title: The genetic covariance between life cycle stages separated by metamorphosis.
abstract: Metamorphosis is common in animals, yet the genetic associations between life cycle stages are poorly understood. Given the radical changes that occur at metamorphosis, selection may differ before and after metamorphosis, and the extent that genetic associations between pre- and post-metamorphic traits constrain evolutionary change is a subject of considerable interest. In some instances, metamorphosis may allow the genetic decoupling of life cycle stages, whereas in others, metamorphosis could allow complementary responses to selection across the life cycle. Using a diallel breeding design, we measured viability at four ontogenetic stages (embryo, larval, juvenile and adult viability), in the ascidian Ciona intestinalis and examined the orientation of additive genetic variation with respect to the metamorphic boundary. We found support for one eigenvector of G: (gobsmax ), which contrasted larval viability against embryo viability and juvenile viability. Target matrix rotation confirmed that while gobsmax shows genetic associations can extend beyond metamorphosis, there is still considerable scope for decoupled phenotypic evolution. Therefore, although genetic associations across metamorphosis could limit that range of phenotypes that are attainable, traits on either side of the metamorphic boundary are capable of some independent evolutionary change in response to the divergent conditions encountered during each life cycle stage.
authors: School of Biological Sciences, University of Queensland, Brisbane 4072, Australia j.d.aguirre@massey.ac.nz.
authors: J David
authors: JD
authors: Aguirre
authors: School of Biological Sciences, University of Queensland, Brisbane 4072, Australia.
authors: Mark W
authors: MW
authors: Blows
authors: School of Biological Sciences, University of Queensland, Brisbane 4072, Australia Marine Evolutionary Ecology Group, School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia.
authors: Dustin J
authors: DJ
authors: Marshall
mesh_terms: D000818:Animals; D002938:Ciona intestinalis / Q000235:genetics* / Q000254:growth & development*; D004625:Embryo, Nonmammalian / Q000196:embryology; D056084:Genetic Fitness; D014644:Genetic Variation; D007814:Larva / Q000235:genetics / Q000254:growth & development; D008018:Life Cycle Stages; D008675:Metamorphosis, Biological; D013021:South Australia
keywords: Ciona; adaptive decoupling; genetic variance–covariance matrix; life-history evolution; target matrix rotation