AP Biology class blog for discussing current research in Biology

Tag: asexual

Males to Become Obsolete?

“No study in the past [has described] a complete elimination of males,” claims Rebeca Rosengaus, an insect sociobiologist and behavioral ecologist at Northeastern University. Professor Rosengaus’ statement relates to the study by postdoctoral researcher Toshihisa Yashiro and Professor Nathan Lo on Japanese 

islands of Shikoku and Kyushu, where termites are evolved to reproduce strictly asexual with a population of only females. The primary question facing the researcher team faces is how does this advanced animal population reproduce without the necessity for their male counterparts? The termite subset of the cockroach family is not the first creature to do so as there are species of hymenopteran insects, both ants and bees, that have gone female.  Due to the recent discovery of the evolutionary change, researchers can only hypothesis on the breeding techniques of the all-female termite populations based on similar populations of bees and prior termite activity. In the strictly feminine bee colony, the label queen, which normally mates and holds a sperm-hoarding pouch within her body from males, reproduces by laying unfertilized eggs which only receives chromosomes from their mothers and hatch producing females with double copies of their mothers’ chromosomes at a far faster rate. These termites, however, also varied from their typical monogamous relationships and queen and king breeders to a queen driven society before in order to avoid inbreeding between fertile kings and their own offsprings. So while there are many suspicions on the reproduction of these highly evolved termites, the answer to how they evolved to such conditions are left unknown as the normal order of society is to maintain the health of a colony through sexual reproduction to protect against diseases and environmental changes. Such diseases are believed to be rather rare, however, on the islands of Shikoku and Kyushu, yet this concept is under-researched as of now. These females are surviving after this shift in sexual dependence approximately fourteen million years ago as their all-female band of soldiers are structured far more uniformly and have increased defensive efficiency. These females are not suffering by any means without their male counterparts. The Glyptotermes nakajima species are the underrated feminist heroes of our insect world despite being only a few millimeters long with soft, doughy bodies. What do you think will human males someday become obsolete? Is this the way the world is going or just a random phenomenon?


Amino Kassid


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Odd Little Species Survives Without Sex

Of the two million know species on Earth, only about two thousand reproduce entirely asexually. Scientists think this is because organisms that reproduce without sex – which provides healthy genes from one parent that act as a template to repair mutated genes, leading to “theoretically healthier offspring” – are unable to mitigate the deleterious effects of gene mutation, which leads to their extinction. The bdelloid, a tiny, all-female, sea creature with a name that means “leechlike” for the way it moves, however, has survived for tens of millions of years without sex. In fact, they have diversified into more than four hundred species.

Researchers at the Marine Biology Laboratory in Woods Hole, MA wanted to find out why the bdelloid had avoided extinction, so they zapped some of the creatures with gamma radiation, which breaks up DNA. Oddly, the bdelloids did not succumb to the exposure even as the scientists pushed the radiation levels far past what would naturally occur on earth. When the mystified biologists examined the bdelloids’ DNA, they discovered that an early mutation had copied the entire genome, giving each organism four copies as opposed to the common two, which allowed it to repair severely damaged DNA. This mutation turned out to be beneficial for the aquatic creatures because it allows them to survive desiccation, a danger for bdelloids because of their transient underwater habitats.

More recently, scientists at the University of Cambridge published a paper in the journal PLoS Genetics recounting their discovery that about ten percent of the bdelloid’s genome is composed of alien DNA amassed through the consumption of bacteria, fungi, and algae. These foreign genes become active when a bdelloid dries out, and are thought to be partly responsible for the creature’s incredible ability to survive dehydration. Those same genes might also be behind “powerful antioxidants that protect bdelloids from the by-products of drying out”.

Evolutionary biologists are hopeful that a better grasp of the mechanisms that allow bdelloids to survive will lead to much greater discoveries such as how sex evolved. Matthew Meselson, a geneticist at Harvard University, said in an interview with LifeScience that “being able to understand how animal cells can be so resistant to radiation may be of some interest in understanding how [cancer, aging, and inflammation, of which DNA damage and repair are factors] might be inhibited in human cells.” Further experimentation could uncover new treatments that prolong life or fight cancer.

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