The effects of experimental manipulation of resources on the behavior of two calopterygid damselflies that exhibit resource-defense polygyny

Abstract

Male odonates offer many examples of resource-defense mating systems and provide opportunities to test the hypothesis that in such systems the amount of resources controlled by a male will determine his mating success. Experimental alterations in oviposition site resources contained in the territories of the calopterygid damselflies Calopteryx maculata and Hetaerina vulnerata yielded different results. Removal of all oviposition resource substrate from occupied territories of H. vulnerata did not cause males to abandon their sites, nor did it affect the probability that females would come to these areas to mate. In contrast, males of C. maculata whose territories had been stripped of floating plant material generally abandoned the area within 1 h. Females of this species were more strongly attracted to sites with the most oviposition resources and males fought more intensely for these territories. Because females and males of C. maculata can assess the amount of floating substrate in a territory, this information influences where individuals mate, which sites they defend, and the intensity with which they fight for a location. In H. vulnerata, however, females oviposit underwater into sunken plant material hidden beneath fast-moving water. Because resource assessment is more difficult in H. vulnerata, females do not secure information on the quantity of oviposition substrate in a male's territory prior to mating, and male mating tactics, therefore, differ substantially from those employed by C. maculata.