Breeding Habitat and Local Population Size of the Oregon Spotted Frog (RANA PRETIOSA) IN OREGON, USA

Pearl, Christopher A.; Adams, Michael J.; Leuthold, Niels

doi:10.1898/nwn08-23.1

Cited by 11 publications

(12 citation statements)

References 25 publications

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“…As such, connectivity among sites may be reduced by landscape changes that reduce moisture availability. A previous census study for Klamath and Deschutes populations indicated that Klamath populations were at greater risk of local extirpation due to the lower number of egg masses and greater distance among breeding sites (Pearl et al., ). However, our estimates of isolation by distance do not necessarily support this conclusion: Deschutes and Klamath populations are relatively equal in terms of overall genetic isolation (with Deschutes slightly more isolated; Figure ), suggesting that long‐term persistence in both of these major drainages will rely heavily on aquatic systems for population connectivity.…”

Section: Discussionmentioning

confidence: 99%

“…We predicted that metrics of moisture availability should be stronger predictors of connectivity in R. pretiosa due to the relatively greater dependence on moisture for population connectivity (Pearl, Adams, & Leuthold, ; Watson, McAllister, & Pierce, ), compared to R. luteiventris , for which overland dispersal has been documented (Goldberg & Waits, ; Pilliod, Peterson, & Ritson, ). When considering regional differences in environmental conditions, we expected that connectivity would be positively related to precipitation or moisture gradients (Pilliod et al., ).…”

Section: Introductionmentioning

confidence: 99%

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Regional variation in drivers of connectivity for two frog species (Rana pretiosa and R. luteiventris) from the U.S. Pacific Northwest

et al. 2018

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Comparative landscape genetics has uncovered high levels of variability in which landscape factors affect connectivity among species and regions. However, the relative importance of species traits versus environmental variation for predicting landscape patterns of connectivity is unresolved. We provide evidence from a landscape genetics study of two sister taxa of frogs, the Oregon spotted frog (Rana pretiosa) and the Columbia spotted frog (Rana luteiventris) in Oregon and Idaho, USA. Rana pretiosa is relatively more dependent on moisture for dispersal than R. luteiventris, so if species traits influence connectivity, we predicted that connectivity among R. pretiosa populations would be more positively associated with moisture than R. luteiventris. However, if environmental differences are important drivers of gene flow, we predicted that connectivity would be more positively related to moisture in arid regions. We tested these predictions using eight microsatellite loci and gravity models in two R. pretiosa regions and four R. luteiventris regions (n = 1,168 frogs). In R. pretiosa, but not R. luteiventris, connectivity was positively related to mean annual precipitation, supporting our first prediction. In contrast, connectivity was not more positively related to moisture in more arid regions. Various temperature metrics were important predictors for both species and in all regions, but the directionality of their effects varied. Therefore, the pattern of variation in drivers of connectivity was consistent with predictions based on species traits rather than on environmental variation.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Regional variation in drivers of connectivity for two frog species (Rana pretiosa and R. luteiventris) from the U.S. Pacific Northwest

et al. 2018

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“…Studies of other amphibians have found negative effects of salmonids (Pearl et al. ; Pilliod et al. ) and that emergent vegetation becomes increasingly important to amphibians such as long toed salamanders ( Ambystoma macrodactylum ) when predatory fish are present in the catchment (Pilliod et al.…”

Section: Discussionmentioning

confidence: 99%

“…, in press) high‐impact livestock grazing, salmonids (Pearl et al. ; Pilliod et al. ), and drought (Hossack et al.…”

Section: Discussionmentioning

confidence: 99%

“…We found evidence that emergent vegetation offsets negative effects of predatory trout, as the difference in spotted frog occupancy rates between sites with and without trout diminished with increasing emergent vegetation coverage in otherwise similar sites. Studies of other amphibians have found negative effects of salmonids (Pearl et al 2009a;Pilliod et al 2012) and that emergent vegetation becomes increasingly important to amphibians such as long toed salamanders (Ambystoma macrodactylum) when predatory fish are present in the catchment (Pilliod et al 2013). The benefit of emergent vegetation cover observed here diminished after approximately 50% of the shoreline contained emergent vegetation (i.e., Nevada sites), or after about 20% of the site surface contained emergent vegetation (i.e., Idaho and Oregon sites).…”

Section: Water Body-scale Habitat Associationsmentioning

confidence: 99%

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Persistence at distributional edges: Columbia spotted frog habitat in the arid Great Basin, USA

