ABSTRACT
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 the evolutionary forces that keep them at intermediate population frequencies are poorly understood. Here, we study a TA element in C. elegans called peel-1/zeel-1. Two major haplotypes of this locus, with and without the selfish element, segregate in C. elegans. Here we study the fitness consequences of the peel-1/zeel-1 element outside of its role in gene drive in non-outcrossing animals. We demonstrate that loss of the toxin peel-1 decreased fitness of hermaphrodites and resulted in reductions in fecundity and body size. This fitness advantage is independent of the antidote zeel-1, suggesting that a distinct peel-1 pathway plays a biological role. 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.
Competing Interest Statement
The authors have declared no competing interest.
