Lesbian Lizards of South America

Lesbian Lizards of South America

Some people may be disappointed that this is not some kind of sci-fi porn script but it is a pretty interesting occurrence (and it is completely true). This article will focus on sexual reproduction and the benefits and shortcomings of both asexual and sexual species. There is, unfortunately, a lot of background necessary before I get to the lesbian lizards so if that’s not your thing, skip down the second section “Species surviving without sex”. Although typically species exhibit two distinct sexes, certain organisms reproduce asexually. Offspring is produced from a single parent and therefore inherits genes from a sole donor. Such species are sometimes present as a single sex and have adapted to survive in this way. Both vertebrates and invertebrates have been observed to express forms of asexual reproduction naturally, however it is often unclear why certain organisms switch from sexual reproduction to asexuality.

Some sensual girl on girl lizard sex.

Sexual Reproduction

To put it very simply, sexual reproduction is the fusion of 2 gametes via fertilisation to form a zygote which will inevitably develop into the complete organism. There are many benefits to utilising the genetic makeup of 2 parents. First and foremost, it allows for genetic mixing and the purging of deleterious or harmful mutations within a population. Sexual reproduction will also increase the rate of adaptation to an ever changing environment as favourable traits are more likely to be passed on to offspring. However, relying on a mate is costly. The “2 fold-cost of sex” is a theory first outlined by John Maynard Smith and accurately states that when undergoing sexual reproduction, only half of your genetic material is being passed on and the overall genome of the offspring is being shared with another member of the population. There is also the risk of potentially breaking up favourable genetic combinations. Some “good genes” might not get passed on, potentially lowering the general fitness of offspring. Finally, finding a mate is in itself costly. Often, seeking a suitable partners requires significant investment of time and energy whilst also increasing the risk of predation and parasite transmission. Several species have such bizarre mating rituals that the male or female are harmed in the process, inhibiting future reproductive ability. So why bother? If the 2-fold cost of sex tells us anything, sexual reproduction is half as effective as asexual reproduction of passing on genes.

A very costly mating strategy. The male preying mantis sacrifices its own life for fecundity. In order to mate with the female, he allows her to literally eat him.

A diagram highlighting the 2-fold cost of sex. Reliance on a mate only allows half of the individuals genetic material to be passed to offspring. Asexual populations do not incur this cost and all genes passed on are the single parents. 

Species Surviving Without Sex - Lesbian Lizards, Bdelloid rotifers and many, many more.

It would appear that most animals utilise 2 parents and sex to produce offspring. We do it, as do dogs, cats, horses, lions, tigers, rabbits etc. etc. However, more animals than you think have scrapped the ‘popular’ system. In my opinion, the best example of this is the Whiptail Lizard (Cnemidophorus). They originated from hybridisations of sexually reproducing species and have since adapted to life without males. Females can produce full clones of themselves through a modified form of meiosis. The female’s germ cells undergo premeiotic doubling so that 2 consecutive division cycles in the meiosis process result in a diploid, instead of a haploid genome. The females in this population have actually been observed to mimic sex acts, as if mating was occurring between a male and female, but with no actual sex taking place, just to get the hormones pumping. I have included a link below to show exactly what I mean because I can’t mention lizard girl on girl action without some kind of video.

http://www.bbc.co.uk/programmes/p006v48r

Obligate parthenogenesis is the process whereby organisms reproduce exclusively asexually, like the whiptail lizard, who have no other option but to do so. The most documented, historic example is bdelloid rotifers. These microscopic organisms have been present for millions of years and yet, not one male has ever been documented. On the other, more adaptive side of asexual reproduction, is the facultative parthenogens. These animals are generally sexually reproducing, but can switch to asexual reproduction when extreme conditions make it necessary. The Komodo dragon, hammerhead shark and blacktip shark are prominent vertebrate examples of this phenomenon. Other creatures capable of parthenogenic reproduction are several snail species, many flatworms, water fleas, some crayfish, honey bees, parasitic wasps as well as at least 20 fish, 25 lizard, 1 snake, frog and salamander species.

Looking for a mate? Doesn't matter, she can reproduce without one!

Disadvantages of Single Sex Reproduction

Although reproducing asexually removes the expenditure associated with finding a mate, copulating and all the other risks involved, sexual reproduction is a much more beneficial mechanism of reproduction. If an organism lives in a changeable environment, it is easy for an individual to fall prey to its own ecosystem. For example, if new predators are introduced, it would be difficult to adapt a form of defence or camouflage; or say the climate changes it may be difficult for the individual to moderate its body temperature effectively. Also with asexual organisms, harmful mutations become “trapped” within a population as there is no genetic mixing/heterozygosity to remove them. Of course this is an issue that can occur in sexually reproducing organisms but it is less likely that these harmful traits will be passed on to subsequent generations (Unless inbreeding is involved – see http://www.stannagescience.blogspot.com.au/2015/01/inbreeding.html for more information). Accumulation of deleterious mutations is known as "Muller's Ratchet".

Conclusion

In many instances, eliminating one gender has proved successful but it is not without its added risks. To conclude, there is not one correct way of survival in regards to reproduction, it is a matter of adaptation to extreme circumstances as well as avoiding the accumulation of harmful mutations within a population. Success stories from either side provide evidence they can co-exist and bdelloid rotifers have shown you can survive exclusively without mating for millions of years! Although they don’t lead a particularly exciting life.

I have done my best to reel this post in as it was quickly becoming a full blown essay. If I haven’t been clear on any areas I can expand on some points and provide more colourful examples!

Cheers!