Ecological strategies predict associations between aquatic and genetic connectivity for dryland amphibians

Abstract

The study of how population genetic structure is shaped by attributes of the environment is a central scientific pursuit in ecology and conservation. But limited resources may prohibit landscape genetics studies for many threatened species, particularly given the pace of current environmental change. Understanding the extent to which species' ecological strategies--their life histories, biology, and behavior-predict patterns and drivers of population connectivity is a critical step in evaluating the potential of multi-taxa inference in landscape genetics. We present results of a landscape genetic study of three dryland amphibians: the canyon treefrog (Hyla arenicolor), red-spotted toad (Anaxyrus punctatus), and Mexican spadefoot (Spea multiplicata). These species characterize a range of ecological strategies, driven primarily by different water dependencies, enabling amphibian survival in arid and semiarid environments. We examined a suite of hypothesized relationships between genetic connectivity and landscape connectivity across species. We found a positive relationship between population differentiation and water dependency, e.g., longer larval development periods and site fidelity for reliable water sources. We also found that aquatic connectivity is important for all species, particularly when considered with topography (slope). The effect of spatial scale varied by species, with canyon treefrogs and Mexican spadefoots characterized by relatively consistent results at different scales in contrast to the stark differences in results for red-spotted toads at different scales. Using ecological information to predict relationships between genetic and landscape connectivity is a promising approach for multi-taxa inference and may help inform conservation efforts where single-species genetic studies are not possible.

Dissimilarity in the riparian arthropod communities along surface water permanence gradients in aridland streams

“…This is not only true of invertebrates, as Mims et al (2015) came to a similar conclusion about amphibians breeding in the study region. It is especially notable that intermittent and ephemeral reaches still host equivalent or greater numbers of total and unique species to their perennial counterparts, and it is important to note that these species still rely on networks of perennial and nonperennial stream segments in seasonal environments.…”

“…This trend is likely to continue based on climate projections and increasing human water demand (Meixner et al, 2016;Serrat-Capdevila et al, 2007). Although perennial streams are undoubtedly important to many species, understanding the broader context of how communities vary among stream reaches of varying flow permanence within fragmented stream networks is essential to conserving them (Mims, Phillipsen, Lytle, Kirk, & Olden, 2015). Although perennial streams are undoubtedly important to many species, understanding the broader context of how communities vary among stream reaches of varying flow permanence within fragmented stream networks is essential to conserving them (Mims, Phillipsen, Lytle, Kirk, & Olden, 2015).…”

Gene-flow in the clouds: landscape genetics of a viviparous, montane grassland toad in the tropics

“…Hence, the distance among regions, the small body size and the harsh conditions during the dry season may result in the highly significant population differentiation. Reproductive mode was shown to influence population structure in amphibians (Measey et al 2007;Fouquet et al 2015;Mims et al 2015;Paz et al 2015). Species showing reproduction independent of open water, e.g.…”

“…For montane amphibians topography, mainly elevation (Funk et al 2005;Kershenbaum et al 2014) and slope (Kershenbaum et al 2014;Mims et al 2015), or abiotic factors, mainly desiccation risk (Peterman et al 2014;Emel and Storfer 2015), were shown to have an important influence on population structure and connectivity. In accordance with these findings, our best model (1400 m asl elevation model) includes topography (elevation) and presumably desiccation risk.…”

The Interplay Between Landscape Structure and Biotic Interactions

“…A number of freshwater ponds and streams are ephemeral or intermittent, which alters connectivity and habitat size, with consequences for species with varying reliance on water (e.g., amphibians, invertebrates) [125,126]. For instance, severe drought extirpated top predators in desert streams in Arizona, USA, allowing mesopredators to increase through release from competition [83].…”