Session 21: ASIH Stoye Genetics, Development, and Morphology IRoom: Ballroom 111C2022-07-29 10:00 - 11:30 |
| Moderator: Hank Bart |
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1. 10:00 Color by Numbers: Using QuantSeq to Quantify Male Nuptial Color Gene Expression in Rainbow Darters (Etheostoma caeruleum). Andrew Sherman*, Southeastern Louisiana University; Kyle Piller, Southeastern Louisiana University andrew.sherman-2@selu.edu
Organismal coloration is a common trait seen throughout the tree of life and serves a variety of important biological functions. A good example of the importance of coloration can be seen in its utility for recognition of conspecifics and sexual selection. While there is a decent body of literature that has expanded our knowledge of how organisms gain coloration as they mature, little work has been done to understand how coloration changes or is gained on a seasonal basis. Darters, a group of small, riverine fish show great potential for expanding our understanding of seasonal changes in coloration, as the males of many species of this group gain a variety of colors during the breeding season. This seasonal change is color is referred to as nuptial coloration. The goal of this study was to use QuantSeq, a cost-effective alternative to traditional RNASeq, to examine the gene expression profiles of Rainbow Darters in order to better understand nuptial coloration in darters. Our results indicate that gene expression profiles are surprisingly similar between males and females outside of the breeding season, and males have distinct gene expression profiles during the breeding season. Comparisons of males during and outside of the breeding season reveal multiple genes potentially relevant for nuptial coloration, including TRYP1 and POMC, two genes involved in melanin synthesis. |
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3. 10:30 Using Mixed Isotope Models and Morphometric Measures to test Optimal Foraging Theory in an Island Population of Tuatara (Sphenodon punctatus). Sarah Lamar*, Centre for Biodiversity and Restoration Ecology, Victoria University of Wellington; Joseph Altobelli, Zoology Department, University of Otago; Nicola Nelson, Centre for Biodiversity and Restoration Ecology, Victoria University of Wellington; Diane Ormsby, School of Biological Sciences, Victoria University of Wellington sarah.lamar@vuw.ac.nz
While we know that key morphological traits are often linked with a species’ feeding ecology, the morphological characteristics that impact feeding ecology in ectotherms, particularly reptiles, is poorly understood. We used a combination of morphometric characteristics and mixed isotope models to assess the feeding ecology of an island population of tuatara (Sphenodon punctatus). Tuatara are omnivorous reptiles endemic to New Zealand, where relict populations are now restricted to offshore islands. One such island, Takapourewa (Cook Strait, New Zealand), also hosts a diverse community of invertebrates, lizards, and seabirds. In the austral summer of 2021, we sampled 56 adult tuatara representing a gradient in body size. Using nail trims, we created stable isotope profiles (carbon-13 and nitrogen-15) for each individual and compared them against key morphometric characteristics: gape size, snout-vent length, body condition, and tail width (as a proxy for fat store). First, we established a significant positive correlation between gape size, overall body size, and fat store. Next, we found a significant relationship between gape size and carbon-13, with tuatara with large gapes showing dietary profiles that suggest a higher intake of marine (seabird) prey. Finally, we determined that the two largest contributors to tuatara diet on the island at the population level were both predatory taxa, suggesting that large tuatara may be optimally foraging by seeking large, nutrient-rich prey. However, whether body size or gape size is the primary adaptive characteristic allowing for more optimal foraging is yet unknown. |
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4. 10:45 A chromosome-level genome assembly and annotation of the desert horned lizard, Phrynosoma platyrhinos, provides insight into chromosomal rearrangements among reptiles. Nazila Koochekian, Miami University; Alfredo Ascanio, Miami University; Keaka Farleigh, Miami University; Daren Card, Harvard University; Drew Schield, University of Colorado; Todd Castoe, University of Texas at Arlington; Tereza Jezkova, Miami University koochen@miamioh.edu
Background: The increasing number of chromosome-level genome assemblies has advanced our knowledge and understanding of macroevolutionary processes. Here, we introduce the genome of the desert horned lizard, Phrynosoma platyrhinos, an iguanid lizard occupying extreme desert conditions of the American southwest. We conduct analysis of the chromosomal structure and composition of this species and compare these features across genomes of 12 other reptiles (5 species of lizards, 3 snakes, 3 turtles, and 1 bird). Findings: The desert horned lizard genome was sequenced using Illumina paired-end reads and assembled and scaffolded using Dovetail Genomics Hi-C and Chicago long-range contact data. The resulting genome assembly has a total length of 1,901.85 Mb, scaffold N50 length of 273.213 Mb, and includes 5,294 scaffolds. The chromosome-level assembly is composed of 6 macrochromosomes and 11 microchromosomes. A total of 20,764 genes were annotated in the assembly. GC content and gene density are higher for microchromosomes than macrochromosomes, while repeat element distributions show the opposite trend. Pathway analyses provide preliminary evidence that microchromosome and macrochromosome gene content are functionally distinct. Synteny analysis indicates that large microchromosome blocks are conserved among closely related species, whereas macrochromosomes show evidence of frequent fusion and fission events among reptiles, even between closely related species. Conclusions: Our results demonstrate dynamic karyotypic evolution across Reptilia, with frequent inferred splits, fusions, and rearrangements that have resulted in shuffling of chromosomal blocks between macrochromosomes and microchromosomes. Our analyses also provide new evidence for distinct gene content and chromosomal structure between microchromosomes and macrochromosomes within reptiles. |
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5. 11:00 Clear as Mud – A First Look at the Phylogeography of the Darter Goby (Ctenogobius boleosoma). Cooper Campbell*, Tulane University; Henry Bart Jr., Tulane University dcampbell@tulane.edu
Phylogenetic systematics aims to describe the evolutionary history of all life and species’ interrelationships. One area of active study in molecular phylogenetics is phylogeography, which examines how genetic variation is structured across the geographic distribution of species. Within Gobiiformes, the genus Ctenogobius is a group of fifteen understudied species presently classified within Oxudercidae, subfamily Gobionellinae. The genus has undergone numerous taxonomic revisions. Formerly regarded as synonymous with the genus Gobionellus, Ctenogobius was resurrected by Pezold in 2004. However, since then, other work has suggested that species diversity within Ctenogobius is greater than currently described. Phylogeographic studies of other species of gobies with similar distribution and ecology as Ctenogobius species (Gobiosoma bosc, Eucyclogobius newberryi, Gnatholepis sp., etc.) have revealed evidence of high levels of cryptic diversity. For example, the darter goby Ctenogobius boleosoma has a large, disjunct distribution spread across the Atlantic coastline of the Americas, matching the distribution of the Naked Goby, Gobiosoma bosc. Due to its unique ecology and distribution, Ctenogobius boleosoma and its genus are perfect for studying both phylogeography and cryptic speciation. Using a phylogeny developed using ddRAD-seq data, I will describe the interrelationships of Ctenogobius species, focusing primarily on the darter goby Ctenogobius boleosoma, which I will use to identify barriers and probable causes of speciation along the North American coastline. Our data shows the most complete phylogeny of Ctenogobius to date. |