Larissa Bailey (Colorado State), USGS, FWS, and SCC volunteers building vernal pools at Patuxent NWR, to adaptively manage for climate change. Photo by: A. Green.
Only a few years ago, amphibians were rarely considered in the development and implementation of management plans. But now, its not uncommon to see amphibian populations as the primary targets of management activities.
ARMI scientists conduct research on the impacts of various traditional management actions on amphibians, and have worked with partners to develop and test novel management options specifically to benefit amphibians.
Important decisions are made every day on management and policy that affect multiple wildlife species. ARMI works with its partners in Federal and State agencies to develop processes for structuring their natural resource decisions to achieve their conservation objectives related to amphibians.
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Evolutionary Hotspots in the Mojave Desert
Authors: Vandergast AG, Inman RD, Barr KR, Nussear KE, Esque TC, Hathaway SA, Wood DA, Medica PA, Breinholt JW, Stephen CL, Gottscho AD, Marks SB, Jennings WB, Fisher RN | Date: 2013-04-15 | Outlet: Diversity 5:293-319 | Format: .PDF
Genetic diversity within species provides the raw material for adaptation and evolution. Just as regions of high species diversity are conservation targets, identifying regions containing high genetic diversity and divergence within and among populations may be important to protect future evolutionary potential. When multiple co-distributed species show spatial overlap in high genetic diversity and divergence, these regions can be considered evolutionary hotspots. We mapped spatial population genetic structure for 17 animal species across the Mojave Desert, USA. We analyzed these in concurrence and located 10 regions of high genetic diversity, divergence or both among species. These were mainly concentrated along the western and southern boundaries where ecotones between mountain, grassland and desert habitat are prevalent, and along the Colorado River. We evaluated the extent to which these hotspots overlapped protected lands and utility-scale renewable energy development projects of the Bureau of Land Management. While 3040% of the total hotspot area was categorized as protected, between 37% overlapped with proposed renewable energy project footprints, and up to 17% overlapped with project footprints combined with transmission corridors. Overlap of evolutionary hotspots with renewable energy development mainly occurred in 6 of the 10 identified hotspots. Resulting GIS-based maps can be incorporated into ongoing landscape planning efforts and highlight specific regions where further investigation of impacts to population persistence and genetic connectivity may be warranted.
Comparative phylogeography reveals deep lineages and regional evolutionary hotspots in the Mojave and Sonoran Deserts
Authors: Wood DA, Vandergast AG, Barr KR, Inman RD, Esque TC, Nussear KE, Fisher RN | Date: 2012 | Outlet: Diversity and Distributions 19:722-737 | Format: .PDF
Aim We explored lineage diversification within desert-dwelling fauna. Our goals were (1) to determine whether phylogenetic lineages and population expansions were consistent with younger Pleistocene climate fluctuation hypotheses or much older events predicted by pre-Pleistocene vicariance hypotheses, (2) to assess concordance in spatial patterns of genetic divergence and diversity among species and (3) to identify regional evolutionary hotspots of divergence and diversity and assess their conservation status.
Location Mojave, Colorado, and Sonoran Deserts, USA.
Methods We analysed previously published gene sequence data for twelve species. We used Bayesian gene tree methods to estimate lineages and divergence times. Within each lineage, we tested for population expansion and age of expansion using coalescent approaches. We mapped interpopulation genetic divergence and intra-population genetic diversity in a GIS to identify hotspots of highest genetic divergence and diversity and to assess whether protected lands overlapped with evolutionary hotspots.
Results In seven of the 12 species, lineage divergence substantially predated the Pleistocene. Historical population expansion was found in eight species, but expansion events postdated the Last Glacial Maximum (LGM) in only four. For all species assessed, six hotspots of high genetic divergence and diversity were concentrated in the Colorado Desert, along the Colorado River and in the Mojave/Sonoran ecotone. At least some proportion of the land within each recovered hotspot was categorized as protected, yet four of the six also overlapped with major areas of human development.
Main conclusions Most of the species studied here diversified into distinct Mojave and Sonoran lineages prior to the LGM supporting older diversification hypotheses. Several evolutionary hotspots were recovered but are not strategically paired with areas of protected land. Long-term preservation of species-level biodiversity would entail selecting areas for protection in Mojave and Sonoran Deserts to retain divergent genetic diversity and ensure connectedness across environmental gradients.
Effects of natural flooding and trapping on the facilitation of invasive crayfish-native amphibian coexistence in a semi-arid perennial stream.
Authors: Kats LB, Bucciarelli G, Vandergon TL, Honeycutt RL, Mattiasen E, Sanders A, Riley SPD, Kerby JL, Fisher RN | Date: 2013-09 | Outlet: Journal of Arid Environments 98:109-112 | Format: .PDF
Aquatic amphibians are known to be vulnerable to a myriad of invasive predators. Invasive crayfish are thought to have eliminated native populations of amphibians in some streams in the semi-arid Santa Monica Mountains of southern California. Despite their toxic skin secretions that defend them from native predators, newts are vulnerable to crayfish attacks, and crayfish have been observed attacking adult newts, eating newt egg masses and larvae. For 15 years we have observed invasive crayfish and native California newts coexisting in one stream in the Santa Monica Mountains. During that period we monitored the densities of both crayfish and newt egg mass densities and compared these to annual rainfall totals. After three seasons of below average rainfall, we reduced crayfish numbers by manual trapping. Our long-term data suggest that crayfish do not fare well in years when rainfall is above the historic average. This invasive predator did not evolve with high velocity streams and observations suggest southern California storm events wash crayfish downstream, killing many of them. Newts exhibit increased reproduction in years when crayfish numbers are reduced. A comparison with a nearby stream that does not contain crayfish suggests that newt reproduction positively responds to increased rainfall, but that fluctuations are much greater in the stream that contains crayfish. We suggest that rainfall patterns help explain invasive crayfish/newt coexistence and that management for future coexistence may benefit from manual trapping.