In the city of Chicago, it is illegal to speak English

It is illegal to mispronounce the name “Joliet” while in Joliet, IL

In Peoria, IL it is illegal to give cigarettes to a monkey

In Indiana, you may not watch while a man

wearing a striped shirt throws knives

It Utah, all husbands are responsible for crimes committed by their wives

In Iowa, kisses may last up to but not more than five minutes

Pennsylvania

• When driving, the man must run in front of the car when the woman is driving, firing a rocket every mile, phoning the chief of police when they enter a town and disassembling the car and hiding it under a bush should they pass a horse

Are there biological “laws” that you cannot obey?

POPULATIONS DO NOT HAVE TO EVOLVE

Neo-Darwinism

• Nature selects not only for certain phenotypes, but for the alleles that produce those phenotypes

• Populations whose allele frequencies change over time are said to be evolving.

Gene Pool & Allele Frequency

• Gene Pool = all of the different alleles in a naturally reproducing population

• Allele Frequency: the % of a given allele form for a trait present in the gene pool

Natural Selection & Alleles

• Since “selected” individuals have higher differential reproduction, their alleles become more frequent in the gene pool

• As a population shifts in terms of allelic frequencies, the phenotypic frequency may also change

Hardy-Weinberg Equilibrium

• If the allele frequencies of a gene pool do not change over time, the gene pool does not undergo evolution.

• KEY POINT: Individuals DO NOT EVOLVE; populations DO

Requirements of Populations At Hardy-Weinberg Equilibrium

• No selective pressures (all must have equal chance of surviving)

• No differential reproduction

• No mutations

• No immigration or emigration

• No changes in allele frequencies

Why don’t populations exhibit Hardy-Weinberg Equilibrium?

Back In The Real World…

• Populations rarely ever exhibit many of the characteristics of HW Equilibrium

• Mutations and environmental change are random

• Alleles that code for adaptations may be reduced to variations in a new environment

Microevolution

•Most changes in allele frequency are small and occur over long periods of time

Sickle Cell Anemia

Genetics of Sickle Cell Anemia

• Sickled red blood corpuscles caused by incompletely dominant allele (s).

• Individuals with ss genotype have terminal sickle cell anemia

• Individuals with As genotype have sickle cell anemia but do not die from the disease. In addition, they will not contract Malaria

• Individuals with AA genotype do not have sickle cell anemia, but will die from Malaria if infected

Setup

• Obtain five (5) containers and label1. Population2. AA non-sickle cell & non-Malarial3. As sickle cell4. ss sickle cell, terminal5. Non-surviving Alleles

Place 150 white/red beans and 50 black beans in the first container. These beads represent the following alleles-White or Red = A Black = s

Natural Selection

• Have one partner randomly remove 2 beans at a time. These two alleles represent an individual and their phenotype/genotype.

• It will take 100 turns to apply the selective pressure to each individual in the pop.

• For groups 4-6, apply the selective pressure of Malaria of 40% (i.e. 40 of 100 turns)

Applying The Selective Pressures…• If two white/red beans (AA) are selected

during a non-Malarial season, place both beads in the first cup, representing surviving alleles

• If two white/red beads (AA) are selected during a Malarial season (Africa ONLY), place both beans in the Non-Surviving Container

• If two black beans (ss) are selected at any time, place them in the fourth (“ss”) cup.

• If a white/red and a black are simultaneously selected, place both beads in the 3rd cup (As/sickle cell)

Totaling The Survivors

• After 100 pairs of alleles have been selected, kill off the “ss” terminal sickle cell alleles by pouring cup #4 into cup #5

• Tally the number of white/red beans (A allele) and the number of black beans (s allele) from cups #2 & 3 combined

• Using the formulas in the lab (under data table 1), calculate the allele frequencies (i.e. how many A or a alleles/total number of alleles in survivors) for the A and s alleles

Successive Generations• Take the surviving A and s alleles from cups 2 & 3 and

recombine them in cup #1• Repeat the selection process, pulling out pairs of

alleles/beans and applying the Malarial selective pressure at the same 40% infection rate (AFRICA ONLY).

• As in the first trial, discard the alleles for the non-surviving and ss individuals (cups #4&5) and tally the combined # of white/red (A) and black (s) beads.

• Calculate the new allele frequencies using the formulae under data table #2

• ADD SPACE IN YOUR DATA TABLE FOR A THIRD and FOURTH TRIAL. Repeat this process through four generations

CALCULATING & SHARING

• Calculate the allele frequencies for the dominant (A) allele and the recessive (a) allele for each generation.

• Share your data with the other side of the room.

• Answer the analysis questions, citing specific detail.

REPLACEMENT/ADDITIONAL ANALYSIS QUESTIONS

• #4) Replace Birgus latro with Trinidadian Guppies

• #6) Did the rate of change in either population increase/decrease more dramatically as you went through successive generations? Why do you think this was/was not happening?