Springtime Science

Spring is almost here. Love is in the air…  Birds are (or will soon be) courting, mating calls heard (or soon to be) heard from every bog and field. The two scientific discoveries I selected for this post are nature and, well, mating related.finch.jpg

Courtship is a spectator sport.

Take Australian zebra finches, for instance. Biologists describe an amazing “audience effect” in their mating habits. Namely, when a male finch is courting a finch-girl in front of another male or is being watched by an audience of his peers while at it, he is more likely to choose a more beautiful, catchy, brighter-colored girl. Specifically, researchers noticed, females with bright red crests on their heads have more chance to be courted while there is an audience of sympathetic but critically inclined friends.  zebra-finch.jpgLone male finch, however, follows “his heart’s desire” and a glamorous chick isn’t necessarily his first choice of mate. Interesting that this same effect has not been observed in female finches — girls, as a rule, seem oblivious to being observed by peers and chose boys despite their “trendy outfits,” completely disregarding other girls “opinions.” Go and figure.  The article Sex-Specific Audience Effect in the Context of Mate Choice in Zebra Finches explains it in scientific terms.sn-frog_0.jpg

Love to the last croak.

In my earlier post, Infectious Courage, the subject was Toxoplasma gondii, known to change the host’s behavior. (Studies showed the capability for the parasite to make rats fearless of cats, only to be eaten by them, so that to get inside of felines, their primary and preferable hosts.)

There is another in a series of examples where the parasite changes the behavior of the host in order to spread more effectively.  Those who are interested in nature, must have heard about the epidemic fungal disease in amphibians that destroyed a huge number of frogs and salamanders in some parts of the world (especially in Australia) over the last twenty years. Close to a hundred rare species are either extinct or soon to disappear.

A fungal disease that has killed amphibians worldwide may be spreading by making the mating calls of infected males more attractive to females. The finding—one of the first—to show that the pathogen can alter a species’s reproductive behavior could explain why frogs and related animals continue to disappear across the globe.

The name of the killer is  a pathogenic fungus, Batrachochytrium dendrobatidis (Bd), that causes chytridiomycosis (also known as chytrid fungus disease.)POTD_Smiling-Frogs.jpgIn what way the reproductive behavior of sick frogs change? It’s their mating call. Scientists noticed that a mating croak of an infected male frog differs in tone from that of a healthy one. And — surprise! — this sound is more attractive to unsuspecting girl-frogs. They become literally mesmerized by these differently tuned songs and choose lethargic, barely moving from the disease gentlemen-frogs as their mates. As a result, the infection is transmitted from males to females and continues to offspring. Hear the frogs croak here: Fungus turns frogs into sexy zombies.




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