AGENDA – 2/2/16 Take out outline from yesterday! Daily Objective: Students will evaluate the effects of other evolutionary mechanisms, including genetic drift and gene flow. Finish Natural Selection notes Work on Evolution Unit Vocabulary –(due Friday 2/5)

2.1 Section Objectives – page 35 Identify how natural selection can not only change a population, but can lead to a new species. Today’s Objective:

Section 15.2 Summary– pages Stabilizing selection is a natural selection that favors average individuals in a population. There are three different types of natural selection: stabilizing, directional, and disruptive. NATURAL SELECTION Middle sized Siberian Huskies are selected for

Stabilizing Selection Example: human birth weight. Babies of low weight lose heat more quickly and get ill from infectious disease more easily, whereas babies of large body weight are more difficult to deliver through the pelvis

Section 15.2 Summary– pages Directional selection occurs when natural selection favors one of the extreme variations of a trait. NATURAL SELECTION This type of selection can lead to rapid evolution of a population.

Examples: Directional Selection Peppered Moths: as the environment changes, so do the traits that are fit for the new environment. In the case of the moths, the forests changed from light to dark and selection moved in the direction of darker moths Antibiotic Resistance Pesticide Resistance

Section 15.2 Summary– pages In disruptive selection, individuals with both extremes of a trait’s variation are selected for. NATURAL SELECTION This results in eventually having no intermediate form of a trait, and leading to two separate species.

What type of selection? Tortoise neck length –Short grasses, for short-necked tortoises –Tall grasses, for long-necked tortoises –No grasses for average-necked tortoises, so over time, they are selected against Disruptive Selection

What type of selection? Lizard body size: –Large lizards are easily seen by predators, but smaller lizards cannot run as fast to escape the predators –Mid sized lizards are most fit in the environment, so they survive and reproduce more often, changing the allele frequencies in the population

What type of selection? Anteater tongue length: –Anteaters with long tongues are most fit because of the depth of the nests of the termites they eat.

So…what is a species? –A population whose members can interbreed & produce viable, fertile offspring –Being reproductively compatible is a key component Western Meadowlark Sturnella magna Eastern Meadowlark Sturnella neglecta Distinct species: songs & behaviors are different enough to prevent interbreeding

Section 15.1 Summary – pages On the Galápagos Islands, Darwin studied many species of animals and plants that are unique to the islands but similar to species on the mainland. These observations led Darwin to consider the possibility that species can change over time, especially if exposed to different environments where they must adapt to different things. Darwin and Natural Selection

Section 15.2 Summary– pages The evolution of new species is called speciation. This occurs when members of similar populations change so much from each other that they no longer interbreed to produce fertile/viable offspring. SPECIATION

Section 15.2 Summary– pages In nature, physical barriers can break large populations into smaller ones. Geographic isolation occurs whenever a physical barrier divides a population and over time they change and become two different species. SPECIATION with a physical barrier

Section 15.2 Summary– pages Some speciation occurs while the organisms still exist in the same area. Behavioral, Temporal, Mechanical SPECIATION without a physical barrier

Rate of Speciation Current debate: Does speciation happen gradually or rapidly? Or both? –Gradualism –Punctuated equilibrium

Gradualism  Gradual change over long spans of time  assume that big changes occur as the accumulation of many small ones develop over time.

Punctuated Equilibrium Rate of speciation is not constant –rapid bursts of change –long periods of no change –species undergo rapid change when they 1 st bud from parent population Time

Section 15.2 Summary– pages Divergent evolution is when species that are similar and closely related become increasingly different from each other. THEY DIVERGE This is also called Adaptive Radiation….because it has to do with ADAPTING to different environments and RADIATING out into different species. Types of Change

Section 15.2 Summary– pages When distantly-related organisms evolve to become more similar, it is called convergent evolution. Convergent evolution occurs when unrelated species occupy similar environments in different parts of the world. Types of Change

AGENDA – 2/3/16 Take out your journals! Bell-Ringer: Types of NS Types of NS Graphing Practice Homework: - Rock Pocket Mouse Video Questions – due tomorrow (I will be checking it in your notebook!)

Bell-Ringer: 2/3/16 Don’t just name or define, EXPLAIN what each of these graphs mean. A.A. B.B. C.C.

