Session 26: HL Graduate Research Award (first 5)/ Contributed General Herpetology (last 4)Room: Ballroom 111B2022-07-29 13:30 - 16:00 |
| Moderator: Brian Halstead |
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1. 13:30 Causes and Consequences of Color Polymorphism: from Individuals Isolated on Islands to Species Spanning Continents. Kinsey Brock*, UC Berkeley kbrock@berkeley.edu
Color polymorphism is an extreme form of phenotypic diversity present in every major animal group and is quite common in lizards. Color morphs have inspired central theories in biology and have been foundational to our understanding of evolution. Theory suggests that color polymorphism is a driver of diversification, where morphs evolve into different species. Despite the ubiquity and allure of color polymorphism, its evolutionary origins and repercussions remain mysterious. When do morphs evolve? What generates, maintains, and erodes morph diversity? And is polymorphism a driver of diversification? I studied 46 Greek island populations of a color polymorphic lacertid lizard, Podarcis erhardii, and hundreds of lacertid species from Africa, Asia, and Europe to understand the causes and consequences of color polymorphism at multiple biological scales. I produced an island population phylogeny of P. erhardii and a species phylogeny of the Lacertidae to reconstruct the evolutionary history of color polymorphism, identify evolutionary correlates of morph diversity and morph loss, and test if color polymorphism drives diversification. I found that color polymorphism is an ancient trait that is lost at a much faster rate than it is gained – both among populations within a species, and among species within a family. Greater morph diversity within and among species is evolutionarily correlated with greater variation in habitat. Color polymorphic lineages exhibit elevated diversification rates in this family of lizards. Taken together, results from my research suggest that color polymorphism is a driver of diversification (consequence), and habitat heterogeneity is the gas in the tank (cause). |
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2. 13:45 More Complex than You'd Skink: Morphological and Molecular Investigation into the Island Biogeography of Flexiseps Skinks in the Comoros Archipelago. Kathleen C. Webster*, University of New Mexico, Museum of Southwestern Biology; Frank Glaw, Ludwig-Maximilians-Universität München, Zoologische Staatssammlung München; Mark D. Scherz, University of Copenhagen, Natural History Museum of Denmark; Oliver Hawlitschek, Leibniz Institute for the Analysis of Biodiversity Change (LIB), Zoological Museum kcwebster11@unm.edu
Colonization of island systems often leads to diversification driven by release from predators and competition and rapid adaptation to isolated environments. Despite clear morphological distinction, previous molecular studies found little genetic differentiation between two semi-fossorial skinks—Flexiseps johannae endemic to all four islands of the Comoros Archipelago and Flexiseps ardouini native to Madagascar. In this study, we used ddRAD-seq data combined with traditional and geometric morphometrics to investigate the molecular and morphological variation among island populations within this species complex. Phylogenomic reconstruction revealed a nested relationship between species, with F. johannae retrieved paraphyletic with respect to F. ardouini. The phylogenomic tree and population structure support that F. johannae is divided into two populations corresponding to the eastern and western islands. Genetic divergence was extremely shallow among island populations, suggesting this complex is of a young evolutionary age. Patterns of morphological variation do not follow the same trends as molecular variation. The two species are morphologically distinct, and significant but minute morphological variation exists among the four Comoran island populations. Molecular results support a complex colonization history of F. johannae on the Comoros Archipelago possibly involving a there-and-back-again scenario, with initial colonization out of Madagascar and secondary re-colonization back to Madagascar in the case of F. ardouini. We propose F. johannae in the Comoros Archipelago as an excellent new system to study dispersal and diversification in skinks, which can provide valuable insights into the mechanisms behind ecomorphological variation on islands and body-form evolution in squamate reptiles. |
