR]

Leptospermum scoparium (Myrtaceae) is a morphologically highly variable species found in mainland Australia, Tasmania and New Zealand. For example, in New Zealand up to six morphologically distinct varieties of this species have been described, although only two (var. scoparium and var. incanum) are now formally recognized. In the present study we provide a first examination of genetic diversity in this culturally and commercially important species with the aim of gaining insights into its origins and evolution. We used anchored hybrid enrichment to acquire sequence data from 485 orthologous low-copy nuclear loci for 27 New Zealand and three Australian accessions of L. scoparium and representatives of several other Leptospermum spp. The final concatenated data matrix contained 421 687 nucleotide positions of which 55 102 were potentially informative. Despite the relative large data set, our analyses suggest that a combination of low and incompatible data signal limits the resolution of relationships among New Zealand populations of L. scoparium. Nevertheless, our analyses are consistent with genetic diversity being geographically structured, with three groups of L. scoparium recovered. We discuss the evolutionary and taxonomic implications of our findings. [ABSTRACT FROM AUTHOR]

The Pacific Ocean is the site of the most important diversification of insular reed warblers (Acrocephalus). In the Marquesas Islands (Eastern Polynesia), reed warblers belong to two distinct lineages that have reached the archipelago independently. We used mitochondrial sequences and microsatellite markers and found evidence of gene flow between the two lineages. One island in particular, Nuku Hiva, seems to act as the main contact zone between the two taxa. We then used reflectance spectrometry to evaluate the variation of carotenoid colouration among all populations. Marquesan reed warblers exhibit convergent evolution in carotenoid-based plumage colouration, but variation among islands was important. Having two different phylogenetic origins, the two lineages acquired their yellow colour independently and there is stochastic variation in plumage among islands. Finally, we analysed the songs of reed warblers from the main islands. Multifactorial analysis showed that vocalisations of Marquesan reed warblers differ slightly between species, significant differences between islands leading to different dialects. Vocal characteristics may act as the main pre-zygotic barriers when birds from different lineages come into contact. This study provides another example of convergence in plumage evolution in insular bird species. Furthermore, it highlights the importance of integrative analyses, using both genetic and phenotypical characters, for the study of the evolutionary history of the Pacific Ocean avifauna. [ABSTRACT FROM AUTHOR]

Islands are renowned for their remarkable biotas and have been widely recognised as natural laboratories for the study of evolution, speciation, and extinction. Large mammals in insular environments typically evolve to dwarfs and small ones to giants, a trend known as the island rule. Despite their dominance in the continental European mammal faunas of Middle-Late Pleistocene, Bison and Bos are usually lacking from the neighbouring endemic insular assemblages. Here, we report the first insular bovin from the Late Pleistocene of Kythera Island, Greece and we carry out a detailed morphometrical analysis with emphasis on its adaptations and palaeogeographic implications. Based on both dental and postcranial qualitative and quantitative comparisons, we attribute the studied material from Kythera to Bos primigenius. Significant differences from both its continental Pleistocene relative and the endemic bovins from Mediterranean islands, allow us to recognize it as a new subspecies, Bos primigenius thrinacius n. ssp., the third known insular dwarf of this taxon in Europe. Our main hypothesis is that the gradual disconnection of Kythera Island from the neighbouring Peloponnese peninsula just after MIS 6 (late Middle Pleistocene, ∼180 ka) resulted in the isolation of a mainland Bos primigenius population in the rocky and predator free environment of palaeo-Kythera Island. Under these particular conditions the population underwent some remarkable changes and gained some peculiar features, especially on metapodials. The timing and reasons of Bos primigenius thrinacius extinction remain unknown. • Description of the first insular auroch from the Late Pleistocene of Greece. • Definition of a new auroch subspecies, representing an insular dwarf. • Morphometrical comparison of insular bovins from Mediterranean. • Discussion of evolutionary trends of aurochs on islands. • Palaeoographic evolution of Kythera Island during the Late Pleistocene. [ABSTRACT FROM AUTHOR]

