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Since Darwin put forward his opposing hypotheses to explain the successful establishment of species in areas outside their native ranges, the preadaptation and competition‐relatedness hypotheses, known as Darwin's naturalization conundrum, numerous studies have sought to understand the relative importance of each. Here, we take advantage of well‐characterized beetle communities across laurel forests of the Canary Islands for a first evaluation of the relative support for Darwin's two hypotheses within arthropods. We generated a mitogenome backbone tree comprising nearly half of the beetle genera recorded within the Canary Islands for the phylogenetic placement of native and introduced species sampled in laurel forests, using cytochrome c oxidase I (COI) sequences. For comparative purposes, we also assembled and phylogenetically placed a data set of COI sequences for introduced beetle species that were not sampled within laurel forests. Our results suggest a stronger effect of species preadaptation over resource competition, while also revealing an underappreciated shortfall in arthropod biodiversity data—knowledge of species as being native or introduced. We name this the Humboldtean shortfall and suggest that similar studies using arthropods should incorporate DNA barcode sequencing to mitigate this problem. [ABSTRACT FROM AUTHOR]

Aim: Understanding the historical and contemporaneous drivers of invasion success in island systems can decisively contribute to identifying sources and pathways that are more likely to give rise to new invaders. Based on a floristic‐driven approach, we aimed at determining the origins of the invasive alien flora of the Canary Islands and shedding light in the mechanisms shaping their distribution within the archipelago. Location: Canary Islands. Taxon: Vascular plants. Methods: An updated checklist of the invasive alien flora of the Canary Islands was assembled along with complementary information related to the native biogeographical regions, stage of invasiveness and dates of naturalization. Statistical models were employed to describe differences in the number of species over space and time. We also used multivariate techniques to evaluate competing hypotheses related to the mechanisms driving invasive floristic composition within the archipelago. Results: We provided a list of 149 alien plant species with a certain degree of invasiveness. The greatest number of invasive species originated from the Neotropics followed by the Cape Region, tropical Africa and the Mediterranean Basin. We observed a slow but steady increase in numbers of invasive species until the 1950s, followed by a stronger rise thereafter. In order to explain composition dissimilarity of the invasive flora among islands, a climatic matching hypothesis was fully supported, with geographic isolation and contemporary human‐mediated connectivity hypotheses receiving less and null support respectively. Main Conclusions: We showed that the Neotropical region is the main source of plant invasions to the Canary Islands, outnumbering those from other regions with a Mediterranean‐type bioclimate. The assembly of the invasive flora within the archipelago appears to be driven primarily by climate, but with geographic distance also playing a role. This study calls for archipelago‐dependent assessments of the underlying mechanisms that contribute to plant invasion success within insular systems. [ABSTRACT FROM AUTHOR]

Aim: Specialisation to the soil environment is expected to constrain the spatial scale of diversification within animal lineages. In this context, flightless arthropod lineages, adapted to soil environments, but with broad geographical ranges, represent something of an anomaly. Here we investigate the diversification process within one such 'anomalous' soil specialist, an eyeless and flightless beetle species strongly adapted to the endogean environment but distributed across several oceanic islands. Location: Canary Islands. Taxon: Geomitopsis franzi Coiffait, 1978 (Coleoptera, Staphylinidae). Methods: We performed an integrative study, including molecular phylogenetics, population genomics and morphometry. Four DNA regions (two mitochondrial and two nuclear) were amplified and sequenced for 159 specimens from 58 localities sampled across five islands for phylogenetic analyses, and a dated phylogenetic tree was obtained using a mitogenome dataset. ddRAD‐seq data were generated to evaluate mtDNA lineages in sympatry against the biological species concept. Results: We found high levels of genetic differentiation (>8% COI gene divergence) among populations from different islands and among geographically coherent lineages within single islands. Lineages within Tenerife presented significant patterns of isolation by distance, with ddRAD‐seq providing evidence that lineages represent biological species. Morphometric analyses revealed limited variation. Main conclusions: Geomitopsis franzi is comprised of at least seven lineages that merit consideration as biological species, and is best considered as a complex of cryptic species. The limited morphological variation across these lineages is consistent with adaptation to the endogean environment placing strong constraints on morphological change. The evolution of cryptic species should be favoured when such constraints are coupled with limited dispersal ability, a trait that broadly characterises the soil mesofauna. [ABSTRACT FROM AUTHOR]

