Unit 8 Evolution & Classification

Study Guide

Part 1 (LT 9, 11-12, & 17)

  1. What does a theory explain in science?

Why we see what we see in nature

  1. What does the theory of evolution explain?

The unity & diversity of life

  1. List the 8 different evidences for evolution we discussed in class.

Biogeography, Fossil Recors, Extinctions, Homologous structures, Analagous Structures, Vestigal structures, DNA, Embryology

  1. What are two ways fossil records can be dated? Briefly explain both (what isotope is used most frequently & why).

Relative dating (older layers deeper under ground)

Radiometric dating (half-lifes of isotopes…C14 commonly used b/c plants & animals absorb it.

  1. What is considered a mass extinction (population level)?

60% population dies

  1. Draw a timeline of the big events in earth’s history (oldest fossils? mass extinctions & when do we see a sudden explosion of different body types?)

Prokaryotes 3.5 billions year old!! Creataceous, Triassic, Permian, Devonian, Ordovician….present time humans! Cambrian explosion!

  1. What percentage of species that have ever lived are extinct?

99%

  1. What benefit comes from extinctions?

Opens up niches for other populations

  1. Define homologous and analogous structures? List at least one example for each.

Homologous similar structures because of a common ancestor (ex bat wing & whale flipper. Both mammals & structure of bones similar…even function ->movement)

Analagous similar function, but NOT b/c of a common ancestor (insect wing & a bat wing)

Part 2 (LT 1 & 2, 6 & 16)

  1. Who recognized that the interaction of an organism with its environment was important in an evolutionary sense?

Both Darwin & Lamarck

  1. What was Lamarck’s theory of evolution?

That individual organisms develop adaptions that get passed on (ex: giraffes stretching its neck longer, passes it on…it would be like saying that you could pass on your 6-pack to your children)

  1. Define “Descent with Modification”.

Descent from a common ancestor…with changes….why species are so diverse, yet still similar

  1. What are three limits to Natural Selection?

Limited to existing variations (can’t select for something that’s not present

Constraints due to history (nat selection has already selected the most fit individuals…finding something “new & improved” is difficult

Trade-off in changes (ex: cheetahs w/longer legs legs frail & break easily=death)

  1. What does the term “fitness” mean?

Best able to survive and pass on genes… NOT STRENGTH!!!!

  1. In order for Natural Selection to occur, what are some necessary conditions?

Not enough resources, survival of the fittest and variation in the gene pool

  1. What does natural selection act directly on?

The individual (the alleles in each individual genotype)

  1. How is fitness affected by human activities? Give an example.

Humans change the environment  variation that is most fit selected for….human are a selective pressure on populations (pollution, loss of habitat, hunting, etc)

  1. Define Directional selection.

Individuals at one extreme are more fit

  1. What would a graph look like for a population that is going through Directional Selection?
  1. Define Stabilizing selection.

Individuals in the middle are more fit

  1. What would a graph look like for a population undergoing stabilization selection?
  1. Define Disruptive selection.

Individuals in middle are less fit—eliminated

  1. What would a graph look like for a population undergoing disruptive isolation?

Part 3 (LT 3 & 7 & 8)

  1. What are two types of Genetic Drift? Explain each below.

Founder’s effect (new population will carry different allele frequencies from original population b/c only the alleles of the “founders” of the new population will be passed on)

Bottleneck effect (when some disaster wipes out a large portion of the population and leaves only a few to reproduce  reduces diversity)

  1. What is the definition of microevolution?

A change in allele frequency

  1. In gene flow, genes are being exchanged between different______populations______.
  2. What are three sources of genetic variation? Briefly define each. Circle the major source of variation.

Mutations mistakes in replication, rare

Gene shuffling mesoisis & crossing over MAJOR SOURCE!!!!

Polygenic traits Polygenic traits ->controlled by many genes

  1. All of the members of a population have the same gene pool, which determines their phenotypes.
  2. When members of the same population interbreed, what happens to the gene pool?

