Journal Article
Losing sight of regressive evolution
Espinasa, M. and Espinasa, L.
Record Number:
5689
Year:
2008
Journal:
Evolution: Education and Outreach
Pages:
509-516
Volume:
1
Abstract:
Abstract When we teach evolution to our students, we tend
to focus on “constructive” evolution, the processes which
lead to the development of novel or modified structures.
Most biology students are familiar with the subjects of
finches’ beaks, giraffes’ necks, and hair in mammals. Of
course, there is nothing inherently wrong with a constructivist
approach to teaching evolution, but if it is our only
focus, we may overlook the flip side of the coin. By the flip
side of the coin, of course, we are referring to regressive
evolution: the loss or degeneration of a trait. Regressive
evolution does not often make its way into biology textbooks,
but it is of great relevance nonetheless. In all
likelihood, when a new trait evolves or an existing one is
modified, something is sacrificed in return. In order to
develop a flipper, a marine mammal must sacrifice individual
digits. You may be familiar with one or more of the
following familiar characters lost through regressive evolution:
teeth in birds, scales in mammals, and tails in higher
primates. For aficionados of cave biology like us, one of the
most interesting examples of regressive evolution concerns
cave fish: Why do cave fish lose their eyes?
Keywords Evolution . Regressive evolution .
Constructive evolution . Organism . Species
Times Cited:
1
Relevent Species: