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Papers & Reports SURGICAL TECHNIQUE FOR THE PLACEMENT OF INTRACOELOMIC RADIO TRANSMITTERS AND EXTERNAL SILICONE PASSIVE SAMPLING DEVICES FOR NORTHERN LEOPARD FROGS (Lithobates pipiens )
Authors: T Yaw; J E Swanson; Clay L Pierce; Erin Muths; Kelly L Smalling; M Vandever; B A Zaffarano
Date: 2017 | Outlet: Journal of Herpetological Medicine and Surgery
Amphibians are excellent sentinels for contaminant exposure in prairie wetlands. Development of passive sampling devices (PSD) has greatly improved in recent years, and they present an innovative sampling technology that can potentially yield individual-specific, quantifiable data on chemical exposure. In this study, PSDs were attached to the ventral skin of 20 northern leopard frogs (Lithobates pipiens) with polypropylene sutures after radio transmitters had been surgically inserted into the coleomic cavity. After a recovery period frogs were released into the wild and located daily using radio telemetry to assess how long PSDs would remain attached in the frogs’ natural habitat. After one week, PSDs remained on 18 of the original 20 frogs. At 2 weeks 16 frogs were recovered and no PSDs remained attached. Although valuable data can be obtained over a short time period, more research will be necessary to demonstrate effectiveness of externally attaching silicone PSDs to northern leopard frogs for time periods longer than 1-2 weeks.
News & Stories ARMI scientists Blake Hossack (NOROCK), Brent Sigafus (SBSC) and Erin Muths (FORT), and ARMI post doc Thierry Chambert traveled to Sonora, Mexico, to survey for Sonoran Tiger Salamanders in May 2016
Authors: Erin Muths; Blake R Hossack; Brent H Sigafus
June 23, 2016
ARMI scientists Blake Hossack (NOROCK), Brent Sigafus (SBSC) and Erin Muths (FORT), and ARMI post doc Thierry Chambert traveled to Sonora, Mexico, to survey for Sonoran Tiger Salamanders in May. Reports existed of the presence of this salamander in Sonora, but the spatial extent of its range is unknown. The Sonoran Tiger Salamander is federally endangered in the US and is found only in the San Rafael Valley in southern Arizona. The identification of additional populations in nearby Sonora has implications for multiple conservation concerns including population biology, genetics, and disease. Data collected about its presence and abundance across the border will contribute to the identification of management objectives and subsequent implementation of conservation actions. The surveys were a collaborative effort with logistical support from Naturalia (http://www.naturalia.org.mx/) that included the expertise of Naturalia employees Daniel Toyos and Ramon Babuca. The trip also benefitted from assistance from Guillermo Molina (Instituto Tecnológico Superior De Cananea), Julio Lemos Espinal (UNAM), and students David Hurtado and Aline Estrella. Jim Rorabaugh contributed much to the trip by sharing knowledge of the Sonoran system gained from his previous expeditions focused on salamanders in Mexico. The effort was based at Rancho Los Fresnos, a Naturalia property located north of the town of Cananea and adjacent to the US–Mexico border. The group sampled a variety of sites on Rancho Los Fresnos, as well as surrounding ranches and locations to the south of Cananea. Tiger salamanders reside primarily in man-made or modified earthen stock tanks. These habitats were seined for salamanders and water samples were collected to test for environmental DNA (eDNA) from salamanders, invasive American bullfrogs, federally-threatened (USA) Chiricahua leopard frogs, and pathogens that cause amphibian diseases. Buccal swabs were collected from captured salamanders for genetic analyses (there is uncertainty in determining the difference among closely related salamanders in the field); and skin swabs were collected to test for disease (both Batrachochytrium salamandrivorans and B. dendrobatidis). This ongoing project has already produced one publication (Hossack et al. 2016. Notes on the Distribution of Tiger Salamanders (Presumed Ambystoma mavortium stebbinsi) in Sonora, Mexico. Herpetological Review 47(2): 177-180), and another is in preparation (Hossack et al. Informing recovery of an imperiled, endemic salamander: coupled dynamics and test of drought-mediated coexistence with invasive predators).