Dispersal ability is known to influence geographical structuring of genetic variation within species, with a direct relationship between low vagility and population genetic structure, which can potentially give rise to allopatric speciation. However, our general understanding of the relationship between dispersal ability, population differentiation and lineage diversification is limited. To address this issue, we sampled mitochondrial DNA variation within lineages of beetles and spiders across the Canary Islands to explore the relationships between dispersal ability, differentiation within lineages and diversification. We found positive relationships between population genetic structure and diversification for both beetles and spiders. Comparisons between dispersive and non-dispersive lineages revealed significant differences for both lineage differentiation and diversification. For both taxa, non-dispersive lineages had stronger population genetic structure. Genus-level endemic species richness and proxies for diversification rate within genera were higher in non-dispersive taxa for both beetles and spiders. Comparisons of average and maximum node divergences within genera suggest that species turnover may be higher in non-dispersive genera. Our results reveal a model where dispersal limitation may shape the diversity of lineages across evolutionary timescales by positively influencing intraspecific and species diversity, moderated by higher extinction rates compared to more dispersive lineages. [ABSTRACT FROM AUTHOR]

Aim: Understanding the drivers of speciation within islands is key to explain the high levels of invertebrate diversification and endemism often observed within islands. Here, we propose an insular topoclimate model for Quaternary diversification (ITQD), and test the general prediction that, within a radially eroded conical island, glacial climate conditions facilitate the divergence of populations within species across valleys. Location: Gran Canaria, Canary Islands. Taxon: The Laparocerus tessellatus beetle species complex (Coleoptera, Curculionidae). Methods: We characterize individual‐level genomic relationships using single nucleotide polymorphisms produced by double‐digest restriction site associated DNA sequencing (ddRAD‐seq). A range of parameter values were explored in order to filter our data. We assess individual relatedness, species boundaries, demographic history and spatial patterns of connectivity. Results: The total number of ddRAD‐seq loci per sample ranges from 4,576 to 512, with 11.12% and 4.84% of missing data respectively, depending on the filtering parameter combination. We consistently infer four genetically distinct ancestral populations and two presumed cases of admixture, one of which is largely restricted to high altitudes. Bayes factor delimitation support the hypothesis of four species, which is consistent with the four inferred ancestral gene pools. Landscape resistance analyses identified genomic relatedness among individuals in two out of the four inferred species to be best explained by annual precipitation during the last glacial maximum rather than geographic distance. Main conclusions: Our data reveal a complex speciation history involving population isolation and admixture, with broad support for the ITQD model here proposed. We suggest that further studies are needed to test the generality of our model, and enrich our understanding of the evolutionary process in island invertebrates. Our results demonstrate the power of ddRAD‐seq data to provide a detailed understanding of the temporal and spatial dynamics of insular biodiversity. [ABSTRACT FROM AUTHOR]

Aim How non-dispersive taxa colonize islands is generalized as being by wind, or rafting, with the implicit assumption that such events involve one (wind) or a few (rafting) individuals. However, because of the evolutionary time-scale for colonization events, the fit of individual species to a conceptual model of wind or rafting is difficult to assess. Here, we describe an alternative testable geological model for inter-island colonization that can result in larger effective founding population sizes than traditionally accepted colonization mechanisms. We then test for the fit of genetic data to this model using weevils from the Laparocerus tessellatus species complex. Location Canary Islands. Methods Using a combination of geological data for the Canary Islands, and mt DNA data from a weevil radiation within the Canary Islands, we test three species-level predictions for mega-landslides as drivers of oceanic rafting between islands and subsequent speciation: (1) colonization should involve multiple female lineages, (2) founding lineages should have a common geographical origin, consistent with a mega-landslide event, and (3) colonization direction should be consistent with ocean currents. Results Both individual-level and population-level analyses support a mega-landslide event as the driver of colonization from the island of Tenerife to La Palma. At least four female lineages colonized La Palma from Tenerife, with the geographical range of ancestral sequences to these four lineages describing the limits of the La Orotava mega-landslide in Tenerife. Main conclusions In the context of island biogeographical theory, mega-landslides may be an important driver of colonization, and subsequent lineage diversification. They provide a framework for hypothesis testing using genetic data from species, or closely related species, with ranges that encompass landslides and potential areas of colonization. [ABSTRACT FROM AUTHOR]

