Grouping World Cetaceans According to Life-history Characteristics Indicates Two Divergent Strategies

Posted on Sep 25, 2013

Author

Steven H. FERGUSON and Jeff W. HIGDON

Correspondence: Steven H. Ferguson, Fisheries and Oceans Canada, 501 University Crescent, Winnipeg, Manitoba, R3T 2N6, Canada. Email: steve.ferguson@dfo-mpo.gc.ca

Received 12 August 2013 – Accepted 25 September 2013


Abstract

Organisms tend to group according to different life-histories, and groups respond differently to environmental change, which forms the basis of conservation biology. Our goal was to assess whether cetaceans species form distinct groupings based on lifehistory parameters which might respond differently to changes in their local environment. Using a phylogenetic approach, we found that world cetacean life-histories clustered into two major groups that we termed “bet-hedgers” and “reproducers”. Cetacean species defined as bet-hedgers were characterized by a life history that was spread over a long life with reduced investment in progeny, perhaps an adaptation to environmental variability. In contrast, reproducer cetacean species were characterized by a greater investment in reproduction relative to adult longevity, a pattern likely well-suited to more productive and stable habitats. The pattern of life history groupings suggests that distributional adjustments of species range with anthropogenic change may depend on differences in the adaptability of the two groups. These results imply that the two groups have evolved adaptive responses to very different environmental forces. Future research should attempt to determine the divergent environmental selective pressure responsible for the life-history dichotomy, such as diet quality, predation, and environmental predictability. Combining knowledge of life-history patterns and monitoring changes in the marine environment may assist efforts to preserve cetacean diversity by predicting demographic response.

Key Words: Biogeography, Cetaceans, Competition, Conservation, Distribution, Life-history Evolution, Phylogeny, Reproduction.

 

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