Evolutionary response to global change: Climate and land use interact to shape color polymorphism in a woodland salamander

Evolutionary change has been demonstrated to occur rapidly in human‐modified systems, yet understanding how multiple components of global change interact to affect adaptive evolution remains a critical knowledge gap. Climate change is predicted to impose directional selection on traits to reduce thermal stress, but the strength of directional selection may be mediated by changes in the thermal environment driven by land use. We examined how regional climatic conditions and land use interact to affect genetically based color polymorphism in the eastern red‐backed salamander (Plethodon cinereus). P. cinereus is a woodland salamander with two primary discrete color morphs (striped, unstriped) that have been associated with macroclimatic conditions. Striped individuals are most common in colder regions, but morph frequencies can be variable within climate zones. We used path analysis to analyze morph frequencies among 238,591 individual salamanders across 1,170 sites in North America. Frequency of striped individuals was positively related to forest cover in populations occurring in warmer regions (\u3e7°C annually), a relationship that was weak to nonexistent in populations located in colder regions (≤7°C annually). Our results suggest that directional selection imposed by climate warming at a regional scale may be amplified by forest loss and suppressed by forest persistence, with a mediating effect of land use that varies geographically. Our work highlights how the complex interaction of selection pressures imposed by different components of global change may lead to divergent evolutionary trajectories among populations

Wetland Occupancy and Landscape Connectivity for Blanding’s and Western Painted Turtles in the Green River Valley

We surveyed all wetlands in a 9277-ha area in Lee County, IL with the intention to use occupancy and least-cost modeling to assess how landscape structure affects the distribution and population connectivity of Emydoidea blandingii (state-threatened Blanding’s Turtle) and the locally common Chrysemys picta (Western Painted Turtle). Both species are members of the Family Emydidae. Originally dominated by open marshes and sand prairie, the Green River valley in Lee County is now characterized by agricultural fields, roads, and fragmented patches of natural habitat. Surveys by the Lee County Natural Area Guardians and Illinois Natural History Survey (INHS) personnel resulted in E. blandingii captures in this area as recent as 2006. However, the current extent and status of this population was unknown. This research was conducted to (1) identify important habitat features affecting the occupancy and connectivity of the threatened Blanding’s turtle and common Painted Turtle in and around managed sand prairie habitat, and (2) assess how occupancy and connectivity patterns vary for a species of conservation concern and a closely related, abundant species in the same landscape.unpublishednot peer reviewedOpe

Correlates of Bird Collisions With Buildings Across Three North American Countries

Collisions with buildings cause up to 1 billion bird fatalities annually in North America. Bird-building collisions have recently received increased conservation, research, and policy attention. However, efforts to reduce collisions would benefit from studies conducted at large spatial scales across multiple study sites, with standardized methods, and with consideration of species- and life history-related variation and correlates of collisions. We addressed these research needs with a coordinated data collection effort at 40 sites across North America. We estimated collision vulnerability for 40 bird species by accounting for their North American population abundance, distribution overlap with study sites, and sampling effort. Of 10 species we identified as most vulnerable to collisions, some have been identified in past studies (e.g., Black-throated Blue Warbler [Setophaga caerulescens]) while others emerged for the first time (e.g., White-breasted Nuthatch [Sitta carolinensis]), possibly because we used a more standardized sampling approach than past studies. Analyses of species-specific collision correlates revealed that building size and glass area were positively associated with numbers of collisions for 5 of 8 species with enough observations to analyze independently. Vegetation around buildings influenced collisions for only 1 of those 8 species (Swainson\u27s Thrush [Catharus fuscescens]). We also found that life history predicted collisions; numbers of collisions were greatest for migratory, insectivorous, and woodland-inhabiting species. This coordinated, continent-wide study provides new insight into the species most vulnerable to building collisions, making them potentially in greatest need of conservation attention to reduce collisions. This study also lends insight into species- and life history-related variation and correlates of building collisions, information that can help refine collision management efforts

Citizen science reveals widespread negative effects of roads on amphibian distributions

Landscape structure is important for shaping the abundance and distribution of amphibians, but prior studies of landscape effects have been species or ecosystem-specific. Using a large-scale, citizen science-generated database, we examined the effects of habitat composition, road disturbance, and habitat split (i.e. the isolation of wetland from forest by intervening land use) on the distribution and richness of frogs and toads in the eastern and central United States. Undergraduates from nine biology and environmental science courses collated occupancy data and characterized landscape structure at 1617 sampling locations from the North American Amphibian Monitoring Program. Our analysis revealed that anuran species richness and individual species distributions were consistently constrained by both road density and traffic volume. In contrast, developed land around wetlands had small, or even positive effects on anuran species richness and distributions after controlling for road effects. Effects of upland habitat composition varied among species, and habitat split had only weak effects on species richness or individual species distributions. Mechanisms underlying road effects on amphibians involve direct mortality, behavioral barriers to movement, and reduction in the quality of roadside habitats. Our results suggest that the negative effects of roads on amphibians occur across broad geographic regions, affecting even common species, and they underscore the importance of developing effective strategies to mitigate the impacts of roads on amphibian populations

