Bet-hedging applications for conservation

Abstract

One of the early tenets of conservation biology is that population viability is enhanced by maintaining multiple populations of a species. The strength of this tenet is justified by principles of bet-hedging. Management strategies that reduce variance in population size will also reduce risk of extinction. Asynchrony in population fluctuations in independent populations reduces variance in the aggregate of populations whereas environmental correlation among areas increases the risk that all populations will go extinct. We review the theoretical rationale of bet-hedging and suggest applications for conservation management of least terns in Nebraska and grizzly bears in the northern Rocky Mountains of the United States. The risk of extinction for least terns will be reduced if we can sustain the small central Platte River population in addition to the larger population on the lower Platte. Similarly, by restoring grizzly bears to the Bitterroot wilderness of Idaho and Montana can reduce the probability of extinction for grizzly bears in the Rocky Mountains of the United States by as much as 69-93%.

Evidence for isolation by time in the European eel (Anguilla anguilla L.)

“…IBT on a broader scale and genetic patchiness on a local scale are not contradictory but a consequence of the catadromous life strategy of the European eel, leading to a large variance in parental contribution and subsequent reproductive success. The protracted spawning season as well as the variance in age at maturity might represent a ‘bet‐hedging strategy’, by spreading reproductive effort over time to protect eggs and larvae against unpredictable environmental conditions and food availability in the Sargasso Sea (Boyce et al . 2002; Flowers et al .…”

Distribution and Abundance of the Interior Population of the Least Tern (Sternula Antillarum), 2005; A Review of the First Complete Range-Wide Survey in the Context of Historic and Ongoing Monitoring Efforts

“…Collaborative efforts are ongoing to discuss and resolve discrepancies among historic data within the Platte River system (Renae Held, Tern and Plover Partnership, personal communication). Hopefully, these efforts will reconcile the many different versions of historic data for the Platte River system that have been presented in Sidle et al (1991), Dinan et al (1993), Sidle and Kirsch (1993), Kirsch (1996), Kirsch and Sidle (1999), Kirsch (2000), Boyce et al (2002) The small percentage of birds breeding on riverine sandbars of the "Lower" Platte River in 2005 is anomalous. Typically, about 58 percent of ILT nest on river sandbars on the "Lower" Platte, whereas only 53 of 381 birds (14 percent) were nesting on the river in 2005 (Appendix C).…”

Degeneracy allows for both apparent homogeneity and diversification in populations

“…However, the resulting phenotypic homogeneity should limit a population’s ability to successfully adapt to novel environmental stresses, and there is an inherent opposition between stable habitat conditions, which reward population convergence to the most beneficial traits, and environmental novelty, which rewards the maintenance of heritable trait differences. Stated more abstractly, there are opposing needs to, on the one hand, maximally exploit currently stable conditions by maintaining trait homogeneity in the population and, on the other hand, to hedge the population’s bets about future unexpected environmental changes by diversifying traits (Boyce et al, 2002; Childs et al, 2010). Similarly, opposing needs for phenotypic stasis and diversification arise within a number of socially and economically relevant non-biological systems that are subjected to variation and selection in a dynamic environment.…”