Tag Archives: transitions

The Nature and Analysis of Phenotype Transitions

“how do new traits arise from old phenotypes?”

“research on selection and adaptation may tell us why a trait persisted and spread, but it will not tell us where a trait came from”

“Of these three elements of evolutionary origin, transformational origin is the most neglected”

“how a phenotypic novelty–a trait that is new in composition or context of expression relative to established ancestral traits–can grow out of previous organization, and why a complex evolutionary change in the phenotype need not depend on a long series of genetic mutations. Because evolution can occur by reorganization, the phenotype divergence between populations or species need not be proportional to the genetic distance between them.”

categories of origins of novelty

  • hybridization between species [I would include introgression and admixture within species]
  • polyploidy [mostly plants, I would include any chromosomal transformation]
  • horizontal transfer of genes [multiple gene function by intron shuffling, gene duplication, random gene creation through action of retrotransposons, and random gene creation]
  • coupling and decoupling of modular traits – fusion, duplication, subdivision (decoupling)

“evolution is often and perhaps always combinatorial” [Algebraic Statistics for Computational Biology]

“Phenotype recombination can produce a new trait without loss of an old one, through repeated gene expression and novel epigenetic interactions.”

“increasing the phenotype repertoire of the genome … is a self-accelerating process that greatly augments the production of selectable variation”

not genetic recombination, a different process

two events in the origin of novel phenotypes:

  1. “new input in the form of a genetic mutation or an environmental change”
  2. “developmental response that produces a new phenotype”

need both

Continue reading