Papers & Reports Survival estimates for reintroduced populations of the Chiricahua Leopard Frog (Lithobates chiricahuensis)
Authors: P E Howell; Blake R Hossack; Erin Muths; Brent H Sigafus; Richard Chandler
Date: 2016 | Outlet: Copeia. 104.4: 824-830.
Global amphibian declines have been attributed to a number of factors including disease, invasive species, habitat degradation, and climate change. Reintroduction is one management action that is commonly used with the goal of recovering imperiled species. The success of reintroductions varies widely and evaluating their efficacy requires estimates of population viability metrics, such as underlying vital rates and trends in abundance. Although rarely quantified, assessing vital rates for recovering populations provides a more mechanistic understanding of population growth than numerical trends in population occupancy or abundance. We used three years of capture-mark-recapture data from three breeding ponds and a Cormack-Jolly-Seber model to estimate annual apparent survival for reintroduced populations of the federally-threatened Chiricahua Leopard Frog (Lithobates chiricahuensis) at the Buenos Aires National Wildlife Refuge (BANWR), in the Altar Valley, Arizona, USA. To place our results in context, we also compiled published survival estimates for other ranids. Average apparent survival of Chiricahua Leopard Frogs at BANWR was https://0.27 (95% CI [https://0.07, 0.74]) and average individual capture probability was https://0.02 (95% CI [0, 0.05]). Our apparent survival estimate for Chiricahua Leopard Frogs is lower than for most other ranids, and is not consistent with recent research that showed metapopulation viability in the Altar Valley is high. We suggest that low apparent survival may be indicative of high emigration rates. We recommend that future research should estimate emigration rates so that actual, rather than apparent, survival can be quantified to improve population viability assessments of threatened species following reintroduction efforts.
Papers & Reports Mitigating amphibian chytridiomycosis in nature
Authors: T WJ Garner; Benedikt R Schmidt; An Martel; Frank Pasmans; Erin Muths; A C Cunningham; C Weldon; Matthew C Fisher; Jaime Bosch
Date: 2016-10 | Outlet: Phil. Trans.R.Soc.B 371: 20160207. dx.doi.org/10.1098/rstb.2016.0207
Amphibians across the planet face the threat of population decline and extirpation caused by the disease chytridiomycosis. Despite consensus that the fungal pathogens responsible for the disease are conservation issues, strategies to mitigate their impacts in the natural world are, at best, nascent. Reducing risk associated with the movement of amphibians, non-amphibian vectors and other sources of infection remains the first line of defence and a primary objective when mitigating the threat of disease in wildlife. Amphibian-associated chytridiomycete fungi and chytridiomycosis are already widespread, though, and in this article we discuss options for mitigating the threats once disease emergence has occurred in wild amphibian populations.
Papers & Reports INFORMING RECOVERY OF THE ENDANGERED SONORAN TIGER SALAMANDER: 10-YEAR TRENDS IN OCCUPANCY OF SALAMANDERS, INVASIVE PREDATORS, AND THEIR CO-OCCURRENCE
Authors: Blake R Hossack; R K Honeycutt; Thierry C Chambert; Brent H Sigafus; T R Jones,; J A Sorensen; James C Rorabaugh; Erin Muths
Outlet: Unpublished Report (see https://doi.org/10.1016/j.biocon.2017.03.004)
The Sonoran Tiger Salamander (Ambystoma mavortium stebbinsi) occurs in a single valley that spans the USA-Mexico border and was listed as federally-endangered in 1997. The listing was driven by a variety of threats, including small geographic range and threats from invasive predators. The recovery plan for this subspecies requires scientifically-credible estimates of changes in occurrence of the Sonoran Tiger Salamander and invasive predators before further evaluation of the listing status. The recent completion of a 10-year (2004–2013) monitoring program, coordinated by the Arizona Game and Fish Department and the U.S. Fish and Wildlife Service, generated data sufficient to estimate (1) trends in breeding site occupancy by the Sonoran Tiger Salamander, (2) trends in occupancy of introduced predators, and (3) probability of co-occurrence between Sonoran Tiger Salamanders and invasive predators. We used Bayesian hierarchical models to estimate annual probabilities of occupancy and co-occurrence, after adjusting for imperfect detection. Our analyses showed that pond-level occupancy of Sonoran Tiger Salamanders increased by an estimated 2.2% (95% credible interval [CI] = 0.4%–3.8%) per year. Occupancy of invasive predators decreased by an estimated 0.7% (95% CI = −2.4%–0.7%) per year. In ponds with water, presence of invasive predators reduced salamander occupancy by 23.01% (95% CI = 8.72–43.73) across the 10-yr monitoring program. These results will assist in evaluating the status of the Sonoran Tiger Salamander and prioritizing management actions that are supported by defensible estimates.
