Estimating the probability of movement and partitioning seasonal survival in an amphibian metapopulation

Abstract

Movement of individuals has been described as one of the best studied, but least understood concepts in ecology. The magnitude of movements, routes, and probability of movement have significant application to conservation. Information about movement can inform efforts to model species persistence and is particularly applicable in situations where specific threats (e.g., disease) may depend on the movement of hosts and potential vectors. We estimated the probability of movement (breeding dispersal and permanent emigration) in a metapopulation of 16 breeding sites for boreal toads (Anaxyrus boreasboreas). We used a multi-state mark-recapture approach unique in its complexity (16 sites over 18 yr) to address questions related to these movements and variation in resident survival. We found that individuals had a 1-2% probability of dispersing in a particular year and that approximately 10-20% of marked individuals were transient and observed in the metapopulation only once. Resident survival probabilities differed by season, with 71-90% survival from emergence from hibernation through early post-breeding and >97% survival from mid-/late active season through hibernation. Movement-related probabilities are needed to predict species range expansions and contractions, estimate population and metapopulation dynamics, understand host-pathogen and native-invasive species interactions, and to evaluate the relative effects of proposed management actions.

Determinants and Consequences of Dispersal in Vertebrates with Complex Life Cycles: A Review of Pond-Breeding Amphibians

“…As dispersal corresponds to movement between breeding patches, the form of the dispersal kernels is intrinsically linked to the structure of the pond network (i.e., median of the distances between ponds, distance to the nearest and farthest pond). As reported in the section titled Transience and Dispersal Distances, the frequency of dispersal events decreases in a nonlinear fashion with the between-patch Euclidean distances (Breden 1987;Berven and Grudzien 1990;Trenham et al 2001;Funk et al 2005;Gamble et al 2007;Hamer et al 2008;Hendrix et al 2017;Muths et al 2018;Cayuela et al 2019a,b).…”

Conservation Implications of Spatiotemporal Variation in the Terrestrial Ecology of Western Spadefoots

“…In the case of pool‐breeding amphibians, genetic connectivity implies that movement between breeding pools and breeding among individuals from different pools is sufficient to maintain genetic diversity (Frei et al 2016, Wang and Shaffer 2017, Covarrubias et al 2021). Demographic connectivity similarly implies that enough individuals move between pools to promote persistence of metapopulations, either through recolonization of breeding pools that become extirpated or through dispersal of individuals from source populations to rescue sink populations from extirpation (Semlitsch 2008, Muths et al 2018, Bailey and Muths 2019). In both cases, intervening terrestrial land use and land cover must, at a minimum, allow safe passage of individuals from one breeding pool to another.…”

Behavior in a Changing Landscape: Using Movement Ecology to Inform the Conservation of Pond-Breeding Amphibians

“…However, a non-negligible proportion of adult individuals do not exhibit site fidelity in homing experiments. Moreover, a detectable level of transience in mark-recapture (MR) studies confirms the reality of nomadism in natural populations, showing that breeding dispersal can be frequent (Perret et al, 2003;Muths et al, 2018). Dispersal rates vary between amphibian species and populations, from near zero to 50% (Reading et al, 1991;Garwood, 2009; see Cayuela et al, 2018 submitted for review).…”

“…Most knowledge in this area relies on the analysis of gene flows or recapture data that indirectly provides information about movement pathways (Rowe et al, 2000). For example, Mark-Recapture data suggests that in the boreal toad, breeding dispersers follow straight pathways (Muths et al, 2018). As predicted by the theory of population genetics, the isolation of amphibian populations decreases genetic diversity as a result of gene flow impediment, genetic drift, and inbreeding when the effective population size is small (Andersen et al, 2004;Broquet et al, 2010;Rhoads et al, 2017).…”

“…Ambystoma maculatum Forest Males: 100 m Females: 200 m 2,000-4,000 m Zamudio and Wieczorek, 2007;Purrenhage et al, 2009 Ambystoma opacum Forest 200-400 m 1,300 m Gamble et al, 2007 Salamandra salamandra Forest 50-300 m 1,000-4,000 m Schulte et al, 2007;Bani et al, 2015 Bufo bufo Forest 550 m 1,000-3,600 m Moore, 1954;Daversa et al, 2012 Anaxyrus hemiophrys Forest 50-100 m 10,000 m Constible et al, 2010;Muths et al, 2018 Epidalaea calamita Open environment 700 m 3,000-12,000 m Miaud et al, 2000;Sinsch et al, 2012;Frei et al, 2016 Rana luteiventris Mixed Males: 200 m Females: 1,030 m 5,750 m Pilliod et al, 2002;Funk et al, 2005 in the others. However, the overall evolutionary challenge is to predict the propensity of leaving the natal population.…”