The insular Caribbean until recently contained a diverse mammal fauna including four endemic platyrrhine primate species, all of which died out during the Holocene. Previous morphological studies have attempted to establish how these primates are related to fossil and extant platyrrhines, whether they represent ancient or recent colonists, and whether they constitute a monophyletic group. These efforts have generated multiple conflicting hypotheses, from close sister-taxon relationships with several different extant platyrrhines to derivation from a stem platyrrhine lineage outside the extant Neotropical radiation. This diversity of opinion reflects the fact that Caribbean primates were morphologically extremely unusual, displaying numerous autapomorphies and apparently derived conditions present across different platyrrhine clades. Here we report ancient DNA data for an extinct Caribbean primate: a limited-coverage entire mitochondrial genome and seven regions of nuclear genome for the most morphologically derived taxon, the Jamaican monkey Xenothrix mcgregori. We demonstrate that Xenothrix is part of the existing platyrrhine radiation rather than a late-surviving stem platyrrhine, despite its unusual adaptations, and falls within the species-rich but morphologically conservative titi monkey clade (Callicebinae) as sister to the newly recognized genus Cheracebus. These results are not congruent with previous morphology-based hypotheses and suggest that even morphologically conservative lineages can exhibit phenetic plasticity in novel environments like those found on islands. Xenothrix and Cheracebus diverged ca. 11 Ma, but primates have been present in the Caribbean since 17.5-18.5 Ma, indicating that Caribbean primate diversity was generated by multiple over-water colonizations. [ABSTRACT FROM AUTHOR]

Abstract: Aim: I provide the first comprehensive study on body size evolution of extinct and living insular bovids, exploring the causal biotic and abiotic selective factors for observed patterns. Location: Islands worldwide. Methods: I assembled data on the geographic characteristics of 13 focal islands (area, isolation, latitude, net primary productivity) and on the ecological and morphological characteristics of 32 insular bovid taxa (number of predators and competitors, richness of large mammals, body mass of mainland relatives). I used linear regressions and machine learning methods (regression trees and random forest analyses) to examine the hypothesized contextual importance of these factors in explaining variation in the body size of island bovids. I also calculated evolutionary rates of body size divergence of focal taxa in order to assess whether this phenomenon is influenced by time in isolation. Results: The results of regression, regression tree and random forest analyses were in agreement with predictions based on a hypothesis of ecological release (more pronounced body size divergence on islands with the fewest competitors and predators). Only limited support for a resource limitation hypothesis (more pronounced body size divergence for the larger taxa on smaller islands) was found. Main conclusions: The majority of insular bovids, as large mammals, do follow the main prediction of the island rule, exhibiting body size reduction, and predator diversity is the main factor influencing body size evolution of these taxa. Results obtained highlighted the crucial role of time in isolation, with body size reduction becoming more pronounced for bovids with longer residence times on the islands. [ABSTRACT FROM AUTHOR]

Historical patterns of diversity, biogeography and faunal turnover remain poorly understood for Wallacea, the biologically and geologically complex island region between the Asian and Australian continental shelves. A distinctive Quaternary vertebrate fauna containing the small-bodied hominin Homo floresiensis, pygmy Stegodon proboscideans, varanids and giant murids has been described from Flores, but Quaternary faunas are poorly known from most other Lesser Sunda Islands. We report the discovery of extensive new fossil vertebrate collections from Pleistocene and Holocene deposits on Sumba, a large Wallacean island situated less than 50 km south of Flores. A fossil assemblage recovered from a Pleistocene deposit at Lewapaku in the interior highlands of Sumba, which may be close to 1 million years old, contains a series of skeletal elements of a very small Stegodon referable to S. sumbaensis, a tooth attributable to Varanus komodoensis, and fragmentary remains of unidentified giant murids. Holocene cave deposits at Mahaniwa dated to approximately 2000-3500 BP yielded extensive material of two new genera of endemic large-bodied murids, as well as fossils of an extinct frugivorous varanid. This new baseline for reconstructing Wallacean faunal histories reveals that Sumba's Quaternary vertebrate fauna, although phylogenetically distinctive, was comparable in diversity and composition to the Quaternary fauna of Flores, suggesting that similar assemblages may have characterized Quaternary terrestrial ecosystems on many or all of the larger Lesser Sunda Islands. [ABSTRACT FROM AUTHOR]

