1. Presence of lactate dehydrogenase
Populations evolve
Natural selection acts on individuals
differential reproductive success
Populations evolve
genetic makeup of population changes over time
Presence of lactate dehydrogenase
The Mummichog (Fundulus heteroclitus heteroclitus) is a small killifish found in the eastern United States. It is capable of tolerating highly variable salinity and temperatures, and is found in estuaries and saltmarshes as well as less salty waters.
A year-round resident of tidal creeks and wetlands, this brownish-green saltwater minnow may reach a maximum length of 5 inches. Its Indian name means "they go in great numbers." It is also known as the common killifish.
A hardy fish, the mummichog is an important food source for larger fish and is often used as bait. The mummichog also has been used as a natural method of mosquito control in marsh ponds and ditches. It has been reported that one mummichog can eat as many as 2,000 mosquito larvae ("wrigglers") a day. The mummichog also feeds on other insects, small fish, crustaceans, and plant material.
Because of the extreme hardiness of the species, it is sometimes the only species found in severely polluted and oxygen-deprived streams, such as the Hackensack River and the Arthur Kill in New Jersey during the height of the water pollution problem in the United States. In 1973 the Mummichog became the first fish in space when carried on Skylab 3 as part of the biological experiments package later space missions by the U.S., such as Bion 3, have also carried Mummichog.
Mummichog

2. Fitness Survival & Reproductive success
Body size & egg laying in water striders
Survival & Reproductive success

3. Variation & natural selection
Variation is the raw material for natural selection

4. Where does Variation come from?
Mean beak depth of parents (mm)
Medium ground finch 8 9 10 11
1977
1980
1982
1984
Dry year
Wet year
Beak depth
Beak depth of
offspring (mm)
Mutation
random changes to DNA
Sex
mixing of alleles
recombination of alleles
new arrangements in every offspring

5. 5 Agents of evolutionary change
Mutation
Gene Flow
Non-random mating
Genetic Drift
Selection

6. 1. Mutation & Variation Mutation creates variation
Mutation changes DNA sequence
Every individual has hundreds of mutations
1 in 100,000 bases copied
3 billion bases in human genome
But most happen in introns, spacers, junk of various kind
Not every mutation has a visible effect.
Some effects on subtle.
May just affect rate of expression of a gene.

7. 2. Gene Flow Movement of individuals & alleles in & out of populations
migration of animals
causes genetic mixing across regions
reduce differences between populations

8. 3. Non-random mating
Sexual selection

9. 4. Genetic drift Effect of chance events founder effect Bottleneck
1 family has a lot of children & grandchildren therefore has a greater impact on the genes in the population than other families
Genghis Khan tracked through Y chromosome.
Warbler
finch
Tree finches
Ground finches

10. Conservation issues
Peregrine Falcon
Bottlenecking is an important concept in conservation biology of endangered species
reduces variation
reduces adaptability
Breeding programs must consciously outcross
Golden Lion Tamarin

11. 5. Natural selection
Differential survival & reproduction due to changing environmental conditions
climate change
food source availability
predators, parasites, diseases
toxins
combinations of alleles that provide “fitness” increase in the population
adaptive evolutionary change

12. Any Questions??

13. Review Questions

14. 2. Genetic analysis of a large population of mink inhabiting an island in Michigan revealed an unusual number of loci where one allele was fixed. Which of the following is the most probable explanation for this genetic homogeneity? *
The population exhibited nonrandom mating, producing homozygous genotypes.
The gene pool of this population never experienced mutation or gene flow.
A very small number of mink may have colonized this island, and this founder effect and subsequent genetic drift could have fixed many alleles.
Natural selection has selected for and fixed the best adapted alleles at these loci.
The colonizing population may have had much more genetic diversity, but genetic drift in the last year or two may have fixed these alleles by chance.
Answer: c
Source: Taylor - Student Study Guide for Biology, Seventh Edition, Test Your Knowledge Question #20
Discussion Notes for the Instructor
The main discussion revolves around the causes of gene fixation. While many of the choices are possible, several are very unlikely. It is also a good question for pointing out that selection rarely leads to allele fixation in a large population
• Choice A: while this is possible the non-random mating would have to be very extreme to produce this result.
• Choice B: this by itself will not produce the results listed
• Choice C: given this is an island in Lake Michigan, this is the best choice
• Choice D: selection generally will not result in fixation.
• Choice E: this assumes that the initial population was large and then became smaller. Given the island location this is not the best explanation.

15. Which of the following statements is NOT true about genetic mutations?
Genetic mutations are always harmful
Mutations can occur when DNA molecules are copied
Mutations are the ultimate source of all variations in a population
Mutations that occur in the skin cells of parents can be passed to offspring
Mutations are the raw material that drives evolution.

16. Which of the following is NOT a component of Darwin’s theory of natural selection?
Mutations cause a significant amount of genetic variation
Evolution is a slow process that occurs over a long period of time
Variations among organisms are the basis by which organisms will or will not reproduce
Organisms who posses the most favorable variations have a higher comparative level of fitness
More individuals are born than can survive

17. Base your answers to the following questions on the choices below:
A. Founder effect
B. Adaptive Radiation
C. Gene Flow
D. Genetic Drift
E. Hardy-Weinberg Equilibrium
Occurs when a population undergoes a dramatic decrease in size.
Describes the introduction or removal of alleles when individuals enter or leave a population.
The term used to describe a theoretical, non evolving population.