Anti-courtship pheromone:
Red-sided
garter snakes (Thamnophis sirtalis parietalis) court and mate in early spring around large communal
overwintering dens in central Manitoba. Emerging females are immediately
covered by dozens or hundreds of vigorously-courting males, potentially
imposing significant costs to the female. By manipulating numbers of courting
males (both directly and by applying anticourtship pheromones), we quantified
the degree to which female dispersal from the den is hindered by courtship.
Courted females dispersed only about half as fast as did solitary females. Blood
lactate levels were higher in mating than in courting or noncourting snakes of
both sexes; the high levels of lactate in mating females support the idea that
courtship is physiologically stressful to these animals, perhaps via
constraints to female respiration (Richard Shine
et al.,2004).
By
manipulating numbers of courting males (both directly and by applying anti-courtship pheromones), we quantified the
degree to which female dispersal from the den is hindered by courtship. Courted
females dispersed only about half as fast as did solitary females (Shine et al.,2001). Aggregation with conspecifics is a
robust phenomenon among snakes that is mediated by chemical cues, although the
source of such cues is unknown. Adult western ribbon snakes (Thamnophis proximus) discriminated between skin lipid extracts from conspecifics
and those from a sympatric heterospecific snake, the corn snake (Elaphe guttata). Additionally, ribbon snakes were attracted to conspecific
skin lipid-marked shelters when paired with control-marked shelters, but no
preference was exhibited when shelters marked with E. guttata skin lipids were paired with
control-marked shelters. Furthermore, prevention of chemical access to the
vomeronasal organs of T. proximus eliminated the ability to respond to
conspecific skin lipids. These results indicate that epidermal lipids are the
source of chemical cues mediating attraction to shelters marked by conspecifics
and that such signals are detected by the vomeronasal system (Graves et al.,1991).
References:
Graves,
Brent M., Mimi Halpern, and Janet L. Friesen.1991.Snake aggregation pheromones:
Source and chemosensory mediation in western ribbon snakes (Thamnophis proximus)." Journal of Comparative Psychology 105(2):140.
Shine R,
Phillips B, Waye H, LeMaster M, Mason RT. 2001. Benefits of female mimicry to
snakes. Nature, 414: 267.
Richard Shine ,Ben Phillips , Tracy
Langkilde , Deborah I.
Lutterschmidt, Heather Waye and Robert T.
Mason.2004. Mechanisms and consequences
of sexual conflict in garter snakes (Thamnophis sirtalis, Colubridae), Behavioral
Ecology.,15(4):654-660
