Discerning homologies: Gene expression, development, and morphology
Donoghue, Michael J. .
Homology, non-homology, and in-betweens.
Non-homology comes in several forms that are worth trying to separate. Parallelisms pass the standard positional, structural, and developmental tests, and are often viewed as providing evidence of developmental constraint on the number of attainable character states. Convergences do not pass the standard tests and are often viewed as providing evidence of the power of selection to mold similar forms out of different structures. Homeoheterotopy, which may underlie instances of the transference of function, adds another wrinkle – what appears to be a convergent feature based on positional and structural criteria may express genes and developmental programs “borrowed” from a similar structure nearby (Baum and Donoghue, 2002). If the recurrence of similar forms sometimes entails a shift in the location of processes rather than their invention from scratch, then “partial homology” needs to be reckoned with and the significance of convergence with respect to constraint and selection needs to be re-considered. A major issue is the relative frequency of convergent evolution via different underlying pathways and the potential evolutionary consequences of such differences. These phenomena will be discussed with reference to several plant examples, such as the epicalyx in Dipsacales.
1 - Yale University, Department of Ecology and Evolutionary Biology, P.O. Box 208105, New Haven, Connecticut, 06520-8105, USA
Presentation Type: Symposium
Location: Ballroom 1 (Cliff Lodge)
Date: Monday, August 2nd, 2004
Time: 3:45 PM