Since we were discussing fruit fly sex the other day in class I thought this would be the perfect blog topic. The subject on which I’m writing has little to do with the actual sexual encounter between male and female frogs and more to do with the mating process. I’m taking a look at how female frogs can determine who would be a good match by the sound of their mating call and comparing it to how humans determine how well off they are with someone depending on how much of a ‘spark’ there is when they kiss.

As it turns out, the female tree frog is the one who chooses which male to mate with. Carl Gerhardt, an expert on tree frogs believes that the lek mating process is the most common; this is when the male is not in control, instead he is the one who must do the ‘wooing.’ During this process the males let out what is known as an “advertisement call” which gives the female tree frogs in the area the signal that that particular male is ready to mate as well as sending a signal to other male tree frogs to back off.  “Just how the male performs his advertisement call matters much to a female. Gerhardt’s own research showed that female gray tree frogs (Hyla versicolor) prefer advertisement calls that are long rather than short, because producing long calls is energetically costly and requires the male to be physically fit. “The females are choosing on the basis of an honest advertisement, on something that is costly to the male,” Gerhardt said.” (http://www.livescience.com/48213-animal-sex-tree-frogs.html)

According to a new study from the University of Missouri, there is a reason behind the female frogs choosiness when picking a mate. Not only does the type of call reveal the physical state of a male frog, but it also reveals the number of chromosomes a male frog possesses; a higher number of chromosomes is more pleasing to a female frog. “In previous studies, the scientists found that tree frogs with more sets of chromosome have larger cell sizes, which slows down the trill rate. What was not known was whether the calling preferences of females are similarly linked to chromosome number.”(http://www.sciencedaily.com/releases/2011/12/111227153754.htm)

Mitch Tucker, a doctoral student at the University of Missouri who was working alongside Carl Gerhardt, created a simulation of male tree frog calls and once the female frogs reached maturity levels, they were exposed to the calls and it was found that they “hopped toward the calls with the trill rate of the males with matching chromosome numbers, which indicates female preference” (http://www.sciencedaily.com/releases/2011/12/111227153754.htm). This also indicates that males with lower trill rates have larger cell sizes with also tells us that they have more chromosomes. 

Because of this discovery, it’s assumed that the chromosome number in the tree frog species is what “controls the behavior that keeps the species separate” (http://www.sciencedaily.com/releases/2011/12/111227153754.htm).

I think this study was very interesting. I always just assumed that animals (specifically male animals) used their calls to simply attract a mate; I didn’t know their was a status quo that female frogs followed in respect to the calls. In a way this is similar to how humans find a mate – there’s actually evidence of the same type of thing happening in the human species which I will discuss in part 2 of this blog.

Works Cited