Natural Selection and Biodiversity Flashcards
Name Darwin’s major problems:
- No system for generating variation; if entire population acquired the best variant, natural selection cannot happen for that trait again.
- Blending inheritance destroys variation; if red and white flowers made pink ones, all flowers would be pink
Which types of mutation are important for evolution? Small effect or large?
Most selection on mutations of small effect as they result in gradual, slow changes
Give an example of an important macro mutation:
Macro mutations in microbes, used for widespread transfer of genetic material between microbes (e.g antibiotic resistance)
What is Heterozygote advantage and give an example:
When the most fit form is heterozygous
e.g Sickle cell anaemia
Altruism =
a behaviour beneficial to others but costly to oneself (being selfless)
How is altruism compatible with the idea of competitive struggle and individual selection?
- Helping relatives - helping to raise offspring of relations, still passing on family genes
- Give now, receive later
Hamilton’s rule =
total fitness = direct fitness + indirect fitness
(direct: producing and raising offspring
indirect: helping raise relatives’ offspring)
Natural selection works on natural genetic variation, and with constraints. These constraints are:
i) population size limits mutation
ii) poor fitness of intermediate form
iii) best form not genetically pure
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On average, each person carries ___ lethal/deleterious mutations
4
what effect does small populations have on diversity?
genetically simplified population
Which population, small or large, is better prepared for change if it occurs?
Large, as small populations will have a less evolutionary response.
Evolutionary lag =
as soon as a problem is fixed, the problem changes
e.g; when the host evolves to resist the parasite, the parasite will evolve to resist this change
Monogamy =
paired partners raise young together
Polygyny =
alpha males have access to all females
Polyandry =
females attract multiple males
Intersexual =
females choose males based on certain factors
Intrasexual =
males on male competition, males compete for access to females
Which of the following represent traits evolved by intersexual sexual selection?
a) Male crickets supplying gifts of food to their female partners during courtship.
b) Large testes sizes in chimpanzees compared to humans
c) Elaborate courtship in fruit flies
d) Large size of male lions compared to female.
e) Mate guarding, where male damsel flies stay with their female partner until she lays eggs
f) Small wingspan in forest birds
A & C
Mayr’s biological species concept =
a species is a population group that can interbreed with each other and produce fertile offspring
Prezygotic isolation =
barriers that prevent offspring pre-fertilisation
reasons for prezygotic isolation:
- temporal - don’t meet in time
- ecological - don’t meet in space
- behavioural - don’t want to mate
- mechanical - can’t physically mate
- gametic - gametes won’t fuse
Postzygotic isolation =
barriers that prevent offspring after fertilisation
reduced hybrid fertility =
babies are sterile
