Where the wild things were: intrinsic and extrinsic extinction predictors in the world's most depleted mammal fauna

Abstract

Preventing extinctions requires understanding macroecological patterns of vulnerability or persistence. However, correlates of risk can be nonlinear, within-species risk varies geographically, and current-day threats cannot reveal drivers of past losses. We investigated factors that regulated survival or extinction in Caribbean mammals, which have experienced the globally highest level of human-caused postglacial mammalian extinctions, and included all extinct and extant Holocene island populations of non-volant species (219 survivals or extinctions across 118 islands). Extinction selectivity shows a statistically detectable and complex body mass effect, with survival probability decreasing for both mass extremes, indicating that intermediate-sized species have been more resilient. A strong interaction between mass and age of first human arrival provides quantitative evidence of larger mammals going extinct on the earliest islands colonized, revealing an extinction filter caused by past human activities. Survival probability increases on islands with lower mean elevation (mostly small cays acting as offshore refugia) and decreases with more frequent hurricanes, highlighting the risk of extreme weather events and rising sea levels to surviving species on low-lying cays. These findings demonstrate the interplay between intrinsic biology, regional ecology and specific local threats, providing insights for understanding drivers of biodiversity loss across island systems and fragmented habitats worldwide.

Plant–frugivore interactions across the Caribbean islands: Modularity, invader complexes and the importance of generalist species

“…These data thus reflect patterns that are typical for oceanic islands, as there is generally a lack of nonvolant, large‐bodied, frugivorous mammals which may be ecologically replaced by birds and reptiles (Kaiser‐Bunbury et al, 2010). The low number of mammal species in the dataset could also reflect past mammal extinctions particularly on the islands of the Greater Antilles (Turvey et al, 2021), potentially leaving some plants without their main seed dispersers.…”

“…The low number of mammal species in the dataset could also reflect past mammal extinctions particularly on the islands of the Greater Antilles (Turvey et al, 2021), potentially leaving some plants without their main seed dispersers.…”

Dwarfism and gigantism drive human-mediated extinctions on islands

“…We also found evidence for downsizing of mammal communities over time, as shown by the disproportionate extinction of large-bodied species ( 23 , 24 , 30 , 35 ) (146 insular and 178 mainland species > 10 kg). Anthropogenic downsizing appears to be ratcheting down to smaller body mass classes, with impacts shifting from the now-extinct megafauna to smaller body mass classes over time [the proportion and number of currently threatened species under 10 kg exceed those for extinct species; Fig.…”

“…These body size shifts in turn influence a multitude of characteristics, including those associated with dispersal, ecological interactions, and resource requirements (4,9,11). Although body mass is a well-known predictor of extinction risk in both extant and recently extinct faunas (24)(25)(26)(27)(28), and size selectivity is a signature of human-mediated extinctions (6,29,30), the relationship between the magnitude of body size evolution and susceptibility to extinction remains unclear.…”

Extinction selectivity obscures patterns of trait‐dependent endangerment in Columbiformes

“…We compiled data on species behaviour and morphometric information from published literature sources (Table 1). We collated data on factors that have been shown to influence bird extinction in previous work (Cox et al, 2022;Sayol et al, 2020Sayol et al, , 2021Turvey et al, 2021) including flight ability, habitat, migratory behaviour and groundforaging, for extant and extinct species (Table S3). Flight ability data were extracted from Sayol et al (2020) and consisted of two categories: volant (n = 378) or flightless (n = 6).…”