Papers & Reports Potential Interactions Among Disease, Pesticides, Water Quality and Adjacent Land Cover in Amphibian Habitats in the United States
Authors: William A Battaglin; Kelly L Smalling; Chauncey W Anderson; Daniel L Calhoun; T Chestnut; Erin Muths
Date: 2016-05-24 | Outlet: Science of the Total Environment 320-332
To investigate interactions among disease, pesticides, water quality and adjacent land cover we collected samples of water, sediment, and frog tissue from 21 sites in 7 States in the United States (US) representing a variety of amphibian habitats. All samples were analyzed for > 90 pesticides and pesticide degradates, and water and frogs were screened for the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) using molecular methods. Pesticides and pesticide degradates were detected frequently in frog breeding habitats (water and sediment) as well as in frog tissue. Fungicides occurred more frequently in water, sediment, and tissue than was expected based upon their limited use relative to herbicides or insecticides. Pesticide occurrence in water or sediment was not a strong predictor of occurrence in tissue, but pesticide concentrations in tissue were correlated positively to agricultural and urban land, and negatively to forested land in 2-kilometer buffers around the sites. Bd was detected in water at 45% of sites, and on 34% of swabbed frogs. Bd detections in water were not associated with differences in land use around sites, but sites with detections had colder water. Frogs that tested positive for Bd were associated with sites that had higher total fungicide concentrations in water and sediment, but lower insecticide concentrations in sediments relative to frogs that were Bd negative. Bd concentrations on frog swabs were positively correlated to dissolved organic carbon, and total nitrogen and phosphorus, and negatively correlated to pH and water temperature.
Data were collected from a range of locations and amphibian habitats and represent some of the first field-collected information aimed at understanding the interactions between pesticides, land use, and amphibian disease. These interactions are of particular interest to conservation efforts as many amphibians live in altered habitats and may depend on wetlands embedded in these landscapes to survive.
Data were collected from a range of locations and amphibian habitats and represent some of the first field-collected information aimed at understanding the interactions between pesticides, land use, and amphibian disease. These interactions are of particular interest to conservation efforts as many amphibians live in altered habitats and may depend on wetlands embedded in these landscapes to survive.
Papers & Reports First Estimates of the Probability of Survival in a Small-bodied, High Elevation Frog or, how Historical Data Can Be Useful
Authors: Erin Muths; R Scherer; Staci M Amburgey; T Matthews; A Spencer; P. Stephen Corn
Date: 2016-06 | Outlet: Canadian Journal of Zoology, doi: 10.1139/cjz-2016-0024
In an era of shrinking budgets yet increasing demands for conservation, the value of existing (i.e., historical) data is elevated. Lengthy time-series on common, or previously common, species are particularly valuable and may be available only through the use of historical information. We provide first estimates of the probability of survival and longevity (https://0.67-0.79; 5-7 yr) for a subalpine population of a small-bodied, ostensibly common amphibian, the boreal chorus frog, using historical data and contemporary, hypothesis-driven information-theoretic analyses. We also test a priori hypotheses about the effects of color morph (as suggested by early reports) and of drought (as suggested by recent climate predictions on survival). Using robust mark-recapture models, we find some support for early hypotheses regarding the effect of color on survival, but we find no effect of drought. The congruence between early findings and our analyses highlights the usefulness of historical information by providing raw data for contemporary analyses and context for conservation and management decisions.
