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Aim To assess the relative contributions of colonization, speciation and human activities on species richness ( S) of mammalian communities among oceanic islands. Location Palaeo-islands world-wide. Methods We compiled species lists from published works and compared species-area and species-isolation relationships for mammalian taxa of 36 islands over three stages of community development during the late Pleistocene and Holocene: at colonization, or founding ( S f); after in situ speciation, but before colonization by humans ( S s); and during the Anthropocene ( S A), that is, following human colonization and subsequent extinctions and species introductions. We used regression and correlation analyses to compare S f and S s patterns to assess the impact of speciation on the native assemblages, and compared these patterns to those expected by island biogeography theory (largely based on patterns for extant insular faunas). We then compared patterns for S s and S A to assess impacts of human activities on insular community structure. Results Although patterns for S f were consistent with those expected based on island biogeography theory ( S f increasing with area and decreasing with isolation), patterns for S s were quite anomalous, with uncharacteristically steep log-log slopes (high z-values) of the species-area relationship, and no significant influence of isolation on S s. Analyses based on contemporary assemblages ( S A) indicated that human activities have rendered native assemblages highly depauperate, while anthropogenic introductions have inflated richness far above S s on all but the largest islands. Main conclusions Long-standing models of island biogeography may prove inadequate unless their conceptual domains are expanded to include the effects of all three fundamental, biogeographical processes (immigration, extinction and speciation), the impact of human activities on each of these processes, and the likelihood that, at least for very large and isolated islands, a long-term equilibrium among these processes is seldom achieved. [ABSTRACT FROM AUTHOR]

Aim We investigated the hypothesis that body size evolution of mammals is strongly influenced by ecological interactions, resulting in evolutionary divergence in body size in species-rich (e.g. mainland) biotas, and convergence on the size of intermediate but absent species in species-poor (e.g. insular) biotas. Location Mediterranean palaeo-islands. Methods We assembled data on temporal variation in body size of palaeo-insular mammals and associated variation in ecological characteristics (colonization or extirpation of mammalian competitors and predators) for 19 species of fossil, non-volant mammals across four large (> 3640 km2) islands ranging between the late Miocene and Holocene. These are the only fossil species for which fine-detailed time series are available at present. Results Our results are consistent with predictions based on an ecological interactions hypothesis of body size evolution. Following colonization (or first appearance in the insular fossil record) small mammals (such as mice, shrews and pikas) tended to increase in body size. These trends, however, ceased or were reversed following colonization of the focal islands by mammalian predators or competitors. Main conclusions While body size evolution is likely to be influenced by a variety of characteristics of the focal islands (e.g. climate, area, isolation and habitat diversity) and species (e.g. diet, resource requirements and dispersal abilities), temporal trends for palaeo-insular mammals indicated that the observed trends for any particular species, island and climatic regime may be strongly influenced by interactions among species. Ultimately, invasion of a competitor often leads to the extinction of the native, insular species. [ABSTRACT FROM AUTHOR]

We studied the temporal and spatial patterns in deforestation and community structure of mammals in a fragmented old-growth, temperate rain forest to test the hypothesis that anthropogenic habitat conversion advances in a nonrandom manner across native landscapes, and that its effects on ecological communities are both persistent and predictable. The location is the Hood Canal district of Olympic National Forest, Washington, USA. Deforestation followed the apparently general pattern observed for deforestation of tropical rain forests and other native landscapes, advancing first along low and relatively level valleys, then to areas at higher elevations and along steeper slopes, and eventually to sites more distant from those of initial land conversion and transportation centres. Mammal surveys within this area indicated that this nonrandom advance of deforestation has created relatively steep geographical and topographic gradients in both local and landscape-level factors and, ultimately, in the structure of mammalian communities. The close and likely causal relationship between anthropogenic habitat loss and the ecological dynamics of mammalian communities and dependent species (e.g. spotted owls) indicates that our abilities to understand and eventually reduce the current extinction crisis may rely heavily on our understanding of, and abilities to modify, the manner in which we expand across and transform native landscapes. [ABSTRACT FROM AUTHOR]

Editorial. Discusses issues related to ecological pattern of species-area relationship. Possible sigmoidal nature of the species-area relationship; Complications arising from species-area curves over large spatial and temporal scales; Plotting of frequency distributions of population densities.

