Life in the Slow Lane: Ecology and Conservation of Long-Lived Marine Animals

The Genetic Consequences of Reproductive Variance: Studies of Species with Different Longevities

Robert W. Chapman, George R. Sedberry, John C. McGovern, and Bradley E. Wiley

doi: https://doi.org/10.47886/9781888569155.ch13

Abstract. —Individuals of many aquatic species produce millions of offspring in a single spawning event, engage in several such events during a spawning season, and may be reproductively active for many years. Out of all of this activity only two offspring must reach reproductive age in order for the species to maintain its numbers. The genetic consequences of this high-risk strategy have been discussed in previous work. At least five null hypotheses concerning the relationship between reproductive output and the distribution of genetic variation can be constructed from theoretical considerations and the biology of weakfish Cynoscion regalis, spotted sea trout Cynoscion nebulosus , and red drum Sciaenops ocellatus . In this paper, we test four of these hypotheses and provisionally reject three. These results indicate the variance in reproductive output tends to reduce effective population size and lead to apparent (and misleading) fine-scale population structure in long-lived species.