LSM1303 Animal Behaviour

Incest!! Taking motherly love to a whole new level

Animals need to mate in order to reproduce. That is the law of nature, and one that ensures the continued survival of the species. Yet during mating rituals, there will be someone left out, be it male or female. Either the male was not strong or attractive enough or the female was not seductive enough that they ended up lonely. Yet one bug has managed to go against all that by creating sexual partners for reproduction.

The Histiostoma murchiei mite goes against most mating laws and rituals that we have learnt in class. Instead of the usual sexual selection that animals go through in order to determine a mate, the female Histiostoma murchiei copulates with her offspring! And this is after creating them from scratch. ie. She lays eggs that can hatch unfertilized into males, and then have sex with them to breed more females.

This is such a weird from of reproduction, but I guess it does help make things a lot simpler. Gone are the days where males had to fight each other for the attention of females, or vice versa. With the Histiostoma murchiei, you are guaranteed a mate! If you don’t have one, create one! Sick as it may sound, it does seem to ensure the continued survival of the species, and keeping everything within the family to boot!

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<!–[if supportFields]> BIBLIOGRAPHY \l 1033 <![endif]–>10 Craziest animal behavior. (2006, May 6). Retrieved from 2spare: http://www.2spare.com/item_55014.aspx

Oliver, J. H. (1962). A Mite Parasitic in the Cocoons of earthworms. The Journal of Parasitology , 120-123.

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Brains or balls… If you can only have one, which would you have?

What a painful decision to make (I am guessing this… since I am not the male in question).

However, in the case of bats, this choice was made through evolution - Bats with smaller brains have bigger testes and bats with bigger brains ended up with the smaller testes.

In a fascinating study done by a research team led by Syracuse University biologist Scott Pitnick, it was found that in bat species with promiscuous females, the males had the largest testicle. However, these bats also sported the smallest brains. Conversely, in populations with faithful females, the male bats ended up with smaller testicles but bigger brains.

It is postulated that if female bats mate with more than one male (meaning a ‘promiscuous’ female), there would be sperm competition amongst the males. In such a case, the male who ejaculates the greatest number of sperm would win the game which is a possiblity behind the evolution of outrageously big testes in male bats from populations with promiscuous females.

This finding (of bigger brains with smaller testes and vice versa) has been tied down to the evolutionary tradeoff between intelligence and sexual prowress by many researchers. It is speculated that there exists a negative evolutionary relationship between the bats’ investment in testes and brains (as both are metabolically expensive tissues and it is extremely costly on the bats to maintain both in tiptop conditions i.e. HUGE).

In fact, according to the article, there has been a growing body of evidence which indicates that costly sexually selected traits (and these includes testis and ejaculatory traits) can tradeoff against other energetically expensive but important characters, such as immune function.

The possibility that investment in either extravagant sexually selected traits such as testes, or other similarly energetically expensive and important body parts or organs such as brains, would constrain investment in the other has certain implications in lieu for the sexual selection theory. It would seem to be that though the brain size could influence reproductive behaviors, sexual reproduction which favors larger or smaller investments in resource intensive organs, ornaments or armaments could similarly influence the brain and behaviour. So it might be too simple to assume your brain rules all. It seems likely that the brain is a result as well as a cause.

This tradeoff between brains and balls makes one wonder about humans, doesn’t it?

Would a more promiscuous society eventually result in males with smaller testes but larger brains? It doesn’t seems like a optimistic picture would be in view for the males of the future if that is indeed the case. However, luckily for the guys, humans are much more complicated organisms and there would probably be a lot more factors that might be involved in this tradeoff - It is unlikely that human males would lose either their brains or their balls.

(Do I hear a collective sigh of relief in the background…?)

References

Pitnick, S., Jones, K. E., & Wilkinson, G. S. (2005). Mating system and brain size in bats. Proceedings of The Royal Society B.

Ruvinsky, J. (2006). Secrets Of Bat Machismo. http://discovermagazine.com/2006/may/bats.

Photo by Sharon Hill, National Geographic

If you think that mosquitoes are detestable, wait till you read about blood-sucking moths. Researchers reported in October 2008 that a previously unknown population of vampire moths has been found in Siberia, and they may have evolved from a purely fruit-eating species. The Russian population’s wing patterns vary slightly from the common Calyptra thalictri, in central and Southern Europe that is known to feed only on fruits. The insects drilled their hook-and-barb-lined tongues under human skin and sucked blood when reseachers experimentally offered their hands to them .

Entomologist Jennifer Zaspel and her team at the University of Florida in Gainesville discovered the first population of vampire moths in Russia in 2006. She suggests that the moth population could be on an “evolutionary trajectory” away from other C. thalictri populations. Further DNA comparisons will be made, and if the results are confirmatory, it could provide clues as to how some moths develop a taste for blood (Zaspel et al., 2007). Researchers have hypothesized that blood-feeding evolved from feeding on tears, dung, and pus-filled wounds, but the big question is, why?

Zaspel noted that only male moths exhibit blood-feeding, and there was the possibility that the Russian moths do it to pass on salt to females during copulation. “There is no evidence it prolongs the life of the male, or anything like that,” she said. “So we suspect that it is probably going to the female.” This would provide a nutritional boost to young larvae that feed on leaf-rich, but sodium-poor, diets.

Professor Kauri Mikkola, who studies Finnish vampire moths, noted that the puncture made by the vampire moth is stronger than a mosquito’s, but he does not believe that it would be dangerous to humans as it is unlikely to spread any diseases (Helsingin Sanomat, 2007).

Vampire moths, National Geographic

Citations:

“Blood-sucking moth becoming more common in Finland”, by Helsingin Sanomat, June 5, 2009. Accessed April 12, 2009.

Zaspel, J. M., Kononenko, V. S., & Goldstein, P. Z., 2007. Another blood feeder? Experimental feeding of a fruit-piercing moth species on human blood in the Primorye territory of far Eastern Russia (Lepidoptera: Noctuidae: Calpinae). Journal of Insect Behavior, 20, 437-451.

“Vampire moth discovered – Evolution at work”, by John Roach. National Geographic News, October 27, 2008. Accessed April 12, 2009.

Pan Kun is not an ordinary Chimpanzee. He was raised by a Japanese researcher as a Japanese boy and has undergone learning of human behaviour as he was brought up as if he was a boy and he probably thinks he is. This is commonly known as social imprinting, with the evident extreme expression of filial piety towards human.
He is often featured on the NTV television show "Tensai! Shimura Dōbutsuen" and the TBS program "Dōbutsu Kisō Tengai!" (Unbelievable Animals!). Most of the segments feature him and his bulldog friend, James, embarking on a variety of "human" tasks, like buying groceries, planting a rice paddy, or catching insects.