The extinction of the woolly rhinoceros (Coelodonta antiquitatis) at the onset of the Holocene remains an enigma, with conflicting evidence regarding its cause and spatiotemporal dynamics. This partly reflects challenges in determining demographic responses of late Quaternary megafauna to climatic and anthropogenic causal drivers with available genetic and paleontological techniques. Here, we show that elucidating mechanisms of ancient extinctions can benefit from a detailed understanding of fine-scale metapopulation dynamics, operating over many millennia. Using an abundant fossil record, ancient DNA, and high-resolution simulation models, we untangle the ecological mechanisms and causal drivers that are likely to have been integral in the decline and later extinction of the woolly rhinoceros. Our 52,000-y reconstruction of distribution-wide metapopulation dynamics supports a pathway to extinction that began long before the Holocene, when the combination of cooling temperatures and low but sustained hunting by humans trapped woolly rhinoceroses in suboptimal habitats along the southern edge of their range. Modeling indicates that this ecological trap intensified after the end of the last ice age, preventing colonization of newly formed suitable habitats, weakening stabilizing metapopulation processes, triggering the extinction of the woolly rhinoceros in the early Holocene. Our findings suggest that fragmentation and resultant metapopulation dynamics should be explicitly considered in explanations of late Quaternary megafauna extinctions, sending a clarion call to the fragility of the remaining large-bodied grazers restricted to disjunct fragments of poor-quality habitat due to anthropogenic environmental change. [ABSTRACT FROM AUTHOR]

Human settlement of islands across the Pacific Ocean was followed by waves of faunal extinctions that occurred so rapidly that their dynamics are difficult to reconstruct in space and time. These extinctions included large, wingless birds called moa that were endemic to New Zealand. Here we reconstructed the range and extinction dynamics of six genetically distinct species of moa across New Zealand at a fine spatiotemporal resolution, using hundreds of thousands of process-explicit simulations of climate-human-moa interactions, which were validated against inferences of occurrence and range contraction from an extensive fossil record. These process-based simulations revealed important interspecific differences in the ecological and demographic attributes of moa and established how these differences influenced likely trajectories of geographic and demographic declines of moa following Polynesian colonization of New Zealand. We show that despite these interspecific differences in extinction dynamics, the spatial patterns of geographic range collapse of moa species were probably similar. It is most likely that the final populations of all moa species persisted in suboptimal habitats in cold, mountainous areas that were generally last and least impacted by people. We find that these refugia for the last populations of moa continue to serve as isolated sanctuaries for New Zealand's remaining flightless birds, providing fresh insights for conserving endemic species in the face of current and future threats., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Drivers and dynamics of initial human migrations across individual islands and archipelagos are poorly understood, hampering assessments of subsequent modification of island biodiversity. We developed and tested a new statistical-simulation approach for reconstructing the pattern and pace of human migration across islands at high spatiotemporal resolutions. Using Polynesian colonisation of New Zealand as an example, we show that process-explicit models, informed by archaeological records and spatiotemporal reconstructions of past climates and environments, can provide new and important insights into the patterns and mechanisms of arrival and establishment of people on islands. We find that colonisation of New Zealand required there to have been a single founding population of approximately 500 people, arriving between 1233 and 1257 AD, settling multiple areas, and expanding rapidly over both North and South Islands. These verified spatiotemporal reconstructions of colonisation dynamics provide new opportunities to explore more extensively the potential ecological impacts of human colonisation on New Zealand's native biota and ecosystems., (© 2024. The Author(s).)