Geological processes and ecological adaptation are major drivers of diversification on oceanic islands. Although diversification in these islands is often interpreted as resulting from dispersal or island hopping rather than vicariance, this may not be the case in islands with complex geological histories. The island of Tenerife, in the Canary Islands, emerged in the late Miocene as 3 precursor islands that were subsequently connected and reisolated by volcanic cycles. The spider Dysdera verneaui is endemic to the island of Tenerife, where it is widely distributed throughout most island habitats, providing an excellent model to investigate the role of physical barriers and ecological adaptation in shaping within-island diversity. Here, we present evidence that the phylogeographic patterns of this species trace back to the independent emergence of the protoislands. Molecular markers (mitochondrial genes cox1, 16S, and nadl and the nuclear genes ITS-2 and 28S) analyzed from 100 specimens (including a thorough sampling of D. verneaui populations and additional outgroups) identify 2 distinct evolutionary lineages that correspond to 2 precursor islands, each with diagnostic genital characters indicative of separate species status. Episodic introgression events between these 2 main evolutionary lineages explain the observed incongruence between mitochondrial and nuclear markers, probably as a result of the homogenization of their ITS-2 sequence types. The most widespread lineage exhibits a complex population structure, which is compatible with either secondary contact, following connection of deeply divergent lineages, or alternatively, a back colonization from 1 precursor island to another. [ABSTRACT FROM AUTHOR]

Coexistence of recently diverged and ecologically similar sister species in complete sympatry represents a particularly compelling case for sympatric speciation. This study investigates the possible sympatric origin of two coexisting bark beetle taxa that utilize the same host plant on the island of La Palma in the Canary Islands. Aphanarthrum subglabrum and Aphanarthrum glabrum ssp. nudum breed inside dead twigs of Euphorbia lamarckii plants and are closely related to the allopatric A. glabrum ssp. glabrum in Tenerife, El Hierro and La Gomera. We tested the various speciation hypotheses in a genealogical context, using mitochondrial gene fragments from Cytochrome Oxidase I and 16S, and nuclear gene fragments from Enolase, Elongation Factor 1α and Histone H3. Phylogenetic analyses of the combined nuclear DNA data strongly supported a sister relationship between two sympatric and reproductively isolated taxa in La Palma. However, network analyses of subdivided nonrecombinant segments of the Enolase locus indicated a closer relationship between the two allopatric A. glabrum subspecies, suggesting multiple colonizations of this island. A bimodal distribution of mtDNA haplotypes in La Palma further documented the independent colonization of this island, with asymmetric introgression of mtDNA between two lineages. Consequently, the sympatric origin of the La Palma species is concluded to have involved allopatric phases before the parallel colonization of this island and subsequent introgression at some loci. The clear genetic and morphological evidence for reproductive isolation between these species suggests that the sympatric completion of divergence was either due to initial genetic incompatibility, morphological character displacement in male genitalia, or a combination of these factors. [ABSTRACT FROM AUTHOR]

Chloroplast microsatellites are becoming increasingly popular markers for population genetic studies in plants, but there has been little focus on their potential for demographic inference. In this work the utility of chloroplast microsatellites for the study of population expansions was explored. First, we investigated the power of mismatch distribution analysis and the FS test with coalescent simulations of different demographic scenarios. We then applied these methods to empirical data obtained for the Canary Island pine ( Pinus canariensis). The results of the simulations showed that chloroplast microsatellites are sensitive to sudden population growth. The power of the FS test and accuracy of demographic parameter estimates, such as the time of expansion, were reduced proportionally to the level of homoplasy within the data. The analysis of Canary Island pine chloroplast microsatellite data indicated population expansions for almost all sample localities. Demographic expansions at the island level can be explained by the colonization of the archipelago by the pine, while population expansions of different ages in different localities within an island could be the result of local extinctions and recolonization dynamics. Comparable mitochondrial DNA sequence data from a parasite of P. canariensis, the weevil Brachyderes rugatus, supports this scenario, suggesting a key role for volcanism in the evolution of pine forest communities in the Canary Islands. [ABSTRACT FROM AUTHOR]

Five new species of land snail (family Enidae) are described from La Gomera (Canary Islands) of which the majority, on the basis of anatomy alone, could be incorporated within a new supraspecific taxon. In addition to the morphological study of these new species, a region of the 16S mitochondrial gene is sequenced from three of the new species and a range of species of Napaeus from within its two subgenera ( Napaeinus and Napaeus) . There is a disparity between the morphological and preliminary molecular phylogenetic data. Possible explanations for this conflict are discussed, as well as the evolutionary relationships among these different taxa, and it is suggested that this group may be an excellent model for further studies of adaptation and diversification. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 89, 169–187. [ABSTRACT FROM AUTHOR]

