BIO 370 Lecture Notes - Lecture 24: Plica Semilunaris Of Conjunctiva, Nictitating Membrane, Deep Homology
Using Phylogenies to Generate Evolutionary Hypotheses
What is deep homology?
The means by which organisms store triglycerides is remarkably conserved across species, from
yeast to fruit flies to humans.
This phylogeny is based on DNA sequences of the FIT2 gene associated with lipid droplet
formation. So?
What are vestigial traits, and why might vestigial traits exist at all?
The next slide shows the vestigial plica semilunaris in humans and the nictitating membrane in
an eagle.
Have no current function, but did in the past.
Remain because:
. No har, so atural seletio did’t rule it out.
. Natural seletio agaist it ad it’s o its ay out.
3. Has function which we failed to ID.
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Document Summary
The means by which organisms store triglycerides is remarkably conserved across species, from yeast to fruit flies to humans. This phylogeny is based on dna sequences of the fit2 gene associated with lipid droplet formation. The next slide shows the vestigial plica semilunaris in humans and the nictitating membrane in an eagle. Have no current function, but did in the past. No har(cid:373), so (cid:374)atural sele(cid:272)tio(cid:374) did(cid:374)"t rule it out. (cid:1006). Natural sele(cid:272)tio(cid:374) agai(cid:374)st it a(cid:374)d it"s o(cid:374) its (cid:449)ay out: has function which we failed to id. Vestigial traits serve as a strong test of darwi(cid:374)"s theory of e(cid:448)olutio(cid:374) (cid:271)y (cid:272)o(cid:373)(cid:373)o(cid:374) a(cid:374)(cid:272)estry. Legless-ness in snakes is not the same as legless-ness in fish (or worms). (and our legs are not homologous with legs in ants). Phylogeny of venomous spiny-rayed fishes an example of the practical utility of phylogenetic trees and the concept of deep homology.
