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UIC / Biology / ANAT 101 / Where does heritable variation come from?

Where does heritable variation come from?

Where does heritable variation come from?


Week 7

Where does heritable variation come from?

Heritable Variation, Assortment, Dominance, and Linkage.  

February 22nd 

Ecology (Darwin's struggle for existence) --> where does heritable variation come  from

Forms of mutation:  

Mutation introduces H.V.

Not just a recipe but something that is also an adaption  

Mutation rate is an adaptation…in the absence of mutation, they don’t evolve (will  get outcompeted)

Rate of mutation is high, producing weird individuals that wont be able to survive.  

If you are perfect, there is nothing to change.  

Rate of mutation, you want a mid rate.  

Ecoli when in stressful environment, they will up-regulate a gene that ups their  mutation rate.  

What is the right amount of variation?

Don't forget about the age old question of Define indifference curve.

Forage of fragments of DNA floating around to consume, they metabolize it. BUT  when in a stressful environment, ecoli and prokaryotes, will incorporate the DNA  into theirs. Original GMO.  

Yeast will up mutation rate and of certain parts of DNA that interact with  environment. (genes that change phenotype)

Cancer: the mutator phenotype. Tumor cells mutate and separate form normal  cells, they begin to degrade. Now we believe, as the tumor cell becomes a single  cell, it is far where it would be to max fitness. They evolve an adaptation to evolve  adaptions faster.  

Human mating patterns. For women, the stress they have affects the number of  sexual partners. (Stress up, adaptations to increase variety) ;)  We also discuss several other topics like What are the three functions of money?
Don't forget about the age old question of What is social interaction?
If you want to learn more check out What is the study of earth’s physical features, processes, and history?

What is the right amount of variation?

Adaptations to keep strings of DNA from being tangled and to be organized.  Histones fold and hold the dna together. Histones: Involved in methylation: slap  methyl groups on genes to make codon unreadable.  

Why diploidy is an adaptation?

If you want to learn more check out What is the liability of parties for substantive offenses?

Sickly fish from Rift valley lakes of Africa, they will grow to have flat heads and flat  teeth: herbivores. If you raise them to eat meat they will have sharp teeth.  

Protists are haploid. Number of single cell protists that are diploid. Diploid undergo  mitosis.

Mitosis:  We also discuss several other topics like Are all collisions between reactants effective? why or why not?

∙ In course of cell cycle, when cycle is not dividing (before division), genetic  material is duplicating.  

∙ By doubling genetic material before, there are less errors.  ∙ Separate diploid is doubled to formed the pairs.  

∙ 2 sets of X (looking) chromosomes = diploid

∙ Chromatids were doubled.  

Sexual reproduction: process where haploid gametes fuse, combine and switch  around genetic material.  

It doesn’t generate mutations but can have aneuploidy

Rye is a polyploidy (entire genome of wheat and barley)

Diploid can have hetero or homozygous  

Diploidy is an adaptation: why?

More opportunity for damage to genes as you have more DNA and histones.  Repair or having a spare gene copy.  

Swapping of ideas, diploidy is most efficient for lineages to exchange good ideas Ex) back up pen may not be the same pen as the original being use (diploidy may  be caused by this)

1 Allows you to purge deleterious mutations

2 And acquire beneficial mutations/ideas  

Haploid goes to diploid due to Meiosis.  


Process of double duplication. (I and II)

Because material is doubles, to get back to original, we need to divide 2 times Double cell division gets 4 ultimate cells.  

You and I, we are used to being diploid.  

Single cell protists, haploid is the adult stage. Live lives as haploid, for reproduction, they fuse.  

Because extra genetic material was useful  

Errors in Meiosis:  

1 Two chromatids wander over cell, one cell may get everything where as the  other gets nothing.  

2 Variation produced by segregation and assortment. Crossing over creates new  combo. Splicing is crossing over.  

3 There are genes and splicing.  

Crossing over link otherwise linked genes.  

In the chromosome you would otherwise had linked to

Ways to generate variability.  

Breeding: dawn of agriculture.

Example: Dogs, heritable variations, variation on which natural selection will work.  

February 24th 

Domestic dogs - Common example. They have evolved from wolves and we have  bred different dogs together. GREAT VARIATION.  

Irish wolf hound: Up to 100 kilos difference between smallest and biggest ones.  

