Lecture 5 Flashcards
2 Major ideas from previous lectures:
1) Populations evolve as allele frequencies change over time
2) Forces that lead to evolution are
- mutation
- genetic drift
- gene flow
- natural selection
What are the main forces that lead to evolution?
1) Mutation
2) Genetic Drift
3) Gene Flow
4) Natural Selection
Species
Distinct types of organisms that represent evolutionarily independent groupings
What causes genetic differences?
Mutation, Natural Selection, Genetic Drift acting on each group independently
Biological Species Concept
Population or group of populations that are reproductively isolated from other groups
Reproductive Isolation
Separation of one population from another by an inability to produce viable offspring when the two populations mate
What are the two types of reproductive isolating mechanisms (RIM’s)?
1) Pre-Zygotic RIM’s
2) Post Zygotic RIM’s
Examples of Pre-Zygotic RIM’s
- Temporal Isolation
- Behavioral Isolation
- Habitat (ecological) Isolation
- Gametic Isolation
- Mechanical Isolation
Examples of Post-Zygotic RIM’s
- Hybrid Inviability (Offspring do not develop properly)
- Hybrid sterility (Offspring mature but are sterile as adults)
Weaknesses of the biological species concept
- Can’t apply to asexually reproducing organisms
- Cannot be used to study extinct species
- Hard to apply to subpopulations that are geographically isolated and therefore do not have the opportunity to interbreed
Morphospecies (morphological) Concept
A group of organisms that is anatomically distinct from another group
Phylogenetic Concept
Smallest monophyletic group on the tree of life constitutes a species
Synapomorphies
Traits that are found in a monophyletic group, and only in that monophyletic group, are synapomorphies.
Ecological Concept
Occupation of a distinct niche or ecological zone
-Similar groups might be placed in different zones if they utilize different resources
