AP Bio - Unit 7: Evolution (speciation)

types of population selection

types of population selection

Directional, stabilizing, and disruptive

Species

A group of living organisms consisting of similar individuals capable of interbreeding and producing fertile offspring

Hardy-Weinberg meaning and equation

Genetic variation will stay consistent across generations in the absence of disturbances

p = dominant

q = recessive

phenotypic frequency:

p² + 2pq + q² = 1

Allele Frequency:

p + q = 1

speciation

The formation of a new and distinct species in the course of evolution

2 Types of speciation

Allopatric and sympatric

Allopatric Speciaiton

One species is separated by geographic environments they undergo allopatric speciation. If they were to meet again in the future they would not interbreed

e.g. california salamanders

Sympatric Speciation

Even though both populations inhabit the same area, a new species evolves through pre-zygotic isolation

Types of pre-zygotic isolation

Gamete Isolation

• gametes cant fuse/fertilize

Behavioral Isolation

• courtship displays and different

Mechanical Isolation

• Incompatible sex organs

Temporal Isolation

• mating timing becomes different (nocturnal vs diurnal)

Habitat Isolation

• different habitats in the same location

post-Zygotic isolation

prevents the creation of a fertile offspring

Advantages of hybridization

favorable traits, survival of endangered species

Disadvantages of hybridizaiton

low zygotic viability (severe abnormalities, fails to mature), infertility, low adult viability (low survival rate because traits arent suited for any environment)

Micro evolution vs Macro evolution

micro: evolution in a short period of time (couple of generations)

macro: evolution over a long period of time