Recombination in interpopulation hybrids of the copepod Tigriopus californicus: release of beneficial variation despite hybrid breakdown

Crosses between divergent populations of the copepod Tigriopus californicus typically result in fitness reductions for both F2 and backcross hybrids. Because females in this species lack chiasmatic meiosis, both recombinant and nonrecombinant backcross hybrids can be created. Re-combinant hybrids were found to have significantly faster development time for both males and females in 2 pairs of crosses, indicating the creation of favorable gene combina-tions by disrupting parental linkage groups. The shuffling of gene combinations by recombination and segregation can have unpredictable effects on the fitness of hybrids. On the one hand, disruption of parental gene interactions can create negative epistasis. It is the exposure of deleterious hybrid gene combinations involving recessive alleles that explains the common pattern of hybrid fitnes