Biology 106 Dr. Dudash

Study Questions Fall 1999

Study Questions Set #6 - Handed out October 18, 1999.

Due: In Lab the following week.

All answers MUST be TYPED unless mathematical computation is needed.

Use no more than one of a page of single spaced typed text.

Please answer 3 of the following questions:

1. Compare and contrast anagenesis and cladogenesis in regards to the formation of new species. How do these processes relate to Phyletic Gradualism and Punctuated Equilibrium?

Anagenesis is the slow directional change over time that can lead to a species transformation. No need to invoke a speciation event. A frequent process in Phyletic gradualism or evolution.

Cladogenesis is the splitting of species to form new species or many new species. Cladogenesis is a process frequently used in explaining Punctuated Equilibrium.

2. Explain adaptive radiation and provide a clear example.

Rapid evolution of many divergent species from a common ancestor. Ex's Galapagos finches, honey creepers in Hawaii, marsupials in Australia.

3. Compare and contrast homologous and analogous structures and provide an example of each.

Homologous structures develop from a common ancestor, ex. forelimb of mammals.

Analogous structures are of different origin (without a common ancestor) but have a similar function, ex., wings of birds and insects, opposable thumb of humans and panda, dessert vegetation: euphorb and cacti.

4. Discuss 2 types of heterochrony and explain how the timing of development is important in understanding macroevolution.

Heterochrony is the change in duration/timing of a trait .

Peramorphosis = adult trait expressed in a juvenile through an increased duration of development.

Paedomorphosis = juvenile trait expressed in an adult through a decrease in duration of development.

Simple changes, such as the duration a trait can develop, can produce major changes in phenotype.

5. Compare and contrast convergent evolution and parallel evolution and provide an example of each.

Convergent evolution = lack of common ancestry but species evolve to a similar phenotype owing to similar selective pressures, ex, stream lining in fish and mammals for moving through the water quickly.

Parallel evolution = common ancestral species that diverges and then evolution of traits/phenotypes in a similar way owing to similar selective pressures. ex, evolution of birds on geographically close islands, elongated body of burrowing salamanders (increases the # of vertebrate), distantly related mammals with similar stream lined bodies.

One normally needs to know the developmental pathway to determine the difference between convergent and parallel evolution and if common ancestry is present.