Using life history trade-offs to understand core-transient structuring of a small mammal community

An emerging conceptual framework suggests that communities are comprised of two main groups of species: core species that are temporally persistent, and transient species that are temporally intermittent. Core and transient species have been shown to differ in spatiotemporal turnover, diversity patterns, and importantly, survival strategies targeted at local vs. regional habitat use. While the core-transient framework has typically been a site-specific designation for species, we suggest that if core and transient species have local vs. regional survival strategies across sites, and consistently differ in population-level spatial structure and gene flow, they may also exhibit different life-history strategies. Specifically, core species should display relatively low dispersal rates, low reproductive effort, high ecological specialization and high survival rates compared to transient species, which may display a wider range of traits given that transience may result from source-sink dynamics or from the ability to emigrate readily. We present results from 21 years of capture-mark-recapture data in a diverse rodent community, evaluating the linkages between temporal persistence, local abundance, and trade-offs among life-history traits. Core species at our site conservatively supported our hypotheses, differing in ecological specialization, survival and dispersal probabilities, and reproductive effort from transient species. Transient species exhibited a wider range of characteristics, which likely stems from the multiple processes generating source-sink dynamics and nomadic transience in local communities. We suggest that trait associations among core-transient species may be similar in other systems and warrants further study.