Biology 106 Dr. Dudash

Study Questions Fall 1999

Study Questions Set #2 - Handed out Sept. 13, 1999.

Due: In Lab the following week.

All answers MUST be TYPED unless mathematical computation is needed.

(Please use no more than 3/4 of a page of single spaced typed text.)

Please answer 3 of the following questions:

1. Explain 3 advantages of sexual and asexual reproduction.

Sexual: -remove disadvantageous/deleterious mutation

-bring together favorable gene combinations

-recombination quicker than mutation in generating genetic variation

-DNA repair mechanism via meiosis

provide a greater response to varying selective pressures

Asexual: -no meiotic cost in producing identical daughters

-no cost/energy used in mate attraction

- ability to maintain favorable genotypes (gene combinations) in a constant environment

2. Explain the key difference between blending inheritance and meiosis .

Blending inheritance does not allow a mechanism for either parent to transmit an advantageous trait to their offspring since there would be a mixing between both parents with the progeny being intermediate to either parent. Meiosis allows the transmission of favorable traits to be transferred from parent to offspring.

3. List 3 types of asexual reproduction and give an example of an organism that may reproduce in each manner?

fission = mitosis in unicellular organisms, ex., a unicellular organism

vegetative repro. = offspring sprout from body and then separate, ex.'s fungi, some plants via runners, rhizomes, starfish

parthenogenesis = unfertilized egg develops into either a diploid or haploid individual, ex.'s some invertebrates, especially arthropods and bees.

agamospermy = unfertilized ovules develop into diploid seeds, ex., some plants, dandelion.

4. Compare and contrast microevolution and macroevolution.

Microevolution = small changes that lead to the evolution of particular fitness traits within a population of organisms over a relatively short period of time (ex., a few generations) .

Macroevolution = evolution above the population level that leads to large changes in traits among groups of organisms. Usually associate d with major evolutionary events viewed through the perspective of geological time.

NOTE: The same processes are responsible for BOTH scales of evolution.

5. Define natural selection and provide an example of one form/type of natural selection. Graphic display is always helpful.

Natural selection is the nonrandom and differential reproduction of different individuals (genotypes) acting to preserve favorable variants and to eliminate less favorable variants in the face of natural competition. or differential survival and reproduction of individuals that has a genetic basis.

Stabilizing or balancing selection - eliminates both extremes in a population, ex., birth weight in humans

Directional selection - eliminates one extreme form in the population, ex., selection on longer flower tube length for a common long tongue insect , short tongue insects less fit and removed from the population

Disruptive or diversifying selection- eliminates intermediate types in the population, ex., both very small and very large birds are favored in the population because the 2 major food resources either produce very small seeded fruit or very large seeded fruit.

Frequency dependent selection - a condition where particular individuals would be favored at say low density but selected against at high density, ex., many predator/prey relationships are driven by frequency dependent selection.

6. What is inclusive fitness and how is it different from individual fitness?

Fitness derived from both an individual's own fitness as well as any progeny produced from it's relatives/kin with the relatives devalued in proportion to their genetic distance from the individual. Remember that you are 1/2 related to both your parents as well as any full sibs (you share the same mom & dad) that you have! Half sibs share either the same mother or father but not both.