BIOL 2400 Lecture Notes - Lecture 8: Convergent Evolution, Subphylum, Deep Homology
12 Sep 2017
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Shape changes in finch beaks late development: deeper and wider beaks: higher bmp4 expression. Longer beaks: higher calmodulin expression: ancient genetic toolkit in segmented animals regulate early development of body form, hox gene order reflect order of body segments, hox genes control axes of symmetry and location and types of appendages. Gene expression variation drive adaptive radiation i(cid:374) (cid:271)eaks of dar(cid:449)i(cid:374)"s fi(cid:374)(cid:272)hes. The distinct beak morphologies are generated by differences in the time and place of expression of different genes. Key concept: changes in the timing, amount or location of expression of genes during early development can alter the shape or properties of a(cid:374) adapti(cid:448)e trait su(cid:272)h as (cid:271)eak shape i(cid:374) dar(cid:449)i(cid:374)"s fi(cid:374)(cid:272)hes. Key concepts: hox genes: different body segment types specified by primary cluster(s) of hox genes, hox genes are transcription factors that can bind to cis-regulatory region of other transcription factor. The type of appendages on each segment also specified by hox genes genes.
