Session 7: SSAR Seibert Systematics/EvolutionRoom: Ballroom 111A2022-07-28 15:30 - 17:00 |
| Moderator: Gareth Hopkins |
|
1. 15:30 Exploring Phylogeographic Patterns in Mesoamerica through the Yucatan Banded Gecko. Brett Butler*, Universidad Nacional Autónoma de México; Lydia Smith, University of California, Berkeley; Oscar Flores Villela, Universidad Nacional Autónoma de México redgcko7@gmail.com
In this study, we evaluate population structuring and phylogeographic history within the Yucatán banded gecko Coleonyx elegans Gray 1845 to assess the role of both physical and environmental barriers in shaping the spatio-genetic distribution of a Mesoamerican tropical forest taxon. We generated RADseq and multi-locus Sanger datasets that recover two distinct evolutionary lineages that diverged during the late Pliocene and show recent population expansions. Furthermore, these genetic lineages largely align with subspecies boundaries defined by morphology. Several mountain ranges identified as phylogeographic barriers in other taxa act as physical barriers to gene flow between the two clades. Despite the absence of a physical barrier between lineages across the lowland Isthmus of Tehuantepec, no introgression was observed. Here, a steep environmental cline associated with seasonality of precipitation corresponds exactly with the distributional limits of the lineages, which are separated by only 30 km. The combination of molecular and environmental evidence, and in conjunction with previous morphological evidence, allow us to reassess the current taxonomy in an integrative framework. |
|
2. 15:45 Pheromone Gene Diversification and the Evolution of Courtship Glands in Plethodontid Salamanders. Madison Herrboldt*, The University of Tulsa; Michael Steffen, The University of Tulsa; Carissa McGouran, The University of Tulsa; Ronald Bonett, The University of Tulsa mah1626@utulsa.edu
Proteinaceous pheromones that diversify through gene duplication can result in shifts in courtship cocktails that may serve as a mechanism for reproductive isolation. The molecular evolution of pheromones has been extensively studied in salamanders but how these genes and associated novel courtship glands have codiversified has not been evaluated. In this study we used transcriptional analyses to examine the relationship between pheromone diversification and gland type in three divergent lineages of plethodontid salamanders. Our results revealed that plethodontid salamanders express up to eight divergent Sodefrin Precursor-like Factor genes (spf, representing both alpha and beta subfamilies) along with Plethodontid Modulating Factor (pmf) and Plethodontid Receptivity Factor (prf). Expression of pheromone genes is tissue specific with pmf, prf, and some spf genes restricted to the mental gland. In contrast, the caudal gland shows strong expression of the other spf genes. We found evidence for punctuated changes in pheromone cocktail composition related to the loss of metamorphosis, and subsequent extreme reduction of the mental gland, in a paedomorphic lineage. Our study provides insight into how pheromone diversification can be partitioned into unique glands, which may lead to cocktail specificity in behavioral modules during courtship. |
|
3. 16:00 The effects of climate and geography on patterns of genomic variation among Hispaniolan trunk anoles (Anolis distichus species group). Tanner Myers*, Auburn University; Pietro de Mello, University of Kansas; Paul Hime, University of Kansas; Rich Glor, University of Kansas tannercmyers@gmail.com
External forces such as selection imposed by differing environments and biogeographic barriers influence patterns of genomic variation and drive diversification. Species complexes that span scales of divergence and occupy distinct habitats make for ideal study systems for investigating how geography and ecology contribute to diversification. The Anolis distichus species group consists of six species and 21 subspecies that span multiple distinct habitats across Hispaniola and the Bahamas. However, morphological and molecular data suggest the current taxonomy inadequately describes the diversity of the group without resolving the number of lineages that warrant recognition as species. Here, we use more comprehensive geographic and genomic sampling than prior studies of the A. distichus species group to quantify the effects of geographic and ecological factors on patterns of genomic variation. We resolve the number of lineages present in the A. distichus species group while accounting for confounding factors like isolation-by-distance. In addition, we identify the environmental variables that are the largest contributors to genomic differentiation, and test whether patterns of genomic differentiation are better explained by isolation-by-distance or isolation-by-environment. |
|
