Bio Evolution

b)Explain THREE methods that have been used to investigate the phylogeny of organisms.

- Fossils (paleontology) Weakness: Not all species leave fossils. Fossil record is incomplete. -Anatomy/morphology STRENGTH: Homologous structures indicate evolutionary relationships. -Behavioral traits: STRENGTH Some behaviors are genetic (e.g., frog calls).

a) Discuss Two evolutionary advantages of asexual reproduction

- It is rapid and efficient - It eliminates the energy code of fertilization

b) How can the Hardy-Weinberg principle of genetic equilibrium be used to determine whether this population is evolving?

-Allelic frequency changes or five conditions that do not change if population is not evolving • Means of measurement/detection

b) Identify three ways that sexual reproduction increases genetic variability. For each, explain how it increases genetic diversity among the offspring.

-Crossing over= a new combination of alleles -Random fertilization= nonspecific gamete selection -Random Mating= nonspecific mate selection

c)For each tree, describe a monophyletic group, the closest relative to the whale, and the point at which the pulley astragalus was lost or gained.

BOTH Tree I and II the camel as the closest relative to the whale in Tree I AND the hippo in Tree II. the gain of the pulley astragalus bone in Tree I occurs between the whale and the camel,

b) draw a phylogenetic tree that reflects the evolutionary relationships of the organisms based on the differences in their cytochrome c amino-acid sequences and explain the relationships of the organisms. Based on the data, identify which organism is most closely related to the chicken and explain your choice.

Cytochrome c: the more differences in amino acids of cytochrome c, the less closely related, OR fewer differences, more closely related. (1 point) • Penguin is most closely related to chicken. (1 point) • Three amino acids differing between penguin and chicken/penguin has fewest differences from chicken

7a) The evolution of a species is dependent on changes in the genome of the species. Identify TWO mechanisms of genetic change, and explain how each affects genetic variation.

DNA (molecular):Mutation, e.g., point, frameshift, insertions, deletions:Change in nucleotide sequence or amino acid sequence or protein structure or gene expression, or change in phenotype Cellular: Crossing over, independent assortment, segregation, nondisjunction (meiosis) Random fertilization (sexual reproduction). Increase gamete diversity.Many possible gamete combinations

c) Propose an evolutionary mechanism that explains the change in average number of spots between 6 and 20 months in the presence of the predator.

Directional selection against individuals with large numbers of spots/Directional selection for individuals with fewer spots

c) Identify a particular environmental change and describe how it might alter allelic frequencies in this population.

Environmental change identified (1 point) (first one scored) • Explanation of how allelic frequency changed (1-2 points) • Which Hardy-Weinberg condition not met (1 point)

c) Describe TWO types of evidence—other than the comparison of proteins—that can be used to determine the phylogeny of organisms. Discuss one strength of each type of evidence you described.

Fossil Observe past organisms STRENGTH- Shows direct evidence of common ancestor, follow evolution (changes over time) from common ancestor Homology: morphology Organismal structure/form Vestigial structures Similarities in form(s) show common ancestry/DNA

6a) What is the frequency of each genotype (AA,Aa,aa) in this population?What is the frequency of the dominant phenotype?

Frequency AA = .36 • Frequency Aa = .48 • Frequency aa = .16 • Frequency dominant phenotype = .84

2a)Describe the change in genetic variation in the population between 0 and 6 months and provide reasoning for your description based on the means and SEM.

Genetic variation is decreasing because the SEM gets smaller.

5a) Discuss TWO mechanisms of speciation that lead to the development of separate species from a common ancestor.

Geographic isolation (or allopatric speciation) takes place when a population of one species becomes physically separated by some geographic barrier such as a river, mountain range, etc. Long-term isolation of two populations eventually leads to reproductive isolation.Reproductive isolation by prezygotic barriers, such as habitat, temporal, behavioral, mechanical, or gametic incompatibility.

6. Evolution is one of the unifying themes of biology. Evolution involves change in the frequencies of alleles in a population. For a particular genetic locus in a population, the frequency of the recessive allele (a) is 0.4 and the frequency of the dominant allele (A) is 0.6.

Hmmmm

Reproduction can be either asexual or sexual

Hmmmmm

4a) Assuming that species I is the ancestral species of the group, explain the most likely genetic change that produced the polypeptide in species II and the most likely genetic change that produced the polypeptide in species III.

II. mutation because an amino acid change only at position 4 III nonsense mutation because of the termination of the polypeptide after the Val at position 8

b) Predict the effects of the mutation on the structure and function of the resulting protein in species IV. Justify your prediction.

Protein may have a different structure and a change in function due to the Change in amino acid sequence of the protein starting at position 5 could alter the overall structure or local structural regions, interfering with function of the protein.

3a) Select the most appropriate sample of rocks in which to search for a transitional species between lobe-finned fishes and amphibians. Justify your selection.

Selection: Rocks from 370 MYA sample because Transitional fossils are found between 380 MYA (when lobe-finned fishes lived) and 363 MYA (when amphibians appeared) OR between different strata/layers in the correct order.

b) Propose ONE type of mating behavior that could have resulted in the observed change in the number of spots per adult male guppy between 6 and 20 months in the absence of the predator.

Sexual selection for individuals with more spots

c) Discuss Two pre prezygotic isolating mechanisms that prevent hybridization between two species. Include in your discussion an example of each mechanism/

Temporal- Different mating time of season of year Behavioral- Different mating rituals between species.

identify which tree is the best representation of the evolutionary relationship of these animals, and justify your answer.

Tree II The camel is the out-group, with none of the 13 sequences.

1a) Describe how organisms can reproduce asexually

a) Bacteria reproduces asexually through binary fission that splits the cell into 2. b) Yeast and sponges reproduce through budding by mitosis c) Kalanchoe leaves generate new plants

b) Describe TWO pieces of evidence provided by fossils of a transitional species that would support a hypothesis that amphibians evolved from lobe-finned fishes.

homologous structures such as scales and teeth, DNA evidence