Biology subjects

Robinson, S. K.

Publications and source records attributed to Robinson, S. K..

4 recordsLinked to original sources

bioRxiv2025

Tropical montane and temperate hummingbirds incubate in small installments over long periods

Life-history strategies and development are shaped by climate and predation. We examined how temperature and nest survival drive incubation behavior in 104 nests of 34 hummingbird species across 2,939m of elevation in the Peruvian and Colombian Andes. At high elevations, cold temperatures led to more frequent, brief incubation bouts and extended incubation periods; survival modulated incubation behavior with no effect on development. Hummingbirds had the highest egg surface-area to volume ratios among all birds; in 147 species, incubation periods increased with decreasing ambient temperatures. We propose a new hypothesis to explain how in cold conditions, heat transfer to the embryo is fragmented into smaller increments and therefore extended over longer periods, underscoring the role of adult behavior in mediating embryonic temperature mismatches and life-history tradeoffs.

ecology↗

bioRxiv2025

MONITORING POPULATION EXTINCTION RISK WITH COMMUNITY SCIENCE DATA

AbstractThe robust estimation of local extinction risk is central to inform management and conservation efforts. Still, estimating this key demographic parameter requires standardized monitoring data that are lacking for most species and systems. The analysis of community science data is emerging as a promising alternative. These expansive datasets leverage observations from multiple volunteers that provide higher temporal and spatial resolution. Nevertheless, the proper analysis of community science data is challenging because it requires accounting for additional complexities in the intrinsic ecological and observational processes. To address this issue, we describe and test a quantitative approach that fits continuous state-space models iteratively to eBird data with the ultimate goal of estimating local persistence probability through time. We evaluated model accuracy by comparing estimates and trends from eBird with those from the endangered Everglades snail kite long-term, standardized monitoring project. We also performed two separate sensitivity analyses (temporal and sampling thinning) to assess how robust the persistence estimates are to a reduction in the number of eBird observations available. Our results showed that the temporal trend trajectory of local population persistence estimated from eBird closely matched that from standardized monitoring. Moreover, the trend remained similar even when reducing the amount of eBird data available to 5% of the original data set - a reduction from 258 to 13 weeks or from 7,714 to 385 lists of observations across 5 years of monitoring. Synthesis and applicationsOur modeling framework provides a robust, computationally efficient, and easy-to-apply tool for monitoring local persistence probability that can support global conservation efforts. This will complement the monitoring of species population viability in places where standardized monitoring is still lacking, but community science observations are common.

ecology↗

bioRxiv2023

Interspecific Aggression Of Two Wrens Along An Environmental Gradient In Western Ecuador

Interspecific territoriality is a prevalent form of interference competition among animals. However, the connections between hybridization, climate, and interspecies territorial aggression in tropical regions remain largely unexplored. Here, we investigated territorial aggression in two hybridizing tropical bird species, C. z. brevirostris and C. f. pallescens, in western Ecuador using playback experiments. We tested three hypotheses: 1) hybridizing species exhibit comparable intra- and inter-specific territorial aggression; 2) asymmetrical aggression driven by C. z. brevirostris dominance determines gene flow patterns; and 3) precipitation influences territorial aggression. Supporting hypothesis 1, the admixed C. f. pallescens North showed no difference in intra-vs inter-specific aggression. However, the non-admixed C. f. pallescens South exhibited greater inter-specific aggression, providing partial support for hypothesis 1. Contrary to hypothesis 2, C. f. pallescens South displayed significantly higher aggression than C. z. brevirostris and C. f. pallescens North. Furthermore, precipitation models outperformed null models, supporting hypothesis 3 that precipitation influences Campylorhynchus territorial aggression. Collectively, these findings suggest hybridization can stabilize coexistence via territoriality, and precipitation strongly affects aggression, potentially through resource availability. Unexpectedly, C. z. brevirostris dominance did not appear to drive asymmetric introgression between species, warranting further investigation into the underlying mechanisms. Complex factors shape territorial aggression in tropical birds, including genetic admixture, group size, latitude, and climate. This study highlights the need for additional research elucidating the relationships between hybridization, territoriality, and environmental stressors in tropical avian communities. We discuss possible mechanisms explaining the detected effects of precipitation on aggression and the lack of C. z. brevirostris dominance in determining introgression patterns.

ecology↗

bioRxiv2023

Exploring The Role Of Isolation By Distance, Isolation By Environment, And Hybridization In Campylorhynchus Wrens Along A Precipitation Gradient In Western Ecuador

Climate variability can cause genetic and phenotypic diversity within species, which affects the evolution of biodiversity. A balance between gene flow and selection maintains changes in the frequency of genetic and phenotypic variants along an environmental gradient. In this study, we investigated a hybrid zone in western Ecuador involving two species of wrens (Aves: Troglodytidae), Campylorhynchus zonatus and C. fasciatus, and their admixed populations. We hypothesized that isolation by distance (IBD) and different ecological preferences, isolation by environment (IBE), result in limited dispersal between populations along the precipitation gradient in western Ecuador. We asked two main questions: (1) What is the relative contribution of IBD and IBE to patterns of genetic differentiation of these species along the environmental gradient in western Ecuador? And (2) Is there evidence of genetic admixture and introgression between these taxa in western Ecuador? We analyzed 4,409 SNPs from the blood of 112 individuals sequenced using ddRadSeq. The most likely clusters ranged from K=2-4, corresponding to categories defined by geographic origins, known phylogenetics, and physical or ecological constraints. Evidence for IBD was strong across all models, and evidence for IBE was less strong but still significant for annual mean precipitation and precipitation seasonality. We observed gradual changes in genetic admixture between C. f. pallescens and C. zonatus along the environmental gradient. Genetic differentiation of the two populations of C. f. pallescens could be driven by a previously undescribed potential physical barrier near the center of western Ecuador. Lowland habitats in this region may be limited due to the proximity of the Andes to the coastline, limiting dispersal and gene flow, particularly among dry-habitat specialists. We do not propose taxonomic changes, but the admixture observed in C. f. pallescens suggests that this described subspecies could be a hybrid between C. z. brevirostris and C. fasciatus, with different degrees of admixture along western Ecuador and northwestern Peru. This study contributes to the knowledge of avian population genomics in the tropics.

evolutionary biology↗