APS121 Evolution - Freckleton + papers & practicals Flashcards
What increased likelihood of making alarm calls in Belding’s ground squirrels?
More relatives in immediate vicinity
r x b >
c
kin selection is actually..
gene selection
A gene will spread in a population if it causes more copies of …
itself to be produced
- kin are more likely to share genes
r is…
the probability that a member of kin contains a gene for an altruistic act
b is…
the number of extra copies of the gene that the act yields
c is…
the cost to the giver in terms of the number of copies of the gene lost
what is the value of r between siblings?
cousins?
- 5
0. 125
Can unrelated individuals still behave altruistically towards each other?
Yes - for example if there is a way in which they can tell another individual shares a gene (e.g. hypothetical “green beard” gene)
- green beard gene confirms phenotype + linked nearby gene determines altruism
What do fire ants use to distinguish BB queens from Bb queens (bb die naturally)
Odours
workers kill BB phenotype
Why are green beards probably evolutionary unstable>
very easy to ‘cheat’ - possess green beard but do not reciprocate altruism
what does the segregation distorter gene do in drosophila?
Performs meiotic drive - ends up with 90% sd sperm and only 10% wildtype
selection acts on…
replicators - individual units that replicate themselves - those that leave the most copies are successful
- species are not replicators, nor are individuals
Rate of evolution varies through time. What are thought to be contributing factors?
- Climate and environmental change
- Competition
- Parasites
- Human exploitation
If 2 species have very similar requirements in the same environment they cannot co-exist. What must happen?
One species must either go extinct or evolve different requirements
- it is usually thought that the ecological process of extinction is faster than evolution and is therefore more likely (although cases such as Darwin’s finches show that this is not always the case - filled different niches in response to competition)
Give 2 examples of how human exploitation can drive the micro-evolution of a species
- Bighorn sheep - larger with bigger horns hunted for trophies, causing a reduction in animal size and horn length (as well as fluctuations in population size)
- fishing of cod led to maturation at a younger age and smaller fish
In British plant there is a negative relationship between flowering date and…
temperature (averaged across 250 years and 405 species)
What virus was introduced to australian rabbits in an attempt to control their population?
Myxoma virus (myxomatosis) - rapid generation time
1st epidemic 99% mortality
2nd 90%
3rd 40-60%
Death of hosts stops spread of parasites
- High virulence of parasite leads to a short period of spread - lower virulence leads to more secondary cases –> selection on parasites for less virulence and therefore higher exposure and spread
What is looking at the phylogenies of viruses and diseases in real time called?
Phylodynamics
What are a couple of situations where fast evolution can occur?
- superbugs
- pesticide resistance
What were the peaks in the measles case chart?
How about the influenza one?
Measles - consequence of school calendar
Influenza - selection, mutation and evolution + outbreaks every year due to lack of immunity
How do human activities change the environment?
What are the consequences?
- habitat loss
- climate change
- pollution
- reduced pop sizes
- extinction of pops and species
- loss of entire ecosystems