Chapter 13 Flashcards
Fitness
ability of an organism to survive and REPRODUCE
Binary Fission
a type of asexual reproduction in which one parental cell divides into two
Gene transfer
the process by which bacteria can exchange segments of DNA between each other
Adaptation
The process by which populations become better suited to their environment as a result of natural selection.
Gene flow
movement of alleles from one population of a species to another
EX: hybrid “grolar” bear
Gene pool
collection of all genes (including alleles) present within a population
Microevolution
Change in allele frequencies in a population over generations.
Hardy-Weinberg Principle
principle that allele frequencies in a population will remain constant unless one or more factors cause the frequencies to change
5 Conditions of Hardy Weinberg Principle
- Very large population
- No gene flow between populations
- No mutations
- Random mating
- No natural selection
Causes of evolutionary change
NATRUAL SELECTION
genetic drift
gene flow
3 ways natural selection can affect populations
stabilizing selection
directional selection
disruptive selection
Stabilizing selection
species with average or moderate phenotypes are more likely to survive and reproduce
Directional selection
favors one extreme phenotype over the others in a population
Disruptive selection
phenotypes of populations is at both extremes of range
Natural selection in bacteria is caused by…
directional selection
bc when antibiotics are present bacteria with genes for resistance have the greatest fitness.
Allen’s Rule
warm climates: body is long & skinny
cold climates: body is more compact
Bergmann’s Rule
warm climates: body is small
cold climates: body is large
Artificial selection
humans intentionally choose specific organisms to breed
EX: dogs and corn
Risks of artificial selection
- increased genetic problems
- changes in behavior
- increased obesity
- increase disease susceptibility
- less ability to adapt
What are the 3 ways natural selection can affect populations?
- stabilizing selection
- directional selection
- disruptive selection
Species
organisms that can be interbreed in nature to produce healthy offspring
Speciation
formation of new species from one
Reproductive isolation
mechanisms that prevent mating (and therefore gene flow) between members of different species
Morphological species concept
- specie that are visibly similar to each other in terms of their physical appearance
- can be applied to ASEXUAL organisms and fossils
