Prolonged life span among endemicGasterosteuspopulations

Abstract

Throughout their circumboreal coastal distribution, the threespine stickleback ( Gasterosteus aculeatus L., 1758) typically reproduce at 1 or 2 years of age (second or third summer) and die during the year of the reproductive cycle. Extending from a previous study on the Haida Gwaii archipelago, western Canada, that identified an exceptionally long life span (8 years) in a population of large-bodied threespine stickleback, we use pelvic spine annuli to examine age of the five largest adult stickleback of 12 additional populations comprising five populations with average-sized adults (45–60 mm standard length (SL)) and seven populations with large-bodied adult stickleback (>75 mm SL). Each of the small-bodied populations had a maximum age of 1 or 2 years typical for the taxon. Among the large-bodied populations, which also reached adult size in the 2nd year, adult stickleback in the populations ranged from 3 to 6 years, indicating extended longevity. Low productivity habitats and refuge against gape-limited piscivores, each of which theoretically predicts reduced rate of senescence, are associated with the greatest longevity among these populations. These data combined with the recent full genome sequence for stickleback provide opportunities for locating genetic markers for extended longevity.