Recombination rate is a heritable quantitative trait that evolves despite the fundamentally conserved role that recombination plays in meiosis. Differences in recombination rate can alter the landscape of the genome and the genetic diversity of populations. Yet our understanding of the genetic basis of recombination rate evolution in nature remains limited. We used wild house mice (Mus musculus domesticus) from Gough Island (GI), which diverged recently from their mainland counterparts, to characterize the genetics of recombination rate evolution. We quantified genome-wide autosomal recombination rates by immunofluorescence cytology in spermatocytes from 240 F2 males generated from intercrosses between GI-derived mice and the wild-derived inbred strain WSB/EiJ. We identified four quantitative trait loci (QTL) responsible for inter-F2 variation in this trait, the strongest of which had effects that opposed the direction of the parental trait differences. Candidate genes and mutations for these QTL were identified by overlapping the detected intervals with whole-genome sequencing data and publicly available transcriptomic profiles from spermatocytes. Combined with existing studies, our findings suggest that genome-wide recombination rate divergence is not directional and its evolution within and between subspecies proceeds from distinct genetic loci. [ABSTRACT FROM AUTHOR]

The eastern Mediterranean has yielded some textbook examples of insular evolution among large mammals such as the world's smallest hippopotamus and mammoth. By contrast, gigantism among small mammals is limited, with the exception of the early Pleistocene murid Kritimys from Crete. The large body size of insular rodents can be related to an energetically advantageous position at the slow end of the mammalian fast–slow continuum. In order to test the hypothesis that the development of gigantism was hampered by the harsher climatic conditions of the middle and late Pleistocene, we constructed a dataset of endemic murids and cricetids from islands all over the world. Upto the middle Pleistocene, giant rodents can be found all over the world. However, in the later part of the Pleistocene and Holocene, these are only found at lower latitudes, suggesting that indeed the harsher conditions of the north no longer allowed insular rodents to develop the slow life-strategy that previously could still be achieved at these latitudes. [ABSTRACT FROM AUTHOR]

Aims The 50th anniversary of the publication of the seminal book, The Theory of Island Biogeography, by Robert H. MacArthur and Edward O. Wilson, is a timely moment to review and identify key research foci that could advance island biology. Here, we take a collaborative horizon-scanning approach to identify 50 fundamental questions for the continued development of the field. Location Worldwide. Methods We adapted a well-established methodology of horizon scanning to identify priority research questions in island biology, and initiated it during the Island Biology 2016 conference held in the Azores. A multidisciplinary working group prepared an initial pool of 187 questions. A series of online surveys was then used to refine a list of the 50 top priority questions. The final shortlist was restricted to questions with a broad conceptual scope, and which should be answerable through achievable research approaches. Results Questions were structured around four broad and partially overlapping island topics, including: (Macro)Ecology and Biogeography, (Macro)Evolution, Community Ecology, and Conservation and Management. These topics were then subdivided according to the following subject areas: global diversity patterns (five questions in total); island ontogeny and past climate change (4); island rules and syndromes (3); island biogeography theory (4); immigration-speciation-extinction dynamics (5); speciation and diversification (4); dispersal and colonization (3); community assembly (6); biotic interactions (2); global change (5); conservation and management policies (5); and invasive alien species (4). Main conclusions Collectively, this cross-disciplinary set of topics covering the 50 fundamental questions has the potential to stimulate and guide future research in island biology. By covering fields ranging from biogeography, community ecology and evolution to global change, this horizon scan may help to foster the formation of interdisciplinary research networks, enhancing joint efforts to better understand the past, present and future of island biotas. [ABSTRACT FROM AUTHOR]

ABSTRACT The general dynamic model of oceanic island biogeography ( GDM) has added a new dimension to theoretical island biogeography in recognizing that geological processes are key drivers of the evolutionary processes of diversification and extinction within remote islands. It provides a dynamic and essentially non-equilibrium framework generating novel predictions for emergent diversity properties of oceanic islands and archipelagos. Its publication in 2008 coincided with, and spurred on, renewed attention to the dynamics of remote islands. We review progress, both in testing the GDM's predictions and in developing and enhancing ecological-evolutionary understanding of oceanic island systems through the lens of the GDM. In particular, we focus on four main themes: ( i) macroecological tests using a space-for-time rationale; ( ii) extensions of theory to islands following different patterns of ontogeny; ( iii) the implications of GDM dynamics for lineage diversification and trait evolution; and ( iv) the potential for downscaling GDM dynamics to local-scale ecological patterns and processes within islands. We also consider the implications of the GDM for understanding patterns of non-native species diversity. We demonstrate the vitality of the field of island biogeography by identifying a range of potentially productive lines for future research. [ABSTRACT FROM AUTHOR]

