Exam 6 Jeopardy Population Evolution Genetics Hardy Weinberg

Exam 6 Jeopardy Population Evolution Genetics Hardy Weinberg Problems Speciation Random $100 $100 $200 $200 $300 $300 $400 $400 $500 $500

1 $100 Idea 1: The species inhabiting the Earth have CHANGED through time n What evidence supports this idea? n By the mid 1850 s, many people (including Darwin) had collected numerous fossils of species that appeared not to currently exist anywhere on Earth n So a large (and still increasing…) body of evidence that the species inhabiting the Earth HAD changed dramatically n The current estimate is that ~ 99% of ALL species that have ever lived on Earth are EXTINCT n

1 $200 Idea 2: Species are related by common ancestry (Darwin called this “descent with modification”) n What evidence supports this idea? n Similar species are often found in the same geographic area (see Fig. 22. 6) n Similar species share “homologies” (we’ll come back to this…) n

1 $300 n What is homology and what are the types we discussed in lecture? Homology is sharing common characteristics due to common ancestry n In class we learned about genetic, developmental, and morphological homology n

1 $400 n Was Charles Darwin the first person to propose the idea of evolution? n No! Jean Baptiste Lamarck and Erasmus Darwin’s grandfather, did before him. Darwin just came up with actual explanations and proof

1 $500 n Instead of natural selection being referred to as “the survival of the fittest”, it would make more sense if it were referred to as… n Reproduction of the fittest n ***Natural selection occurs when individuals with certain heritable traits produce more surviving offspring than do individuals without those traits

2 $100 n Define population and gene pool. n Population: Group of individuals in the same place, at the same time, belonging to the same species n Gene pool: All alleles, at all gene loci, in all individuals of a population

2 $200 n Explain the founder effect. n small number of individuals leaving populations and moving to a new location. This small number of individuals is not likely to have all the genes that the whole population had. So, loss of alleles by random chance.

2 $300 n Explain genetic bottleneck. n Bottleneck effects happen when some catastrophe, like an earthquake or a tsunami, kills off most of a population at random and leaves only a handful of survivors. The catastrophe has to be something that strikes at random, however, and kills individuals irrespective of the genes they carry.

2 $400 n What is genetic drift? n Changes in allele frequency due to chance

2 $500 n Give an example of founder effect. n Colonization of an island by one or few members of the population.

3 $100 n In Hardy Weinberg Equilibrium, what does p, q, p 2, q 2 and 2 pq mean? n p = frequency of dominant allele in population q = frequency of recessive allele in population p 2= frequency of homozygous dominant n n individuals in population n q 2= frequency of homozygous recessive individuals in population n 2 pq= frequency of heterozygous individuals in population

3 $200 n Pretend you have a population of cats in Hardy Weinberg equilibrium. You are examining color, which has alleles C and c. The frequency of allele c is 0. 3. What percentage of the population is heterozygous for color? n q=0. 3 p+q=1 1 q=0. 7 heterozygous=2 pq = 2(0. 7 )(0. 3) = 0. 42= 42% heterozygous

3 $300 n To remain in Hardy Weinberg equilibrium, the population must meet what 5 conditions? Do natural populations ever satisfy all of these conditions? n No “genetic drift” No gene flow (migration) No natural selection No mutation Random mating *Natural populations NEVER satisfy all five of these conditions. So allele frequencies change through future generations, which is EVOLUTION! SO, not meeting the conditions on which the hardy weinberg equation is based tells us that evolution is always occurring. n n n

3 $400 n Assume that in a population of birds, two alleles exist for tail color: red, which is recessive, and blue, which is dominant. You do a field study of a population of 1, 000 birds and find that 420 have red tails and 580 have blue. If the population is in H W equilibrium, what is the frequency of the recessive allele in this population? p^2 = 0. 580 n q^2 =0. 420 n q = frequency of recessive allele so we want to find q n To find q, take the square root of 0. 42 (q^2) = 0. 64 n

3 $500 n The frequency of alleles at one locus in the gene pool of a large population is A (dominant) = 40% and a (recessive) = 60%. What would you predict is the frequency of the Aa genotype in this population when it is in Hardy Weinberg equilibrium? A = p = 0. 4 n a = q = 0. 6 n Aa = 2 pq = 2 x 0. 4 x 0. 6 = 0. 48 n

4 $100 n What are the two types of speciation? Describe each. n. Allopatric Speciation – requires geographic barriers. Examples vary depending on the nature of the organism involved. Include: rivers, oceans, mountain ranges, newly formed islands, etc. Can occur due to dispersal events or vicariance (fragmentation of the environment (as by splitting of a tectonic plate) in contrast to dispersal as a factor in promoting biological evolution by division of large populations into isolated subpopulations) n. Sympatric Speciation – development of new species in the same place, i. e. no “geographic barrier”

4 $200 n What is a pre zygotic barrier and post zygotic barrier? Pre zygotic barriers that act PRIOR to formation of a zygote barriers to mating or fertilization Post zygotic barriers that prevent the hybrid zygote from developing into a viable, fertile adult

4 $300 n Horses and donkeys are separate species (according to the Biological Species concept) because their offspring (mules) are sterile. Pre zygotic or post zygotic barrier? n Post-zygotic. The hybrid is sterile making this reproduction unsuccessful.

4 $400 n Habitat isolation. Pre zygotic or post zygotic barrier? n Pre-zygotic barrier. When two species occupy different habitats within the same area. An aquatic species vs a terrestrial species.

4 $500 n What is the out of Africa hypothesis? The oldest known (~ 200, 000 years old) fossil remains of our species are from Ethiopia, in Africa n All the available evidence supports the idea that our species evolved in Africa and reached other parts of the world by migration n Humans probably first reached the western hemisphere by ~ 20, 000 years ago n AKA we are all Africans!!! n

5 $100 n Did humans evolve from apes? n NO! Humans and modern apes shared a common ancestor

5 $200 n What is the difference between natural selection and artificial selection? Naturally selection occurs naturally the process whereby organisms better adapted to their environment tend to survive and produce more offspring. n Artificial selection is where humans select which individuals reproduce (ex: dog breeds) n

5 $300 n If two different populations do not interbreed in nature, or if they fail to produce viable fertile offspring when mating takes place, they are considered to be ______. n Different species

5 $400 n What is the example of sympatric speciation we discussed in class? n flies. Change in the environment occurred with the intro of apples into North America by humans. Represented a change in environment fro Rhagoletis flies – apples became available for reproduction. There is now strong evidence for two distinct populations of Rhagoletis pomonella flies – those that lay eggs on hawthorns, and those that lay eggs on apples

5 $500 n The theory of evolution is an explanation for the origin of life on earth – true or false n False this is a myth