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Life Ch. 20
the modern study of evolution and development
molecular pathways that determine different developmental processes operate independently from one another.
morphological differences between species
due to differences in their genomes (what happens due to...?)
genomes of different species share
similar regulatory and coding sequences
gene that controls eyes in fruit flies
gene that controls eyes in mice
Hox gene cluster
provides positional information and control pattern formation in early Drosophila embryos
functional entities encompassing genes and various signaling pathways that determine physical structures such as body segments and legs.
gene that encodes for protein that triggers cell death - as in unwebbed feet
gene in ducks that represses BMP4, stops apoptosis, and results in webbed feet
a period of developmental or reproductive arrest that allows the organism to better survive
The capacity of an organism to alter its pattern of development in response to environmental conditions.
Alteration in the timing of developmental events, leading to different results in the adult organism.
A functional entity in the embryo encompassing genes and signaling pathways that determine a physical structure independently of other such modules.
In evolutionary developmental biology, DNA sequences controlling developmental mechanisms that have been conserved over evolutionary time.
evolved from a gene present in a common ancestor.
example of heterochrony
human necks vs. giraffe necks
example of spatial expression pattern
duck's feet versus chicken's feet
expression promotes formation of legs in centipedes
activates DII gene (legs in centipedes)
6-legged, like insects
result of repression of DII by a modified Ubx protein
converts testosterone to estrogen.
if aromatase is expressed
estrogens dominate; female organs develop.
if aromatase is not expressed
testosterone dominates, and male organs develop.
Sonic Hedgehog gene
loss of expression equalled loss of legs in ancestors of genes
Parallel phenotypic evolution
highly conserved developmental genes make it likely that similar traits will evolve repeatedly.
Pitx 1 gene
when expressed, develops spines.