Variation in life-history traits and behaviour among wolf spider (Hygrolycosa rubrofasciata) populations

Abstract

Differences in growth and reproduction related traits between closely located populations were studied in the drumming Hygrolycosa rubrofasciata wolf spider. Adult body mass varied greatly among populations and years. The variation was partly explained by environmental factors, and there were genetic differences among populations in body mass. It is probable that they reflect adaptive responses to habitat differences. Males and females had divergent growth strategies when reared on different feeding levels. In laboratory, females tried to attain as large body size as possible, while growth of males among populations responded differently to the amount of food and there was no clear tendency to grow as much as possible. Males from different habitats had variable mating tactics, i.e. males from bogs and meadows allocated differently on sexual signalling and mate searching. Females had no preference between the drumming signals of males from the own and strange habitats. Drumming activity was higher in large bog populations, and the pulse rate of the drumming signal correlated strongly with population size. The linear relationship between male pulse rate and population size may indicate weaker selection on drumming signal characters in smaller populations due to the lower encounter rate with females or males. Also population density and female presence seems to affect male allocation between components of mating effort. In sum, there appears to be considerable variation in growth and sexual courtship behaviour between the different habitats and populations, and part of this variation seems to be adaptive even if the distances between populations are in the scale of a few kilometres or less.