Male ornamentation is usually costly and may show trades-offs with other life-history traits such as paternal care, which can subsequently affect female preference. Studies on female mate choice have mostly examined how mate-choice cues differ in their expression or ability to be detected in different environmental contexts. However, less focus has been placed on examining how external forces affect female preferences. The purpose of this study was to explore how parental investment strategy and mate choice were mediated by ambient temperature. Specifically, we examined how male ornamentation characteristics and subsequent female incubation investment were impacted by ambient temperature in four plover populations that were breeding across an environmental gradient. We discovered that larger males had more ornamented plumage in warmer conditions, and they were favored by larger females who invested an elevated time into incubation. In contrast, in cooler conditions, males' body size and the color of their ornaments were inversely associated, and females showed weak preference for males with more colorful ornaments. These results imply that female preference for male ornament can change in response to ambient temperature and demonstrate that female preference for male ornamentation may be limited in harsher conditions with higher parental care expenses.

A document by Chenqing Zheng. Click on the document to view its contents.

Changing drought regimes is a rising threat to biodiversity, but reported drought impacts on species varied greatly. Acknowledging the factors associating with these impacts will bring novel understandings to species vulnerability to the changes of extreme climatic events, and facilitate effective mitigation of climate change risks. Based on the peer-reviewed studies of a well-monitored taxonomic group – birds, we examined the effects of droughts on population persistence with a focus on two aspects: population abundance and reproductive success. Responses of relevant indicators of 172 bird species were extracted across eight terrestrial biomes, and the droughts triggering these responses were measured with a climate-comparable and multi-scalar index of drought severity. A meta-analysis was then conducted for the drought effect on relative abundance and reproductive success separately, which included the temporal scale and severity of droughts, as well as biological and life-history traits of species to explain the effect. We found that droughts had an overall negative effect on bird abundance and reproductive success. Apparent abundance generally declined for severe droughts lasting over a year, while the examined responses varied greatly due to the disparities of sensitivity and plasticity among species under droughts occurring at 3-month scale. Drought-induced declines in abundance were identified for species feeding on invertebrates, fruits or nectar, and species of a smaller range showed lower reproductive success during or after droughts. A small clutch size additionally contributed to the reductions in relative abundance or reproductive success under severe droughts. Our findings indicate that bird species with above drought-susceptible traits would confront greater challenges to population persistence in the regions where the duration of severe droughts extends. The study also highlights the necessity of exploring the unknowns that lie in the links between population persistence and drought responses of bird behaviors, distribution, morphology and physiology.

Changing drought regimes is a rising threat to biodiversity, but reported drought impacts on species varied greatly. Acknowledging the factors associating with these impacts will bring novel understandings to species vulnerability to the changes of extreme climatic events, and facilitate effective mitigation of climate change risks. Based on the peer-reviewed studies of a well-monitored taxonomic group – birds, we examined the effects of droughts on population persistence with a focus on two aspects: population abundance and reproductive success. Responses of relevant indicators of 172 bird species were extracted across eight terrestrial biomes, and the droughts triggering these responses were measured with a climate-comparable and multi-scalar index of drought severity. A meta-analysis was then conducted for the drought effect on relative abundance and reproductive success separately, which included the temporal scale and severity of droughts, as well as biological and life-history traits of species to explain the effect. We found that droughts had an overall negative effect on bird abundance and reproductive success. Apparent abundance generally declined for severe droughts lasting over a year, while the examined responses varied greatly due to the disparities of sensitivity and plasticity among species under droughts occurring at 3-month scale. Drought-induced declines in abundance were identified for species feeding on invertebrates, fruits or nectar, and species of a smaller range showed lower reproductive success during or after droughts. A small clutch size additionally contributed to the reductions in relative abundance or reproductive success under severe droughts. Our findings indicate that bird species with above drought-susceptible traits would confront greater challenges to population persistence in the regions where the duration of severe droughts extends. The study also highlights the necessity of exploring the unknowns that lie in the links between population persistence and drought responses of bird behaviors, distribution, morphology and physiology.

The long-term persistence of a population which has suffered a bottleneck partly depends on how historical demographic dynamics impacted its genetic diversity and the accumulation of deleterious mutations. Here we provide genomic evidence for the detrimental genetic effect of a recent population bottleneck in the endangered black-faced spoonbill (Platalea minor) even after its rapid population recovery. Our population genomic data suggest that the bird’s effective population size, Ne, had been relatively stable (7,500-9,000) since the end of the last glacial maximum; however, a recent brief yet severe bottleneck (Ne= 20) around the 1940s wiped out more than 99% of its historical Ne in roughly three generations. By comparing it with its sister species, the royal spoonbill (P. regia) whose conservation status is of lesser concern, we found that despite a more than 15-fold population recovery since 1988, genetic drift has led to higher levels of inbreeding (7.4 times more runs of homozygosity longer than 100 Kb) in the black-faced spoonbill than in the royal spoonbill genome. Although the two spoonbills have similar levels of genome-wide nucleotide diversity and heterozygosity, because of relaxed purifying selection, individual black-faced spoonbills carry 3% more nonsynonymous substitutions than royal spoonbills each of which is 7% more deleterious. Our results imply that the persistence of a threatened species cannot be inferred from a recovery in its population. They also highlight the necessity of continually using genomic indices to monitor its genetic health and employing all possible measures to assure its long-term persistence in the ever-changing environment.

A document by Yang Liu. Click on the document to view its contents.