Dwarfism and gigantism drive human-mediated extinctions on islands

Rozzi, Roberto; Lomolino, Mark V.; Geer, Alexandra van der; Silvestro, Daniele; Lyons, S. Kathleen; Bover, Pere Rosselló; Alcover, Josep Antoni; Benítez‐López, Ana; Tsai, Ching-Hui; Fujita, Masaki; Kubo, Mugino O.; Ochoa, Janine; Scarborough, Matthew Edward; Turvey, Samuel T.; Zizka, Alexander; Chase, Jonathan M.

doi:10.1126/science.add8606

Cited by 27 publications

(16 citation statements)

References 1,075 publications

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“…Moreover, a significant decrease of FRic can be expected in 50% of the islands if only two species become extinct. This finding, added to the increasing extinction rates (Rozzi et al, 2023;Smith et al, 2019), points to a dramatic future for island communities, and reinforces the idea that most threatened mammal species tend to be functionally more distinct than non-threatened species (Chichorro et al, 2022;Rozzi et al, 2023).…”

Section: F I G U R Esupporting

confidence: 70%

“…Human expansion during the Holocene has accelerated global extinction rates (Rozzi et al., 2023; Smith et al., 2019), which have been staggeringly high since industrialization (Ceballos et al., 2015). Such events have been particularly frequent on oceanic islands (Kier et al., 2009; Russell & Kueffer, 2019; Whittaker et al., 2017), where human activities such as wildlife overexploitation and introduction of alien species (Fernández‐Palacios et al., 2021; Leclerc et al., 2018) have caused significant changes in their biota (Nogué et al., 2021).…”

Section: Introductionmentioning

confidence: 99%

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Island biodiversity in peril: Anticipating a loss of mammals' functional diversity with future species extinctions

Llorente‐Culebras,

Carmona,

Carvalho

et al. 2024

Global Change Biology

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Islands are biodiversity hotspots that host unique assemblages. However, a substantial proportion of island species are threatened and their long‐term survival is uncertain. Identifying and preserving vulnerable species has become a priority, but it is also essential to combine this information with other facets of biodiversity like functional diversity, to understand how future extinctions might affect ecosystem stability and functioning. Focusing on mammals, we (i) assessed how much functional space would be lost if threatened species go extinct, (ii) determined the minimum number of extinctions that would cause a significant functional loss, (iii) identified the characteristics (e.g., biotic, climatic, geographic, or orographic) of the islands most vulnerable to future changes in the functional space, and (iv) quantified how much of that potential functional loss would be offset by introduced species. Using trait information for 1474 mammal species occurring in 318 islands worldwide, we built trait probability density functions to quantify changes in functional richness and functional redundancy in each island if the mammals categorized by IUCN as threatened disappeared. We found that the extinction of threatened mammals would reduce the functional space in 63% of the assessed islands, although these extinctions in general would cause a reduction of less than 15% of their overall functional space. Also, on most islands, the extinction of just a few species would be sufficient to cause a significant loss of functional diversity. The potential functional loss would be higher on small, isolated, and/or species‐rich islands, and, in general, the functional space lost would not be offset by introduced species. Our results show that the preservation of native species and their ecological roles remains crucial for maintaining the current functioning of island ecosystems. Therefore, conservation measures considering functional diversity are imperative to safeguard the unique functional roles of threatened mammal species on islands.

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Section: F I G U R Esupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Island biodiversity in peril: Anticipating a loss of mammals' functional diversity with future species extinctions

Llorente‐Culebras,

Carmona,

Carvalho

et al. 2024

Global Change Biology

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“…Recent studies have highlighted the “island syndrome”, which includes the frequent dwarfism of large-bodied mammals on islands (Rozzi et al ., 2023). Since the TAF is a rather short cattle population, it was tempting to speculate that the size resulted from a rapid dwarfism (Rozzi and Lomolino, 2017) and that the feralization process and food restriction in the island may indeed have favored selection for small animals.…”

Section: Discussionmentioning

confidence: 99%

Genomic reconstruction of the successful establishment of a feralized bovine population on the subantarctic island of Amsterdam