Papers & Reports Quantitative evidence for the effects of multiple drivers on continental-scale amphibian declines
Authors: Evan HC Grant; David AW Miller; Benedikt R Schmidt; Michael J Adams; Staci M Amburgey; Thierry C Chambert; Sam S Cruickshank; Robert N Fisher; David E Green; Blake R Hossack; P TJ Johnson; M B Joseph; Tracy A. Rittenhouse; Maureen E Ryan; Hardin J Waddle; Susan C Walls; Larissa L Bailey; Gary M Fellers; Thomas A Gorman; Andrew M Ray; David S Pilliod; S J Price; D Saenz; Erin Muths
Date: 2016-05-23 | Outlet: Scientific Reports xx:xxx-xxx
Since amphibian declines were first proposed as a global phenomenon over a quarter century ago, the conservation community has made little progress in halting or reversing these trends. The early search for a "smoking gun" was replaced with the expectation that declines are caused by multiple drivers. While field observations and experiments have identified factors leading to increased local extinction risk, evidence for effects of these drivers is lacking at large spatial scales. Here, we use observations of 389 time-series of 83 species and complexes from 61 study areas across North America to test the effects of 4 of the major hypothesized drivers of declines. While we find that local amphibian populations are being lost from metapopulations at an average rate of 3.79% per year, these declines are not related to any particular threat at the continental scale; likewise the effect of each stressor is variable at regional scales. This result - that exposure to threats varies spatially, and populations vary in their response - provides little generality in the development of conservation strategies. Greater emphasis on local solutions to this globally shared phenomenon is needed.
Papers & Reports Influence of Demography and Environment on Persistence in Toad Populations
Authors: Brad A Lambert; R A Schorr; S C Schneider; Erin Muths
Date: 2016-07 | Outlet: Journal of Wildlife Management
Effective conservation of rare species requires an understanding of how potential threats impact population dynamics. Unfortunately, information about population demographics prior to threats (i.e., baseline data) is lacking for many species. Perturbations, caused by climate change, disease or other stressors can lead to population declines and heightened conservation concerns. A dearth of baseline information challenges our ability to anticipate and respond to agents of population decline. Boreal toads (Anaxyrus boreas boreas) have undergone rangewide declines due mostly to the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd), with only a handful of sizable populations remaining in the southern Rocky Mountains USA, very few of which are disease-free
News & Stories ARMI gave IGNITE talks in Washington D.C.
Authors: Erin Muths
February 26, 2016
The scientists of The Amphibian Research and Monitoring Initiative traded their field clothes for suits in December. Seven ARMI scientists gave presentations to partners and amphibian enthusiasts from the Department of Interior and other Federal Agencies at the Main Interior Building just off the Washington D.C. Mall on December 4th2015. The five-minute presentations were made in an “Ignite” style which means that each speaker has only 20 slides that advance automatically every 15 seconds. These talks were entertaining and dynamic, and packed with information about topics as diverse as the salamander chytrid fungus, contaminants, oil and gas, synthetic approaches to catalyze understanding of amphibian declines, reintroduction successes, and innovative ways to move conservation decision-making forward. Following the Ignite session, the Association of Fish & Wildlife Agencies, Amphibian Survival Alliance, and Amphibian and Reptile Conservancy sponsored a short reception. The reception was designed to encourage follow-up conversation among ARMI scientists and partners with the aim of developing relationships and talking about goals and needs that might be addressed by ARMI. A number of new collaborations are now in development. This event at Main Interior was in conjunction with the annual ARMI meeting that was held at the Smithsonian Institution National Museum of Natural History, hosted by Dr. Roy McDiarmid, a 2015 “Friend of ARMI”.
