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.
Highlights
Habitat suitability models (HSMs) and species distribution models (SDMs) have become popular research tools for spatial ecology, population ecology, and biodiversity conservation (Evcin, Kucuk, & Akturk, 2019; Mohammadi, Ebrahimi, Shahriari Moghadam, & Bosso, 2019; Monsarrat, Novellie, Rushworth, & Kerley, 2019). These two models may differ in spatial scopes, with the latter covering a larger spatial extent that may include the entire geographic range of species, HSMs and SDMs are often based on ecological niche theory (Elith & Leathwick, 2009; Hirzel & Le Lay, 2008)
Under the assumption of ideal free distribution, habitat selection models predict that an animal's spatial distribution is proportional to the amount of resources available in habitat patches and that fitness of individuals is equal among habitat patches at the equilibrium (Fretwell & Lucas, 1969)
Our results did not support the prediction (P1) that survival of American beaver would be positively related to habitat suitability index (HSI)
Summary
Habitat suitability models (HSMs) and species distribution models (SDMs) have become popular research tools for spatial ecology, population ecology, and biodiversity conservation (Evcin, Kucuk, & Akturk, 2019; Mohammadi, Ebrahimi, Shahriari Moghadam, & Bosso, 2019; Monsarrat, Novellie, Rushworth, & Kerley, 2019). The American beaver (Castor canadensis) is a semi-aquatic rodent that feeds on deciduous trees, shrubs, and aquatic plants (Baker & Hill, 2003) It is deemed an ecosystem engineer (Jones, Lawton, & Shachak, 1994) because of its substantial impacts on the composition and physiognomy of forest communities and landscapes through herbivory and water impoundment with dam construction (Naiman, Johnston, & Kelley, 1988). Our study focused on American beaver, this study has broad implications for SDMs in general
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