The flightless beetle genus Tarphius Erichson (Coleoptera: Colydiidae) is a distinctive element of the beetle fauna of the Canary Islands with 29 species distributed across the five western islands. The majority of Tarphius species are rare and intimately associated with the monteverde forest and only two species occur on more than one island. In this study we investigate the phylogeography of the Canary Island Tarphius, and their relationship to Tarphius from the more northerly archipelagos of Madeira and the Azores using maximum parsimony and Bayesian inference analysis of mitochondrial cytochrome oxidase I and II sequence data. We use geological datings for the Canary Islands, Azores, and Madeira to calibrate specific nodes of the tree for the estimation of divergence times using a penalized likelihood method. Data suggest that the Canary Island species assemblage is of some antiquity, however, much of this species diversity is relatively recent in origin. The phylogenetic relationships of species inhabiting the younger islands of El Hierro and La Palma indicate that colonization events between islands have probably been a significant factor in the evolutionary history of the Canary Island species assemblage. A comparison of molecular phylogenetic studies of arthropods on the Canary Islands suggests that, in the evolution of the arthropod species community of an island, the origin of endemic species is initially the result of colonizing lineages differentiating from their source populations. However, as an island matures a greater proportion of endemic species originate from intra-island speciation. [ABSTRACT FROM AUTHOR]

Presents information on a phylogeographic study regarding the colonization and speciation of Calathus genus in Canary and Madeira islands. Information on the island; Materials and methods used in the study; Result and discussion.

The Canary Island pine weevil Brachyderes rugatus (Wollaston) consists of four allopatric subspecies that are thought to have arisen from several historic colonization events within the archipelago. We have isolated and optimized seven microsatellite loci from Brachyderes rugatus calvus from Gran Canaria. Six of these loci are polymorphic within B. rugatus (11–22 alleles per locus; heterozygosity between 0.43 and 0.84). There is no evidence for heterozygote deficit within populations or for linkage disequilibrium between pairs of loci. These molecular markers are likely to prove useful tools for quantifying the genetic variability of bottlenecked island populations. [ABSTRACT FROM AUTHOR]

A fundamental question in evolutionary ecology and conservation biology is: why do some areas contain greater species diversity than others? Island biogeographic theory has identified the roles of immigration and extinction in relation to area size and proximity to source areas, and the role of speciation is also recognized as an important factor. However, one as yet unexplored possibility is that species diversity itself might help to promote speciation, and indeed the central tenets of island biogeographic theory support such a prediction. Here we use data for plants and arthropods of the volcanic archipelagos of the Canary and Hawaiian Islands to address whether there is a positive relationship between species diversity and rate of diversification. Our index of diversification for each island is the proportion of species that are endemic, and we test our prediction that this increases with increasing species number. We show that even after controlling for several important physical features of islands, diversification is strongly related to species number. [ABSTRACT FROM AUTHOR]

In non-fire prone ecosystems, like some subtropical humid forests, fire produces habitat destruction and intensifies land degradation by inducing changes in native species composition, soil properties and erosive processes. Bryophytes are key components of the Macaronesian laurel forests playing an important role in regulating water cycling and microclimate. Ecological and taxonomical bryophytes groups have distinct ecological and physiological requirements and may respond in a different way to the same fire events. Therefore, analysing post fire recovery of bryophyte communities represents a key step towards a better understanding of forest fire drivers and post fire management. We investigated how species richness and composition of different ecological and taxonomical bryophyte groups varied in 1158 samples within a fire chronosequence from 5 to 57 years in the best-preserved laurel forest from Canary Islands (Garajonay National Park) analysing communities in terms of differences with comparable surrounding old growth unburnt stands. Epiphyte, terricolous and saxicolous bryophytes were sampled at each plot and the influence of the time since fire was analyzed together with environmental variables (temperature, precipitation, mist precipitation and elevation) and forest structure variables. Our results indicate that there is no general pattern of post fire recolonization, as recolonization varies depending on the ecological and phylogenetic groups considered. Climate and forest structure play an important role in post-fire recolonization, such that time since fire is not the most important variable influencing richness and composition. The results increase the understanding of the processes that shape compositional patterns in groups with high dispersal capacities and high microclimate dependence, such as mosses and liverworts. • Bryophytes are evaluated here as potential bioindicators of heterogeneous fire effects in non-fire prone subtropical cloud forests. • There is no general post-fire recolonization pattern by bryophytes and the effects vary depending on the ecological and phylogenetic studied group. • Climate and forest structure play an essential role in post-fire recolonization. • Time since fire is not the most important driver influencing abundance and composition in bryophytes. • There is a notable influence of colonization from the surrounding non-burnt forests and the distance to the dispersal source. [ABSTRACT FROM AUTHOR]