Lecture 20 Flashcards
What is Microevolution?
changes in allele frequencies in a
population (with in the same species)
What is Macroevolution?
Evolutionary change above the species level
What does this include?
Includes the origin of a new group of organisms (speciation) or the cumulative evolutionary change over a long period
What is Speciation?
the process by which one species splits into
2 or more species, i.e. new species
What is Evolutionary theory?
Must explain how new species originate in addition to how populations evolve
What has traditionally been used to distinguish species?
Morphological differences.
What does the biological species concept emphasize?
emphasizes reproductive isolation
How is a population or group of populations defined according to the biological species concept?
As a group whose members can potentially breed with each other to produce viable, fertile offspring.
What distinguishes this group from others according to the biological species concept?
They CANNOT produce viable, fertile offspring with members of other species.
What are isolating mechanisms?
they are biological factors that impede members of two species from producing viable, fertile hybrids.
What do isolating mechanisms do?
They preserve genetic integrity
How do they preserve genetic integrity? By preventing WHAT?
by preventing gene flow between species
What do prezygotic barriers impede or hinder?
impede mating between species or HINDER fertilization if members of different species attempt to mate
What do prezygotic barriers ensure?
They ensure that a zygote is never produced
How many types of prezygotic barriers are there?
5
What do postzygotic barriers prevent?
often prevent the hybrid zygote from developing into a viable, fertile adult
complete the sentence: This means that while a zygote is produced…..
the resulting hybrid cannot reproduce itself once mature
How many types of postzygotic barriers exist?
3 types
For Prezygotic Barriers, name an example of habitat isolation
Aquatic vs Terrestrial
For Prezygotic Barriers, name an example of temporal isolation
Breed at different times of the year
Name an example of behavioral isolation
For Prezygotic Barriers, the female will only mate with a male with a certain courtship ritual
For Prezygotic Barriers, name an example of mechanical isolation (2)
-Shells spiral in different directions
-Genital openings not aligned
For Prezygotic Barriers, name an example of gametic isolation
Sperm will not fertilize the egg of another species (i.e. unable to survive, cannot penetrate egg…)
What are the 3 types of Postzygotic Barriers?
- Reduced Hybrid Viability
- Reduced Hybrid Fertility
- Hybrid Breakdown
When you think of Prezygotic Barriers, what should you immediately think of?
Prezygotic Barriers -> impede fertilization
When you think of Postzygotic Barriers, what should you immediately think of?
Postzygotic Barriers -> impede hybrid offspring
The biological species concept cannot be applied to 2 types of organisms, which ones?
- Asexual organisms
- Organisms about which little is known regarding their reproduction (ex. Fossils)
What are 2 other definitions of Species?
1) The morphological species concept
2) The ecological species concept
3) The phylogenetic species concept
What is the main idea of The morphological species concept?
Characterizes a species in terms of its body shape, size, and other structural features
What is the main idea of The ecological species concept?
Views a species in terms of its ecological NICHE
What is the main idea of The phylogenetic species concept?
trace the phylogenetic history of organisms (comparing morphology & molecular sequences)
Speciation can occur in two ways, name them:
1) Allopatric speciation
2) Sympatric speciation
Which one is related to the geographic separation of populations?
Allopatric speciation
What does the geographic separation of populations restrict?
gene flow
When does Sympatric speciation occur?
occurs in geographically overlapping
populations
Sympatric speciation is when biological factors reduce gene flow, give 2 examples of these biological factors
- chromosomal changes
- non-random mating
Let’s talk about Allopatric speciation: What are examples of geographic barriers that cause separation?
Mountain ranges, glaciers, land bridges, lakes splitting, and island colonization.
The significance of the barrier depends on what?
on the ability of organisms to move about