Genes that regulate development are highly conserved This me

Genes that regulate development are highly conserved. This means that they have been lost in some lineages. they have changed very little over the course of evolution. large differences have evolved among multicellular organisms. they are always turned on. they have undergone mutation. Which change would most likely result in snakes developing rudimentary hindlimbs? Loss of expression of Ubx in the appropriate location Loss of expression of Sonic hedgehog in the appropriate location Gain of expression of Sonic hedgehog in the appropriate location Gain of expression of Distalless in the appropriate location Loss of expression of Distalless in the appropriate location Which species concept can be used when describing organisms that reproduce asexually? The daughter species concept The lineage species concept The morphological species concept The biological species concept The reproductive isolation concept

Solution

1. b

Conserved genes change very less during the course of evolution. Any mutation in the devolepmental genes will not result in a fertile/ viable offspring therefore these mutations cannot be propagated.

2. b

Loss of expression of Sonic hedgehog gene in the appropriate location. Upstream region of Sonic hedgehog genes in snakes contain enhancer elements. Deletion mutations in three regions of these enhancer genes resulted in the loss of activator binding sites to the genes. Since activators to the sonic hedgehog genes can not bind to the gene, it is only feebly transcribed for a very less amount of time ( <24hr, The expression lasts for weeks in lizards, their close ancestors which devolep limbs)

3. b The lineage species concept.

Lineage species concept is like a pedigree, marking all the descendents as a lineage. The divergences w.r.t. a common ancestor can be marked based on the family tree. It fits asexual reproduction because a lineage doesn\'t necessarily have to be sexually compatible pairs as defined in biological speciation.