Lecture 8: Development and evolution

Question 1

what is an example of how development is not determined solely by genes active in early life

Answer 1

fish that change sex

Question 2

the phenotype of an adult organism results from an

Answer 2

an interaction of genes, gene products, and the environment.

Question 3

similarities among organisms are due to them having a

Answer 3

common ancestor

Question 4

differences among organisms result from

Answer 4

natural selection, which has adapted them to different environments

Question 5

Darwin recognised that relationships among organisms could be deduced from

Answer 5

similarities among their embryos

- Changes in developmental processes will modify the form of an adult organism over evolutionary time

Question 6

Genetics + Embryology =

Answer 6

Evo Deov (evolutionary developmental biology)

Question 7

what is evolutionary developmental biology all about

Answer 7

1. How changes in the genes that regulate development affect the adult forms of organisms
2. How those genes have changed during the course of evolution
3. How these changes have influenced evolution

Question 8

many developmental genes are highly ____ + e.g.

Answer 8

conserved.

e. g. same gens drive the development of the fruit fly’s compound eye and the house mouse’s camera-like eye

Question 9

what will develop in place of a fruit flys leg when a mouse Pax6 gene is expressed in it?

Answer 9

AN EYE

Question 10

the same set of how genes provide anterior-posterior information in both

Answer 10

mammal & insect embryos.

Question 11

a ___ variety of animals are produced by a common set of instructions

Answer 11

HIGHLY.

The differences in form mean that the instructions alone can’t determine an organism’s morphology

Question 12

morphological changes can result from:

Answer 12

a) Mutations in genes that regulate development
b) Changes in the spatial expression of developmental genes
c) Changes in the temporal expression of developmental genes

-Modularity makes all of these pathways of evolution easier

Question 13

Mutations: The insect Ultrabithorax (Ubx) gene

Answer 13

• The insect Ultrabithorax (Ubx) gene has a mutation. This mutated gene is expressed in the abdomen where it represses the dll gene
• The distal-less (dll) gene is essential for leg formation in arthropods.
• So insects don’t form legs on their abdomens

Question 14

changes in spatial expression: In most birds what instructs the cells to undergo apoptosis, which destroys the webs between their toes

Answer 14

-the gene encoding bone morphogenetic protein 4 (BMP4) is expressed between the developing toes

ACCEPTION:
Ducks have a BMP inhibitor protein called Gremlin in their webs.
This stops BMP4 from signaling cell death, leaving a web.

Question 15

Changes in Temporal Expression:

Answer 15

• Modularity allows the timing of developmental processes to shift independently (heterochrony).
• The webs of most salamanders disappear as the animals mature.
• If expression of genes that dissolve the webs is delayed, the digits don’t grow, and “juvenile” webbed feet result.

Question 16

environmental effects on developmental patterns: Development is sensitive to _________

Answer 16

ENVIRONMENTAL CONDITIONS

A single genotype may encode a range of phenotypes under different environmental conditions

Question 17

types of cues that determine development:

Answer 17

1) Cues necessary for normal development
- -Organisms have a fixed adaptive response.
2) Signals closely correlated with future conditions
- -Organisms are likely to respond differently to different cues.

Question 18

Cues that determine NORMAL development: In Aedes aegypti

Answer 18

a blood meal stimulates production of vitellogenin, unnecessary component of eggs

Question 19

Cues that determine NORMAL development: In Euscelis leafhoppers

Answer 19

gut bacteria are necessary for normal abdomen development

Question 20

Cues that predict FUTURE conditions: West African butterfly

Answer 20

• The West African butterfly Bicyclus anynana has a dry-season and a wet-season form with different wing colouration.
• Temperature during pupation determines adult form.

Question 21

Cues that predict FUTURE conditions: spring larvae of Nemoria arizonaria

Answer 21

• The spring larvae of Nemoria arizonaria feed on and resemble oak flowers, the summer larvae feed on oak leaves and resemble oak leaf stems.
• Spring caterpillars can be experimentally converted to summer caterpillars by feeding them oak leaves.

Question 22

Developmental Response to Predators in Daphnia

Answer 22

• Daphnia increase the size of their “helmets” when they encounter Chaoborus.
• Helmet induction occurs if they are exposed to water in which the larvae have been swimming.
• Offspring developing inside mothers with large helmets are born with large helmets.

Question 23

Developmental response to the environment in Spadefoot Toads. If their pond begins to dry up, the tadpoles…

Answer 23

1) Develop a wider mouth, powerful jaw muscles & a modified intestine.
2) Speed up development by eating other tadpoles.

Question 24

Can organisms evolve to responses they have yet to encounter?

Answer 24

NO

-This is important because humans have changed the environment so much (e.g. by the release of chemicals).

Question 25

EvoDevo Evolutionary developmental biology is generating ….

Answer 25

new insights which help us to understand the evolution of life and how to protect it