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3. 14:00 No snakes but legless lizards yes in Ireland: the first evidence based on genetic data. Oleksandra Oskyrko*, Department of Zoology, Faculty of Science, Charles University; Nicholas Parry, Fiddaun, Tubber; Daniel Jablonski, Department of Zoology, Comenius University in Bratislava sashaoskirko@gmail.com
Slow worms, the genus Anguis, represents legless lizards (Squamata: Anguidae) distributed in the Western Palearctic region. As an island, Ireland belongs among areas of potential biogeographic and/or conservation importance, however, its herpetofauna is formed by one, native, land species, Zootoca vivipara. Traditionally, Ireland was believed to be absent of slow worms. However, according to published data, a supposedly introduced population of Anguisof unknown origin occurs in the Burren area (western Ireland). However, there have not been further molecular studies solving the genetic affiliation and possible relict origin of the genus in Ireland. In the present study, we aim to use novel sequences of slow worms from Ireland (ND2 gene mitochondrial DNA) to determine the genetic affiliation of the Irish population and compare data with known haplotypes from Europe. We collected and analyzed samples of 12 individuals (8 adults and 4 juveniles) from the Burren (Ireland) and compared them together with published data. The Irish lizards belong to A. fragilis, particularly to the widely distributed, so-called Illyrian-Central European haplogroup (ICE). This haplogroup includes populations from the north-western Balkans, Spain, western Hungary, Austria, Germany, Poland, Czech Republic, Russia (only Kaliningrad Oblast) Slovakia, United Kingdom, Sweden and southern Norway. We confirmed that the Irish slow worms are not genetically unique and were most likely introduced from the United Kingdom. Thus, our results on the Irish population and their genetic affiliation will largely contribute to the design of further conservation management and strategy for this population on the island. |
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4. 14:15 Combining Experiments and Field Surveys to Estimate Comparative Effects Of Energy-Related Saline Wastewaters and Sodium Chloride on Two Amphibian Species. Brian Tornabene*, University of Montana; Creagh Breuner, University of Montana brian.tornabene@gmail.com
Increased salinity (sodium chloride; NaCl) is a prevalent contaminant that negatively affects freshwater ecosystems and many amphibian species. Although most studies focus on NaCl road salts, high-salinity wastewaters from energy extraction (wastewaters) could be more harmful because they contain NaCl and other toxic components. Additionally, there are few investigations that include eggs and larvae sequentially in long-term exposures or pair experimental and field studies to connect patterns of sensitivity. We investigated the effects of wastewaters and NaCl on two widespread amphibian species (Northern Leopard Frogs and Boreal Chorus Frogs) in Montana and North Dakota. First, we determined abundance of larvae at 33 wetlands spanning a gradient of wastewater contamination. Then, we exposed eggs in the laboratory and tracked effects of wastewaters and NaCl on hatching, survival, and fitness-related traits for 24 days. Abundance, hatching, and survival of chorus frog larvae were more sensitive than leopard frog larvae to wastewaters and NaCl. In the laboratory, wastewaters and NaCl caused similar reductions in hatching and larval survival, growth, development, and activity while also increasing deformities. Eggs of both species were less sensitive to salinity than larvae, suggesting accumulating effects of exposure. Concentrations limiting abundance in wetlands were lower than those limiting survival in the laboratory, suggesting that laboratory studies under-estimated negative effects of contaminants and that sublethal effects may contribute to reduced field abundance. The comprehensive negative effects and persistence of salts warrants investigations with other species and sources of salinity and studies combining laboratory and field-based studies. |
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5. 14:30 Effect of Maternally-transferred Mercury on Development, Behavior, and Survival in Alligator (Alligator mississippiensis) Hatchlings. Josiah Johnson*, Eugene P. Odum School of Ecology, University of Georgia; Samantha Bock, Eugene P. Odum School of Ecology, University of Georgia; Christopher Smaga, Eugene P. Odum School of Ecology, University of Georgia; Benjamin Parrott, Eugene P. Odum School of Ecology, University of Georgia jmjohnsonxc@gmail.com
