Modern attempts to produce biogeographic maps focus on the distribution of species, and the maps are typically drawn without phylogenetic considerations. Here, we generate a global map of zoogeographic regions by combining data on the distributions and phylogenetic relationships of 21,037 species of amphibians, birds, and mammals. We identify 20 distinct zoogeographic regions, which are grouped into 11 larger realms. We document the lack of support for several regions previously defined based on distributional data and show that spatial turnover in the phylogenetic composition of vertebrate assemblages is higher in the Southern than in the Northern Hemisphere. We further show that the integration of phylogenetic information provides valuable insight on historical relationships among regions, permitting the identification of evolutionarily unique regions of the world.
Despite decades of research, the roles of climate and humans in driving the dramatic extinctions of large-bodied mammals during the Late Quaternary remain contentious. We use ancient DNA, species distribution models and the human fossil record to elucidate how climate and humans shaped the demographic history of woolly rhinoceros, woolly mammoth, wild horse, reindeer, bison and musk ox. We show that climate has been a major driver of population change over the past 50,000 years. However, each species responds differently to the effects of climatic shifts, habitat redistribution and human encroachment. Although climate change alone can explain the extinction of some species, such as Eurasian musk ox and woolly rhinoceros, a combination of climatic and anthropogenic effects appears to be responsible for the extinction of others, including Eurasian steppe bison and wild horse. We find no genetic signature or any distinctive range dynamics distinguishing extinct from surviving species, underscoring the challenges associated with predicting future responses of extant mammals to climate and human-mediated habitat change.
Mountains contribute disproportionately to the terrestrial biodiversity of Earth, especially in the tropics, where they host hotspots of extraordinary and puzzling richness. With about 25% of all land area, mountain regions are home to more than 85% of the world’s species of amphibians, birds, and mammals, many entirely restricted to mountains. Biodiversity varies markedly among these regions. Together with the extreme species richness of some tropical mountains, this variation has proven challenging to explain under traditional climatic hypotheses. However, the complex climatic characteristics of rugged mountain regions differ fundamentally from those of lowland regions, likely playing a key role in generating and maintaining diversity. With ongoing global changes in climate and land use, the role of mountains as refugia for biodiversity may well come under threat.
Mountain regions are unusually biodiverse, with rich aggregations of small-ranged species that form centers of endemism. Mountains play an array of roles for Earth’s biodiversity and affect neighboring lowlands through biotic interchange, changes in regional climate, and nutrient runoff. The high biodiversity of certain mountains reflects the interplay of multiple evolutionary mechanisms: enhanced speciation rates with distinct opportunities for coexistence and persistence of lineages, shaped by long-term climatic changes interacting with topographically dynamic landscapes. High diversity in most tropical mountains is tightly linked to bedrock geology—notably, areas comprising mafic and ultramafic lithologies, rock types rich in magnesium and poor in phosphate that present special requirements for plant physiology. Mountain biodiversity bears the signature of deep-time evolutionary and ecological processes, a history well worth preserving.
Islands provide classic model biological systems. We review how growing appreciation of geoenvironmental dynamics of marine islands has led to advances in island biogeographic theory accommodating both evolutionary and ecological phenomena. Recognition of distinct island geodynamics permits general models to be developed and modified to account for patterns of diversity, diversification, lineage development, and trait evolution within and across island archipelagos. Emergent patterns of diversity include predictable variation in island species-area relationships, progression rule colonization from older to younger land masses, and syndromes including loss of dispersability and secondary woodiness in herbaceous plant lineages. Further developments in Earth system science, molecular biology, and trait data for islands hold continued promise for unlocking many of the unresolved questions in evolutionary biology and biogeography.
The Anthropocene is witnessing a loss of biodiversity, with well-documented declines in the diversity of ecosystems and species. For intraspecific genetic diversity, however, we lack even basic knowledge on its global distribution. We georeferenced 92,801 mitochondrial sequences for >4500 species of terrestrial mammals and amphibians, and found that genetic diversity is 27% higher in the tropics than in nontropical regions. Overall, habitats that are more affected by humans hold less genetic diversity than wilder regions, although results for mammals are sensitive to choice of genetic locus. Our study associates geographic coordinates with publicly available genetic sequences at a massive scale, yielding an opportunity to investigate both the drivers of this component of biodiversity and the genetic consequences of the anthropogenic modification of nature.
The positive relationship between a species' geographic distribution and its abundance is one of ecology's most well-documented patterns, yet the causes behind this relationship remain unclear. Although many hypotheses have been proposed to account for distribution-abundance relationships none have attained unequivocal support. Accordingly, the positive association in distribution-abundance relationships is generally considered to be due to a combination of these proposed mechanisms acting in concert. In this review, we suggest that much of the disparity between these hypotheses stems from differences in terminology and ecological point of view. Realizing and accounting for these differences facilitates integration, so that the relative contributions of each mechanism may be evaluated. Here, we review all the mechanisms that have been proposed to account for distribution-abundance relationships, in a framework that facilitates a comparison between them. We identify and discuss the central factors governing the individual mechanisms, and elucidate their effect on empirical patterns.
Aim Island biogeography focuses on understanding the processes that underlie a set of well‐described patterns on islands, but it lacks a unified theoretical framework for integrating these processes. The recently proposed general dynamic model (GDM) of oceanic island biogeography offers a step towards this goal. Here, we present an analysis of causality within the GDM and investigate its potential for the further development of island biogeographical theory. Further, we extend the GDM to include subduction‐based island arcs and continental fragment islands. Location A conceptual analysis and a simulation of oceanic islands. Methods We describe the causal relationships between evolutionary and ecological processes implied by the GDM, implement them as a computer simulation and use this to simulate two alternative geological scenarios. Results The dynamics of species richness and rates of evolutionary processes in simulations derived from the mechanistic assumptions of the GDM corresponded broadly to those initially suggested, with the exception of trends in extinction rates. Expanding the model to incorporate different scenarios of island ontogeny and isolation revealed a sensitivity of evolutionary dynamics to attributes of island geology. Main conclusions We argue that the GDM of oceanic island biogeography has the potential to provide a unified framework for island biogeography, integrating geological, ecological and evolutionary processes. Our simulations highlight how the geological dynamics of distinct island types are predicted to lead to markedly different evolutionary dynamics. This sets the stage for a more predictive theory incorporating the processes governing temporal dynamics of species diversity on islands.
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