Age- and size-dependent mating performance and fertility in a pelagic copepod, Temora longicornis

Abstract

In many species, size and age can be strong determinants of the reproductive success for both sexes. We examined age- and size-dependent reproductive performance (egg and sperm production, mating success) in a pelagic copepod, Temora longicornis. Compared with smaller males, larger males produced larger spermatophores containing more spermatozoa and fertilized a larger fraction of available females. Females mating with large males produced more offspring than those mating with small males. Similarly, large females had higher egg production rates as well as a higher lifetime egg production than did small females. Ageing effects were evident in this species: Mortality rate increased and fertility decreased rapidly with age. The average adult longevity under optimal laboratory conditions was 30 d in both males and females, but females produced eggs for only 18 d, and males could fertilize females for only about 8 d after they matured. The strong size- and age-dependent fertility observed in this species is conducive to the development of sexual selection via mate choice for young and large partners, as has been shown in another copepod species. © Inter-Research 2011.