Follow-up ecological studies for cryptic species discoveries: Decrypting the leopard frogs of the eastern U.S.

Cryptic species are a challenge for systematics, but their elucidation also may leave critical information gaps about the distribution, conservation status, and behavior of affected species. We use the leopard frogs of the eastern U.S. as a case study of this issue. We refined the known range of the recently described Rana kauffeldi, the Atlantic Coast Leopard Frog, relative to the region's two other leopard frog species, conducted assessments of conservation status, and improved methods for separating the three species using morphological field characters. We conducted over 2,000 call and visual surveys and took photographs of and tissue samples from hundreds of frogs. Genetic analysis supported a three-species taxonomy and provided determinations for 220 individual photographed frogs. Rana kauffeldi was confirmed in eight U.S. states, from North Carolina to southern Connecticut, hewing closely to the Atlantic Coastal Plain. It can be reliably differentiated in life from R. pipiens, and from R. sphenocephala 90% of the time, based on such characters as the femoral reticulum patterning, dorsal spot size and number, and presence of a snout spot. However, the only diagnostic character separating R. kauffeldi from R. sphenocephala remains the breeding call described in 2014. Based on our field study, museum specimens, and prior survey data, we suggest that R. kauffeldi has declined substantially in the northern part of its range, but is more secure in the core of its range. We also report, for the first time, apparent extirpations of R. pipiens from the southeastern portion of its range, previously overlooked because of confusion with R. kauffeldi. We conclude with a generalized ecological research agenda for cryptic species. For R. kauffeldi, needs include descriptions of earlier life stages, studies of niche partitioning with sympatric congeners and the potential for hybridization, and identification of conservation actions to prevent further declines.

Adult activity and temperature preference drives region-wide damselfly (Zygoptera) distributions under a warming climate.

We analysed a recently completed statewide odonate Atlas using multivariate linear models. Within a phylogenetically explicit framework, we developed a suite of data-derived traits to assess the mechanistic distributional drivers of 59 species of damselflies in New York State (NYS). We found that length of the flight season (adult breeding activity period) mediated by thermal preference drives regional distributions at broad (10(5) km(2)) scales. Species that had longer adult flight periods, in conjunction with longer growing seasons, had significantly wider distributions. These intrinsic traits shape species' responses to changing climates and the mechanisms behind such range shifts are fitness-based metapopulation processes that adjust phenology to the prevailing habitat and climate regime through a photoperiod filter.

Cryptic diversity in metropolis: confirmation of a new leopard frog species (Anura: Ranidae) from New York City and surrounding Atlantic coast regions.

We describe a new cryptic species of leopard frog from the New York City metropolitan area and surrounding coastal regions. This species is morphologically similar to two largely parapatric eastern congeners, Rana sphenocephala and R. pipiens. We primarily use bioacoustic and molecular data to characterize the new species, but also examine other lines of evidence. This discovery is unexpected in one of the largest and most densely populated urban parts of the world. It also demonstrates that new vertebrate species can still be found periodically even in well-studied locales rarely associated with undocumented biodiversity. The new species typically occurs in expansive open-canopied wetlands interspersed with upland patches, but centuries of loss and impact to these habitats give some cause for conservation concern. Other concerns include regional extirpations, fragmented extant populations, and a restricted overall geographic distribution. We assign a type locality within New York City and report a narrow and largely coastal lowland distribution from central Connecticut to northern New Jersey (based on genetic data) and south to North Carolina (based on call data).

Wildlife habitat connectivity in the changing climate of New York's Hudson Valley.

Maintaining and restoring connectivity are key adaptation strategies for biodiversity conservation under climate change. We present a novel combination of species distribution and connectivity modeling using current and future climate regimes to prioritize connections among populations of 26 rare species in New York's Hudson Valley. We modeled patches for each species for each time period and modeled potential connections among habitat patches by finding the least-cost path for every patch-to-patch connection. Finally, we aggregated these patches and paths to the tax parcel, commonly the primary unit of conservation action. Under future climate regimes, suitable habitat was predicted to contract or appear upslope and farther north. On average, predicted patches were nine times smaller and paths were twice as long under future climate. Parcels within the Hudson Highlands, Shawangunk Ridge, Catskill Mountains, and Harlem Valley had high species overlap, with areas upslope and northward increasing in importance over time. We envision that land managers and conservation planners can use these results to help prioritize parcel-level conservation and management and thus support biodiversity adaptation to climate change.

Conservation of avian diversity in the Sierra Nevada: moving beyond a single-species management focus.

BACKGROUND: As a result of past practices, many of the dry coniferous forests of the western United States contain dense, even-aged stands with uncharacteristically high levels of litter and downed woody debris. These changes to the forest have received considerable attention as they elevate concerns regarding the outcome of wildland fire. However, attempts to reduce biomass through fuel reduction (i.e., thinning of trees) are often opposed by public interest groups whose objectives include maintaining habitat for species of concern such as the spotted owl, Strix occidentalis, the northern goshawk, Accipiter gentilis, and the Pacific fisher, Martes pennanti. Whether protection of these upper-trophic level species confers adequate conservation of avian forest diversity is unknown. METHODOLOGY AND PRINCIPAL FINDINGS: We use a multi-species occurrence model to estimate the habitat associations of 47 avian species detected at 742 sampling locations within an 880-km(2) area in the Sierra Nevada. Our approach, which accounts for variations in detectability of species, estimates occurrence probabilities of all species in a community by linking species occurrence models into one hierarchical community model, thus improving inferences on all species, especially those that are rare or observed infrequently. We address how the avian community is influenced by covariates related to canopy cover, tree size and shrub cover while accounting for the impacts of abiotic variables known to affect species distributions. CONCLUSIONS AND SIGNIFICANCE: Environmental parameters estimated through our approach emphasize the importance of within and between stand-level heterogeneity in meeting biodiversity objectives and suggests that many avian species would increase under more open canopy habitat conditions than those favored by umbrella species of high conservation concern. Our results suggest that a more integrated approach that emphasizes maintaining a diversity of habitats across environmental gradients and minimizing urbanization may have a greater benefit to ecosystem functioning then a single-species management focus.

Distinguishing stressors acting on land bird communities in an urbanizing environment.

Urbanization has profound influences on ecological communities, but our understanding of causal mechanisms is limited by a lack of attention to its component stressors. Published research suggests that at landscape scales, habitat loss and fragmentation are the major drivers of community change, whereas at local scales, human activity and vegetation management are the primary stressors. Little research has focused on whether urbanization stressors may supplant natural factors as dominant forces structuring communities. We used model selection to determine the relative importance of urban development, human activity, local and landscape vegetation, topography, and geographical location in explaining land bird species richness, abundance, and dominance. We analyzed the entire community and groups of species based on ecological characteristics, using data collected in remnant forests along a gradient of urban development in the Lake Tahoe basin, California and Nevada, USA. Urbanization stressors were consistently among the principal forces structuring the land bird community. Strikingly, disturbance from human activity was the most important factor for richness in many cases, surpassing even habitat loss from development. Landscape-scale factors were consistently more important than local-scale factors for abundance. In demonstrating considerable changes in land bird community structure, our results suggest that ecosystem function in urban areas may be severely compromised. Such changes compel local- and landscape-scale management, focused research, and long-term monitoring to retain biodiversity in urban areas to the extent possible.