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Aim: The accumulation of species through time has been proposed to have a hump‐shaped relationship on volcanic islands (highest species richness during intermediate stages of an island's lifespan). Change in topographic complexity (TC) of islands over time is assumed to follow the same relationship. However, TC can be measured in different ways and may not have the same impact across taxonomic groups. Here, we quantify TC across the Galápagos Islands and test the assumption that TC follows a predictable trajectory with island age. Subsequently, we ask whether including TC improves statistical models seeking to explain variation in species richness across islands. Location: Galápagos Archipelago, Ecuador. Taxon: Native and endemic terrestrial animals and plants. Methods: For each island, we generated eight TC indices from a 30‐m resolution digital elevation model. We tested for a relationship between each index and island age, and whether it significantly contributes to observed variation in species richness, using 11 different models for 12 taxonomic groups across the Galápagos Islands. Results: Four TC indices were significantly negatively correlated with either island age or ontogenetic age and only one index followed the hump‐shaped relationship with age. No index consistently contributed to the variation in species richness for all taxonomic groups. However, for all 12 taxonomic groups, incorporating at least one TC index in modelling species richness improved one or more models. The most common TC index improving models was standard deviation of slope, although each index improved at least five models across all taxa. Different factors predicted taxon‐specific richness, and habitat diversity was significant for all taxa. Main conclusions: Topographic complexity is an important component influencing species richness, but its impact likely differs among taxonomic groups and different scales. Therefore, future studies should incorporate broad, multi‐dimensional measures of TC to understand the biological importance of TC. [ABSTRACT FROM AUTHOR]

The tribe Loteae of the family Leguminosae has major centers of diversity in the Mediterranean Region and California. It is used here to illustrate different traditions of taxonomic interpretation of infraspecific variation among researchers in different continents. Recent accounts of European and Mediterranean taxa commonly make an emphasis on recognizing subspecies. In contrast, accounts of North American Loteae recognize all infraspecific taxa as varieties. Harmonization of taxonomic concepts across continents is essential for a more accurate representation of data in global biodiversity databases. It is reasonable to use the rank of subspecies for geographically defined infraspecific units with localized zones of intergradation. Such subspecies may be at least partially compatible across continents and taxonomic groups. In the present paper, we discuss taxa traditionally included in or associated with Acmispon glaber (Vogel) Brouillet (=Syrmatium glabrum Vogel) and demonstrate a need for recognizing three species, of which one has three geographically defined subspecies. Required nomenclatural combinations are proposed. It is proposed that subspecies rather than varieties should be recognized in a number of other species of North American Loteae (and other plant groups). Inland subspecies of Acmispon glaber and A. maritimus offer an opportunity for comparative analysis in an eco-evo-devo framework. [ABSTRACT FROM AUTHOR]

Aim: Threats faced by narrowly distributed endemic plant species in the face of the Earth's sixth mass extinction and climate change exposure are especially severe for taxa on islands. We investigated the current and projected distribution and range changes of Cochemiea halei, an endemic island cactus. This taxon is of conservation concern, currently listed as vulnerable on the International Union for the Conservation of Nature Red List and as a species of special concern under Mexican federal law. The goals of this study are to (a) identify the correlations between climate variables and current suitable habitat for C. halei; (b) determine whether the species is a serpentine endemic or has a facultative relationship with ultramafic soils; and (c) predict range changes of the species based on climate change scenarios. Location: The island archipelago in Bahía Magdalena on the Pacific coast, Baja California Sur, Mexico. Methods: We used temperature and precipitation variables at 30‐arc second resolution and soil type, employing multiple species distribution modeling methods, to identify important climate and soil conditions driving current habitat suitability. The best model of current suitability is used to predict possible effects of four climate change scenarios based on best‐case to worst‐case representative concentration pathways, with projected climate data from two general circulation models, over two time periods. Main conclusions: The occurrence of the species is found to be strongly correlated with ultramafic soils. The most important climate predictor for habitat suitability is annual temperature range. The species is predicted to undergo range contractions from 21% to 53%, depending on the severity and duration of exposure to climate change. The broader implications for a wide range of narrowly adapted, threatened, and endemic plant species indicate an urgent need for threat assessment based on habitat suitability and climate change modeling. [ABSTRACT FROM AUTHOR]