Regional and scale-specific effects of land use on amphibian diversity [poster]

Background/Question/Methods Habitat loss and degradation influence amphibian distributions and are important drivers of population declines. Our previous research demonstrated that road disturbance, development and wetland area consistently influence amphibian richness across regions of the U.S. Here, we examined the relative importance of these factors in different regions and at multiple spatial scales. Understanding the scales at which habitat disturbance may be affecting amphibian distributions is important for conservation planning. Specifically, we asked: 1) Over what spatial scales do distinct landscape features affect amphibian richness? and 2) Do road types (non-rural and rural) have similar effects on amphibian richness? This is the second year of a collaborative, nationwide project involving 11 U.S. colleges integrated within undergraduate biology curricula. We summarized North American Amphibian Monitoring Program data in 13 Eastern and Central U.S states and used geographic information systems to extract landscape data for 471 survey locations. We developed models to quantify the influence of landscape variables on amphibian species richness and site occupancy across five concentric buffers ranging from 300m to 10,000m. Results/Conclusions Across spatial scales, development, road density and agriculture were the best predictors of amphibian richness and site occupancy by individual species. Across regions, we found that scale did not exert a large influence on how landscape features influenced amphibian richness as effects were largely comparable across buffers. However, development and percent impervious surface had stronger influence on richness at smaller spatial scales. Richness was lower at survey locations with higher densities of non-rural and rural roads, and non-rural road density had a larger negative effect at smaller scales. Within regions, landscape features driving patterns of species richness varied. The scales at which these factors were associated with richness were highly variable within regions, suggesting the scale effects may be region specific. Our project demonstrates that networks of undergraduate students can collaborate to compile and analyze large ecological data sets, while engaging students in authentic and inquiry-based learning in landscape-scale ecology

Connectivity, metapopulation dynamics, and genetic structure of tiger salamanders in a heterogeneous landscape

Metapopulation biology has been integral for understanding the impact of spatial habitat structure on ecological and evolutionary processes. In fragmented landscapes, theory predicts that species occupancy and turnover dynamics depend on habitat area and isolation, and isolation has historically been an important predictor of gene flow. However, metapopulation theory is neutral with respect to the effects of habitat heterogeneity on population processes. Landscape ecology approaches have begun to account for effects of habitat quality and matrix structure on occupancy and gene flow, but few empirical studies have integrated the area-isolation and habitat paradigms to understand metapopulation dynamics and genetic structure in the same system. Here, I employ both approaches to understand the spatial population dynamics and genetic structure of tiger salamanders (Ambystoma tigrinum tigrinum) in an agricultural landscape in Illinois. First, I assessed the degree to which matrix heterogeneity influences A. tigrinum movement behavior. Using a field experiment, I showed that a physiological constraint, desiccation risk, varied significantly among matrix habitats (corn, soybean, forest, prairie). Water loss was greater in corn and prairie than in forest and soybean, indicating that dispersal costs can vary among agricultural crops. To assess whether movement decisions were influenced by desiccation risk, I tracked the movements of individuals released on habitat boundaries for two treatment combinations: soybean-corn, soybean-prairie. I observed that movements were oriented towards soybean in both cases, suggesting that variation in desiccation risk among matrix habitats influenced salamander movement decisions. Next, I examined the effects of area, isolation, and habitat heterogeneity on metapopulation dynamics of A. tigrinum. Emphasis was placed on understanding the role of connectivity in moderating interactions between A. tigrinum and predatory fish. Occupancy and turnover of A. tigrinum were documented in 90 wetlands for three years. Since desiccation risk influenced A. tigrinum movements, I tested whether a connectivity metric that accounted for desiccation was a better predictor of occupancy and turnover than metrics based on Euclidean distance or expert opinion. Occupancy and colonization probabilities were related positively to connectivity and negatively to fish presence. Extinction probability was related positively to fish presence, but extinction risk was low in connected networks, suggesting a rescue effect. A desiccation-informed connectivity metric was a better predictor of colonization probability than alternative metrics, whereas a Euclidean model was the best predicator of occupancy and extinction probabilities. The results indicated that the effect of desiccation risk on individual movement can scale up to influence metapopulation processes, and that the effects of predatory fish on metapopulation dynamics depended on spatial connectivity. Finally, I evaluated whether ecological factors underlying occupancy and turnover were also important predictors of metapopulation genetic structure. Newly colonized populations were more genetically differentiated than established populations, indicating that founder effects influenced genetic structure. However, the degree of genetic differentiation varied spatially. Genetic differentiation was related negatively to both wetland area and spatial connectivity. Differentiation was not strongly related to habitat quality, suggesting that metapopulation factors were more effective at reflecting the historical strength of genetic drift and gene flow than current habitat suitability