Maternal transfer of environmental contaminants is a widely recognized component of the developmental environment; however, the sub-lethal and long-term impacts of these exposures, particularly within the context of offspring survival, have seldom been studied. Here, we investigate how maternal deposition of mercury, a widespread and highly toxic contaminant, interacts with incubation temperature to influence maternal reproductive success, offspring behavior, and subsequent survival in the American alligator (Alligator mississsippiensis). Nine clutches of eggs were collected from a former industrial reservoir with a history of mercury contamination on the Savannah River Site, South Carolina, and incubated at both male- and female-promoting temperatures until hatch. Clutch-averaged mercury in egg yolk ranged from 248-554 ppb, compared to 18-52 ppb for a reference site; blood mercury ranged from 90-445 ppb (x̅ = 214 ppb) for males and 113-490 ppb (x̅ = 271 ppb) for females. Linear regressions coupled with AICc model selection revealed positive relationships between total mercury and egg mass, clutch size, and clutch viability, but a negative relationship with hatchling mass and body condition. Hatchling behavior was also associated with mercury exposure, with positive relationships between blood mercury concentration and time spent basking and in open areas. Predator avoidance was affected by incubation temperature but not mercury, with females (x̅ = 7.08 minutes) freezing for longer than males (x̅ = 4 minutes) when presented with a predator decoy. Hatchlings were released 10-14 days post-hatch, with monthly recapture surveys implemented to assess survival and growth; forthcoming data from the survival study will be discussed. |
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6. 15:00 Is honesty the best policy? Aposematic coloration and tetrodotoxin (TTX) in Pacific newts (Taricha). Haley A Moniz*, University of Nevada, Reno; Sage M Kruleski, University of Nevada, Reno; Amar D Risbud, University of Chicago; Samuel JH Louden, California State University; Roger T Hanlon, Marine Biological Laboratory; Amber N Stokes, California State University; Stephanie E Palmer, University of Chicago; Chris R Feldman, University of Nevada, Reno haleymoniz@nevada.unr.edu
Colorful displays are used by diverse animals to communicate within and between species. Some of the most well-known signals are the conspicuous colors and patterns used by prey to warn predators of noxious or toxic defense (aposematism). Aposematic coloration is widespread among amphibians and is often revealed or enhanced by defensive posturing to expose vibrant colors that are otherwise concealed. Pacific newts (Taricha) are held up as a model of aposematism because when confronted by predators they perform 'unken reflex', exposing a bright orange belly by pulling the head and tail backwards over a dark dorsum. Because newts are defended by the potent neurotoxin tetrodotoxin (TTX), this behavior is assumed to warn predators that an attack would be unprofitable or even fatal. Nevertheless, there have been no analyses of newt coloration, so it remains unknown whether ventral coloration in Taricha is qualitatively honest (signaling toxic defense) or quantitatively honest (signaling toxin level). Here we use two color capturing methods (spectrometer and hyper-spectral imaging camera) to measure chromatic (hue) and achromatic (brightness) qualities of contrasting ventral and dorsal coloration in two newt species (T. granulosa and T. sierrae). We assess qualitative honesty using viewer-dependent models of potential newt predators. Next, we evaluate quantitative honesty by examining the potential correlation between defense level (amount of TTX) and colorimetrics (hue and/or brightness). We find support for a model of qualitative honesty but not quantitative honesty. Finally, we discuss selective pressures and evolutionary constraints that may impede honest quantitative signaling in this system. |
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7. 15:15 Maternal influence of microbiota on offspring via diet in an oviparous lizard. Kaitlyn Murphy*, Auburn University; Kendall Preston, Auburn University; Mary Mendonca, Auburn University; Daniel Warner, Auburn University kmm0155@auburn.edu
