Session 11: ASIH Stoye Ecology and Ethology IRoom: Room 206C2022-07-28 15:30 - 16:45 |
| Moderator: Frank McCormick |
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1. 15:30 Rattlesnake Hunting Behavior: A Case Study Across a Hybrid Zone. Dylan Maag*, San Diego State University; Noelle Shaw, San Diego State University; Ashana Soni, San Diego State University; Zachary Nikolakis, University of Texas at Arlington; Kathleen Ivey, University of Texas at Arlington; Todd Castoe, University of Texas at Arlington; Rulon Clark, San Diego State University dmaag3229@sdsu.edu
The last several decades of work have demonstrated that hybridization between diverged species is relatively common occurrence. Studying hybrid zones can provide unique insight into the factors that contribute to both pre- and postzygotic isolation and yield critical insights into the processes of introgression and speciation. There is a rich literature characterizing morphology, rates of gene flow, and relative reproductive success at the population level across hybrid zones involving species with strong prezygotic isolating mechanisms. Here we focus on a system that lacks apparent strong prezygotic mechanisms, which provides the opportunity to examine how postzygotic mechanisms related to the behavior and ecology of individuals may impact hybrids. In this study we focus on a narrow hybrid zone between two rattlesnake species, Crotalus viridis and C. scutulatus, in Southwestern New Mexico, and analyze the relationships between ecologically relevant behaviors and the ancestry of individuals. We used a combination of radiotelemetry and field videography to analyze individual snake hunting behaviors across habitat gradients across this hybrid zone. Individuals from all lineages (parentals and hybrids) exhibited similar rates of encounters and successful attacks toward prey (mainly nocturnal mammals). However, in contrast to hybrids and C. viridis, adult C. scutulatus hunted almost exclusively during the night, and never encountered or struck at lizard prey. These findings indicate that C. scutulatus may be more of a small mammal specialist than the other lineages. We discuss the potential implications of these findings in the context of hybrid zone dynamics and postzygotic isolation. |
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2. 15:45 Feeling Rattled: Linking Attitudes and Habitat Features to Patterns of Snake Occurrence in Urban Landscapes. Annika Enloe*, Arizona State University; Heather Bateman, Arizona State University amenloe@asu.edu
Understanding how wildlife is adapting to urban environments is critical as urbanization contributes to habitat change and fragmentation globally. Patterns of human-wildlife interactions can be informative when trying to ascertain information about urban wildlife and possible conflicts with humans. In Phoenix, Arizona, these conflicts commonly involve reptiles, especially venomous and nonvenomous snakes. Researchers have partnered with a local business, Rattlesnake Solutions, LLC, which removes and relocates snakes from residential yards and businesses in the greater Phoenix area. This partnership has provided records of snake removals to pair with social and ecological datasets. During 2021, we measured snake habitat along 100m front yard transects in residential areas with snake removals and from randomly paired residential areas. Analyses have shown a positive relationship between snake removals and habitat variables relating to available cover, vegetation, and tidiness of the yard. Along with habitat features, social data was collected on perceptions of snakes. Clients of Rattlesnake Solutions, LLC, were asked to answer a short survey regarding attitudes towards snakes that mirrors questions asked in the 2021 Phoenix Area Social Survey (PASS). From the social surveys, we found that both clients of the snake removal service and PASS respondents felt snakes were an important part of the desert ecosystem. Although PASS respondents were split on if it's okay to kill snakes, a majority of clients of the removal service responded it was not okay to kill snakes, perhaps suggesting that clients are using the snake removal service as a wildlife stewardship action. |
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3. 16:00 What makes a morph? Tests of intraspecific variation in phenotypes and genotypes between anoles with divergent dewlap colors. John David Curlis*, University of Michigan; Daniel Nicholson, Smithsonian Tropical Research Institute; Albert Chung, Princeton University; Claire Williams, University of Nevada, Reno; Noah D. Gripshover, Florida International University; Molly A. Hirst, University of Michigan; Hayley L. Crowell, University of Michigan; Elissa Connolly-Randazzo, Portland State University; Christian Cox, Florida International University; Michael Logan, University of Nevada, Reno; W. Owen McMillan, Smithsonian Tropical Research Institute; Alison Davis Rabosky, University of Michigan curlisjd@umich.edu
