Parningen och att välja rätt partner är väldigt betydelsefull för ... - IT

Kristina GrahnFemale Choice in Shore Crabs Carcinus maenas - a study of Sizeand Colour DependencyAbstractSexual selection in shore crabs, Carcinus maenas, appears to be controlled by male-malecompetition rather than female choice, as the male physically controls the female in the matingprocess. Here, the female choice was investigated and a female was given a choice of twotethered males. It was shown that females prefer the larger male of a pair and the larger the sizeof the largest male, the more time females spent with them. The shore crabs occur in two colourforms - red and green, but colour did not appear to be a signal to females, as they did notdiscriminate between red and green males. Morphological measurements showed that red crabswere heavier than green and had shorter chelipeds. Besides this, no noteworthy morphologicaldifferences were found between the colour forms. The crabs had a high prevalence of internalSacculina carcini (30.66 %), a parasite that may sterilize the crabs. However, this did not interferewith female behaviour. The shore crab is a lekking species and dominance hierarchy is establishedthrough male-male competition. The female shore crab can make a distinction between dominantand subordinate males on pheromone basis. In this experiment, no prior ranking was establishedand the males were not able to perform sexual display since they were tethered. Pheromones signallingdominance and posing from the males are together with body size probably alsoimportant for mate choice.