Shrinking body size under climate warming is not associated with selection for smaller individuals in a migratory bird

Journal of Animal Ecology, Journal Year: 2025, Volume and Issue: unknown

Published: April 2, 2025

How species are responding to climate change is a key topic in evolutionary ecology. Increasing temperatures expected affect phenotypic traits involved thermoregulation, thus decreasing body size and/or increasing appendages associated with heat exchange, as predicted by Bergmann's and Allen's rules. Results from long-term studies of variation morphology over time have generally provided results supporting these predictions. However, two outstanding questions frequently raised relating changes phenotypes temperatures: (1) whether such involve shift animal shape through the non-proportional different parts; (2) they result adaptive responses. Relying on capture-recapture histories almost 9000 breeding individuals declining Italian population an Afro-Palearctic migratory bird, barn swallow (Hirundo rustica), we documented decrease some (body mass, keel wing length) 31-year period (1993-2023), mass most (up 4.0% males). this was not case for bill partly tarsus length. Intra-individual lifelong morphological sexually mature birds showed only limited contribution trends phenotypically plastic traits. Viability fecundity selection analyses revealed that smaller did enjoy greater success compared larger ones. For traits, opposite actually case. The shifts and, partly, observed were coherent predictions deriving Yet, natural consistently favour individuals. We call caution interpreting recent decreases responses warming, may rather reflect changing climatic/environmental conditions occurring during early ontogenetic stages.

Language: Английский

Global Decline in the Size of Sea Turtles

Global Change Biology, Journal Year: 2025, Volume and Issue: 31(5)

Published: May 1, 2025

ABSTRACT Changes in mean adult body size may be a universal response to global warming and sometimes lead conservation concerns. We show that reductions sea turtles are now the norm have another explanation. From 18,707 measurements of nester (curve carapace length) for spanning 30 years from Redang Island (Malaysia), where nearly all nesting individuals been tagged, we was initially fairly stable then decreased by 4.0 cm 100.8 2005 96.8 2022, which likely translates change mass 120 105 kg. At same time, increased around 300 2000 nests per year. Consistent with this finding reduction an expanding population, at 27 31 sites across globe changes assessed, is decreasing, most marked decreases population increasing dramatically. Taken together, these focal findings suggest important driver influx small first‐time nesters (neophytes) populations, hence, partially consequence successful turtle measures recoveries. observations Malaysia neophytes has also getting smaller over time: 99.6 between because foraging environments. While lower reproductive output, negative will often more than offset increases numbers occurring widely.

Language: Английский

Shared temporal increases in bill size among songbirds of the San Francisco Bay Area provide evidence for different seasonal selective pressures

Ecography, Journal Year: 2025, Volume and Issue: unknown

Published: May 16, 2025

Museum specimens offer a unique and powerful tool for understanding the impact of anthropogenic change on populations over time. Morphological traits can be impacted by many different environmental variables that are difficult to separate from one another as potential driving factors. Comparative analyses among similar species jointly experiencing in same help pinpoint selective pressures temporal morphological change. We assessed bill size, tarsus length, body size between six songbirds San Francisco Bay Area past 150 years. Wing proxy exhibited idiosyncratic changes species. In contrast, we found significant increase surface area across all but Quantile regression variation additionally revealed increases century have been driven largest sizes some species, smallest bills time others. The climate best explaining also differed with responding more changing summer (e.g. maximum annual temperature) others response winter climate. These results together suggest sympatric, resident bird may experienced at seasons. Our finding provides support season critical thermal stress hypothesis suggests functional will shaped imposes greatest force population. Overall, this study has important implications future research role thermoregulation conservation efforts based adaptive capacity birds respond

Language: Английский