Arkle

Pilliod

2015

Ecology and Evolution

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A common challenge in the conservation of broadly distributed, yet imperiled species is understanding which factors facilitate persistence at distributional edges, locations where populations are often vulnerable to extirpation due to changes in climate, land use, or distributions of other species. For Columbia spotted frogs (Rana luteiventris) in the Great Basin (USA), a genetically distinct population segment of conservation concern, we approached this problem by examining (1) landscape-scale habitat availability and distribution, (2) water body-scale habitat associations, and (3) resource management-identified threats to persistence. We found that areas with perennial aquatic habitat and suitable climate are extremely limited in the southern portion of the species’ range. Within these suitable areas, native and non-native predators (trout and American bullfrogs [Lithobates catesbeianus]) are widespread and may further limit habitat availability in upper- and lower-elevation areas, respectively. At the water body scale, spotted frog occupancy was associated with deeper sites containing abundant emergent vegetation and nontrout fish species. Streams with American beaver (Castor canadensis) frequently had these structural characteristics and were significantly more likely to be occupied than ponds, lakes, streams without beaver, or streams with inactive beaver ponds, highlighting the importance of active manipulation of stream environments by beaver. Native and non-native trout reduced the likelihood of spotted frog occupancy, especially where emergent vegetation cover was sparse. Intensive livestock grazing, low aquatic connectivity, and ephemeral hydroperiods were also negatively associated with spotted frog occupancy. We conclude that persistence of this species at the arid end of its range has been largely facilitated by habitat stability (i.e., permanent hydroperiod), connectivity, predator-free refugia, and a commensalistic interaction with an ecosystem engineer. Beaver-induced changes to habitat quality, stability, and connectivity may increase spotted frog population resistance and resilience to seasonal drought, grazing, non-native predators, and climate change, factors which threaten local or regional persistence.

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A new parameterization for integrated population models to document amphibian reintroductions

Duarte

Pearl

Adams

et al. 2017

Ecological Applications

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Managers are increasingly implementing reintroduction programs as part of a global effort to alleviate amphibian declines. Given uncertainty in factors affecting populations and a need to make recurring decisions to achieve objectives, adaptive management is a useful component of these efforts. A major impediment to the estimation of demographic rates often used to parameterize and refine decision-support models is that life-stage-specific monitoring data are frequently sparse for amphibians. We developed a new parameterization for integrated population models to match the ecology of amphibians and capitalize on relatively inexpensive monitoring data to document amphibian reintroductions. We evaluate the capability of this model by fitting it to Oregon spotted frog (Rana pretiosa) monitoring data collected from 2007 to 2014 following their reintroduction within the Klamath Basin, Oregon, USA. The number of egg masses encountered and the estimated adult and metamorph abundances generally increased following reintroduction. We found that survival probability from egg to metamorph ranged from 0.01 in 2008 to 0.09 in 2009 and was not related to minimum spring temperatures, metamorph survival probability ranged from 0.13 in 2010-2011 to 0.86 in 2012-2013 and was positively related to mean monthly temperatures (logit-scale slope = 2.37), adult survival probability was lower for founders (0.40) than individuals recruited after reintroduction (0.56), and the mean number of egg masses per adult female was 0.74. Our study is the first to test hypotheses concerning Oregon spotted frog egg-to-metamorph and metamorph-to-adult transition probabilities in the wild and document their response at multiple life stages following reintroduction. Furthermore, we provide an example to illustrate how the structure of our integrated population model serves as a useful foundation for amphibian decision-support models within adaptive management programs. The integration of multiple, but related, data sets has an advantage of being able to estimate complex ecological relationships across multiple life stages, offering a modeling framework that accommodates uncertainty, enforces parsimony, and ensures all model parameters can be confronted with monitoring data.

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Breeding Habitat and Local Population Size of the Oregon Spotted Frog (RANA PRETIOSA) IN OREGON, USA

Cited by 11 publications

References 25 publications

Regional variation in drivers of connectivity for two frog species (Rana pretiosa and R. luteiventris) from the U.S. Pacific Northwest

Regional variation in drivers of connectivity for two frog species (Rana pretiosa and R. luteiventris) from the U.S. Pacific Northwest

Persistence at distributional edges: Columbia spotted frog habitat in the arid Great Basin, USA

A new parameterization for integrated population models to document amphibian reintroductions

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