Gautier,

Micol,

Camus

et al. 2023

Preprint

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The feral cattle of the subantarctic island of Amsterdam provide an outstanding case study of a large mammalian population that was established by a handful of founders and thrived within a few generations in a seemingly inhospitable environment. Here, we investigated the genetic history and composition of this population using genotyping and sequencing data. Our inference showed an intense but brief founding bottleneck around the late 19thcentury and revealed contributions from European taurine and Indian Ocean zebu in the founder ancestry. Comparative analysis of whole genome sequences further revealed a moderate reduction in genetic diversity despite high levels of inbreeding. The brief and intense bottleneck was associated with high levels of drift, a flattening of the site frequency spectrum and a slight relaxation of purifying selection on mildly deleterious variants. However, we did not observe any significant purge of highly deleterious variants.Interestingly, the population’s success in the harsh environment can be attributed to pre-adaptation from their European taurine ancestry, suggesting no strong bioclimatic challenge, and also contradicting evidence for insular dwarfism. Genome scan for footprints of selection uncovered a majority of candidate genes related to nervous system function, likely reflecting rapid feralization driven by behavioral changes and complex social restructuring. This unprecedented case study provides valuable insights into rapid population establishment, feralization, and genetic adaptation in challenging environments. It highlights the importance of preserving the unique genetic legacies of feral populations and raises ethical questions in the eyes of conservation efforts.

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“…The arrival of an efficient, novel predator (humans) was therefore potentially catastrophic to these predator-näive populations. Despite strong evidence that large accumulations of Phanourios and Palaeoloxodon bones are anthropogenic in origin 31,33,38 , and global evidence that the likelihood of extinction is highest in the most extreme island dwarfs and giants 39 , many contend that humans played no part in their extinction 29,[40][41][42] .…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of hunting native megafauna to extinction by Palaeolithic humans on Cyprus

Bradshaw,

Saltre,

Crabtree

et al. 2024

Preprint

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The hypothesised main drivers of megafauna extinctions in the late Quaternary have wavered between over-exploitation by humans and environmental change, with recent investigations demonstrating more nuanced synergies between these drivers depending on taxon, spatial scale, and region. However, most studies still rely on comparing archaeologically based chronologies of timing of initial human arrival into naïve ecosystems and palaeontologically inferred dates of megafauna extinctions. Conclusions arising from comparing chronologies also depend on the reliability of dated evidence, dating uncertainties, and correcting for the low probability of preservation (Signor-Lipps effect). While some models have been developed to test the susceptibility of megafauna to theoretical offtake rates, none has explicitly linked human energetic needs, prey choice, and hunting efficiency to examine the plausibility of human-driven extinctions. Using the island of Cyprus in the terminal Pleistocene as an ideal test case because of its late human settlement (~ 14.2 ka–13.2 ka), small area (~ 11,000 km2), and low megafauna diversity (2 species), we developed stochastic models of megafauna population dynamics, with offtake dictated by human energetic requirements, prey choice, and hunting-efficiency functions to test whether the human population at the end of the Pleistocene could have caused the extinction of dwarf hippopotamus (Phanourios minor) and dwarf elephants (Palaeoloxodon cypriotes). Our models reveal not only that the estimated human population sizes (N = 3,000–7,000) in Late Pleistocene Cyprus could have easily driven both species to extinction within < 1,000 years, the model predictions match the observed, Signor-Lipps-corrected chronological sequence of megafauna extinctions inferred from the palaeontological record (Phanourios at ~ 12 ka–11.1 ka, followed by Palaeoloxodon at ~ 10.3 ka–9.1 ka).

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Dwarfism and gigantism drive human-mediated extinctions on islands

Cited by 27 publications

References 1,075 publications

Island biodiversity in peril: Anticipating a loss of mammals' functional diversity with future species extinctions

Island biodiversity in peril: Anticipating a loss of mammals' functional diversity with future species extinctions

Genomic reconstruction of the successful establishment of a feralized bovine population on the subantarctic island of Amsterdam

Mechanisms of hunting native megafauna to extinction by Palaeolithic humans on Cyprus

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