Are Dark Throats Selected for in Eastern Gray Treefrogs?
Mentor 1
Gerlinde Höbel
Location
Union Wisconsin Room
Start Date
5-4-2019 1:30 PM
End Date
5-4-2019 3:30 PM
Description
Sexual dimorphism in morphology (physical differences between the sexes) or color is widespread in the animal kingdom, and this pattern is frequently accentuated during the mating season. Male frogs reaching sexual maturity generally develop a vocal sac, which is primarily involved in the mechanisms of call production. However, in many species the throat area is also pigmented and conspicuous, suggesting that the vocal sac might act as a visual signal as well. We examined vocal sac coloration in Eastern Gray Treefrogs (Hyla versicolor). We found that throat pigmentation of Eastern Gray Treefrogs is a sexually dimorphic trait that varies among males. This suggests that it could have a function in social communication and mate choice. Our hypothesis is that males are selected for the darkness of their throats. If this is true, then successful males will have darker throats than unsuccessful males. We took pictures of the throats of males in amplexus (successful) and males that did not mate (unsuccessful) to find the darkness and area of their throat pigmentation. We used ImageJ software to find the average grey value and size of each throat. We found that unsuccessful males have darker and larger throat areas when compared to successful males. Our hypothesis was unsupported by this data. In future field seasons we might duplicate this experiment to see if it was not the cold weather during this particular season that caused pressure to breed. If the frogs were constrained, there may not have been strong selection.
Are Dark Throats Selected for in Eastern Gray Treefrogs?
Union Wisconsin Room
Sexual dimorphism in morphology (physical differences between the sexes) or color is widespread in the animal kingdom, and this pattern is frequently accentuated during the mating season. Male frogs reaching sexual maturity generally develop a vocal sac, which is primarily involved in the mechanisms of call production. However, in many species the throat area is also pigmented and conspicuous, suggesting that the vocal sac might act as a visual signal as well. We examined vocal sac coloration in Eastern Gray Treefrogs (Hyla versicolor). We found that throat pigmentation of Eastern Gray Treefrogs is a sexually dimorphic trait that varies among males. This suggests that it could have a function in social communication and mate choice. Our hypothesis is that males are selected for the darkness of their throats. If this is true, then successful males will have darker throats than unsuccessful males. We took pictures of the throats of males in amplexus (successful) and males that did not mate (unsuccessful) to find the darkness and area of their throat pigmentation. We used ImageJ software to find the average grey value and size of each throat. We found that unsuccessful males have darker and larger throat areas when compared to successful males. Our hypothesis was unsupported by this data. In future field seasons we might duplicate this experiment to see if it was not the cold weather during this particular season that caused pressure to breed. If the frogs were constrained, there may not have been strong selection.
