The integrative effects of behavior and morphology on amphibian movement

Abstract

Animal movement and dispersal are key factors in population dynamics and support complex ecosystem processes like cross‐boundary subsidies. Juvenile dispersal is an important mechanism for many species and often involves navigation in unfamiliar habitats. For species that metamorphose, such as amphibians, this transition from aquatic to terrestrial environments involves the growth and use of new morphological traits (e.g., legs). These traits strongly impact the fundamental ability of an organism to move in novel landscapes, but innate behaviors can regulate choices that result in the realized movements expressed. By assessing the integrative role of morphology and behavior, we can improve our understanding of juvenile movement, particularly in understudied organisms like amphibians. We assessed the roles of morphological (snout‐vent length and relative leg length) and performance (maximal jump distance) traits in shaping the free movement paths, measured through fluorescent powder tracking, in three anuran species, Pacific treefrog (Hyliola regilla), Western toad (Anaxyrus boreas), and Cascades frog (Rana cascadae). We standardized the measurement of these traits to compare the relative role of species' innate differences versus physical traits in shaping movement. Innate differences, captured by species identity, were the most significant factor influencing movement paths via total movement distance and path sinuosity. Relative leg length was an important contributor but significantly interacted with species identity. Maximal jump performance, which was significantly predicted by morphological traits, was not an important factor in movement behavior relative to species identity. The importance of species identity and associated behavioral differences in realized movement provide evidence for inherent species differences being central to the dispersal and movement of these species. This behavior may stem from niche partitioning of these sympatric species, yet it also calls into question assumptions generalizing anuran movement behavior. These species‐level effects are important in framing differences as past research is applied in management planning.

Movement patterns within an urban population of fire salamanders highlight the importance of conserving small habitat patches

“…Amphibian movement typically involves environmentally or resource‐directed movement between habitat patches that is often influenced by individual condition (e.g. condition‐dependent dispersal; Cayuela et al., 2020), thereby requiring a consideration of life history parameters to understand movement biology (Bowler & Benton, 2005; Bredeweg et al., 2019). Understanding the mechanisms underpinning movement is crucial in the management of populations and predicting population responses to environmental changes (e.g.…”

Asymmetric competition shapes amphibian response to rapid environmental change

“…The importance of biotic interactions in this context may help to explain why other studies of the experimental effects of drying on amphibian species have shown little or no negative impacts in the absence of other stressors (e.g., Amburgey et al 2012, Cook et al 2013). These results also suggest that drying alone may not be a significant stressor on larvae, but instead may manifest as latent effects on juveniles (Bredeweg et al 2019). Further, many of the measured responses in the interactive treatment involving three-species competition and drying were either the only significant effects for a species, or the responses were significantly different (and exacerbated) relative to those treatments involving single and pairwise competition.…”

“…These results also suggest that drying alone may not be a significant stressor on larvae, but instead may manifest as latent effects on juveniles (Bredeweg et al. ). Further, many of the measured responses in the interactive treatment involving three‐species competition and drying were either the only significant effects for a species, or the responses were significantly different (and exacerbated) relative to those treatments involving single and pairwise competition.…”

Carryover effects of pesticide exposure and pond drying on performance, behavior, and sex ratios in a pool breeding amphibian

“…Locomotor ability is a good proxy for dispersal potential in amphibians (Denton et al., 2017; Yagi & Green, 2017). Size at metamorphosis influences locomotor ability, with smaller individuals (SVL and limb length) traveling shorter distances (Bredeweg et al., 2019), and sublethal effects of neonicotinoid pesticide exposure may further exacerbate these patterns. We found that aquatic exposure to sublethal concentrations of imidacloprid led to increased endurance of post‐metamorphic frogs at 18°C (Fig.…”