Meeting Abstract
P3.83 Wednesday, Jan. 6 Energy Investment during Courtship by Male vs. Female Red-Sided Garter Snakes (Thamnophis sirtalis parietalis) MICHAELSON, Jessi-Ann B.*; POWERS, Donald R.; FRIESEN, Chris R.; MASON, Robert T.; George Fox Univ, Newberg, OR; George Fox Univ, Newberg, OR; Oregon State Univ, Corvallis, OR; Oregon State Univ, Corvallis, OR dpowers@georgefox.edu
Male red-sided garter snakes (Thamnophis sirtalis parietalis) incur large energetic costs during reproduction (about 18X SMR) due to prolonged courtship of females and direct male-male competition. This is not surprising since reproductive success is a primary component of male fitness. In most sexually reproducing species energy expended during reproduction differs between males and females as females spend more energy on production of young. However when females are courted by many males it might also be necessary for females to spend energy on courtship activity in order to increase fitness through female choice. If true then interesting evolutionary questions arise as we try to understand what reproductive success means to females when faced with fixed energy availability. We assessed energy expenditure of both males and females and ventilation patterns (VP) of females during courtship and mating. Trials involved either a receptive or nonreceptive female that was courted by either a small (6 males) or large (12 males) mating group. Metabolic rate (MR) was measured using open-circuit respirometry (VO2) and VP measured using whole-body plethysmography. Females did not upregulated their MR or changed their VP in response to male courtship. Thus courtship and mating does not appear to be a major component of a female’s reproductive costs. Further, if females are exercising choice in mate selection then they are likely doing so by some other means. Males courting receptive females had MR > 2X males courting nonreceptive females. This adds support for the importance of chemical cues provided by females in the efficient selection of potential mates.
