Genetics Species and speciation

• Allopatric "other place"
• Parapatric "beside place"
• Sympatric
• Hybridization

• Populations become seperated by a physical barrier and the evolve reproductive barriers
• Most common

• 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

When species reconverge after speciation

Closest relative will be in different geographic area

• Hunted to samll number
• small colony near Mexico - Founder effect
• very small genetic diversity (population bottleneck)
• -conservation issue

• Strong selection causes a continuous population to diverge
• Populations are contifuous
• No physical barrier (gene flow) speciation between niches within ecosystem

When a species diverges, but populations come back together. The area the two pop meet is the hybrid zone (secondary contact)

Primary differenctiona Find slide

No geographic separation

• 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)

• 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