Data from: Decoupling of genetic and phenotypic divergence in a headwater landscape

In stream organisms, the landscape affecting intraspecific genetic and phenotypic divergence is comprised of two fundamental components: the stream network and terrestrial matrix. These components are known to differentially influence genetic structure in stream species, but, to our knowledge, no study has compared their effects on genetic and phenotypic divergence. We examined how the stream network and terrestrial matrix affect genetic and phenotypic divergence in two stream salamanders, Gyrinophilus porphyriticus and Eurycea bislineata, in the Hubbard Brook Watershed, New Hampshire, USA. Based on previous findings and differences in adult terrestriality, we predicted that genetic divergence and phenotypic divergence in body morphology would be correlated in both species, but structured primarily by distance along the stream network in G. porphyriticus, and by overland distance in E. bislineata. Surprisingly, spatial patterns of genetic and phenotypic divergence were not strongly correlated. Genetic divergence, based on AFLPs, increased with absolute geographic distance between sites. Phenotypic divergence was unrelated to absolute geographic distance, but related to relative stream vs. overland distances. In G. porphyriticus, phenotypic divergence was low when sites were close by stream distance alone and high when sites were close by overland distance alone. The opposite was true for E. bislineata. These results show that small differences in life history can produce large differences in patterns of intraspecific divergence, and the limitations of landscape genetic data for inferring phenotypic divergence. Our results also underscore the importance of explicitly comparing how terrestrial and aquatic conditions affect spatial patterns of divergence in species with biphasic life cycles

Data from: Rapid genetic restoration of a keystone species exhibiting delayed demographic response

Genetic founder effects are often expected when animals colonize restored habitat in fragmented landscapes, but empirical data on genetic responses to restoration are limited. We examined the genetic response of banner-tailed kangaroo rats (Dipodomys spectabilis) to landscape-scale grassland restoration in the Chihuahuan Desert of New Mexico, USA. D. spectabilis is a grassland specialist and keystone species. At sites treated with herbicide to remove shrubs, colonization by D. spectabilis is slow and populations persist at low density for ≥10 yrs (≥6 generations). Persistence at low density and low gene flow may cause strong founder effects. We compared genetic structure of D. spectabilis populations between treated sites and remnant grasslands, and we examined how the genetic response to restoration depended on treatment age, area, and connectivity to source populations. Allelic richness and heterozygosity were similar between treated sites and remnant grasslands. Allelic richness at treated sites was greatest early in the restoration trajectory, and genetic divergence did not differ between recently colonized and established populations. These results indicated that founder effects during colonization of treated sites were weak or absent. Moreover, our results suggested founder effects were not mitigated by treatment area or connectivity. Dispersal is negatively density-dependent in D. spectabilis, and we hypothesize that high gene flow may occur early in the restoration trajectory when density is low. Our study shows genetic diversity can be recovered more rapidly than demographic components of populations after habitat restoration, and that founder effects are not inevitable for animals colonizing restored habitat in fragmented landscapes

Effects of Urbanization on the Population Structure of Freshwater Turtles Across the United States

Landscape‐scale alterations that accompany urbanization may negatively affect the population structure of wildlife species such as freshwater turtles. Changes to nesting sites and higher mortality rates due to vehicular collisions and increased predator populations may particularly affect immature turtles and mature female turtles. We hypothesized that the proportions of adult female and immature turtles in a population will negatively correlate with landscape urbanization. As a collaborative effort of the Ecological Research as Education Network (EREN), we sampled freshwater turtle populations in 11 states across the central and eastern United States. Contrary to expectations, we found a significant positive relationship between proportions of mature female painted turtles (Chrysemys picta) and urbanization. We did not detect a relationship between urbanization and proportions of immature turtles. Urbanization may alter the thermal environment of nesting sites such that more females are produced as urbanization increases. Our approach of creating a collaborative network of scientists and students at undergraduate institutions proved valuable in terms of testing our hypothesis over a large spatial scale while also allowing students to gain hands‐on experience in conservation science

Eurycea_bislineata_AFLP_Data

AFLP data for Eurycea bislineata individuals at downstream and upstream sites in 6 streams in the Hubbard Brook Watershed, New Hampshire, USA