11/16: Unit 4 Blog

1. Explain in your own words the difference between species evenness and species richness.

Species evenness is the closeness of the number of each species in an area, whereas species richness is the number of species in the area.

2. List and describe four random processes that can cause evolution.

Random mating is breeding in which the choice of partner is not influenced by the genotype.

Genetic variation provides the basis of natural selection.

Genetic recombination produces a new combination of alleles.

Genetic mutation is a permanent change in the DNA sequence.

3. Summarize in your own words allopatric speciation.  Give an example.

Allopatric speciation is the formation of a new species, caused by geographic isolation. An example is the Galapagos finches.

4. What factors determine the rate of evolution?

A factor that may determine the rate of evolution is the kind of species: r and K selection. R species would allow for slightly higher rate of evolution, since offspring are produced more in quantity and higher in frequency, and K species would allow for a lower rate, since offspring are produced less.

5. Do you agree with the statement below?  Why or why not?

“We are currently experiencing a sixth global extinction.”

Yes, I agree with the statement, because so many species today are endangered, close to extinction.

6. Give an example of each of symbiotic relationships/terms below.

Predator/prey: Lion eats zebra.

Competition: Sea anemones compete for territory.

Mutualism: Plover bird cleans crocodile's teeth and obtains nutrition.

Commensalism: Cattle egrets eat insects that are found in the land the cattle disturb as they move in herds.

Parasitism: Mosquito feeds on blood from human.

Keystone species: The sea otter feeds on sea urchins, controlling their population. The urchins would otherwise eat up the entire kelp population.

K-selected species: Humans.

R-selected species: Rodents.

7. In your own words explain the difference between primary and secondary succession in terms of cause and the types of plant species that begin to grow in each.  Give an example of each.

Primary succession occurs in areas that lacked vegetation prior to the disturbance, whereas secondary succession occurs in areas previously supported with vegetation. Primary succession also involves a greater disturbance such as a volcano eruption and pioneer species such as hardwood trees, while secondary succession involves comparatively smaller disturbances such as forest fire and non-pioneer species such as grass.