Chapter 25 - Iowa State University

Leader: Adam
Course: Biology 211
Instructor: Dr. Holscher
Chapter 25:
Supplemental Instruction
Iowa State University
1. Genetic Drift:
a. Refers to changes in _______ frequency due to _______.
b. Has a great impact on what size of populations?
c. Tends to reduce what?
d. Can cause _______ alleles to become fixed
2. There are two types of genetic drift:
-A sudden change in the environment may
drastically reduce the size of the population
Occurs for two reasons
-Occurs when a few individuals become isolated
from a larger population, this new group establish a new population whose
gene pool differs from the source population
1. The founding populating is expected to have _____ genetic
variation than the larger population.
3. Migration
a. Can alter allele frequencies between what?
b. Tends to ________ differences in allele frequencies between populations while
_________ genetic diversity within populations.
4. Macroevolution it the evolutionary change that creates new _________.
Reproductive Isolation
1. Prezygotic isolating mechanisms:
What are the 3 types of prezygotic isolating mechanism called? Describe each.
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2. Postzygotic isolating mechanism: (describe)
What are the 3 types of postzygotic isolating mechanism called?
_________This views a species in terms of its unique ecological niche.
_________This characterizes a species based in the separate evolution of its lineages
_________This characterizes a species in terms of its genome sequence.
a. Molecular species concept
b. Ecological species concept
c. Evolutionary lineage concept
Mechanism of Speciation
1. Allopatric speciation:
a. Occurs when some members of a species……(fill in)…………..from other
b. Most common form of _________
2. Regions in which members of different species meet and mate, producing some
offspring of mixed alleles is called?
3. Sympatric speciation
a. Occurs in populations that live in _______ geographic area.
Evo-devo (Evolutionary developmental biology)
1. Field of biology that compared the development of different organisms in attempt to
understand ancestral relationships between organisms and the developmental mechanism
that brings about evolutionary change
Genes that affect growth:
A. Heterochrony:
B. Paedomorphosis
Question: The first step in allopatric speciation is ______.
a. Mutation
b. Genetic Drift
c. Geographic isolation