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Biol Lett. Jun 23, 2010; 6(3): 382–386.
Published online Dec 9, 2009. doi:  10.1098/rsbl.2009.0780
PMCID: PMC2880035
Improved viability of populations with diverse life-history portfolios
Correigh M. Greene,1* Jason E. Hall,1 Kimberly R. Guilbault,2 and Thomas P. Quinn3
1Northwest Fisheries Science Center, 2725 Montlake Boulevard East, Seattle, WA 98112, USA
2Graduate Degree Program in Ecology, Colorado State University, Fort Collins, CO 80523, USA
3School of Aquatic and Fisheries Sciences, University of Washington, Seattle, WA 98195, USA
*Author for correspondence (correigh.greene/at/noaa.gov).
Received September 26, 2009; Accepted November 18, 2009.
Abstract
A principle shared by both economists and ecologists is that a diversified portfolio spreads risk, but this idea has little empirical support in the field of population biology. We found that population growth rates (recruits per spawner) and life-history diversity as measured by variation in freshwater and ocean residency were negatively correlated across short time periods (one to two generations), but positively correlated at longer time periods, in nine Bristol Bay sockeye salmon populations. Further, the relationship between variation in growth rate and life-history diversity was consistently negative. These findings strongly suggest that life-history diversity can both increase production and buffer population fluctuations, particularly over long time periods. Our findings provide new insights into the importance of biocomplexity beyond spatio-temporal aspects of populations, and suggest that maintaining diverse life-history portfolios of populations may be crucial for their resilience to unfavourable conditions like habitat loss and climate change.
Keywords: biocomplexity, life-history diversity, population dynamics
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