Sara Ceballos, Mie Hylstofte Sichlau, Jan Heuschele, and Thomas Kiørboe
Low fertilization rates in a pelagic copepod caused by sexual selection?
Journal of Plankton Research. 2014 doi: http://dx.doi.org/10.1093/plankt/fbu021
The study assesses the prevalence of fertilization limitation within copepod populations, due to its importance for understanding secondary productivity in coastal food webs. It investigated the fraction of fertilized females in the field (North Sea) and in the laboratory, and found that a large fraction of the females were not fertilized in both populations (< 50 %). The found fraction of fertilized females was compared with predicted values from a theoretical model assuming random mating and were much smaller than predicted by the model.
Low fertilization rates are normally attributed to detrimental or a poor female diet, the occurrence of sex change and suboptimal temperatures, however the low fraction of fertilized females could not be related to food availability, sex ratio or male mating rate. However, the fraction of fertilized females was negatively correlated with both adult and male density. On average males mated < 1.5 times per day and a large fraction 25-57 % of the males did not mate. The male mating rate was not influenced by the sex ratio, or by female, male or adult abundance in their original population.
This study suggests that mating in Temora longicornis is not random and proposes that sexual selection by mate choice, male-male competition and other reproductive behaviours could explain the low fraction of fertilized females. Thereby, sexual selection reduces the females mating success and causes fertilization limitation.
Read the full study here: Journal of Plankton Research
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