The Process of Evolution How it Works and How we See It

Topic Outline Evolution in a Genetic Context Evolution in a Genetic Context - Microevolution - Microevolution Hardy-Weinberg Hardy-Weinberg Causes of Microevolution Causes of Microevolution Natural Selection Natural Selection Types of Selection Types of Selection Maintenance of Variations Maintenance of Variations Speciation Speciation Modes of Speciation Modes of Speciation

Background Vocabulary Gene Gene Allele Allele Phenotype vs Genotype Phenotype vs Genotype Homozygous Homozygous Heterozygous Heterozygous Gene pool Gene pool Microevolution Microevolution Polygenic (Quantitative) vs Monogenic Traits Polygenic (Quantitative) vs Monogenic Traits

The Hardy-Weinberg Model p 2 + 2pq + q 2 And p+q=1

What Does it Mean? p=Frequency of Dominant allele p=Frequency of Dominant allele q=Frequency of recessive allele q=Frequency of recessive allele p 2 =frequency of Homozygous dominant individuals p 2 =frequency of Homozygous dominant individuals q 2 =frequency of homozygous recessive indviduals q 2 =frequency of homozygous recessive indviduals 2pq=frequency of heterozygotes 2pq=frequency of heterozygotes

So What? The Hardy-Weinberg principle states an equilibrium of allele frequencies in a gene pool of a sexually reproducing population, p 2 + 2pq + q 2, won’t change as long as certain conditions are met. What are these conditions? The Hardy-Weinberg principle states an equilibrium of allele frequencies in a gene pool of a sexually reproducing population, p 2 + 2pq + q 2, won’t change as long as certain conditions are met. What are these conditions?

Example: Industrial Melanism

Causes of Microevolution Genetic Mutations Genetic Mutations Gene Flow Gene Flow Nonrandom Mating Nonrandom Mating Genetic Drift Genetic Drift Natural Selection Natural Selection

MUTATIONS Gene mutations the only source of new alleles Gene mutations the only source of new alleles Chromosomal mutations alterations in the number, composition, or the arrangement of gene’s on a chromosome Chromosomal mutations alterations in the number, composition, or the arrangement of gene’s on a chromosome

Chromosomal mutations

Deletion

Translocation

Duplication

Inversion

Gene Flow Physical Movement of Alleles

Nonrandom Mating Assortative mating Sexual selection

Genetic Drift Genetic Drift Bottleneck Effect Bottleneck Effect Founder Effect Founder Effect

Bottleneck Effect

Founder Effect

Founder Effect 2

Natural Selection

Types of Selection Directional Selection Directional Selection Stabilizing Selection Stabilizing Selection Disruptive Selection Disruptive Selection

Directional Selection

Stabilizing Selection

Disruptive Selection

Maintenance of Variations Are there any advantages to variation in a population?

Sickle Cell Distribution

Speciation Species Definition Species Definition Morphological Morphological Biological Biological Reproductive Isolation Reproductive Isolation Phylogenetic Phylogenetic

Species A group of interbreeding populations that share a gene pool and are reproductively isolated from other species. A group of interbreeding populations that share a gene pool and are reproductively isolated from other species. Subpopulations can exchange genes. Different species can’t. Subpopulations can exchange genes. Different species can’t.

Reproductive Isolating Mechanisms Prezygotic Isolating Mechanisms Postzygotic Isolating Mechanisms

Modes of Speciation Allopatric Speciation-spatial separation Allopatric Speciation-spatial separation Sympatric Speciation- no spatial separation Sympatric Speciation- no spatial separation

SYMPATRIC SPECIATION --EX SPECIES A: 2N=14,  N = 7 DUPLICATION SPECIES A’: 2N=28  N = 14 SPECIES A X SPECIES B 2N=21  N=?

Adaptive Radiation

Review Evolution in a Genetic Context Evolution in a Genetic Context - Microevolution - Microevolution Hardy-Weinberg Hardy-Weinberg Causes of Microevolution Causes of Microevolution Natural Selection Natural Selection Types of Selection Types of Selection Maintenance of Variations Maintenance of Variations Speciation Speciation Modes of Speciation Modes of Speciation