AGENDA – 2/4/16 Take out your journals and the Rock Pocket Mouse Video Questions handout! Rock Pocket Mouse Video ?’s Fitness Discussion/Letter Homework: -EXAM is next THURSDAY

Below are descriptions of four male lions. Which lion would biologists consider the “fittest”? Explain your thinking.

1. You are a wildlife biologist working in Africa. Another biologist makes the statement that “George was the largest lion, so he had the best chance of fighting off enemies. George must have the most evolutionary fitness.” Write a letter to your colleague either agreeing or disagreeing with her. In your letter, make sure you support your position with evidence from the data, from your notes, and from your own thinking. Closing: (Next Page in Notebook)

AGENDA – 2/5/16 Take out your journals and your notes outline! Turn in Vocab – gray bin Bell-Ringer: Types of NS/Genetics Review Gene Pool/Hardy-Weinberg notes Homework: - EXAM IS NEXT THURSDAY!

1. What is the difference between an allele, a genotype, and a phenotype? 2. What do the following genotypes mean? (B= Dark eyes, b= light eyes) - BB - Bb - bb Bell-Ringer: 2/5/16

1.DIRECTIONAL 2. DISRUPTIVE 3. STABILIZING Problem 1: The only types of food on an island for finches are small seeds and nectar from long tubular flowers. Finches with small beaks can easily grasp and crack the seeds. Finches with long beaks can reach inside the long flowers to reach the nectar. After several generations, there are two populations of finches: those with short beaks and those with long beaks. What kind of selection has acted on these finches? Problem 2: The pollution of the industrial revolution made the tree bark in the forest of New England darker. Darker moths started becoming more frequent, because they blend in better. This is an example of what type of selection? Problem 3: Human babies are more likely to survive if they have a “medium” birth weight. Overtime this leads to fewer babies being born with extreme birth weights. What type of selection is this?

Section 15.2 Summary– pages Picture all of the alleles of a population as being together in a large pool called a gene pool. The percentage of any specific allele in the gene pool is called the allelic frequency. Look around the room…. What is the gene pool for hair color??? What is the allelic frequency of people with blonde hair?

Genetic Drift Genetic DriftGenetic Drift – the random fluctuation in allele frequencies over time, due to chance occurrences alone It is more significant in smaller populations It increases the chance of any given allele becoming more or less prevalent when the number of individuals is small

Original Population Mechanisms of Evolution: Genetic Drift

After Lightning Mechanisms of Evolution: Genetic Drift

Many Generations Later Mechanisms of Evolution: Genetic Drift

Gene Flow Genes move with individuals when they move (emigrate or immigrate) into and out of a population…and it changes the gene pool

Mechanism of Evolution: Gene Flow Original Population Neighboring Population

Mechanism of Evolution: Gene Flow After Migration

Mechanism of Evolution: Gene Flow Many Generations Later

Section 15.2 Summary– pages Evolution occurs as a population’s genes and their frequencies change over time. This can take millions of years for a species to change GENETICS AND EVOLUTION

Section 15.2 Summary– pages A population in which the frequency of alleles remains the same over generations as being in genetic equilibrium. GENETICS AND EVOLUTION A population that is in genetic equilibrium is NOT evolving or changing.

Hardy-Weinberg came up with five basic reasons why a population would stay at genetic equilibrium: 3. no mutations occur in the DNA of any organisms within this population. Under these conditions it is obvious that evolution would not occur. There are no mechanisms for change acting on the population, so the process cannot happen--the gene pool frequencies will remain unchanged. 5. natural selection is not occurring 1. no catastrophes/disasters occur -- the population must be large. 4. all mating is totally random (No sexual selection) 2. there is no migration in or out of the population

However, since it is highly unlikely that any one of these five conditions, let alone all of them, will happen in the real world, evolution is inevitable. Mutations will occur at random….creating new alleles… Organisms will move in and out of a population, bringing with them or taking away alleles from the gene pool. Reproduction will not be random, organisms will choose mates based on certain traits….. Catastrophes and predation will occur that can change allelic frequencies. There will be traits that are more beneficial to have than others….

The definition of evolution was developed in the early 20th century by Godfrey Hardy, an English mathematician, and Wilhelm Weinberg, a German physician. Hardy Weinberg “Evolution is simply a change in frequencies of alleles in the gene pool over time.”