Color polymorphism, in which multiple color patterns (“morphs”) exist concurrently within a population, is a widespread phenomenon that is often prominent in taxa that use color for signaling. In many systems, polymorphic sexual signals are associated with coadapted suites of traits driven by frequency-dependent selection favoring alternative mating strategies. In turn, this can lead to morphs that differ markedly in morphology, behavior, physiology, and/or life history, but the associations between polymorphic color signals and other traits are poorly understood in many species. We tested whether the slender anole (Anolis apletophallus), a species that exhibits color polymorphism in its dewlap (a throat fan used in sexual signaling), may also show inter-morph differences in traits beyond dewlap color. We sampled over 500 individuals from a population in Panama where individuals can have a solid orange dewlap (the “solid” morph) or a white dewlap with an orange center (the “bicolor” morph). We measured various aspects of their morphology, thermal physiology, and perch behavior and analyzed the population’s genetic structure. We found very few traits that differed between solid and bicolor morphs, as well as little genetic differentiation between them. This could suggest that slender anoles may represent an unusual system in which polymorphic sexual signals do not lead to divergence in other traits. However, our findings may instead suggest that alternative mating strategies in this species are difficult to detect given the limited parameters that we sampled, or that perhaps male polymorphism is maintained by unmeasured variation in female mate-choice strategies. |
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4. 16:15 The Importance of Dispersal in Mojave Desert Tortoise Genetic Connectivity. Steven Hromada*, University of Nevada, Reno; Todd Esque, United States Geological Survey; Amy Vandergast, United States Geological Survey; Derek Friend, University of Nevada, Reno; Kirsten Dutcher, University of Nevada, Reno; Kenneth Nussear, University of Nevada, Reno stevehromada@gmail.com
Describing the long-term space use of animals is key to understanding how population connectivity functions across a landscape. Dispersal is a key component of connectivity, though in species with limited movement capacity shifts in local space use may also determine how genetic information flows across the landscape. Understanding the relative importance of these processes is important in preserving historic genetic and demographic connectivity in imperiled species such as the Mojave desert tortoise (Gopherus agassizii). Drivers of dispersal in the desert tortoise are poorly known, though life stage and climatic conditions are suspected to play a role, as they do in home-range size. We used long-term telemetry datasets from across the range of the species to understand patterns in dispersal and home-range stability. Based on over 3000 collective tortoise-years of over 900 subadult and adult tortoises, we found dispersal movements in roughly 3% of tortoise-years. We found that most dispersals were < 5 km, though there was one individual that dispersed over 20 km. Home ranges of non-dispersing individuals were relatively consistent across years, with some exceptions. A mixed-effects logistic regression model suggested that higher levels of spring and summer precipitation and lower levels of winter precipitation increased the odds of a dispersal event and that smaller tortoises are more likely to disperse than larger adults. We used this information to inform an individual based model to demonstrate the how future climatic scenarios may alter genetic connectivity in this declining species. |
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5. 16:30 Niche Divergence Plane: New conceptual framework to classifying and quantifying ecological niche divergence between taxa. Alfredo Ascanio*, Miami University; Jason Bracken, Miami University; Hank Stevens, Miami University; Tereza Jezkova, Miami University ascaniaa@miamioh.edu
Comparisons between a pair of ecological niches are often performed by contrasting hypervolumes generated using ecologically relevant variables. Currently, most comparisons test the null hypothesis of niche conservatism or equivalency, with niche divergence representing the departure from the former. However, niches can shift, expand, shrink, or tilt, and individual environmental axes might diverge in different ways and magnitudes. Our objective is to introduce a new framework that allows quantification and classification of niche divergence between two taxa along a niche axis. This framework, the Niche Divergence Plane, relies on two indices: niche exclusivity and niche dissimilarity, representing the range of values along the axis that is exclusive to each taxon and the area under response curves not shared between the taxa, respectively. Based on the position of the indices on a plane, we can distinguish niche conservatism from four general types of niche divergence: hard, soft, weighted, and nested. We demonstrate the utility of the niche divergence plane, by exploring intra- and inter-specific ecological niche divergence in two species of sympatric salamanders, Ambystoma opacum and A. maculatum. |