4. 16:15 Genomic Data Reveal Patterns of Hybridization in Appalachian Salamanders. Cynthia Carter*, Warnell School of Forestry and Natural Resources, University of Georgia; Todd Pierson, Department of Ecology, Evolution, and Organismal Biology, Kennesaw State University; James Martin, Warnell School of Forestry and Natural Resources, University of Georgia; John Maerz, Warnell School of Forestry and Natural Resources, University of Georgia ccarter@uga.edu
Among ecologically distinct lineages, hybridization has the potential to yield novel combinations of traits upon which natural selection can act, thereby altering the adaptive capacity of populations. We investigate how particular traits and behaviors are distributed across a hybrid zone formed by two lungless salamanders, Plethodon shermani and P. teyahalee, in the southern Appalachian Mountains and determine how those patterns might be influenced by climate, weather, and ancestry. We collected tissues from salamanders across this hybrid zone, created RADseq style genomic libraries, and used genome-wide SNP data to estimate a genomic index of hybridization. Using this index, we examined patterns of differentiation and introgression and evaluated the relationship between hybrid ancestry and phenotypic traits that are hypothesized to vary with climate. We also used models of genomic clines to identify outlier loci that may be under selection. Models examining the influence of climate on the distribution of hybrids revealed strong relationships between phenotype, genetic ancestry, and climate—particularly mean annual precipitation. |
|
5. 16:30 Lungless in the desert: Conservation genetics of the Inyo Mountains Salamander,Batrachoseps campi. Nick Van Gilder*, University of Connecticut; Elizabeth Jockusch, University of Connecticut; Christopher Norment, State University of New York, Brockport nicholas.van_gilder@uconn.edu
The Inyo Mountains Slender Salamander (Batrachoseps campi) is one of only two desert-restricted salamander species on the planet and may be the only such salamander species still extant. This species of conservation concern is limited to 21 localities in remote canyons across the Inyo Mountains of southeastern California, where individuals are found in discrete patches of riparian habitat surrounded by inhospitable desert terrain. These canyons broadly share a historic human footprint of water diversion and impacts from mining operations. Previous work on this salamander using allozymic data has demonstrated considerable genetic differentiation along the relatively small range of this species, with studies indicating there are populations entirely isolated from wider gene flow. In our work, we revisit the genetic structure of this species using modern genetic techniques and an expanded data set of samples, including samples from previously uncharacterized populations. Our sampling strategy will allow for novel insight into the genetic structure and relationships of populations from across the mountain range and will also permit the first glimpse of effective population sizes and the demographic makeup of two paired, adjacent canyon populations of B. campi. Simultaneously, we will be able to explore the intraspecific phylogenetic makeup of this species to characterize evolutionarily significant units, if applicable. |
|
6. 16:45 Major and Minor Scales: Thorough Investigation of Integumentary Characters Across Squamate Reptiles. Daniel Doucet*, Sam Houston State University; Juan Daza, Sam Houston State University danieldoucet1998@gmail.com
Squamate phylogenies heavily rely on molecular and osteological data. Recent analyses have combined these complimentary datasets to determine the relationships between the major clades in Squamata. While there has been tremendous progress on squamate classification since the publication of Camp’s Classification of Lizards nearly 100 years ago, potentially relevant characters from the scales of lizards and snakes have yet to be fully explored. Available studies dealing with integumentary morphology will typically focus on a small group, limiting inferences that can be made when considering Squamata as a whole. Here, we expand an existing dataset of integumentary characters and test its utility in phylogenetic analyses. We scored 180 characters in 122 specimens representing 60 of the 69 squamate families. High resolution digital images of scales were obtained using both a KEYENCE VHX Digital Microscope as well as a KEYENCE Wide-Area 3D Measurement System. Comparative phylogenetic analysis of the discrete character state dataset through the R package phytools suggests that novel characters (such as the distribution of scales in respect to the body axis) possess a phylogenetic signal. In a case study, scoring of the fossil lizard Retinosaurus hkamtiensis and subsequent comparative analysis with our dataset agrees with recent inference of the lizard as a proto-xantusiid. These investigations further highlight the value of analyses of integumentary characters, particularly for their potential to resolve the placement of fossil lizards trapped in amber, which retain soft tissue but few or no skeletal elements. |