Look over your Standard Deviation notes from last term. Make sure that you are able to carry out calculations for next week (I will email you one to try)

Starter: Why do we all look different?

Genetic Diversity(3.2.3)

Learning Outcomes:

Explain why organisms are different from each otherIdentify what factors influence genetic diversity by describing the founder effect and genetic bottlenecks

Members of the same speciesHave the same genesTheir alleles differThe combination of alleles they possess that make species different from one another.The greater the number of different alleles that all members of a species possess the greater the genetic diversity of the species.The greater the genetic diversity, the more likely that a species will be able to adapt to some environmental change.

Selective BreedingIs also known as artificial selection. It involves identifying individuals with the desired characteristics and using them to parent the next generation

Selective breeding in cattleimagine you are farmers, write what they would look for in a Friesian and Angus cow - how would you go about selectively breeding these animals?

AdvantagesDisadvantagesGet desired characteristicsGenetic variation reducedGet high yielding breedsResistance to diseaseProne to infection and adverse weather conditions

Half the class is going to become experts on The Founder EffectHalf the class is going to become experts on the Genetic Bottlenecks

Make notes / diagrams about the key points using pg. 147 of your textbook including:cause what happens to the population?Effect (what happens to the variety of alleles and genetic diversity?Examples* You may want to model the idea using beads ***

you are going to teach someone else without having your text book with you.Task: You are the Teacher

Pair up with someone in the other side of the class and teach each other

Once you have covered each topic give some feedback about how the other person taught you

(Did they explain clearly? Could they answer questions?)

Then swap with another person who wasnt in your group and teach them what youve just learned.You are the teacher

Home Learning Due Friday 16th Jan

1.Read Pg. 147-149 and complete q. 1-6 and correct using the back of the book (Ethics of Selective Breeding)

2. Complete analysis of your test and set 3 targets on the back of your sheet to be handed into me.

Difference between founder effect and genetic bottlenecksFounder effects A founder effect occurs when a new colony is started by a few members of the original population.

Population bottlenecks occur when a populations size is reduced for at least one generation.

The founder effectA small group from a large population colonise a new area.Their alleles may not be representative of the large population, but develop. They have less genetic variation from the original population and may develop into a new species over time.The new species have less variation in their alleles and are less able to adapt to changing conditions.

e.g. Ellis-van Creveld syndrome. The syndrome is commonly found among the Old Order Amish of Pennsylvania, a population that experiences the "founder effect.

is a rare genetic disorder characterized by short-limb dwarfism, polydactyly (additional fingers or toes), malformation of the bones of the wrist, dystrophy of the fingernails, partial hare-lip, cardiac malformation and often prenatal eruption of the teeth. Genetically inherited diseases like Ellis-van Creveld are more concentrated among the Amish because they marry within their own community, which prevents new genetic variation from entering the population.

Children are therefore more likely to inherit two copies of the particular recessive genes that lead to genetic disease.

The Amish are a group of people who live in America. This group was founded by 30 Swiss people, who moved to America many years ago. The Amish do not usually marry people from outside their own group.

One of the 30 Swiss founders had a genetic disorder called Ellis-van Creveld syndrome. People with this disorder have heart defects, are short and have extra fingers and toes. Ellis-van Creveld syndrome is caused by a faulty allele.

In America today, about 1 in 200 Amish people are born with Ellis-van Creveld syndrome. This disorder is very rare in people in America who are not Amish.

(a) Use the information provided and your knowledge of the founder effect to explain why Ellis-van Creveld syndrome occurs at a higher frequency in the Amish population than in people in America who are not Amish.Lets try an exam question.

(a)1. Population formed by a small number of founders / people / 30 people;Accept: converse arguments for the non-Amish population

2. (Founders show) less genetic diversity / small(er) gene pool / less variety of alleles; Q Neutral: fewer alleles

3. Individuals breed within group / do not breed with outsiders; Accept: inbreeding for individuals breed within group Accept: do not interbreed Q Reject: interbreeding for individuals breed within group

4. High(er) chance of inheriting allele (than in non-Amish population); Do not award for allele passed on only3 max

e.g. Afrikaner population of Dutch settlers in South Africa the Afrikaner population of Dutch settlers in South Africa is descended mainly from a few colonists. Today, the Afrikaner population has an unusually high frequency of the gene that causes Huntingtons disease, because those original Dutch colonists just happened to carry that gene with unusually high frequency. This effect is easy to recognize in genetic diseases, but of course, the frequencies of all sorts of genes are affected by founder events.

Genetic BottlenecksWhen a population of a species from time to time suffer a dramatic drop in numbers.Small proportion of population and therefore small variety of alleles continue and the population has less genetic diversity.Usually due to a chance event (e.g. volcanic eruption) or hunting*not small number of alleles

North Elephant sealSouth elephant seale.g. Why are these same species of elephant seals different?New population has very little genetic diversity compared to the southern elephant sealsNorthern Elephant seals hunted by humans in late 1800sOriginal population reduced to around 50 seals (unlike southern elephant seal) now population of around 100 000

Cheating cheetahs!Who said cheetahs never prosper!

Read the newsarticle

Cheating cheetahs! Why did the female cheetahs begin to cheat?http://evolution.berkeley.edu/evolibrary/news/070701_cheetah

I want to produce the ideal wheat plant by selective breeding. What sort of features could I select for? Large grains with high gluten contentshort stemsresistance to disease etc.Starter:

Plenary: What is the question?1. Drop in population numbers due to chance eventFew surviving individuals likely to have fewer, less diverse alleles. As population grows its alleles are equally less diverseReduced genetic diversity

Involves identifying individuals with the desired characteristics and using them to parent the next generationFounder Effect