Salamander paedomorphosis: linking thyroid hormone to life history and life cycle evolution

摘要: Many salamanders have biphasic life cycles with aquatic larval and terrestrial adult phases. In these species, the transition between phases-metamorphosis-requires thyroid hormone (TH) activation of transcriptional programs that cause regression traits development traits. During salamander evolution, TH signaling pathways been altered in species to yield paedomorphic retain attain sexual maturity habitats. We review literature concerning ecology, hormonal regulation metamorphic, paedomorphic, facultative histories. then discuss recent microarray results detail gene expression signatures metamorphosis paedomorphosis, genetic establish responsiveness as a continuous trait quantitative locus (QTL) basis. TH-responsive QTL from ambystomatid explain variation metamorphic timing, versus fitness propose model for history evolution links adaptation habitats loci pleiotropically alter timing body size. Future studies adopt genomic approaches will further ideal models investigating mechanisms regulate postembryonic alternate