Evolution in Real Time (Freckleton) Flashcards
Evolution is gradual and proceedes the accumulation of small changes. Big jumps are thought to be unlikely.
-The rate of evolution varies through time.
Macro vs micro evolution
-Macro, changes with species and large groups
-Micro, smaller changes, e.g. the environment
Macro-evolution is slow, but microevolution can be fast
E.g. Biston betularia (peppered moth)
Very fast response of species to change
Sources of rapid evolutionary change
- Climate Change
An ecological process when two species have similar requirements, e.g. food and shelter.
- If they have similar requirements, they cannot coexist
- One species must either go extinct or evolve different requirements.
- Thought that ecological process of extinction is faster than evolution.
- Niche/ limited similarity
- (Macro evolution) E.g. Darwin’s finches
- Many species are exploited by humans in some way, much of this is selective, e.g. harvest the biggest, so biggest yield.
- Much like the process of natural selection, directional selection.
Exploitation - Hunting of bighorn sheep in US
E.g. Hunting of bighorn sheep in US. Hunted as ‘trophies’, large rams are a target.
-Overall reduction of animal, and horns. Populations size went up, big animals being taken out when hunted, frees up space for smaller animals (more can fit into the environment, so pop increased). As hunting continued, population decreased.
Exploitation - Body size and maturity in cod
E.g. body size and maturity in cod, fished for food. Nets target the larger fish.
Indeterminate growth, sexual maturity determined on size. Selective fishing caused changes in maturity schedules.
-Age at maturity decreased
-Growth rates declined by up to 50%
- Changes at an unprecedented rate. Affects average condition and extreme events (e.g. droughts becoming more severe). Habitat changes too much can lead to extinction.
- Predicting phenology (study of decision on timing of life history evens, e.g. when do things start to flower, when do offspring leave) after climate change
Parasites - Rabbits and myxomatosis
E.g. rabbits and myxomatosis. Biological control agents to deal with rabbits. Virus efficient in killing rabbit, transferred from one to the other, so biological control.
- European rabbits were introduced to Australia in 1859, enormous capacity for reproduction, so quickly reaches pest status. Biological control, myxoma virus. Population never seen virus.
- 1st epidemic; 99% mortality
- 2nd epidemic; 90%
- 3rd; 40-60%
Parasites - Consequence of evolution
Consequence of evolution, selection pressure:
- Death of host stops spread of parasite.
- High virulence of parasite leads to more secondary cases. Hence selection on parasites for less virulence
- Higher exposure –> resistance; no good if kills host after a few hours, might not pass parasite on
Parasites and evolution
- Parasites provide some of the best evidence for evolution in action.
- Parasites have a large number of generations in a short time.
- Intense selection pressure on hosts.
- Hence rapid evolution.
- Important biomedical applications.
Applications of fast evolution
- Evolution of herbicide resistance
- Drug resistance