Warm Up 2/24 Open Ended Response Question on

Biology Counts as a grade!!! Do your best! Remember – Analyze, Prove, and Explain!

Turn in Your Reading Guide 16-1 and 16-2 to the class folder!!!

Question….. How many alleles does each individual

carry for a particular trait? So how many alleles for tongue rolling

do we have in this class?

Question….. How many alleles does each individual

carry for a particular trait? 2 So how many alleles for tongue rolling

do we have in this class? # of people x 2

Evolution in our lives Why Do Dogs Bark? We tend to take it for granted that a dog barks--but in the wild, canines hardly ever do, instead whining or yipping or howling. A few studies have examined why this is, and the current conclusion is that dogs bark, well, for us.

Evolution in our lives

The most feared and panic-causing insect in New York isn't the cockroach--it's the bedbug. In the late 1990s, after a half-century of "relative inactivity," the bedbug suddenly reappeared, stronger than ever. Turns out the bedbug had evolved in ways that make it much harder to eradicate, including a thick, waxlike exoskeleton that repels pesticides, a faster metabolism to create more of the bedbug's natural chemical defenses, and dominant mutations to block search-and-destroy pyrethroids.

You almost have to admire the little monsters.

Evolution and IslandsEver since Charles Darwin formulated his hypothesis on how the finches of the Galapagos Islands evolved into 13 species, islands have been a prime target for the study of evolution. By their very nature, islands are isolated and are essentially a living laboratory of evolution.

Today you will create your own Evolution Island.

Take some notes in your notebook.

Title: Population Genetics

I will begin checking notebooks for

grades – do your warm-ups, take notes

The number and type of alleles in a population is constantly changing.

Evolution occurs when there is a change in the allele frequency of a population

Allele Frequencies and Gene Pools

Changes in allele frequencies can occur in a number of different ways:

1) Mutation 3) Gene Flow 2) Genetic Drift 4) Natural

Selection

Evolution

Evolution Island Read the summary and answer the

introduction questions.

Work together in your team but answer

your own questions.

This will be turned in for a GRADE.

You will turn in all the labs but one will

randomly be chosen to be graded.

Evolution Island How many alleles in the population? 200 How many Y alleles in the population? 130 What is the allele frequency for Y? 0.65 or 65% A change of allele frequency in a

population is called evolution

Evolution Island How many beads make up and

individual? 2 Why? Each individual has 2 alleles – each

bead represents an allele.

Allele FrequencySample Population

48% heterozygous

black

36% homozygous

brown

16% homozygous

black

Frequency of Alleles

allele for brown fur

allele for black fur

RELATIVE FREQUENCY is often expressed as a __________________.

EX: In this population Dominant B allele (black) = 40% Recessive b allele (brown) = 60%

Image from BIOLOGY by Miller and Levine; Prentice Hall Publishing ©2006

percentage

RELATIVE FREQUENCY has _________ to do with whether an allele is

____________ or _____________

In this population, the recessive allele is more frequent.

DOMINANT RECESSIVE

Image from BIOLOGY by Miller and Levine; Prentice Hall Publishing ©2006

NOTHING

Mutation

Mutation - a heritable change in the genetic code (DNA)

Mutations are random events, they may be helpful or harmful

EVOLUTION

Evolution Telephone Line up (single file) along the window-

side of the room. I am going to start a message by

whispering it to the first person. We will take turns passing the message. You cannot repeat the message.

Evolution Telephone Did the message stay the same from

beginning to end? What caused the changes? Small mistakes in DNA (mutations) can

change populations over time, like the mistakes in the message we passed along

Genetic Drift

Allele frequencies can change randomly through generations because of chance. This process is called genetic drift

The appearance of coywolves in the northeastern North America indicates a population of wolves that suffered hunting, poisoning, habitat destruction, and near extinction after early colonization and population of North America by humans. This led to isolated wolves taking coyotes for mates in Southern Canada. These hybrids survived have been able to breed during the last 400 years leading to a population of reproducing hybrids that have an affinity for surviving and even thriving among human populations. This is evolution's way of deriving new species through genetic drift.

EVOLUTION

Gene Flow 

Allele frequencies change when individuals leave a population (migration) or enter a population.

This movement of individuals is called gene flow.

EVOLUTION

Gene flow is the transfer of alleles from one population to another population through immigration of individuals. In this example, one of the birds from population A immigrates to population B, which has fewer of the dominant alleles, and through mating incorporates its alleles into the other population.

Natural Selection

Natural Selection - the differential survival and reproduction of individuals in a population based on the traits they posses

Selection Pressure - Those factors that influence the direction of natural selection

EVOLUTION

Natural Selection in Action The warrior ants in Africa are probably one of the most

impressive examples of adaptation. Within any single colony, ants emit a chemical signal that lets the others know they all belong to the same compound. Or, put more simply, a signal that says "Don't attack me, we're all family." However, warrior ants have learned how to imitate the signal from a different colony. So if a group of warrior ants attacks a colony, they will be able to imitate that colony's signal. As a result, the workers in the colony will continue on, now under the direction of new masters, without ever realizing an invasion has taken place.

Evolution Island Let’s begin the lab…