Microevolution

Question 1

What was Cuvier attempting to explain with his idea of Catastrophism?

Answer 1

Through Catastrophism, Cuvier was attempting to explain why the fossils looked so different over time

Question 2

Before Darwinism’s time, what was the prevailing idea for the age of the earth?

Answer 2

Earth was only a few thousand years, created by God in a single week, species were fixed

Question 3

Describe Lamarck’s explanation for a mechanism of evolution.

Answer 3

Body parts evolved in correlation to how much they were used, with more used parts becoming larger and stronger and the opposite occurred to the least used body parts
The second part is modifications an organism acquires is passed to their offsprings

Question 4

Summarize the ideas of Natural Selection

Answer 4

1. All species pop. size would increase exponentially if all species born reproduced successfully
2. Pops tend to remain stable in size
3. Environmental Resources are limited
4. Individuals of a pop. vary greatly in their characteristics
5. Much of the variation is heritable

Question 5

Describe homologous, analogous, and vestigial structures

Answer 5

Homologous Structures = structures that are similar because of common ancestry
Analogous structures = same function, different structure
Vestigial Organs = Rudimentary structures of marginal or no use to the organism

Question 6

What are the five conditions of the Hardy-Weinburg Equilibrium?

Answer 6

1. Large Population Size
2. No Immigration or Emigration
3. No Mutations
4. Random Mating
5. No Natural Selection

Question 7

What is a cline?

Answer 7

graded change in a trait along a geographical transect

Question 8

What does an organism’s level of “fitness” mean?

Answer 8

the ability of an organism to pass on its genetic material to its offspring

Question 9

Describe directional, stabilizing, disruptive, and sexual selection.

Answer 9

Stabilizing = favors intermediate variants, selects against the extremes
Directional = favors variants of one extreme
Disruptive = opposite phenotypic extremes are favored
Sexual = natural selection arising through preference by one sex

Question 10

(FRQ) Describe how the following have contributed evidence in support of evolution: molecular biology, the fossil record, biogeography, embryology, homologous structures, and vestigial structures.

Answer 10

• Molecular biology: Molecular similarities provide evidence for the shared ancestry of life. DNA sequence comparisons can show how different species are related.
• Fossil record: The fossil record is not a complete record of evolutionary history, but it confirms that life on earth was once different from life found today
• Biogeography: the study of the geographical distribution of organisms, provides information about how and when species may have evolved.
• Embryology: closely related organisms go through similar stages in their embryonic development, some homologous structures can be seen only in embryo development
• Homologous Structures: structures that are similar because species have a common ancestry,
• Vestigial Structures: body parts that are no more functional the way they were in their ancestral form of the trait; suggest that an organism used the structure in the past but has since stopped using it or is using it for a different reason

Question 11

Describe the FIVE causes of microevolution

Answer 11

1. Genetic Drift = changes in the gene pool of a small population due to chance
2. Gene Flow = The migration of fertile individuals or the transfer of gametes between populations
3. Mutations = change at a single locus
4. Nonrandom Mating = Increases the number of homozygous loci in a pop.
   A.)Inbreeding – self-fertilization or
   mating with neighbors
   B.)Assortative Mating – Individuals
   mate with partners that are like
   themselves in certain phenotypes
5. Natural Selection = variation among individuals exists, and some leave more offspring than others; only one which is adaptive