Determining the necessity and mechanisms of assortative mating in an adaptively diverging salamander population (Salamandra salamandra)
Final Report Abstract
Assortative mating - preferred mating with the own type - is a central theme within the concept of adaptive speciation, as it is required to prevent gene flow between differentially adapted types. Recent studies on a population of the terrestrial fire salamander (Salamandra salamandra) in Germany (the Kottenforst near Bonn) suggest that the adaptation to different reproduction habitats within the small forest initiated a process of adaptive divergence under sympatric conditions. Goal of the project was to analyse the isolation mechanism in this population with main emphasis on the importance of assortative mating and to identify the traits that are involved in mate recognition and mate choice. Within the three years of the project the following results have been found. Females of the two habitat linked genetic clusters show behavioural differences with respect to their larval deposition behaviour. Reproductive success is positively linked to the level of polyandry and genetic similarity, with polyandrous females siring on average more larvae. There is evidence for non-random mating under natural conditions. Females sired more often than expected by random choice offspring from fathers that match to the habitat of the female. In mating experiments, females also showed a preference to mate with males that match the habitat type of the female. Substrate born olfactory cues, which are known to play a role in sex recognition, do not seem to be involved in mate recognition, i.e. females do not distinguish between males of the two habitat linked genetic clusters based on olfactory cues. Early nutritional stress in fire salamander larvae causes behavioural differences with respect to risk-taking behaviour in larvae and has an influence on the color pattern after metamorphosis. Fire salamanders seem to benefit from having a higher proportion of yellow, as this reduces the risk of being attacked by predators.
Publications
- (2011). Poor-nutritional conditions during the early larval stage reduce risk taking activities of fire salamander larvae (Salamandra salamandra). Ethology 117: 416-421
Krause ET, Steinfartz S, Caspers BA
- (2011): Preference for the other sex: Olfactory sex recognition in terrestrial fire salamanders (Salamandra salamandra). Amphibia-Reptilia 32:503-508
Caspers, B.A., & Steinfartz, S.