Papers & Reports Notes on the Distribution of Tiger Salamanders (presumed <i>Ambystoma mavortium stebbinsi</i>) in Sonora, Mexico
Authors: Blake R Hossack; Erin Muths; James C Rorabaugh; J A Lemos-Espinal; Brent H Sigafus; Thierry C Chambert; A rr Carreon; F el Hurtado; M ar Toyos; T R Jones,
Date: 2016-06 | Outlet: Herpetological Review
Papers & Reports Integrating biology, field logistics, and simulations to optimize parameter estimation for imperiled species
Authors: W E Lanier; Larissa L Bailey; Erin Muths
Date: 2016 | Outlet: Ecological Modeling
Conservation of imperiled species often requires knowledge of vital rates and population dynamics. However, these can be difficult to estimate for rare species and small populations. This problem is further exacerbated when individuals are not available for detection during some surveys due to limited access, delaying surveys and creating mismatches between the breeding behavior and survey timing. Here we use simulations to explore the impacts of this issue using four separate boreal toad (Anaxyrus boreas boreas) populations, representing combinations of logistical access (accessible, inaccessible) and breeding behavior (synchronous, asynchronous). We examine the bias and precision of survival and breeding probability estimates generated by survey designs that differ in effort and timing for these populations.
Papers & Reports A Model to Inform Management Actions as a Response to Chytridiomycosis-Associated Decline
Authors: S J Converse; Larissa L Bailey; Brittany A Mosher; W C Funk; B D Gerber; Erin Muths
Date: 2016-02-15 | Outlet: Ecohealth
Decision-analytic models provide forecasts of how systems of interest will respond to management. These models can be parameterized using empirical data, but sometimes require information elicited from experts. When evaluating the effects of disease in species translocation programs, expert judgment is likely to play a role because complete empirical information will rarely be available. We illustrate development of a decision-analytic model built to inform decision-making regarding translocations and other management actions for the boreal toad (Anaxyrus boreas boreas), a species with declines linked to chytridiomycosis caused by Batrachochytrium dendrobatidis (Bd).
Papers & Reports Non-native and native organisms moving into high elevation and high latitude ecosystems in an era of climate change: new challenges for ecology and conservation
Authors: Ann Albihn; Jake Alexander; Treena Burgess; Curt Daehler; G Englund; Franz Essl; Birgitta Evengård; Greg Greenwood; Sylvia Haider; Jonathan Lenoir; K McDougall; Erin Muths; Martin Nuñez; J Olofsson; Lois Pellissier; Wolfgang Rabitsch; Lisa Rew; Mark Robertson; Nathan Sanders; Christoph Kueffer; Ann Milbau; Anibal Pauchard
Date: 2016 | Outlet: Biological Invasions
Cold environments at high elevation and high latitude are often viewed as resistant to biological invasions. However, climate warming, land use change and associated increased connectivity all increase the risk of biological invasions in these environments. Here we present a summary of the key discussions of the workshop ‘Biosecurity in Mountains and Northern Ecosystems: Current Status and Future Challenges’ (Flen, Sweden, 1-3 June 2015). The aims of the workshop were to (i) increase awareness about the growing importance of species expansion – both non-native and native – at high elevation and high latitude with climate change, (ii) review existing knowledge about invasion risks in these areas, and (iii) encourage more research on how species will move and interact in cold environments, and the consequences for animal and human health and wellbeing. The diversity of potential and actual invaders reported at the workshop and the likely interactions between them create major challenges for managers of cold environments. However, since these cold environments have experienced fewer invasions when compared with many warmer, more populated environments, prevention has a real chance of success, especially if it is coupled with prioritisation schemes for targeting invaders likely to have greatest impact. Communication and co-operation between cold environment regions will facilitate rapid response and maximise use of limited research and management resources.
