Symposium: Biogeography & Diversification of Amphibians & Reptiles - Pacific Northwest & CA Floristic Province IRoom: Ballroom 111B2022-07-30 08:00 - 09:30 |
| Moderator: Gwen Bury |
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1. 08:00 Introduction: Biogeography and Diversification of the Pacific Northwest Herpetofauna. Bruce Bury*, Herpetological Conservation and Biology clemmys@gmail.com
We dedicate this symposium to David B. Wake, who was to be our featured speaker prior to his untimely passing. He had a major impact on the discovery of many western species and their distribution patterns. The goal of this symposium is to better understand the biogeography and species diversification of the herpetofauna in western North America. This biota has been influenced by a rugged montane terrain, volcanism, massive lava flows, Cordilleran Ice Sheet, dry Interglacial Periods, and the Missoula floods. Today, there are moderate numbers of amphibians and reptiles in the region compared to similar-sized landscapes elsewhere. Still, there are distinct taxa in the mountain ranges, especially in California. There are few endemic species of reptiles, but a fair number frequent inland areas and high deserts. Most amphibians occur in a linear “green ribbon” of forests covering 1,500 km N-S X 240 km W-E. Many amphibians are endemic, including three unique families of stream amphibians. Earlier these taxa had one species each, but recent studies mostly based on genetic analyses suggest 10+ species or Evolutionary Significant Units. The nearest relatives for several taxa are not eastern North America, but Europe or Latin America. The region is also home to Tailed Frogs, an ancient lineage with Its nearest relative in New Zealand. Future studies need to reveal remaining cryptic species and to define biogeographic patterns of the herpetofauna, especially in face of human disturbances and climate change. Presentations today will address many of these topics. |
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2. 08:15 200 Million Years of Violence: How Geologic Upheaval and Glaciation Shaped the Pacific Northwest. Nicholas Geist*, Sonoma State University nick.geist@sonoma.edu
The creation of the Pacific Northwest began with the breakup of Pangea and formation of the North American Plate in the Late Triassic Period (~200 Ma). This event initiated the subsequent creation of a unique patchwork of landscapes as bits and pieces of oceanic rocks were added onto the new Pacific coastline, steadily expanding the province westward. The process of accretion that characterizes the geologic history of the Pac NW was further modified by a series of major volcanic events that “welded” this patchwork together; volcanism that continues to shape and reshape the region. Additionally, cycles of Pleistocene glaciation scoured the lands and dramatically altered sea levels, periodically creating land bridges that connected Eurasia and North America, connections that created faunal and floral interchanges and shaped the biogeography of the Pac NW. |
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3. 08:30 Phylogeography of Endemic Stream Amphibians in the Pacific Northwest Reveal Distinct Species or Clades in Need of Conservation Attention. Karen Kiemnec-Tyburczy*, Cal Poly Humboldt; R. Bruce Bury, U.S. Geological Survey; Tanya Wahbe, University of British Columbia; Gwendolynn Bury, Pacific Northwest Research Station USFS; Nick Waters, Phoenix; Brain Lavin, Sonoma State University; Hartwell Welsh, U.S. Forest Service kmk877@humboldt.edu
Three ancient lineages of stream amphibians are endemic to the Pacific Northwest: Tailed frogs (Ascaphus), Torrent salamanders (Rhyacotriton), and Giant salamanders (Dicamptodon). All are evolutionarily distinct, and some have been proposed to be in their own families. The number of species in these groups has increased from 3 to 10 over the last 50 years. To better understand their genetic variation at finer geographic scales, we used predominantly mtDNA markers to study the phylogeography of these three groups. We found genetic differences in R. varegiatus at the California-Oregon border. We identified three clades within D. tenebrosus, plus a distinct isolated population east of the Oregon Cascade Mountains. Within A. truei, at least two geographic groups are highly distinct: the Shasta region of interior northern California and the Oregon Coast Range. We identified other clades in A. truei: the Olympic Mountains, northern region (coastal British Columbia and Washington Cascade Mountains), Oregon Cascades, and the Klamath-Siskiyou ecoregion. Current evidence suggests several new clades and, possibly, new species in all three genera. Generally, areas with degraded habitats have lower effective population sizes and reduced genetic diversity. These populations are likely to become more isolated with projected climate change. Thus, we propose that we reevaluate our designation of these groups as widespread taxa, and instead focus on investigating the status of the clades, some of which may be threatened with extinction. |
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4. 08:45 Variation in the mouth parts of the Coastal Tailed Frog (Ascaphus truei). Mark Leppin*, Oregon State University; Gwen Bury, US Forest Service, Pacific Northwest Research Station; R. Bruce Bury, Herpetological Conservation and Biology leppinm@oregonstate.edu