Maternal transfer of microbiota to offspring is documented in many taxa, but remains largely unexplored in oviparous vertebrates. Microbiota associated with the eggshell are hypothesized to shield developing embryos from pathogenesis, and because both the digestive and reproductive tracts empty into one cavity, maternal gut microbe composition can influence the eggshell microbiome. The aim of this study is to evaluate how diet influences the maternal gut microbiome, and its consequences on the bacterial community on the eggshell of the brown anole lizard (Anolis sagrei). Fifty female A. sagrei were randomly assigned to one of two treatments: those fed crickets gut-loaded with antibiotics and those with no antibiotic exposure. Female lizards were maintained on these diets for 8 weeks while eggs were collected under environments with minimized contamination. After oviposition, a subset of female cloacae and eggshells were swabbed and maternal digestive tracts were removed. DNA was extracted from gut tissue, cloacal samples, and eggshell samples, and sequenced at the 16S rRNA gene. Eggs were incubated and embryo/hatchling phenotypes were recorded. We predict that 1) treatment individuals will have reduced gut microflora abundance and diversity, 2) this reduction will correlate to changes on the eggshell microbiome in offspring, and 3) hatchlings from treatment mothers will have different morphology and physical performance compared to those from control mothers. While data analyses are underway, findings from this study will provide new insight into the role of maternal diet on bacterial transfer from mothers to eggs and its potential functional significance. |
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8. 15:30 Assessing Factors That Increase Dusky Gopher Frog (Rana sevosa) Larval Performance In Open-Canopy Wetlands. C. Myles Lance, Western Carolina University; Joseph Pechmann*, Western Carolina University myleslance@gmail.com
The federally endangered dusky gopher frog, Rana sevosa, breeds exclusively in open canopy wetlands, usually with extensive herbaceous growth. It is known that dusky gopher frog larvae have higher performance under open canopy than under closed canopy conditions; however, the mechanisms whereby this occurs are poorly understood. I conducted a factorial experiment in mesocosms to compare the relative influence of factors differing between open and closed canopy ponds. A heat/light treatment consisted of one third of tanks being exposed to full sunlight, one third of tanks shaded with 70% shadecloth, and the final third shaded with 70% shadecloth but heated to mimic the temperature of the full sun tanks. In addition, tanks received either a closed canopy leaf litter mixture or an open canopy herbaceous mixture, and vertical vegetation-like structure made of polypropylene rope or not. Shaded tanks and heated tanks had identical survival to metamorphosis at 74.7% and produced frogs with an average mass of 2.21 g and 2.09 g respectively, while tanks in full sunlight achieved significantly higher 93.4% survival to metamorphosis and 2.64 g mass. The herbaceous vegetation mixture yielded an average tank survival of 88.3% and mass of 2.94 g, compared to leaf litter tanks with a survival of 73.5% and mass of 1.61 g. Structure had no effect on survival or mass. These results indicate that sunlight (not heat alone) and herbaceous vegetation are important in increasing dusky gopher frog survival and mass over closed canopy conditions, with implications for captive-rearing and habitat restoration. |
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9. 15:45 Responses of Reptiles to Removal of Woody Plants in the Intermountain West. Coral Gardner*, University of Arizona coralgardner1@gmail.com
Encroachment by woody plants alters multiple ecological processes that can affect the quantity and quality of wildlife habitat. Climate change is expected to increase aridity and the rate of woody plant encroachment in many parts of North America, therefore strategies to remove woody plants will become increasingly important. Our study area includes areas in the Great Basin Desert and Colorado Plateau in southern Utah, where vegetation communities are dominated by sagebrush (Artemisia sp.) and pinyon-juniper (Pinus sp. and Juniperus sp.). We evaluated the effects of three mechanical methods to remove woody plants on the density of reptiles. We used distance sampling to survey 60 plots that ranged from 34 to 1,974 ha and capture-mark-recapture to survey 21 plots during the monsoon seasons of 2020 and 2021. In total, we observed 1,447 reptiles, 419 of which we captured and marked. For distance-sampling surveys, we observed a mean of 31 reptiles (SD = 13.2, n = 218) on sites dominated by pinyon-juniper and 20 reptiles (SD = 6.3, n = 123) on sites dominated by sagebrush. The mean number of reptiles varied among treatment, and was highest on sites with mastication (x̄ = 41, SD = 18.9, n = 291) and tree felling (x̄ = 42, SD = 17.1, n = 299), and lower on sites with harrowing (x̄ = 20, SD = 19.5, n = 124). Our results will help inform land managers on the relative effectiveness of these removal strategies on reptiles. |