What do these images have in common?

What do these images have in common?

Tahina spectabilis, a rare species of palm, was discovered in Madagascar. It grows very tall, blooms spectacularly once, produces fruit, then dies.

Microbacterium hatanonis is a new species of extremophile bacteria so hardy that it lives and reproduces in cans of hairspray.

A thread snake, Leptotyphlops carlae, is the smallest known snake. Here, it is coiled on an American quarter

These photographs represent new species discovered and named since the year 2005.

Microevolution is when allele frequencies change from generation to generation

App - Recent Adaptations in Humans HHMI's all slides

is evolution on the smallest scale-

An example of in humans is the prevalence of sickle-cell disease in Africa.Sickle-cell disease causes weakness, pain, and even death.The disease is caused by a allele; if a person has two of these recessive alleles, they sickle-cell disease.Carriers (Heterozygotes) of the sickle-cell allele have the disease, but are resistant to malaria.

App - Sickle Cell Anemia

microevolution

recessivehave

do not

Evolution = Without mutations and/or sexual reproduction, evolution does not occur.No changes to the gene pool is called the .The Hardy-Weinberg Equilibrium occurs when the frequency of alleles in a gene pool is constant over time.This equilibrium requires random mating, a large population, no movement in or out of the population, no mutations, and no natural selection.In real life, .

changes to the gene pool

Hardy-Weinberg Equilibrium

there are always some changes to disrupt this

Microevolution is the of the Hardy-Weinberg Equilibrium.disruption

By applying genetics and mathematics to the theory of natural selection we can determine whether a population is evolving!!!!!!

Hardy-Weinberg Equilibrium

Frequencies of alleles are constant

Let p represent dominant alleleLet q represent recessive allele

Therefore p + q = 1 formula to calculate frequency of alleles

In order to determine if a population is evolving or not we need a baseline, the formula to calculate frequency of genotypes (2 alleles) in a population

p2 + 2pq + q2 = 1 p2 - homozygous dominant

2pq - heterozygous q2 - homozygous recessivep2 + 2pq + q2 = 1

HWE Example

Approximately 16% of the population of mice have brown fur. The rest of the population has black fur. If we assume that the brown fur are homozygous recessive for the gene b, what is the frequency of homozygous dominants (BB) in the population? Of heterozygotes (Bb)?

Let B - black fur dominantLet b - brown fur recessive

We need to determine whether the question is talking about one allele or about a genotype which consists of 2 alleles.

Brown fur - in order to show brown your genotype has to be bb, therefore the question is genotype

bb = 0.16 = q2 frequency of the homozygous recessive

square root of q = 0.4

p + q = 1

p = 1 - q = 0.6

BB = p2 = 0.36 = 36%

2 pq = 2 (0.6) (0.4) = 0.48 = 48%

frequency of the homozygous dominant

frequency of the heterozygotes

We now have a baseline to determine if evolution occurs over a period of time!

BB - 36%Bb - 48%bb - 16%

Microevolution is driven by natural selection, sexual selection, artificial selection, genetic drift, and gene flow.

Natural selection is not random.The individuals have a reproductive advantage, so the frequency of their alleles in the gene pool is higher.S in the environment change the relative frequencies of phenotypes in a population.

App - Natural and Artificial Selection Slide 5 with videos

1) NATURAL SELECTION

fittest

elective pressures

Stabilizing selection: the phenotypes are favouredDirectional selection: of the phenotypes is favouredDisruptive selection: of phenotypes are favoured

most frequent

one extreme

two or more extremes

Changes in the fitness of individuals changes the normal distribution of phenotypes in the population. - Masses of human babies at birth is an example of stabilizing sel. - Pesticide and antibiotic resistance are examples of directional selection. - Darwin's finches is an example of disruptive selection

2) Sexual Selection - Sexual selection is not random; mates are often chosen based on their phenotype. - Other individuals in the species screen, or select, the traits. The most common forms are and competition

 - In natural selection, the environment screens the traits.

female mate choice male vs. male

3) Artificial Selection Examples - Artificial selection is not random.   - Breeding programs are used to produce desirable traits. (cats)

 - Artificial selection can have usually in the form of genetic diseases. Eg. Horses HYPP (Hyperkalemic periodic paralysis is an inherited disease of the muscle which is caused by a genetic defect) Reducing genetic diversity making species vulnerable to evolutionary forces

This registered American shorthair cat is the result of artificial selection.

Activity C6 - Natural vs. Artificial

unintended consequences

4) Genetic Drift

 Is , changing the gene pool due to chance

Each new generation has a shift in the frequency of alleles based on which alleles get passed along to offspring (for example, the recessive gene may be lost in a few generations)

Has a much greater effect on small populations

Can have a major effect on a population

  - the occurs when a population suddenly decreases, often due to a natural disaster - this decrease variation in alleles in the population, decreasing genetic diversity

 - the occurs in a new, isolated population  - this is likely what occurred with Galapagos finches

random

bottleneck effect

reduces

founder effect

5) Gene Flow

 Gene flow is a process. Populations of a species are often by physical barriers, like mountains or oceans. - In gene flow, genes are exchanged between two different populations if these barriers are overcome. Interbreeding between populations or changes the frequency of alleles already present. Gene flow tends to genetic differences between populations. If extensive enough, a single population might replace the smaller ones that originally interbred.

randomisolated

adds new alleles

reduce

Homework3Cpg. 209 # 3~7, 12, 14, 15pg. 223 # 7, 8, 9, 10, 12, 13

3Upg. 209 # 3~7, 12, 14, 15pg. 223 # 6~13