MALE TO FEMALE POPULATION CHANGING PARASITES
Gender is a very strange and odd thing in our current age. What used to be a concrete is now a fluid sense of identity that is defined by the individual and not society. This is a new phenomena to us humans but, nature has always held this fluid identity when it comes to gender in a plethora of ways. Simple examples of this are animals such as the black spotted angelfish in which there can only be one dominant male. When the male dies the largest of the females will become the new male until that one dies and the process repeats itself. Among all of the organisms that do this there are two that alter other organisms genders instead of themselves.
The first of the two is called Sacculina and it is a small barnacle that parasitizes crabs. The female larva of Sacculina will find a joint on the crab and then molts into a kentrogon which is a soft bodied form. Once in this form it will inject itself into the crab while it molts its shell. The parasite develops inside the crab until it appears as a medium sized sac on the bottom of the crab. Invasion of the crab by the Sacculina results in two major changes. The first is that the crab is no longer capable of molting and therefore cannot get any bigger or regrow any missing claws. This comes as a result of the parasite siphoning away the crabs nutrients for itself. The second change is that Sacculina starts drastically altering the crabs hormones. For female crabs it makes them behave as if they are pregnant but for males its a bit of a different story. The change in hormones sterilizes the males and alters the crabs body makeup to resemble that of the female. In addition the infected crabs will care for the Sacculina’s eggs once it lays them, even distributing them into the ocean as it would its own eggs.
The second of the two and true king of gender bending is the bacteria known as Wolbachia. Wolbachia infects a variety of arthropods with a high majority being insects. Wolbachia is a very special parasite in that in some cases it has become more symbiotic than parasitic but, before that lets see what it does to its hosts gender. Wolbachia alters gender and controls reproduction through four major pathways. The first two effect the larva of the host species by making male larva more likely to die before maturity and by making male larva more likely to be born female or sterile. This makes it so males of the host are scarce, especially fertile ones. So one might ask how in the world is this organism going to reproduce now? Well luckily Wolbachia figured that one out through a process called parthenogenesis. Parthenogenesis is a process of asexual reproduction that creates embryos without fertilization. Last but not least is kind of a fail safe to make sure that even if a male manages to make it through it can’t do anything to change the fate of its species. This fail safe is called cytoplasmic incompatibility and it makes it so even if an infected male manages to survive and stay fertile it will be unable to reproduce with any uninfected organisms and organisms with a different strain of wolbachia, thus giving wolbachia a sort of monopoly on the genus of that species. Now this doesn’t exactly harm the organism per se, as the reproductive control it enacts isn’t really a negative thing to the organism. In fact in some cases Wolbachia actually provides benefits to its host. It has been shown that infection with the parasite has resulted in increased viral resistance to a variety of viruses that infect their hosts. In addition Wolbachia also increases the number of offspring the host has and in some cases even provides chemicals for metabolic processes. For example, without Wolbachia the common fruit fly would be unable to metabolize iron.