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- A global analysis of avian island diversity–area relationships in the AnthropocenePublication . Matthews, Thomas J.; Wayman, Joseph P.; Whittaker, Robert J.; Cardoso, Pedro; Hume, Julian P.; Sayol, Ferran; Proios, Konstantinos; Martin, Thomas E.; Baiser, Benjamin; Borges, Paulo A. V.; Kubota, Yasuhiro; dos Anjos, Luiz; Tobias, Joseph; Soares, Filipa C.; Si, Xingfeng; Ding, Ping; Mendenhall, Chase D.; Sin, Yong Chee Keita; Rheindt, Frank E.; Triantis, Kostas; Guilhaumon, François; Watson, David M.; Brotons, Lluís; Battisti, Corrado; Chu, Osanna; Rigal, FrançoisResearch on island species–area relationships (ISAR) has expanded to incorporate functional (IFDAR) and phylogenetic (IPDAR) diversity. However, relative to the ISAR, we know little about IFDARs and IPDARs, and lack synthetic global analyses of variation in form of these three categories of island diversity–area relationship (IDAR). Here, we undertake the first comparative evaluation of IDARs at the global scale using 51 avian archipelagic data sets representing true and habitat islands. Using null models, we explore how richness-corrected functional and phylogenetic diversity scale with island area. We also provide the largest global assessment of the impacts of species introductions and extinctions on the IDAR. Results show that increasing richness with area is the primary driver of the (non-richness corrected) IPDAR and IFDAR for many data sets. However, for several archipelagos, richness-corrected functional and phylogenetic diversity changes linearly with island area, suggesting that the dominant community assembly processes shift along the island area gradient. We also find that archipelagos with the steepest ISARs exhibit the biggest differences in slope between IDARs, indicating increased functional and phylogenetic redundancy on larger islands in these archipelagos. In several cases introduced species seem to have ‘re-calibrated’ the IDARs such that they resemble the historic period prior to recent extinctions.
- Defaunation erodes the diversity of rodent personality traits in fragmented forestsPublication . Zeng, Di; Matthews, Thomas; Wang, Rui; Zhao, Yuhao; Yan, Chuan; ding, ping; Si, Xingfeng; Bijleveld, AllertABSTRACT: Habitat fragmentation is a primary driver of biodiversity loss globally. One impact of habitat fragmentation is the resultant decline and loss of large and medium mammal populations (also known as defaunation). While the effects of habitat fragmentation and associated defaunation on species diversity are well documented, their impacts on intraspecific diversity are less studied. One understudied source of intraspecific diversity is the animal personality traits within populations. As individuals with contrasting personality traits may disproportionately contribute to ecosystem functions, losing diversity of personality traits could thus impair ecosystem functions, even if some individuals of the species still persist. However, it is still unclear how the diversity of animal personality traits changes in fragmented habitats with severe defaunation. Here, we conducted mammal surveys and comprehensive behavioural assessments of Niviventer confucianus (Chinese white-bellied rat)—the most abundant rodent—on 11 forested islands in Thousand Island Lake, China, a fragmented reservoir island system formed by dam construction. We used Bayesian structural equation modelling and a functional diversity framework considering intraspecific variation to disentangle the direct and indirect effects of habitat fragmentation and defaunation on the functional diversity of N. confucianus personality traits. We found that defaunation directly decreased the functional divergence of N. confucianus personality traits. Decreasing island area indirectly reduced the functional divergence of N. confucianus personality traits through intensifying defaunation. We also found that island area directly increased rodent abundance but simultaneously exerted an indirect negative effect via defaunation. However, we did not find an effect of rodent abundance on the functional divergence, nor any effects of habitat fragmentation and defaunation on the functional richness or functional evenness of N. confucianus personality traits. These results indicate that defaunation may play a key role in mediating the negative effects of habitat fragmentation on animal behavioural diversity. The defaunation-resultant declines of intraspecific behavioural diversity highlight the importance of measuring intraspecific diversity to better understand the ecological consequences of human-driven environmental changes on biodiversity.
- Island Biogeography and Life-History Traits Stabilize Island Bird CommunitiesPublication . Zhao, Yuhao; Zeng, Di; Matthews, Thomas; Craven, Dylan; Tingley, Morgan; Wang, Shaopeng; Li, Shao-peng; ding, ping; Si, XingfengABSTRACT: Islands are model systems for testing and developing ecological theories. Despite extensive research on island biodiversity, the importance of the biogeographic context for biodiversity–stability relationships is poorly understood. We addressed this knowledge gap by integrating the Equilibrium Theory of Island Biogeography (ETIB) with a functional perspective to explore island biodiversity–stability relationships. We conducted annual breeding bird surveys across 36 land-bridge islands in eastern China over 13 years. Using this long-term dataset, we quantified avian temporal community stability (and its components of population stability and population asynchrony) and tested how island biogeographic factors (i.e., island area, isolation, colonization rates, and extinction rates) and biodiversity facets (i.e., species richness, average population size, and life-history traits) interact to influence stability. We found larger islands supported higher species richness due to colonization–extinction dynamics and habitat heterogeneity, which in turn promote both population stability and asynchrony. In addition, larger islands harbored larger and individually more stable populations over time. In contrast, island isolation had a weak net effect on stability, as its positive and negative influences through different pathways balanced each other out. Furthermore, species with ‘fast’ life-history traits, characterized by shorter generation times, contributed more to community stability. These findings clarify multiple pathways through which biogeographic factors shape avian community dynamics on islands. Our study thus illustrates how island biotas maintain community stability and provides insights for preserving biodiversity and ecosystem functioning in fragmented or island-like landscapes facing rapid biodiversity loss in an era of global change.