Anthropogenic extinctions conceal widespread evolution of flightlessness in birds

Human-driven extinctions can affect our understanding of evolution, through the nonrandom loss of certain types of species. Here, we explore how knowledge of a major evolutionary transition—the evolution of flightlessness in birds—is biased by anthropogenic extinctions. Adding data on 581 known anthropogenic extinctions to the extant global avifauna increases the number of species by 5%, but quadruples the number of flightless species. The evolution of flightlessness in birds is a widespread phenomenon, occurring in more than half of bird orders and evolving independently at least 150 times. Thus, we estimate that this evolutionary transition occurred at a rate four times higher than it would appear based solely on extant species. Our analysis of preanthropogenic avian diversity shows how anthropogenic effects can conceal the frequency of major evolutionary transitions in life forms and highlights the fact that macroevolutionary studies with only small amounts of missing data can still be highly biased

The past and future human impact on mammalian diversity

To understand the current biodiversity crisis, it is crucial to determine how humans have affected biodiversity in the past. However, the extent of human involvement in species extinctions from the Late Pleistocene onward remains contentious. Here, we apply Bayesian models to the fossil record to estimate how mammalian extinction rates have changed over the past 126,000 years, inferring specific times of rate increases. We specifically test the hypothesis of human-caused extinctions by using posterior predictive methods. We find that human population size is able to predict past extinctions with 96% accuracy. Predictors based on past climate, in contrast, perform no better than expected by chance, suggesting that climate had a negligible impact on global mammal extinctions. Based on current trends, we predict for the near future a rate escalation of unprecedented magnitude. Our results provide a comprehensive assessment of the human impact on past and predicted future extinctions of mammals

Loss of functional diversity through anthropogenic extinctions of island birds is not offset by biotic invasions

Human impacts reshape ecological communities through the extinction and introduction of species. The combined impact of these factors depends on whether non-native species fill the functional roles of extinct species, thus buffering the loss of functional diversity. This question has been difficult to address, because comprehensive information about past extinctions and their traits is generally lacking. We combine detailed information about extinct, extant, and established alien birds to quantify historical changes in functional diversity across nine oceanic archipelagos. We found that alien species often equal or exceed the number of anthropogenic extinctions yet apparently perform a narrower set of functional roles as current island assemblages have undergone a substantial and ubiquitous net loss in functional diversity and increased functional similarity among assemblages. Our results reveal that the introduction of alien species has not prevented anthropogenic extinctions from reducing and homogenizing the functional diversity of native bird assemblages on oceanic archipelagos

Mammal species composition reveals new insights into Earth’s remaining wilderness

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156493/8/fee2192-sup-0004-FigS4.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156493/7/fee2192-sup-0005-FigS5.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156493/6/fee2192-sup-0006-FigS6.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156493/5/fee2192.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156493/4/fee2192-sup-0003-FigS3.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156493/3/fee2192-sup-0002-FigS2.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156493/2/fee2192-sup-0001-FigS1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156493/1/fee2192_am.pd

Trophic rewilding presents regionally specific opportunities for mitigating climate change

Large-bodied mammalian herbivores can influence processes that exacerbate or mitigate climate change. Herbivore impacts are, in turn, influenced by predators that place top-down forcing on prey species within a given body size range. Here, we explore how the functional composition of terrestrial large herbivore and carnivore guilds vary between three mammal distribution scenarios: Present-Natural, Current-Day, and Extant-Native Trophic (ENT) Rewilding. Considering the effects of herbivore species weakly influenced by top-down forcing, we quantify the relative influence keystone large herbivore guilds have on methane emissions, woody vegetation expansion, fire dynamics, large-seed dispersal, and nitrogen and phosphorous transport potential. We find strong regional differences in the number of herbivores under weak top-down regulation between our three scenarios with important implications for how they will influence climate change relevant processes. Under the Present-Natural non-ruminant, megaherbivore, browsers were a particularly important guild across much of the world. Megaherbivore extinction and range contraction and the arrival of livestock means large, ruminant, grazers have become more dominant. ENT Rewilding can restore the Afrotropics and Indo-Malay to the Present-Natural benchmark, but causes top-down forcing of the largest herbivores to become common place elsewhere. ENT Rewilding will reduce methane emissions, but does not maximise Natural Climate Solution potential

Response: Where Might We Find Ecologically Intact Communities?

A Commentary on Where Might We Find Ecologically Intact Communities? by Plumptre, A. J., Baisero, D., Belote, R. T., Vázquez-Domínguez, E., Faurby, S., Jȩdrzejewski, W., Kiara, H., K, H., Benítez-López, A., Luna-Aranguré, C., Voigt, M., Wich, S., Wint, W., Gallego-Zamorano, J., and Boyd, C. (2021). Front. For. Glob. Change 4:626635. doi: 10.3389/ffgc.2021.62663

Conceptual and empirical advances in Neotropical biodiversity research

The outstanding biodiversity found in the American tropics (the Neotropics) has attracted the attention of naturalists for centuries. Despite major advances in the generation of biodiversity data, many questions remain to be answered. In this review, we first summarize some of the knowns and unknowns about Neotropical biodiversity, and discuss how human impact may have drastically affected some of the patterns observed today. We then link biodiversity to landscape, and outline major advances in biogeographical research. In particular, we argue that it is crucial to test the effect of landscape and climatic evolution to biotic diversification and distribution in order to achieve a comprehensive understanding of current patterns. In this context, it is also important to consider extant and extinct taxa, as well as to use probabilistic and parametric methods that explicitly include landscape evolution models. We subsequently explore different scales in Neotropical biogeography, focusing on the intersection between biogeography and community ecology, both of which often address similar questions from different angles. The concepts of community assembly, island biogeography, neutral processes, and ecological interactions are then discussed as important components of the complex processes that determine the patterns observed today. Single-taxon and cross-taxonomic studies are complementary and greatly needed, but achieving synthesis remains challenging. Finally, we argue that phylogenetic approaches hold great potential to connect across taxonomic, spatial and temporal scales, despite current difficulties to generate and cross-analyze large volumes of molecular data. We conclude by outlining major prospects and hindrances for further advancing our knowledge on the rich Neotropical biodiversity.</p