Scientists Turn To Yeast To Uncover If Sex Is Really Worth The Effort

Yeast on sex: Is it worth the faff? Kateryna Kon/Shutterstock

Rachael Funnell 13 Feb 2020, 13:06

If you’ve used dating apps then you’ll probably appreciate how exhausting finding a mate, keeping a mate, and mating can be. Apparently so too do researchers at Monash University, who recently found themselves asking if it’s really worth the effort. After all, why not cut out the hassle and just make a clone of yourself? A recent study published in the journal Nature Ecology and Evolution turned to the sex lives of yeast to suss out if it really is worth all the palaver.

Before we get into the study methods, let’s talk about genes (baby). Yeasts are an ideal subject for studying the potential benefits (or lack thereof) of sex, as they reproduce on their own, known as asexual reproduction, as well as sexually reproducing with other yeast organisms. The main difference between these two modes of reproduction (minus the lack of hanky-panky) is that one method creates a carbon copy of the parent genotype while the other creates a mixture of both parents’ genetic material.

“Figuring out why most animals and plants bother going through the process of having sex is one of the longest-standing questions in biology,” said Dr Mike McDonald from the Monash University School of Biological Sciences, in one of the most romantic declarations of 2020.

In order to answer this question, McDonald and his research team, a collaboration between research groups in Academia Sinica in Taiwan, and Monash University, carried out evolution experiments using baker’s yeast and observed the genetic effects of the sexual and asexual populations. After nearly 1,500 generations, they found that both the sexual and asexual populations were surviving equally well. The lack of any benefit in the sexually reproducing group would imply that in fact no, sex is not worth the faff, but the key difference comes when you consider the process of adaptation in a changing environment.

“Every time yeast makes another cell by asexual or sexual reproduction mutations can happen. Most mutations are deleterious or have no effect, however some mutations may be beneficial,” said McDonald. “We discovered that even though asexual populations of yeast accumulated more mutations during evolution than sexual populations, the sexual populations accumulated their mutations in similar genes across the different replicate populations.”

This phenomenon is known as "parallel evolution" and it reveals that by mixing genetic codes through sexual reproduction, organisms better enable themselves to keep good mutations and get rid of bad ones, effectively streamlining the process of natural selection and making future generations the best fit for their environment. Essentially, for your offspring, sex pays.

The team also went back to look at the two evolved populations from both the sexually and asexually reproducing groups. They used molecular engineering techniques to assess the fitness effects of some mutations and herein lay the perks of a solitary life. In a statement, McDonald explained: “Yeast, like humans, have two copies of each chromosome. We found that for some mutations the most fit combination is when one chromosome has the version of the gene with the new beneficial mutation, and the other chromosome has the original gene.” In this instance, mating will result in half of all offspring losing this beneficial combination.

So, if you’re on your Tod this Valentine’s, rejoice! If the sex life of yeast is anything to go by, there are some perks to kicking it solo after all.

Why not continue this deep dive into copulation with some common sex myths everyone really needs to stop believing or look below for the facts on female ejaculation.

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