The fossil and extant faunas of Sulawesi, the largest island within the Wallacea biogeographic region, exhibit a high degree of endemism. The lowland anoa Bubalus depressicornis and the mountain anoa Bubalus quarlesi , two closely-related dwarfed buffaloes, are among the most peculiar endemic mammals of the region. Here, I describe a new species, Bubalus grovesi , from the Late Pleistocene/Holocene of South Sulawesi and I give a revised diagnosis of Anoa . Bubalus grovesi sp. nov. differs from all previously described Bubalus in both the size and proportions of the skeleton and in possessing a unique combination of discrete character states. Body mass estimates suggest an average mass of 117 kg for Bubalus grovesi sp. nov. and a body size reduction of about 90% with respect to a typical water buffalo. A comprehensive overview of body mass estimates of dwarfed buffaloes and differences in their dental and postcranial features is included. Finally, new evidence on the taxonomy and island dwarfing of the anoas and available data from different disciplines are used to discuss the timing and mode of their evolution. The representatives of the subgenus Anoa would be dwarfed forms of the Asian water buffalo that arose following dispersal to Sulawesi during the Middle/Late Pleistocene. [ABSTRACT FROM AUTHOR]

Although it has been traditionally accepted that Arenaria balearica (Caryophyllaceae) could be a relict Tertiary plant species, this has never been experimentally tested. Nor have the palaeohistorical reasons underlying the highly fragmented distribution of the species in the Western Mediterranean region been investigated. We have analysed AFLP data (213) and plastid DNA sequences (226) from a total of 250 plants from 29 populations sampled throughout the entire distribution range of the species in Majorca, Corsica, Sardinia, and the Tuscan Archipelago. The AFLP data analyses indicate very low geographic structure and population differentiation. Based on plastid DNA data, six alternative phylogeographic hypotheses were tested using Approximate Bayesian Computation (ABC). These analyses revealed ancient area fragmentation as the most probable scenario, which is in accordance with the star-like topology of the parsimony network that suggests a pattern of long term survival and subsequent in situ differentiation. Overall low levels of genetic diversity and plastid DNA variation were found, reflecting evolutionary stasis of a species preserved in locally long-term stable habitats.

The interest in mammalian palaeohistology has increased dramatically in the last two decades. Starting in 1849 via descriptive approaches, it has been demonstrated that bone tissue and vascularisation types correlate with several biological variables such as ontogenetic stage, growth rate, and ecology. Mammalian bone displays a large variety of bone tissues and vascularisation patterns reaching from lamellar or parallel-fibred to fibrolamellar or woven-fibred bone, depending on taxon and individual age. Here we systematically review the knowledge and methods on cynodont and mammalian bone microstructure as well as palaeohistology and discuss potential future research fields and techniques. We present new data on the bone microstructure of two extant marsupial species and of several extinct continental and island placental mammals. Extant marsupials display mainly parallel-fibred primary bone with radial and oblique but mainly longitudinal vascular canals. Three juvenile specimens of the dwarf island hippopotamid Hippopotamus minor from the Late Pleistocene of Cyprus show reticular to plexiform fibrolamellar bone. The island murid Mikrotia magna from the Late Miocene of Gargano, Italy displays parallel-fibred primary bone with reticular vascularisation and strong remodelling in the middle part of the cortex. Leithia sp., the dormouse from the Pleistocene of Sicily, is characterised by a primary bone cortex consisting of lamellar bone and a high amount of compact coarse cancellous bone. The bone cortex of the fossil continental lagomorph Prolagus oeningensis and three fossil species of insular Prolagus displays mainly parallel-fibred primary bone and reticular, radial as well as longitudinal vascularisation. Typical for large mammals, secondary bone in the giant rhinocerotoid Paraceratherium sp. from the Late Oligocene of Turkey is represented by dense Haversian bone. The skeletochronological features of Sinomegaceros yabei, a large-sized deer from the Pleistocene of Japan closely related to Megaloceros, indicate a high growth rate. These examples and the synthesis of existing data show the potential of bone microstructure to reveal essential information on life history evolution. The bone tissue and the skeletochronological data of the sampled island species suggest the presence of various modes of bone histological modification and mammalian life history evolution on islands to depend on factors of island evolution such as island size, distance from mainland, climate, phylogeny, and time of evolution.