Papers & Reports Salamander chytrid fungus (Batrachochytrium salamandrivorans) in the United States — Developing research, monitoring, and management strategies
Authors: Evan HC Grant; Erin Muths; R A Katz; Stefano Canessa; Michael J Adams; Jennifer R Ballard; Lee Berger; Cheryl J Briggs; Jeremy T Coleman; M J Gray; Maria-Richetta C Hopkins; Reid N Harris; Blake R Hossack; Kathryn P Huyvaert; Jonathan E Kolby; Karen R Lips; Robert E Lovich; Hamish I McCallum; Joseph R Mendelson III; Priya Nanjappa; Deanna H Olson; Jenny G Powers; Katherine LD Richgels; Robin E Russell; Benedikt R Schmidt
Date: 2016 | Outlet: U.S. Geological Survey Open-File Report 2015–1233
The recently identified pathogenic chytrid fungus, Batrachochytrium salamandrivorans (Bsal), poses a severe threat to the distribution and abundance of salamanders within the United States and Europe. Development of a response strategy for the potential, and likely, invasion of Bsal into the United States is critical to protect global salamander biodiversity. A formal working group, led by Amphibian Research and Monitoring Initiative (ARMI) scientists from the U.S. Geological Survey (USGS) Patuxent Wildlife Research Center, Fort Collins Science Center, and Forest and Rangeland Ecosystem Science Center, was held at the USGS Powell Center for Analysis and Synthesis in Fort Collins, Colorado, USA from June 23 to June 25, 2015, to identify critical Bsal research and monitoring needs that could inform conservation and management strategies for salamanders in the United States. Key findings of the workshop included the following: (1) the introduction of Bsal into the United States is highly probable, if not inevitable, thus requiring development of immediate short-term and long-term intervention strategies to prevent Bsal establishment and biodiversity decline; (2) management actions targeted towards pathogen containment may be ineffective in reducing the long-term spread of Bsal throughout the United States; and (3) early detection of Bsal through surveillance at key amphibian import locations, among high-risk wild populations, and through analysis of archived samples is necessary for developing management responses. Top research priorities during the pre-invasion stage included the following: (1) deployment of qualified diagnostic methods for Bsal and establishment of standardized laboratory practices, (2) assessment of susceptibility for amphibian hosts (including anurans), and (3) development and evaluation of short- and long-term pathogen intervention and management strategies. Several outcomes were achieved during the workshop, including development of an organizational structure with working groups for a Bsal Task Force, creation of an initial influence diagram to aid in identifying effective management actions in the face of uncertainty, and production of a list of potential management actions and key research uncertainties. Additional products under development include a Bsal Strategic Action plan, an emergency response plan, a monitoring and surveillance program, a standardized diagnostic approach, decision-models for natural resource agencies, and a reporting database for salamander mortalities. This workshop was the first international meeting to address the threat of Bsal to salamander populations in the United States, with more than 30 participants from U.S. conservation and resource management agencies (USFWS, USFS, DoD, NPS, and AFWA) and academic research institutions from Australia, the Netherlands, Switzerland, the United Kingdom, and the United States.
Papers & Reports Why you cannot ignore disease when you reintroduce animals. In: Reintroduction of Fish and Wildlife Populations
Authors: Erin Muths; Hamish I McCallum
Date: 2016-09 | Outlet: Univeristy of California Press
Book chapter: All wild animal populations harbor a range of parasitic organisms, ranging from viruses and bacteria to multicellular parasites such as helminths and arthropods. While some of these are mutualists and some are commensal, others cause infectious disease in at least some members of the population and some may have substantial population-level impacts. The reintroduction of animals requires an immense amount of effort, and considering known and potential diseases is crucial to all phases of a well-formulated reintroduction plan (site and donor selection, implementation and monitoring). While disease has been recognized as a potential factor in reintroductions for decades (e.g. Griffith et al. 1993), heightened conservation concerns and increasing numbers of emerging pathogens bring a consideration of disease to the forefront of many projects.
Papers & Reports Restored agricultural wetlands in central Iowa: habitat quality and amphibian response
Authors: Rebecca A Reeves; Clay L Pierce; Kelly L Smalling; R W Klaver; M Vandever; William A Battaglin; Erin Muths
Date: 2016-02 | Outlet: Wetlands
Amphibians are declining throughout the United States and worldwide due, partly, to habitat loss. The Iowa Conservation Reserve Enhancement Program (CREP) strategically restores wetlands to denitrify tile drainage effluent and restore ecosystem services. Understanding how eutrophication , hydroperiod, predation, and disease affect amphibians in restored wetlands is central to maintaining healthy amphibian populations in the region. We examined the quality of amphibian habitat in restored CREP wetlands relative to reference wetlands by comparing species richness, developmental stress, and adult leopard frog (Lithobates pipiens) survival probabilities to a suite of environmental metrics. Although measured habitat variables differed between restored and reference wetlands, differences appeared to have sub-lethal rather than lethal effects on resident populations . There were few differences in amphibian species richness and no difference in estimated survival probabilities between wetland types. Restored wetlands had more nitrate and alkaline pH, longer hydroperiods, and were deeper, whereas reference wetlands had more amphibian chytrid fungus zoospores and resident amphibians exhibited increased developmental stress. Restored and reference wetlands are both important components of the landscape in central Iowa and maintaining a complex of fish-free wetlands with a variety of hydroperiods will likely contribute to the persistence of amphibians in this landscape.
