Genetics Species and speciation
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What are the modes of speciation?
- Allopatric "other place"
- Parapatric "beside place"
What is Allopatric speciation?
- Populations become seperated by a physical barrier and the evolve reproductive barriers
- Most common
What are two types of Allopatry + examples?
- Vicariant: pop divided into two widespread populations by a physical barrier - no dispersal - result = 2 large pop
- ex: freshwater fish and snapping shrimp (land bridge formation)
- Peripatric: A small colony disperses from a widespread population to a new area and evolves reproductive isolation Physical barrier - dispersal - 2 small pop.
- Usually caused by genetic drift/founder effect
What is secondary contact?
When species reconverge after speciation
How can you tell if a vicarian event ocured by looking at a phylogeny tree
Closest relative will be in different geographic area
Why are elephant seals and example of peripatric speciation?
- Hunted to samll number
- small colony near Mexico - Founder effect
- very small genetic diversity (population bottleneck)
- -conservation issue
What is Parapatric Speciation?
- Strong selection causes a continuous population to diverge
- Populations are contifuous
- No physical barrier (gene flow) speciation between niches within ecosystem
What is a Hybrid Zone?
When a species diverges, but populations come back together. The area the two pop meet is the hybrid zone (secondary contact)
What does a hybrid zone indicate?
Primary differenctiona Find slide
What is Sympatric speciation?
No geographic separation
What is Hybridization?
- Model of speciation
- Two parental species hybridize and produce offspring that can breed with each other, but are reproductively...
- Much more common in plants (rare in animals)
Speciation by polyploidy is caused by __?__.
- Errors in mitosis or meiosis resulting in diploid gametes instead of normal haploid gametes.
- Individuals with diploid gametes mate with each other and produce polyploid offspring
- Resulting individuals can not breed with progenitors (parents), but can breed with each other
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