Recombination rate is a heritable trait that varies among individuals. Despite the major impact of recombination rate on patterns of genetic diversity and the efficacy of selection, natural variation in this phenotype remains poorly characterized. We present a comparison of genetic maps, sampling 1212 meioses, from a unique population of wild house mice ( Mus musculus domesticus) that recently colonized remote Gough Island. Crosses to a mainland reference strain (WSB/EiJ) reveal pervasive variation in recombination rate among Gough Island mice, including subchromosomal intervals spanning up to 28% of the genome. In spite of this high level of polymorphism, the genomewide recombination rate does not significantly vary. In general, we find that recombination rate varies more when measured in smaller genomic intervals. Using the current standard genetic map of the laboratory mouse to polarize intervals with divergent recombination rates, we infer that the majority of evolutionary change occurred in one of the two tested lines of Gough Island mice. Our results confirm that natural populations harbour a high level of recombination rate polymorphism and highlight the disparities in recombination rate evolution across genomic scales. [ABSTRACT FROM AUTHOR]

A human-mediated invasion of a temperate rodent Microtus rossiaemeridionalis on the High Arctic Archipelago of Svalbard in the first half of the 20th century provides an opportunity to explore extent and rate of morphological divergence over decades of isolation. We studied dental size and morphology in 124 voles captured on Svalbard (Spitsbergen) in 1997-2005 and compared the data to mainland conspecific populations across northern Eurasia. Both dental and cranial sizes in the Svalbard population fall within the limits of natural variation of the species. Dental morphology suggests that the population experiences strong effects of isolation as indicated by the significant increase in the frequency of rare dental morphs, possibly caused by inbreeding. No evidence for directional shift towards increased or decreased complexity of the morphotype dental patterns is revealed. Although the population on Svalbard is phenotypically different from the mainland populations (due to increased frequency of rare morphs), those differences are not enough to support the idea of initial rapid evolution related to colonization. The limited spatial extent and environmental homogeneity of suitable habitats on the island allowed the species to initially multiply but not to diversify so that the species exhibits phenotypic conservatism but suffers the consequences of small population size. [ABSTRACT FROM AUTHOR]

Species variation in functional traits may reflect diversification relating to convergence and/or divergence depending on environmental pressures and phylogenetic history. We tested trait-environment relationships and their basis in finer-scale evolutionary processes among nine extant Hawaiian species of Scaevola L. (Goodeniaceae), a taxon with a complex history of three independent colonizations by different phylogenetic lineages, parallel ecological specialization, and homoploid hybridization events in Hawai'i. Using a wild population for each species, we evaluated traits related to plant function (morphology, leaf and wood anatomy, nutrient and carbon isotope composition). Hawaiian Scaevola species were distributed across coastal, dry forest and wet forest environments; multivariate environmental analysis using abiotic and biotic factors further showed that species from distantly related lineages inhabited similar environments. Many traits correlated with environment (based on the multivariate environmental analysis), considering both distantly related species and more closely related species. Scaevola species within shared habitats generally showed trait convergence across distantly related lineages, particularly among wet forest species. Furthermore, trait diversification through divergence was extensive among closely related Scaevola species that radiated into novel environments, especially in plant morphology and traits affecting water relations. Homoploid hybrid-origin species were 'intermediate' compared to their ancestral parent species, and possessed trait combinations relevant for their current habitat. The diversity in functional traits reflected strong influences of both ecology and evolutionary history in native Hawaiian Scaevola species, and trait correspondence with environment was due to the combination of multiple processes within the taxon: trait pre-adaptation and filtering, evolutionary convergence, divergence, and hybridization. [ABSTRACT FROM AUTHOR]

