Meeting Abstract
P1.53 Thursday, Jan. 3 Metabolic costs of courtship <&> mate searching in male garter snakes FRIESEN, Chris/R.*; MASON, Robert/T.; Oregon St. Univ. friesenc@science.oregonstate.edu
Females of most sexually reproducing organisms invest more in the production of offspring than do males. Males then tend to compete for access to females and in the process expend their energetic capital on mate searching, male-male competition and courtship rather than directly on offspring. Red-sided garter snakes (Thamnophis sirtalis parietalis) emerge from large communal dens to form large mating aggregations where the operational sex ratio is highly skewed toward males. Males must search through these aggregations to find and then court females, a so-called �scramble� mating system. In addition, courtship is a vigorous activity that can last for 30 minutes to an hour per bout, during which males struggle to stay in contact with females, maintaining body alignment while many other males compete for the same female. Once mated, females tend to disperse from the den while males remain to seek further mating opportunities. I examined the metabolic rates of males using the Doubly Labeled Water (DLW) technique. I injected 60 males with DLW at a communal den and recaptured 27 after 8 days. In addition, to separate the costs of courtship and mating from the overall cost of mate searching and other costs associated with remaining around the den, I injected males with DLW and placed them in one of three treatment groups: control, which were kept in a semi-natural arena without access to females (n = 24), males that were allowed access to females for courtship but were not allowed to mate (n = 24), and finally, males that were allowed access to females for courtship and were allowed to mate (n =24). Preliminary analysis suggests that courtship accounts for a significant proportion of the metabolic costs of reproduction for these males, but that mate searching and other costs associated with remaining at the den are also of major importance.
