Unit 5 Lecture 25 Flashcards
Explain the Rough-Skinned Newt study
- Rough-Skinned Newts contained TTX (lethal neurotoxin)
- Common garter snakes are non-venomous snakes across North America (mutations in muscle sodium channel enable resistance to TTX)
- These snakes can eat these newts mainly because not all newts are that toxic
Explain the coevolution within the newts and snakes
- In populations where newts are not very toxic, snakes have little resistance
- In populations where newts are very toxic, snakes have higher resistance
- Some newts evolve toxicity
- Resistance to TTX favored selection in snakes
- More toxic newts
- More resistant snakes
What is coevolution?
Reciprocal evolutionary change between interacting species
What is antagonistic coevolution?
Adaptation in one species to exploit another leads to selection for counter adaptation in other (also called coevolutionary arms race)
Why will there be some limits to toxicity/resistance or some mismatch (strong resistance in areas with low toxicity etc.)
- There can be evolutionary limits (maybe newts can’t get anymore toxic)
- Adaptations may come with costs (cost of maintaining resistance/toxicity causes a reduction in animal fitness)
- Coevolution depends on what other species are around (maybe there’s other animals around in that area the snakes prefer eating)
- Gene flow
Should character displacement be considered a form of coeveolution?
No
- Character displacement is not reciprocal i.e. when the larger beak size in medium ground finch is selected for, that does not impose small beak size selection for small ground finch
Name an example of how coevolution is common between parasites and hosts?
Red Queen Dynamics
- Parasite infects a host, increasing frequency of parasite
- Hosts picks new genotype causing a decrease in infections, i.e. increase in population
- This causes parasites to decrease, then increase once adapted to new genotype
What makes the Brood Parasite birds a good study?
Brood parasites come in different flavors, but some things that seem to be common are:
- There are a lot of birds that lay their eggs in other birds nests
- Birds will raise the eggs that aren’t their own cause they don’t recognize
In the brood study, there was a coevolutionary arms race over what?
Egg recognition
1. Parasite lays egg in host nest
2. Hosts recognize the egg
3. Parasite mimic the host eggs better
4. Hosts get better at recognizing own eggs
What birds can do chick mimicry?
- African finches
- Australian cuckoos
Name a devious cuckoo chick strategy?
- Egg eviction of the host eggs as soon as they are born
- Common cuckoo chick makes begging calls that sound like 4 chicks
- Horsefield Hawk-cuckoo in Japan has spots on wings to mimic extra mouths
Name the type of ecological interactions in each case scenario:
1. Predation & parasitism
2. Commensalism
3. Mutualism
4. 3 types of competition
Effects on Species 1: Effects on Species 2:
1. + -
2. + 0
3. + +
4. - 0
5. 0 -
6. - -
What is commensalism?
An association between two organisms in which one benefits and the other derives neither benefit nor harm.
- Remoras (fish) attach to large predators (shark) and eat scraps
What is mutualism?
The ecological interaction between two or more species where each species has a net benefit.
- Fungi help plants absorb nutrients from soil; fungi gets sugars from plants
- Anemone provides protection from predators; clownfish waste is nutrient from anemone
What is facultative mutualism? obligate mutualism?
- Facultative: Optional mutualism; one species can cope without the other
- Obligate: not optional; two species rely on each other
