Relationships between survival and habitat suitability of semi‐aquatic mammals

Abstract

Spatial distribution and habitat selection are integral to the study of animal ecology. Habitat selection may optimize the fitness of individuals. Hutchinsonian niche theory posits the fundamental niche of species would support the persistence or growth of populations. Although niche‐based species distribution models (SDMs) and habitat suitability models (HSMs) such as maximum entropy (Maxent) have demonstrated fair to excellent predictive power, few studies have linked the prediction of HSMs to demographic rates. We aimed to test the prediction of Hutchinsonian niche theory that habitat suitability (i.e., likelihood of occurrence) would be positively related to survival of American beaver (Castor canadensis), a North American semi‐aquatic, herbivorous, habitat generalist. We also tested the prediction of ideal free distribution that animal fitness, or its surrogate, is independent of habitat suitability at the equilibrium. We estimated beaver monthly survival probability using the Barker model and radio telemetry data collected in northern Alabama, United States from January 2011 to April 2012. A habitat suitability map was generated with Maxent for the entire study site using landscape variables derived from the 2011 National Land Cover Database (30‐m resolution). We found an inverse relationship between habitat suitability index and beaver survival, contradicting the predictions of niche theory and ideal free distribution. Furthermore, four landscape variables selected by American beaver did not predict survival. The beaver population on our study site has been established for 20 or more years and, subsequently, may be approaching or have reached the carrying capacity. Maxent‐predicted increases in habitat use and subsequent intraspecific competition may have reduced beaver survival. Habitat suitability‐fitness relationships may be complex and, in part, contingent upon local animal abundance. Future studies of mechanistic SDMs incorporating local abundance and demographic rates are needed.

Individual fitness is decoupled from coarse‐scale probability of occurrence in North American trees

“…Because our results suggest that fitness-centre correlations across multiple species are normally distributed around the zero, restricting the analysis to only few species makes the hypothesis more likely to be supported by chance alone (Santini et al 2019). Thus, while positive fitness-centre associations are clear for certain species, these may simply not hold true in other species (Thuiller et al 2010, Pellissier et al 2013 or even show a negative relationship (Barela et al 2020). Indeed, our analysis did not detect an effect of speciesspecific traits (dispersal ability and climatic breadth) on the fitness-centre relationship, suggesting that correlations are randomly distributed across ecologically different species.…”

“…The fitness-centre hypothesis has been detected for certain species in previous studies (Nagaraju et al 2013, Wittmann et al 2016, Sangüesa-Barreda et al 2018, Mammola et al 2019 but not in others (Larson et al 2010, Barela et al 2020, Chardon et al 2020. However, these studies show three main methodological limitations (which we will discuss in detail below).…”

“…Previous studies using SDMs to address the fitness-centre hypothesis used various functional traits as surrogates of individual fitness in both animals (Larson et al 2010, Pellissier et al 2013, Wittmann et al 2016, Mammola et al 2019, Barela et al 2020) and plants (Elmendorf and Moore 2008, Thuiller et al 2010, Sangüesa-Barreda et al 2018, Chardon et al 2020) and overall reported heterogeneous results. These studies generally tested the hypothesis on single species (but see Thuiller et al 2010) or normally used few observations of trait data collected in the field (but see Chardon et al 2020), possibly due to the rarity of the species under consideration (Mammola et al 2019) or because sampling functional traits at the intraspecific level over large areas is time-consuming and expensive.…”

A new approach to assessing the space use behavior of macroinvertebrates by automated video tracking

“…Recent theoretical and experimental efforts have highlighted the relevance of various individual movement modes, for example, searching (Auger-Méthé et al, 2015;Chakravarty et al, 2019), patch use, and giving-up behaviors (Brown, 1988;Charnov, 1976;Davidson & Hady, 2019). Studies of animal movement have become more frequent in recent years, emphasizing the conceptual significance of space use behavior (Barela et al, 2020;Nathan et al, 2008;Potts et al, 2014). Nevertheless, gaining insight into the motivations and limitations of individual behavior is still a major challenge in empirical studies (Froy et al, 2018), with implications for theoretical development (Stevens, 2010).…”

Predicting the Potential Habitat of Three Endangered Species of Carpinus Genus under Climate Change and Human Activity

“…Maximum entropy (MaxEnt) is a SDM with good simulation accuracy [14]. It has been widely used to predict habitats for endangered species, invasive species, and marine animals [15][16][17][18].…”