Evolution and Development

Question 1

Heterochrony

Answer 1

Differences in the rate and timing of development in a species relative to its ancestor

Question 2

Recapitulation via Acceleration

Answer 2

Somatic trait seen late in development in an ancestral species, but appears earlier in development in descendent species

Question 3

Paedomorphosis via Progenesis

Answer 3

Reproductive trait that was formerly seen early in development in an ancestral species; appears later in development in descendent species

Question 4

Paedomorphosis via Neoteny

Answer 4

Somatic trait that was formerly seen early in development in an ancestral species appears later in development in descendent species
-Earlier maturation and development of terrestrial species

Question 5

Recapitulation via Hypermorphosis

Answer 5

Reproductive trait seen late in development in an ancestral species, but which appears earlier in development in a descendent species

Question 6

MADS-Box Genes

Answer 6

Flower homeotic genes, MADS-Box Genes (controls timing) are genes specific to flower formation rather than leaf formation

Question 7

Hox Genes

Answer 7

Determine body segment identity

Question 8

Homologous Hox Genes

Answer 8

-Similar in DNA sequence
-Collinear arrangement

Question 9

Collinearity

Answer 9

Physical chromosome location matches animals’ body location

Question 10

Neural Crest Cells

Answer 10

-Temporary group of cells found in vertebrate embryos
-Develop in ectoderm germ layer
-Ability to become many different types of cells

Question 11

How are Hox and MADS-Box genes expressed?

Answer 11

MADS-Box Genes; the order of flower is dependent on these genes (sepal, petal, stamen, carpel)
Hox Genes; They indirectly specify what structures other genes should form in particular regions. Determines the ultimate fate of various cells in the head, thorax, and abdomen regions in a developing fruit fly and in other organisms.

Question 12

What determines if homeotic genes are duplicated? (What happens if the gene is costly versus beneficial?

Answer 12

Outcomes of Duplicated Genes:
-If costly; lost by natural selection or loss of function
-Continued expression as paralogs; diverge & divide work through subfunctionalization, diverge with one taking on new functions, and influence gene expression through other mechanisms (histone, RNA, etc…)