Being able to clone yourself does have some advantages. There’s no more need to find mates, which means you save quite a bit of time and. Turns out, South African Cape bees have almost mastered this art: when workers reproduce, they create almost perfect clones.
Parthenogenesis is a form of asexual reproduction. It doesn’t require any male fertilization — which makes it very convenient in some regards. Parthenogenesis occurs naturally in some plants and invertebrate species, and quite rarely, in a few vertebrate species (like fish, amphibians, reptiles, and very rarely birds). For all its advantages though, it also has a few major drawbacks.
The first is a lack of genetic diversity — you’re essentially reproducing by yourself, which means your gene pool doesn’t get any fresh input. But there’s perhaps an even bigger problem: the parthenogenesis itself.
Oftentimes, the approach doesn’t lead to perfect offspring as tiny bits of genetic material get mixed up. These mistakes (called recombinations) can lead to non-productive eggs or birth defects. But the African Cape honey bees appear to be able to avoid recombinations and produce near-perfect clones of themselves. The queens reproduce sexually, but for the workers, it’s asexual all the way.
To reach this conclusion , the researchers employed a cruel trick: they taped the reproductive organs of a queen, preventing males from mating with her. At the same time, they allowed both her and the worker bees in the same hive to reproduce asexually. They then tested the degree of recombination in both cases.
They found that the offspring of the queen had almost 100 times more genetic defects than the worker bees — while the offspring of worker bees were almost perfect clones of them. Even more testing found that one line of worker bees had been cloning themselves for almost 30 years, without showing any notable defects — suggesting that this is a viable long-term strategy, at least under some circumstances.
“We tested our hypothesis that Cape workers have evolved mechanisms that restrain genetic recombination, whereas queens have no need for such mechanisms because they reproduce sexually,” the researchers conclude.
The team also adds that despite their unique abilities, the bees are very much in line with evolution — they’re doing what serves them best in the long run.
Journal Reference: Benjamin P. Oldroyd et al, Adaptive, caste-specific changes to recombination rates in a thelytokous honeybee population, Proceedings of the Royal Society B: Biological Sciences (2021). DOI: 10.1098/rspb.2021.0729
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