Alleles: Genotype: Phenotype: One of two or more forms of a gene that code for different versions of the same trait. The genetic combination of two alleles, which decides what a person’s trait will be (ex. Bb) The physical expression of a genetic trait (ex. Bb means Brown eyes) B=brown b=blonde

Hardy and Weinberg developed an equation we can use to calculate how many individuals in a population are: BB (Homozygous Dom.) Bb (Heterozygous) bb (Homozygous Rec.) Or in other words, determine the allelic frequencies and genotypic frequencies in a particular gene pool. This is used to track allelic frequencies from generation to generation in a population to monitor evolution OR changes in the gene pool.

This is the Hardy-Weinberg equilibrium equation. p² + 2pq + q² = 1 p is defined as the frequency of the dominant allele p = B q is defined as the frequency of the recessive allele q = b

Because there are only two alleles in this case, “B” and “b” the frequency of one plus the other must equal 100%, so… p + q = 1 (or 100%)

p² + 2pq + q² = 1 In this equation: p² = homozygous dominant (BB) organisms in a population. 2pq = heterozygous (Bb) organisms q² = homozygous recessive (bb) ones p = Bq = b

Albinism is a rare genetically inherited trait that is only expressed homozygous recessive individuals (aa). The most characteristic symptom is a marked deficiency in the skin and hair pigment melanin. This condition can occur among any human group as well as among other animal species. The average human frequency of albinism in North America is only about 1 in 20,000.

The Hardy-Weinberg equation (p² + 2pq + q² = 1), and the frequency of homozygous recessive individuals (aa) in a population is q². Therefore, in North America the following must be true for albinism: q² = 1/20,000 = By taking the square root of both sides of this equation, we get: q =.007 (rounded) Knowing one of the two variables (q) in the Hardy-Weinberg equation, it is easy to solve for the other (p). p = 1 – q p = p =.993

The frequency of the dominant, normal allele (A) is, therefore, or about 99 in 100. The next step is to plug the frequencies of p and q into the Hardy-Weinberg equation: p² + 2pq + q² = 1 (.993)² + 2 (.993)(.007) + (.007)² = = 1 This gives us the frequencies for each of the three genotypes for this trait in the population: p² = AA =.986 = 98.6% 2pq = Aa =.014 = 1.4% q² = aa = =.005%

AGENDA – 2/8/16 Take out your journals and open up to your Hardy-Weinberg notes page! Late Vocab – turn in to the gray bin! Hardy-Weinberg Practice Problems Homework: –Hardy-Weinberg Lab tomorrow –EXAM is this THURSDAY!

You have sampled a population in which you know that the percentage of the homozygous recessive genotype (aa) is 36%. Using that 36%, calculate the following: 1. The frequency of the "aa" genotype. The frequency of the “aa” genotype is given in the problem as 36%!

2. The frequency of the "a" allele. The frequency of aa is 36%, which means that q 2 = 0.36, by definition. If q 2 = 0.36, then q = 0.6, again by definition. Since q equals the frequency of the a allele, then the frequency is 60%. 3. The frequency of the "A" allele. Since q = 0.6, and p + q = 1, then p = 0.4; the frequency of A is by definition equal to p, so the answer is 40%.

4. The frequencies of the genotypes "AA" and "Aa." The frequency of AA is equal to p 2, and the frequency of Aa is equal to 2pq. So, using the information above, the frequency of AA is 16% (p 2 = 0.4 x 0.4 = 0.16) and Aa is 48% (2pq = 2 x 0.4 x 0.6 = 0.48)

5. The frequencies of the two possible phenotypes if "A" is completely dominant over "a." Because "A" is totally dominate over "a", the dominant phenotype will show if either the homozygous "AA" or heterozygous "Aa" genotypes occur. The recessive phenotype is controlled by the homozygous aa genotype. Therefore, the frequency of the dominant phenotype equals the sum of the frequencies of AA and Aa, and the recessive phenotype is simply the frequency of aa. Therefore, the dominant frequency is 64% and, in the first part of this question above, you have already shown that the recessive frequency is 36%.

PRACTICE HARDY-WEINBERG! Pick any 5 problems to complete in your notebook. Round to 3 decimal places (thousandths place).