Previous genetic and morphological research suggest that the Coastal Tailed Frog (Ascaphus truei) may have several cryptic clades within the species. Larval oral morphology is useful in identifying many anuran larvae to the species level. The examination of the oral apparatus’ morphological traits in larvae may be useful in identification and support these cryptic clades as these traits are important in larval anuran identification. We examined over 500 larvae, both from collections and the field, for oral characteristics, development, and body length. The 3 clades within Oregon and California were our primary focus. We conducted a classic and Welch’s ANOVA with respective post-hoc tests to evaluate the differences in traits between clades. Our findings suggest that all clades tested have at least one trait that is significantly different from each other with the most differences between the Oregon Coast Range clade and the Cascade-Klamath Range clade (F-statistics > 35, p-values < 0.001). There is a significant difference in larval morphological traits between the clades; one trait, posterior toothrow counts, may even be useful for field identifications between certain clades. |
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5. 09:00 Amphibian Occupancy Modeling of an Inland Northwest Farmed Ecosystem: A Surprising Predictor of Occupancy. Erim Gomez*, University of Montana erimgomez@gmail.com
Amphibians are the most endangered groups of vertebrates globally and their future conservation relies heavily on wetland and moisture-dependent environments that will be challenged by climate change, increasing human use, and loss and degradation of landscapes. We studied amphibian populations during 2009-2021 in four ecoregions along a 215 km gradient within the Inland Northwest. We used machine-learning algorithmic techniques to evaluate the performance of 32 environmental variables in ecological models predicting the occurrence of amphibian larva of 8 species captured in 99 wetlands. We found that classification trees and boosted regression trees predict wetland occupancy with relatively high accuracy (i.e., 62-99% correct classifications). Negative factors often influencing the occurrence of amphibians in wetlands were the presence of predatory fish or tiger salamanders and proximity to agriculture and other human development. Positive factors associated with occurrence of amphibian species in wetlands varied among species but often included landscape variables such as proximity to grasslands, forested or woodland areas, and streams. Important ecological features of wetlands in predictive models often included wetland hydroperiod, size, amount of emergent vegetation, and the co-occurrence of several common amphibian species. Only 4 of 8 amphibian species were common in the intensively farmed Palouse Hills ecoregion. Prairie or in arid, shrub-steppe rangelands along the Snake River or in the central Columbia River Basin. The future of amphibian conservation in the Inland Northwest rests upon successful application of conservation techniques necessarily applied in landscapes intensively used by humans. Occupancy models provide guidance for wetland management for amphibian conservation. |
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6. 09:15 Fraying edges and holes in the fabric: How range disintegration influences genetic structuring in the California red-legged frog Rana draytonii. Jonathan Richmond*, U.S. Geological Survey; Michael Westphal, U.S. Bureau of Land Management; Anny Peralta-García, Fauno del Noroeste; Adam Backlin, U.S. Geological Survey; H.Brad Shaffer, University of California; Bradford Hollingsworth, San Diego Natural History Museum; Elizabeth Gallegos, U.S. Geological Survey; Robert Fisher, U.S. Geological Survey jrichmond@usgs.gov
The California red-legged frog Rana draytonii has experienced dramatic declines at the tips of its range and the widening of gaps within its interior range due to extirpation. Both influence how genetic variation moves across the landscape and can lead to greater population structure in certain parts of the range compared to others. In this talk, we describe the use of population genetic and genomic data to better understand how these dynamics have interfaced with latitudinal variation in climate and hydrology to ‘decompose’ the species into discrete regional units in California and Northern Baja California. Our findings support a center-edge effect, where interior populations along the central coast of California have higher genetic diversity, are less differentiated, and show greater conformity to a pattern of genetic isolation-by-distance (IBD) than do isolated populations near the edges, where diversity tends to be lower, population differentiation is higher, and IBD is diminished due to the effects of genetic drift. We describe how this information is being used to reestablish populations in extirpated parts of the range in southern California, where gaps may be more prone to develop than in other areas due to natural abiotic stressors like arid climate and limited perennial water. These gaps are now widening because humans have added urbanization, non-native species, aridification, and other forms of disturbance to the mix, such that without recovery intervention, the range of this iconic species may continue to fragment and collapse as the density of populations grows smaller relative to the environmental gradient. |