Landscape genetics reveals unique and shared effects of urbanization for two sympatric pool‐breeding amphibians

Abstract

Metapopulation‐structured species can be negatively affected when landscape fragmentation impairs connectivity. We investigated the effects of urbanization on genetic diversity and gene flow for two sympatric amphibian species, spotted salamanders (Ambystoma maculatum) and wood frogs (Lithobates sylvaticus), across a large (>35,000 km2) landscape in Maine, USA, containing numerous natural and anthropogenic gradients. Isolation‐by‐distance (IBD) patterns differed between the species. Spotted salamanders showed a linear and relatively high variance relationship between genetic and geographic distances (r = .057, p < .001), whereas wood frogs exhibited a strongly nonlinear and lower variance relationship (r = 0.429, p < .001). Scale dependence analysis of IBD found gene flow has its most predictable influence (strongest IBD correlations) at distances up to 9 km for spotted salamanders and up to 6 km for wood frogs. Estimated effective migration surfaces revealed contrasting patterns of high and low genetic diversity and gene flow between the two species. Population isolation, quantified as the mean IBD residuals for each population, was associated with local urbanization and less genetic diversity in both species. The influence of geographic proximity and urbanization on population connectivity was further supported by distance‐based redundancy analysis and multiple matrix regression with randomization. Resistance surface modeling found interpopulation connectivity to be influenced by developed land cover, light roads, interstates, and topography for both species, plus secondary roads and rivers for wood frogs. Our results highlight the influence of anthropogenic landscape features within the context of natural features and broad spatial genetic patterns, in turn supporting the premise that while urbanization significantly restricts interpopulation connectivity for wood frogs and spotted salamanders, specific landscape elements have unique effects on these two sympatric species.

Topography, more than land cover, explains genetic diversity in a Neotropical savanna tree frog

“…When analysing contemporary barriers to gene flow, landscape genetic studies must take into account the spatial scale of sampling relative to habitat suitability and disturbance (Epps & Keyghobadi, 2015; Manel, Schwartz, Luikart, & Taberlet, 2003). Although we did not detect contemporary barriers to gene flow, studies with other amphibians that sampled at scales comparable to ours found genetic signatures of land cover disruption (Homola, Loftin, & Kinnison, 2019; Zancolli, Rödel, Steffan‐Dewenter, & Storfer, 2014). Specifically, our sampled populations, which cover the entire species’ known range, showed enough variation in the seven land cover classes between population pairs (Figure 1c).…”

Contemporary Philosophy and Methods for Studying Speciation and Delimiting Species

“…For instance, effective estimates of migration surfaces (EEMS; Petkova et al, 2016) can visualize where genetic similarity by migration decays faster than expected by IBD, thus highlighting areas of reduced gene flow at geographic boundaries. This method has been used successfully in studies on reptiles and amphibians to identify areas of low migration (Homola et al, 2019;Myers et al, 2019b;Chan and Brown, 2020;Burbrink et al, 2021). Modeling population structure given continuous (geographic) and discrete (reproductive isolation) processes can be used to separate clines vs. geographic clusters using programs such as conStruct (Bradburd et al, 2018).…”

Amfibi sebagai model untuk mengembangkan media dan alat peraga pembelajaran sains

“…(2) perbedaan katak dan kodok, (3) lingkup genus Rana dan Bufo, (4) amfibi sebagai hewan ovipar, dan (5) siklus hidup amfibi yang memiliki fase berudu berenang bebas di air. Banyak spesies yang ovipar dan membutuhkan air sebagai tempat pemijahan (Homola et al, 2019;Smith & Harmon, 2019), namun ada juga spesies yang ovovivipar (Iskandar et al, 2014;Sandberger-Loua et al, 2016). Demikian pula dengan metamorfosis, ada berudu dari spesies amfibi yang tidak berenang bebas di habitat perairan sebelum juvenile (Iskandar, 1998).…”

“…Selain dengan komponen biotik, amfibi juga berinteraksi dengan komponen abiotik. Banyak spesies amfibi yang memanfaatkan air sebagai sumberdaya untuk melakukan tahapan metamorfosis sebelum menjadi dewasa (Homola et al, 2019). Oleh karenanya kehidupan amfibi sangat tergantung pada ketersediaan air di habitat (Brannelly et al, 2019).…”