Name: E Vega
How do patterns of embryological development support evolutionary
relationship? Why is variation among members of a species advantageous?
The basic idea is that related species show similar patterns of early
development. The differences among species are not established until
relatively late in embryo development. These shared patterns of
development are thought to have evolved only once. Therefore,
organisms that share these patterns must be related.
Variation among members of a species can be advantageous for a
number of reasons. Perhaps most importantly, variation allows
for adaptation to a variety of environmental conditions or habitats.
A species that exhibits significant variation may be better suited
to survive changes in the environment.
Hey!! No fair!! That's two questions in one message!!
My brain can't handle that!
Okay, I'm calm now.. first, embryology is extremely important,
in that the way an embryo develops can tell you a lot about where
it came from. Different species develop differently, right down
to the level where a single fertilized egg splits into two --
every species does it in a slightly different way, and you can
sometimes even take embryos of different species at the same stage
of development, and line them up, showing evolutionary lineage.
Also, you can see vestigial developmental schemes when you watch
a zygote develop into a viable organism -- humans look like sharks
at one point, right down to the gill slits...
As for your second question, intraspecific variability can be of
great advantage in survival because it allows members of the same
species to inhabit slightly different niches in the environment,
lowering the competition for space and resources.
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Update: June 2012