Biology subjects

Lee-Yaw, J. A.

Publications and source records attributed to Lee-Yaw, J. A..

4 recordsLinked to original sources

bioRxiv2026

Changes in microhabitat structure around amphibian breeding ponds in the northern Rocky Mountains following severe wildfire

Microhabitats promote diverse and resilient forests. Wildfire may alter critical microhabitat, yet studies directly quantifying these effects are limited. Here, we use a rare before-after-control-impact dataset to assess the impacts of severe wildfire on fine-scale gradients in microhabitat structure associated with amphibian breeding ponds in the Rocky Mountains. Using 462 photoquadrats sampled eight years before and two years after the 2017 Kenow wildfire in Waterton Lakes National Park, we quantified changes in 14 microhabitat features at three different distances (0, 3, and 10 m) away from burned and unburned ponds. Non-parametric multivariate analysis of variance suggested distance from pond edge was a significant predictor of microhabitat composition prior to the wildfire, with the proportion of soil (bare ground) decreasing and the proportion of shrubs and forbs increasing away from pond edges. A significant interaction between distance, burn status, and time was observed, suggesting that the relationship between microhabitat and distance depended on the joint effects of burn status and time. This result was driven by changes 10 m away from pond edges in the burn zone, where sites experienced an increase in the proportion of forbs, soil, gravel, and rocks, and the loss of moss cover following the fire. Microhabitat change was more pronounced at high elevation sites, although power to statistically test the effect of elevation was limited. Our study demonstrates heterogeneity in the impacts of wildfire on microhabitats along fine-scale gradients. We discuss implications of these findings for the management of amphibians using these sites.

ecology↗

bioRxiv2025

Pronounced genetic structure associated with differences in a reproductive trait and climatic barriers in Canadian populations of the western toad (Anaxyrus boreas)

Identifying genetic groups within species is critical for inventorying biodiversity, understanding species distributions, and delineating conservation units. The western toad (Anaxyrus boreas) is one of the most widespread amphibians in western Canada and one of just two amphibian species to maintain an extensive range on both sides of the Canadian Rocky Mountains. Curiously, toads on the eastern side of the mountains have a vocal sac and produce a distinct advertisement call whereas toads on the western side of the mountains lack these traits. However, the extent to which these "Calling" and "Non-Calling" populations are genetically and ecologically distinct remains unclear. We used reduced representation sequencing (ddRAD-seq) to genotype individuals from across the Canadian portion of the species range. Combining population genomic analysis with the original phenotypic data used to delineate the Calling and Non-Calling populations and with predictions from ecological niche models, we show that Calling and Non-Calling populations of western toads represent distinct genetic groups separated by both differences in a major reproductive trait and by climate barriers. We additionally find evidence for a third, undescribed group in southwestern Alberta and southeastern British Columbia. Our results suggest Calling and Non-Calling populations should be managed as distinct groups and highlight the potential for there to be cryptic and strong genetic structure among northern populations of widespread species.

evolutionary biology↗

bioRxiv2023

Latitudinal gradients in predation persist in urban environments

Urbanization can profoundly disrupt local ecology. But while urban areas now stretch across latitudes, little is known about urbanizations effects on macroecological patterns. We used standardized experiments to test whether urbanization disrupts latitudinal gradients in seed predation, a macroecological pattern that shapes community assembly and diversity. Using >56,000 seeds, we compared predation in urbanized and natural areas across 14,000 km of latitude, spanning the Americas. Predation increased 5-fold from high latitudes to the tropics, and latitudinal gradients in predation persisted in urban areas despite significant habitat modification. Urbanization reduced predation by vertebrates, but not invertebrates, and seemed to increase ant predation specifically. Our results show that macroecological patterns in predation intensity can persist in urbanized environments, even as urbanization alters the relative importance of predators. One-Sentence SummaryAcross 56,000 seeds and 112{degrees} of latitude, latitudinal gradients in seed predation are equally strong in natural vs. urban areas

ecology↗

bioRxiv2020

Expansion dynamics and marginal climates drive adaptation across geographic ranges

Every species experiences limits to its geographic distribution. Some evolutionary models predict that populations at range edges are less well-adapted to their local environments due to drift, expansion load, or swamping gene flow from the range interior. Alternatively, populations near range edges might be uniquely adapted to marginal environments. In this study, we use a database of transplant studies that quantify performance at broad geographic scales to test how local adaptation, site quality, and population quality change from spatial and climatic range centers towards edges. We find that populations from poleward edges perform relatively poorly, both on average across all sites (15% lower population quality) and when compared to other populations at home (31% relative fitness disadvantage), consistent with these populations harboring high genetic load. Populations from equatorial edges also perform poorly on average (18% lower population quality) but, in contrast, outperform foreign populations (16% relative fitness advantage), suggesting that populations from equatorial edges have strongly adapted to unique environments. Finally, we find that populations from sites that are thermally extreme relative to the species niche demonstrate strong local adaptation, regardless of their geographic position. Our findings indicate that both nonadaptive processes and adaptive evolution contribute to variation in adaptation across species ranges.

evolutionary biology↗