Geological history of oceanic islands can have a profound effect on the evolutionary history of insular flora, especially in complex islands such as Tenerife in the Canary Islands. Tenerife results from the secondary connection of three paleo-islands by a central volcano, and other geological events that further shaped it. This geological history has been shown to influence the phylogenetic history of several taxa, including genus Micromeria (Lamiaceae). Screening 15 microsatellite markers in 289 individuals representing the eight species of Micromeria present in Tenerife, this study aims to assess the genetic diversity and structure of these species and its relation with the geological events on the island. In addition, we evaluate the extent of hybridization among species and discuss its influence on the speciation process. We found that the species restricted to the paleo-islands present lower levels of genetic diversity but the highest levels of genetic differentiation suggesting that their ranges might have contracted over time. The two most widespread species in the island, M. hyssopifolia and M. varia, present the highest genetic diversity levels and a genetic structure that seems correlated with the geological composition of the island. Samples from M. hyssopifolia from the oldest paleo-island, Adeje, appear as distinct while samples from M. varia segregate into two main clusters corresponding to the paleo-islands of Anaga and Teno. Evidence of hybridization and intraspecific migration between species was found. We argue that species boundaries would be retained despite hybridization in response to the habitat's specific conditions causing postzygotic isolation and preserving morphological differentiation. [ABSTRACT FROM AUTHOR]

Aim The general dynamic model ( GDM) of oceanic island biogeography integrates rates of immigration, speciation and extinction in relation to a humped trajectory of island area, species carrying capacity and topographic complexity through time, based on a simplified island ontogeny. In practice, many islands have more complex ontogenies, featuring surfaces of varying age. Here, we extend the GDM to apply at a local scale within islands, and test the predictions analytically within individual islands. Location El Hierro, La Palma and Tenerife (Canary Islands). Methods Following the GDM logic, we derive predictions for the distributions and richness of single island endemics ( SIEs) across island landscapes of different age. We test these predictions by means of generalized linear models and binominal tests using gridded species occurrence data for vascular plant SIE species and a set of climatic, topographic and terrain age variables. We also examined phylogenetic divergence times for a subset of endemic lineages. Results Geological age, in interaction with slope, and topographic variables, best explained SIE richness at the landscape scale. About 70% of SIEs had ranges strongly biased to, or largely restricted to old terrain. Available phylogenetic divergence times of SIEs of radiated plant lineages suggested an origin on the older parts of the islands. Metrics of anthropogenic disturbance and habitat availability were unrelated to the observed SIE pattern. Main conclusions Our findings support the hypothesis that SIEs have evolved and accumulated on older and topographically complex terrain, while colonization processes predominate on the youngest parts. These results imply that evolutionary processes shape species distributions at the landscape scale within islands. This opens the perspective of extending the GDM framework to understand processes at a local scale within individual islands. [ABSTRACT FROM AUTHOR]

Aim The islands of the Tropical Oceanic Pacific ( TOP) host both local radiations and widespread, colonizing species. The few phylogeographical analyses of widespread species often point to recent human-aided expansions through the Pacific, suggesting that the communities are recently assembled. Here we apply multilocus data to infer biogeographical history of the gekkonid lizard, Gehyra oceanica, which is widespread, but for which prior analyses suggested a pre-human history and in situ diversification. Location Tropical Oceanic Pacific. Methods We generated a data set including mt DNA and diagnostic SNPs for 173 individuals of G. oceanica spanning Micronesia, Melanesia, and Polynesia. For a subset of these individuals, we also sequenced nuclear loci. From these data, we performed maximum likelihood and Bayesian inference to reveal major clades. We also performed Bayesian clustering analyses and coalescence-based species delimitation tests to infer the number of species in this area. Results We found evidence for six independent evolutionary lineages (candidate species) within G. oceanica that diverged between the Pliocene and the early Pleistocene, with high diversity through northern Melanesia, and pairing of northern Melanesian endemic taxa with widespread lineages across Micronesia and Polynesia. Main conclusions The islands of northern Melanesia not only have unrecognized diversity, but also were the source of independent expansions of lineages through the more remote northern and eastern Pacific. These results highlight the very different evolutionary histories of island faunas on remote archipelagos versus those across Melanesia and point to the need for more intensive studies of fauna within Melanesia if we are to understand the evolution of diversity across the tropical Pacific. [ABSTRACT FROM AUTHOR]