Lecture 25 - Evolution and Development EVO-DEVO

Question 1

Baer’s Law of Embryology

Answer 1

1. ) General characteristics of group to which an embryo belongs develop before special characteristics
2. ) general structural relations are likewise formed before most specific appear
3. ) form of any given embryo does not converge upon other definite forms, but separates itself from them
4. ) embryo of a higher animal form never resembles the adult of another form, such as one less evolved, but only its embryo

Question 2

Heterochrony

Answer 2

refers to changes in rate or timing of developmental processes

Question 3

Paedomorphosis

Answer 3

underdevelopment

Question 4

Peramorphosis

Answer 4

overdevelopment

Question 5

Rate (k) of paedomorphosis : slower or faster?

Answer 5

slower (neoteny)

Question 6

Rate (k) of peramorphosis: slower or faster?

Answer 6

faster

Question 7

Onset time (alpha) of paedomorphosis: earlier or later?

Answer 7

Later

Question 8

Onset time (alpha) of peramorphosis: earlier or later?

Answer 8

Earlier

Question 9

Offset time (beta) of paedomorphosis: earlier or later?

Answer 9

Earlier (progenesis)

Question 10

Offset time (beta) of peramorphosis: Earlier or later?

Answer 10

Later (hypermorphosis)

Question 11

What are the evolutionary significance of heterochrony?

Answer 11

1. ) large changes in phenotype easily accomplished
2. ) Important in speciation
3. ) May release lineages from “phylogenetic contraints”

Question 12

How can Hox genes influence morphological evolution in 3 ways?

Answer 12

1. ) changes in total number of Hox genes
2. ) changes in spatial expression
3. ) changes in gene interactions

Question 13

Common Characteristics of Homeotic Genes

Answer 13

1. ) organized in multigene families
2. ) Each gene has distinctive 180 bp homeobox domain
3. ) Perfect correlation between 3’-5’ order of genes and their embryonic expression/targets