Evolution and Development Flashcards
How do anemone fish prove development is due to genes and environment?
Start as males
Develop into females if the female population decreases
What happens when you expressed mouse Pax6 gene at the leg of a fly?
An eye will develop instead of a leg
What Drosophila gap genes are expressed in the anterior region of the brain?
ems
tll
otd
What can morphological changes result from?
Mutations in genes that regulate development
Changes in spatial expression of development genes
Changes in temporal expression of development genes
What makes pathways of evolution easier?
Modularity
Why do all insects have the mutated ultrabithorax gene?
Mutated gene is expressed in the abdomen where is repressed the dll gene
Distal-less gene is essential for leg formation in arthropods
Insects don’t form legs of abdomen
Mutated just before evolution of insects - so all have the mutation
How does spatial expression change in birds?
BMP4 is expressed between developing toes - instructs cells to undergo apoptosis
Gremlin is a BMP4 inhibitor and is around digits to prevent them undergoing apoptosis
Gremlin moves between toes in ducks - causes webbed feet
How does temporal expression change in salamanders?
Modularity allows timing of expression to shift
Webs of most salamanders disappears as the animal matures
If expression of gene that dissolves webs is delayed get juvenile feet
Means feet can act as suction cups and live arboreally
No delay means no suction cup feet so live terrestrially
What causes a dry and a wet season in Squinting Bush Brown butterflies?
Temperature during pupation as it acts on distal-less gene
Low temps = predicts future environment will be dry so dry-season emerges (has decreased distal-less expression)
High temps = predicts future environment to be wet so wet season emerges (has increased distal-less expression)
What is polyphenism?
Ability to develop along two different phylogenetic pathways
How do Spadefoot toads change their development?
Tadpoles typically omnivorous - causes slow development as insects not nutritious
If pond dries up pond size decreases and overcrowding happens
Stimulates some tadpoles to develop a wider mouth, powerful jaw muscles and modifies gut to eat meat
Modified forms eat smaller tadpoles
New diet allows them to develop faster before the pond dries up
Stops overcrowding issue
Why do mosquitos need to bite?
Only females
Digested blood products stimulate brain to secrete egg developing hormones
These act on the ovaries to produce ecdysteroid
This instructs fat body cells to produce vitellogenin
Vitellogenin is a necessary component of eggs
Why do mice need microbic environments?
Mice raised in microbe free environments lack gut bacteria
Gut bacteria induce gene expression in the intestines - necessary for normal capillary development
Why do leafhoppers need symbiotic bacteria?
Bacteria live in egg cytoplasm and are transferred through generations like mitochondria - only live in leafhopper cytoplasm
Leafhoppers can’t finish embryogenesis without it - necessary for normal abdomen development