Islands harbour a spectacular diversity and unique species composition. This uniqueness is mainly a result of endemic species that have evolved in situ in the absence of mammal herbivores. However, island endemism is under severe threat by introduced herbivores. We test the assumption that endemic species are particularly vulnerable to generalist introduced herbivores (European rabbit) using an unprecedented dataset covering an entire island with enormous topographic, climatic and biological diversity (Tenerife, Canary Islands). With increasing endemism, plant species are more heavily browsed by rabbits than non-endemic species with up to 67% of endemics being negatively impacted by browsing, indicating a dramatic lack of adaptation to mammal herbivory in endemics. Ecosystems with high per cent endemism are most heavily browsed, suggesting ecosystem-specific vulnerability to introduced herbivores, even within islands. Protection of global biodiversity caused by disproportionally high endemism on oceanic islands via ecosystem-specific herbivore control and eradication measures is of utmost importance. [ABSTRACT FROM AUTHOR]

Aim The general dynamic model ( GDM) proposed by Whittaker et al. () has become a widely accepted theoretical framework in island biogeography. In this study, we explore whether GDM predictions hold when overall plant diversity is deconstructed into major plant families. Location 101 islands from 14 oceanic archipelagos world-wide. Methods Occurrence data for all species of nine large, cosmopolitan flowering plant families were used to test predictions derived from the GDM. We analysed the effects of island area and age on species richness as well as number and percentage of single-island endemic species per family using mixed-effect models. Results Total species and endemic richness as well as the percentage of endemic species showed the predicted hump-shaped relationship with island age. The overall pattern was mainly driven by few species-rich plant families. Varying patterns were found for individual families, some of them opposing the general trend. In most cases, native and endemic species richness peaked much earlier in the island life cycle than suggested by the GDM. The contribution of area to the explained variation of all dependent variables was much higher than that of island age. Main conclusions The results suggest that biodiversity-age relationships reported for large taxonomic groups like plants are driven by only a few species-rich clades. The way these families influence the overall patterns of species richness and endemism is related to family-specific properties, such as evolutionary history or dispersal strategies. Deviances from the GDM predictions can hence largely be explained by family characteristics and considering taxon-specific traits may help to further improve the explanatory power of the GDM. Families not following the expectations, like Orchidaceae, may be particularly valuable candidates to unveil so far neglected drivers of island biogeographical patterns. [ABSTRACT FROM AUTHOR]

Aim We examined data for ermine ( Mustela erminea) to test two sets of diversification hypotheses concerning the number and location of late Pleistocene refugia, the timing and mode of diversification, and the evolutionary influence of insularization. Location Temperate and sub- Arctic Northern Hemisphere. Methods We used up to two mitochondrial and four nuclear loci from 237 specimens for statistical phylogeographical and demographic analyses. Coalescent species-tree estimation used a Bayesian approach for clade divergence based on external mutation rate calibrations. Approximate Bayesian methods were used to assess population size, timing of divergence and gene flow. Results Limited structure coupled with evidence of population growth across broad regions, including previously ice-covered areas, indicated expansion from multiple centres of differentiation, but high endemism along the North Pacific coast ( NPC). A bifurcating model of diversification with recent growth spanning three glacial cycles best explained the empirical data. Main conclusions A newly identified clade in North America indicated a fourth refugial area for ermine. The shallow coalescence of all extant ermine reflects a recent history of diversification overlying a deeper fossil record. Post-glacial colonization has led to potential contact zones for multiple lineages in north-western North America. A model of diversification of ermine accompanied by recent gene flow was marginally less well supported than a model of divergence of major clades in response to the most recent glacial cycles. [ABSTRACT FROM AUTHOR]