Discerning homologies: Gene expression, development, and morphology
Hufford, Larry .
Homology in transformation: morphological evolution and perceptions of diversity.
From its essentialist origins, homology has been a concept in transformation. Evolutionary knowledge created tensions between phylogenetic and non-phylogenetic concepts of homology. Even the recognition that homology assessment is hierarchical—proceeding from initial deductions of primary homology (non-phylogenetic inferences of similarity that underlie the definition of characters and character states) and to inferences of phylogenetic/taxic homology (states in different organisms derived from those of a most recent common ancestor)—has left rifts, primarily between workers concerned narrowly with the application of taxic homologies as synapomorphies for cladogram construction and those who are interested in character diversification. Studies of morphological diversification employ additional steps in the hierarchy of homology assessment; they must notably use taxic homologies to infer transformational homologies and ask why synapomorphic states differ among taxa in a clade. Data from both morphological development and developmental genetics (gene family diversification and gene expression patterns) contribute to comprehending transformational homologies but may reveal independent evolutionary histories that create quite different perceptions of character state diversification. This independence can arise because of the ways that gene families diversify and paralogues become co-opted for new functions. An understanding of transformational homologies may require the reconstruction of complex sets of data that include gene families, gene expression patterns, and morphological development.
1 - Washington State University, School of Biological Sciences, P.O. Box 644236, Pullman, Washington, 99164-4236
Presentation Type: Symposium
Location: Ballroom 1 (Cliff Lodge)
Date: Monday, August 2nd, 2004
Time: 1:05 PM