Molecular basis of the copulatory plug polymorphism in Caenorhabditis elegans

[摘要] Heritable variation is the raw material for evolutionary change, and understanding its genetic basis is one of the central problems in modern biology. We investigated the genetic basis of a classic phenotypic dimorphism in the nematode Caenorhabditis elegans. Males from many natural isolates deposit a copulatory plug after mating, whereas males from other natural isolates - including the standard wild- type strain ( N2 Bristol) that is used in most research laboratories - do not deposit plugs(1). The copulatory plug is a gelatinous mass that covers the hermaphrodite vulva, and its deposition decreases the mating success of subsequent males(2). We show that the plugging polymorphism results from the insertion of a retrotransposon into an exon of a novel mucin- like gene, plg-1, whose product is a major structural component of the copulatory plug. The gene is expressed in a subset of secretory cells of the male somatic gonad, and its loss has no evident effects beyond the loss of male mate- guarding. Although C. elegans descends from an obligate- outcrossing, male - female ancestor(3,4), it occurs primarily as self- fertilizing hermaphrodites(5-7). The reduced selection on male - male competition associated with the origin of hermaphroditism may have permitted the global spread of a loss-of-function mutation with restricted pleiotropy.

[关键词] C-ELEGANS;NATURAL-POPULATIONS;TEMPORAL DYNAMICS;MATING-BEHAVIOR;EVOLUTION;MUCINS;RNAI;PREDICTION;PHYLOGENY