Selfish genetic elements can promote their transmission at the expense of individual survival, creating conflict between the element and the rest of the genome.Recently, a large number of toxin-antidote (TA) post-segregation distorters have been identified in non-obligate outcrossing nematodes.Their origin and Memes the evolutionary forces that keep them at intermediate population frequencies are poorly understood.Here, we study a TA element in Caenorhabditis elegans called zeel-1;peel-1.
Two major haplotypes of this locus, with and without the selfish element, segregate in C.elegans.We evaluate the fitness consequences of the zeel-1;peel-1 element outside of its role in gene drive in non-outcrossing animals and demonstrate that loss of the toxin peel-1 decreased fitness of hermaphrodites and resulted in reductions in fecundity and body size.These findings suggest a Medication Management biological role for peel-1 beyond toxin lethality.
This work demonstrates that a TA element can provide a fitness benefit to its hosts either during their initial evolution or by being co-opted by the animals following their selfish spread.These findings guide our understanding on how TA elements can remain in a population where gene drive is minimized, helping resolve the mystery of prevalent TA elements in selfing animals.