[p4irs]

Did that title get your attention? Well, yes, it’s a bit sensationalistic—wait till The Daily Mail gets hold of this!—but there are also evolutionary lessons here. I’ve previously posted about necrophilia in penguins, but those sex acts were largely unproductive with respect to offspring. In this case, though, males of a tropical frog have what is an apparently evolved behavior to get dead females to eject their eggs, fertilizing them as they’re squeezed out. Offspring are produced.

The behavior is reported in a recent paper by Thiago Izzo and colleagues in the Journal of Natural History (reference below; free download here). The species at issue, Rhinella proboscidea, is an Amazonian frog that engages in what is called “explosive breeding.” Over two or three days, several hundred males gather in streams or ponds, competing with each other to fertilize the females who drop by. But the frenzy to mount the females and copulate with them (eggs are expelled by the females, with males covering them with sperm as they emerge) is so heated that females are often drowned.

One would think that that would be the end of the story, but it isn’t. The males have an adaptation to copulate with recently-drowned females, squeezing their bellies with the male’s hindlimbs to make the corpse expel the eggs. The researchers observed at least four males doing this near the city of Manaus in Brazil, collecting the eggs and confirming that they were fertilized. Here are photos from the paper. Photo (c), with the dead female, is especially saddening.

Now I’m not sure whether the behavior involved in squeezing dead females differs from normal male copulatory behavior, but I suspect it does, since I’d guess that females voluntary expel eggs during copulation. I’m sure some herpetologist will weigh in here. But if the behavior does differ, then the necrophiliac squeezing is probably an evolved adaptation, since males squeezing dead females who still contain viable eggs will leave more offspring than non-squeezing males. The authors suggest that some morphological features of males, such as spines on their thumbs and large size, might also have evolved as adaptations for necrophilia. I find that more problematic, since these features probably exist in males of species that don’t commit such immoral acts.

The interesting question to ponder is whether dead females have also evolved to expel their eggs more easily. Let us not forget that natural selection can act post mortem, though I can hardly think of another case (a related case involved male spiders who catapault themselves into the jaws of their female mates after copulation, presumably giving the females a meal that increases their reproductive output). Any morphological feature of females that facilitates their expulsion of eggs after death will be selected for, as those features give the bearers a higher reproductive output than non-expellers. It’s not clear, though, whether that adaptation has evolved in females of this species.

The authors note that necrophilia has been seen in several vertebrates, including mammals, birds, reptiles, and other amphibians, but they add that this “is the first case where the necrophilia brings a direct fitness gain, generating descendants.”

http://whyevolutionistrue.wordpress....tropical-frog/

Photo Caption :
Figure from paper with caption: Figure 1. Necrophilia in Rhinella proboscidea in a central Amazonian headwater stream. Thousands of eggs (arrow) from a single reproductive event, in a small patch of a headwater stream (A). Two males in a battle for a drowned female. The larger (arrowed) is in amplexus and compressing the female’s abdomen with his legs, which resulted in expulsion of the oocytes (B). Male compressing the abdomen of a dead female, which resulted in expulsion of her oocytes (C).

[p4irs]

well its not mine, so when it says " i ".. its referring to the writer, not me lol

[Sharon]

Weird

Frogs are that cold anyway, they probably didn't realise she was dead.

[Sharon]

records of “depraved sex acts” by penguins finally released after a century

[bob351]

necrophilia is largely unproductive with respect to offspring...

[BadAshly]

If they have evolved to literally push the eggs out of the dead female I bet they know she's dead. A live female gives the eggs willingly, while a dead one needs to have them pushed out. I bet they know she's dead. Wether or not they care is another story. Lol