The Evolutionary Process

1. Variation

2. Natural Selection

3. Genetic Divergence

4. Reproductive Isolation

5. Speciation

- Pop's evolve not individuals

-Pop's have variation in traits among individuals

Microevolution

Features that Characterize a population

1. Morphological Traits (Form)

2. Physiological Traits (Function)

3. Behavioral Traits (Behavior)

Variation

Variation: Traits may be (+) or (-) or neutral to any        individual within a population.

Adaptation

Adaptation: Adjustment or change to meet environment conditions.

1. Adaptive Traits (+)

 -advantageous trait in terms of survival & reproduction

2. Maladaptive Traits (-)

 -disantageous trait in terms of survival & reproduction

3. Neutral Traits (0)

 -trait that is neither a disadvantage or advantage in terms of survival & reproduction

Gene

-Hereditary unit of DNA that codes for specific traits

Alleles

-2 or more different molecular forms of a gene (alternate form of a gene)

Gene Pool

-All the genes in a population

(pool of genetic resources)

Genome

-All the genes in a species

Genotype

individuals inherit different combinations of alleles

(genetic expression)

Phenotype

- individuals express different details of traits

(Physical expression)

-each genotype= one specific phenotype

Determination of Allele

in a gamete

(chan-cross-mut-ind-fert)

5 Events:

1. Gene Mutation (produces new alleles)

2. Crossing over in Meiosis I (recombinations)

3. Independent Assortment at Meiosis I (random pairing of paternal and maternal chromosomes)

4. Fertilization (combines alleles from 2 parents)

5. Change in Chromosome # or structure (deletion,duplication,translocation)

Traits:

Types

Features

Sources

Types: Adv (+), Mal (-), Neutral (0)

Features: BPM

Source: PAGGGG

            phenotype,allele,gene,genotype,gene pool,genome,

Note: each human gemete has 10^(600) possible allelic combinations.

Phenotypic Frequencies

(# of individuals w/ phenotype)/ (population size)

            ex:blue,red,green              ex: 50 individuals

def: the abundance of phenotype in a population.

ex: pop size=50

   Phenotypic frequencies

Brown (BB)...25 --> 25/50= 50%

Blue (Bb)........20 --> 20/50= 40%

Green .............3   -->  3/50 = 6%

Hazel .............2   -->  2/50 = 4%

Conclusion: all combined =100%,

note: with this info we can track the rate of genetic change over multiple generations

Allele Frequencies

(# of each allele)/(total alleles in Pop)

def: the abundance of each kind of allele in a pop.

pop size: 500-->all diploid so 500x2=1000 gene copies

Red: 300 (AA)...300x2(alleles)=600 (A) alleles

White: 150(aa)...150x2(alleles)=300 (a) alleles

Pink:50(Aa)....50x2= 100--> 50 (a) & 50 (A)

[pink carries half (a) allele's and half (A) allele's, which contribute to total of each]

Total: 650 (A) & 350 (a) alleles

          65% (A) Allele in Population

          35% (a) Allele in Population

Genetic EQ

def: frequencies of alleles at a given gene locus are stable for multiple generations.

How do we know whether or not a population is evolving with respect to any trait ???

We use the "Hardy-Weinberg Principle"

Hardy- Weinberg Principle

(frequencies of the genotypes add up to 1)

in a population in Genetic EQ:

• The proportion of genotypes at one gene locus with 2 kinds of alleles

p²(AA)+2pq(Aa)+q²(aa)=1

p=allele frequency of (A)     q=allele frequency of (a)

Rules to stable Allele frequencies

over successive generations

(As long as these 5 basic assumptions are met, frequencies stay the same through successive generations)

1. No Mutations

2. Pop is Large

3. Pop is Isolated

4. Mating is Random

5. Gene has no effect on Survival or Reproduction

Problems with Hardi-Weinberg EQ

Sometimes geno/phenotype predictions dont match!

1. One or more conditions were violated.

2. Start looking for another evolutionary reason!

3 Processes that drive Pop

away from EQ

1. Natural Selection

2. Gene Flow

3. Genetic Drift