Papers & Reports An alternative framework for responding to the amphibian crisis
Authors: Erin Muths; Robert N Fisher
Date: 2017-04 | Outlet: Oryx
Volumes of data illustrate the severity of the crisis affecting amphibians, where >32% of amphibians worldwide are threatened with declining populations. Although there have been isolated victories, the current approach to the issue is unsuccessful. We suggest that a radically different approach, something akin to human emergency response management (i.e. the Incident Command System), is one alternative to addressing the inertia and lack of cohesion in responding to amphibian issues. We acknowledge existing efforts and the useful research that has been conducted, but we suggest that a change is warranted and that the identification of a new amphibian chytrid provides the impetus for such a change. Our goal is to recognize that without a centralized effort we (collectively) are likely to fail in responding to this challenge.
Papers & Reports Elevational speciation in action? Restricted gene flow associated with adaptive divergence across an altitudinal gradient
Authors: W C Funk; M A Murphy; K L Hoke; Erin Muths; Staci M Amburgey; L em Moriarty; A R Lemmon
Date: 2015 | Outlet: Journal of Evolutionary Biology
Previous work in the boreal chorus frog (Pseudacris maculata) has demonstrated adaptive divergence in morphological, life history, and physiological traits across an elevational gradient from approximately 1500–3000 m in the Colorado Front Range, USA. We tested whether this adaptive divergence is associated with restricted gene flow across elevation—as would be expected if incipient speciation were occurring—and if so, whether behavioral isolation contributes to reproductive isolation. Our analysis of 12 microsatellite loci in 797 frogs from 53 populations revealed restricted gene flow across elevation, even after controlling for geographic distance and topography. Calls also varied significantly across elevation in dominant frequency, pulse number, and pulse duration, which was partly, but not entirely, due to variation in body size and temperature across elevation. However, call variation did not result in strong behavioral isolation: in phonotaxis experiments, low elevation females tended to prefer an average low elevation call over a high elevation call, and vice versa for high elevation females, but this trend was not statistically significant. In summary, our results show that adaptive divergence across elevation restricts gene flow in P. maculata, but the mechanisms for this potential incipient speciation remain open.
Papers & Reports How spatio-temporal habitat connectivity affects amphibian genetic structure
Authors: A G Watts; P Schlichting; Shawn M Billerman; B Jesmer; S Micheletti; M Fortin; W C Funk; P Hapeman; Erin Muths; M A Murphy
Date: 2015 | Outlet: Frontiers in Genetics
Heterogeneous landscapes and fluctuating environmental conditions can affect species’ dispersal, population genetics, and genetic structure, yet understanding how biotic and abiotic factors affect population dynamics in a fluctuating environment is critical for species management. We evaluated how spatio-temporal habitat connectivity influences dispersal and genetic structure in a population of boreal chorus frogs (Pseudacris maculata) using a landscape genetics approach. We developed gravity models to assess the contribution of various factors to the observed genetic distance as a measure of functional connectivity. We selected (a) wetland (within-site) and (b) landscape matrix (between-site) characteristics; and (c) wetland connectivity metrics using a unique methodology. Specifically, we developed three networks that quantify wetland connectivity based on: (i) P. maculata dispersal ability, (ii) temporal variation in wetland quality, and (iii) contribution of wetland stepping-stones to frog dispersal. We examined 18 wetlands in Colorado, and quantified 12 microsatellite loci from 322 individual frogs. We found that genetic connectivity was related to topographic complexity, within- and between-wetland differences in moisture, and wetland functional connectivity as contributed by stepping-stone wetlands. Our results highlight the role that dynamic environmental factors have on dispersal-limited species and illustrate how complex asynchronous interactions contribute to the structure of spatially-explicit metapopulations.