No change in gene pool ….allele frequencies same

  1. What would be the impact on evolution if mutations stopped occurring?

No new variations could enter a population, but frequencies of existing alleles could still change

Part 4 (LT 4 & 5)

  1. What are the 5 requirements for Hardy Weinberg Equilibrium?

Large Population; Random Mating; No Natural Selection; No Migration; No Mutation

  1. Write down the Hardy-Weinberg Equation & label each part Homozygous Dominant, Heterozygous, and Homozygous Recessive.

p2 + 2pq + q2 HD (p2 ), Hetero (2pq), hr (q2)

  1. As the allele frequency of p increases, what happens to q?

It decreases

  1. If the dominant allele is present in a gene at a frequency of 60%, what is the frequency of the recessive allele?

40%

  1. Cystic fibrosis is caused by a recessive allele. If 91% of the population does not have cystic fibrosis, what is the frequency of the dominant allele? The recessive allele? What percent of the population is heterozygous?

91% is the Dominant geneotype 100%-91% Q2 =.09 q=.3

p+q=1  1-.3=.97  p = .97

Dominant allele (p) .97, Recessive allele (q)  .3, Hetero (2pq) .582 or 58.2%

Part 5 (LT 14 & 16)

  1. List & briefly define the 5 types of prezygotic isolation.

Behavioral isolation  behavior prevents mating

Habitat/Geographic isolation  physical barrier/habitat differences or rare encounters prevent mating

Temporal isolation  mate at different times

Mechanical Isolation  morphological differences prevent mating

Gamteic Isolation Sperm cannot survive/fuse with egg

  1. List & briefly define the 3 types of postzygotic isolation

Reduced hybrid viability  hybrid dies before born or developmental impairment makes hybrid frail

Reduced hybrid Fertility  hybrid fine, but can’t reproduce

Hybrid Breakdown hybrid fine, can reproduce, but second or third generation cannot

  1. Allopatric speciation results from Geographic Reproductive Isolation_____.

Part 6 (13)

  1. What is macroevolution?

Large scale changes in evolutionay patterns bigger than species

  1. What is Adaptive Radiation?

Evolution of diverse species from a common ancestor.

  1. Convergent Evolution?

Unrelated organisms develop similar structures

  1. How does the concept of punctuated equilibrium differ from “normal” evolutionary theory?

Punctuated equilibrium says evolution can proceed both quickly and slowly.

Part 7 (15, 17-25)

  1. Why do researchers think RNA came 1st?

RNA can act as an enzyme & because researchers have been able to create it in a lab

  1. What evidence supports the endosymbiotic hypothesis?

Mitochondria and chloroplasts both have their own DNA, which is similar to bacteria

  1. What did Miller & Urey’s experiment prove?

That conditions are early Earth were favorable enough to form molecules needed for life

  1. All organisms use the same genetic code. What does that tell you about their relationship?

They share a common ancestor

  1. Hemoglobin is a common protein, whose amino acid sequence is known. There are 20 amino acids different between a dog and a rattlesnake hemoglobin structure. There are 10 amino acids different between a dog and a coyote. Rattlesnakes and coyotes have 25 amino acids different in their hemoglobin structure. Which 2 species are more closely related? Justify your answer (complete sentences!!)

Dog and coyote, less difference between the two

  1. What distinguishes one branch from another in a cladogram?

Derived characters

  1. What is an outgroup?

A group that does not have a recent common derived characteristic, used for scale

  1. Using the Cladoragm above, circle a taxa.
  2. Using the Cladogram above, draw a square around the sister group of turtles.
  3. Using the cladogram above, draw a triangle over a common ancestor (node).
  1. Using the cladogram below, what two organisms are the closest relatives? The furthest?

Closest: flies & butterflies, furthest: Flies & beetles

  1. What ancestor gave rise to both nonseeded and seeded plants in this phylogenic tree?First vascular plants

  1. According to the phylogenetic tree to the right, which organism would you expect to not have an amnion (membranes around their embryos during development)?

Lungfish & amphibians

  1. Using the table, draw a cladogram of species 1-5 (hint, identify your outgroup first).