INDIRECT COMPETITION BETWEEN A RESIDENT UNISEXUAL AND AN INVADING BISEXUAL GECKO

Abstract

AbstractEstablished populations of the unisexual gecko, Lepidodactylus lugubris, decline around man-made lights when the bisexual gecko, Hemidactylus frenatus, invades the environment. Some of the decline in L. lugubris numbers could occur through the process of exploitative competition for food resources. Our experiments were designed to see if other variables were important in the decline. We found that L. lugubris were more likely to use a hiding platform in enclosures with 2 rather than 1 platform when conspecific or heterospecific pairs of geckos were housed in an enclosure. Additionally, when two H. frenatus were housed in the same enclosure, they maintained closer proximity to each other than when their cagemates were L. lugubris. L. lugubris developed and laid more eggs when housed with another L. lugubris than when housed with either a female or male H. frenatus. Most interestingly, L. lugubris housed in enclosures previously occupied by H. frenatus males required more time for egg development and laying than geckos housed in enclosures previously occupied by another L. lugubris. In conclusion, variables in addition to food competition may influence the declines in L. lugubris numbers when an area in which they are established is invaded by the bisexual gecko, H. frenatus. L. lugubris numbers may decline in response to their reluctance to share a hiding place with another gecko, leaving them more vulnerable to predators. Additionally, L. lugubris fecundity may be negatively affected by the exudates from H. frenatus femoral pores or the odors of their feces.