Characterizing variation:

1 Attributes: we can see them but we are not able to compare them with values.  It is qualitative (ex. Loyalty)  

2 Quantitative

a Ex. Cats have 30 teeth. (made up example)

b Traits that are measurable and can have any value. Ex) length of dog tail.  

Brassica oleracea: Kale is closest to the original species. Cauliflower is one of the  most derived form of the original species.  

Canidae versus Felidae: Wolves, mountain lions, etc.  

Dogs have stamina. Ex. Huskie race


Cats do not have stamina. They have the ability to climb.  

Mountain lions: Beagles are trained to track mountain lions. Mountain lions can  swipe claws to kill the beagle. This is an attribute. Cats have free floating clavicles,  meaning they can't do things like go on monkey bars.  

Dogs don't have clavicles but they have more body mass, giving them stamina.  

**Big difference: Dogs have 42 teeth, more generalized--they are able to chew  various foods. Cats have 30 teeth. The shape and forms are different. Cat's teeth  are specialized to hurt, stab, and slice prey.  

No one in Idaho has been attacked by a lion or wolf. Dogs and cats have  disappeared though.  

Variation within a species:

Squirrels: Grey squirrel ranges from Chicago (weighing 650g) to Florida (weighing  400g). Grey squirrels in Chicago come in many different squirrels, but in Florida,  they are uniform in color.

Bergman's rule: Species that live in hotter areas are smaller. (Quantitative)  Chubbier squirrels do better at keeping warm in the winter.  

Fox squirrels are opposites: They weigh 750g in Chicago and in Florida they are  1200g.  

1 They are bigger in Florida.  

2 In Chicago, they are more uniform looking.  

How do fox and grey squirrels coexist: Grey squirrels are better at competing for  resources, and fox squirrels are better at avoiding predators.  

--> Test body sizes and attributes of how they look.  

How to examine traits:

In the past ecology= majoring in natural philosophy (because there was a lack of  quantitative data).  

How to display data:

1 Create a histogram (look at a variable that can be ordered). Use statistics to  smooth out distribution.  

The statistical moments:  

1 Mean

2 Measure of distribution around mean: Standard deviation or variance.  3 Skew

4 Kurtosis

Types of distribution:

Normal: Can have a centered on mean at zero and have a variance of one. 2/3rds of scores are one standard deviation plus and minus the mean. Measure each data for  individuals.  

Skewed: To the left or right. Ex. Salaries today are skewed. The mean is different  than the mode.  

Kurtosis: Bunched up or spread. More scrunched up: Leptokurtic (+). More spread  out: Platyurtic (-).  

Bimodal Distributions: Ex) Squirrels: Females are pregnant right now, and give birth  in June. So there will be two categorizes that are popular. Ex) (Man eaters of Savos)  Having manes or not having manes.  

Mean, Median, and Variance:

Mean: Sum of measures, divide by number of values.  

Median: Middle value.

Variance: Sum of squared deviations and divide by n-1.  

Standard Deviation: Sq root of variance.  

Gregor Mendel: Studied physics, mathematics, and statistics. Combined his studies  with heritable variation.  

∙ He and UIC has a connection. Czech residents came to UIC library.

∙ Mendel was Czech's hero.  

∙ He was a renegade. King of Bohemia did not want radical thinking. He burned all of Mendel's notes.

∙ Collector had all the leftover notes and came to US. When he died, he gave  all his resources to UIC library.  

February 26th 

Mendel: Data was made up. We know this because the statistics showed that the  results were TOO good. Other people did not understand statistics, but may have  been skeptical.  

Cave fish: Occupy caves and they will transform from looking normal to losing  pigments and eyesight. Pigments don't serve a purpose as not much sin comes in.  Also, eyes can be a source of infections. Caves have short life expectancy because  they collapse or dry out. Afterwards, the fish go to other caves or become extinct.  

Mendel bred cave fish from two different cave, 95% of the offspring had evolution  undone (original version because of DOMINANCE). When bred together, they are all  heterozygous.  

Phenotype vs. genotype:  


Dominant trait in Homozygous or Heterozygous but the dominant allele will cause  that phenotype.  

Natural selection takes path of least resistance. A gene that is turned off will be  recessive, genes that are turned on are dominant or codominant.  

Ex) Albinism (lack of skin pigments): recessive alleles.

Ex) Genetic diseases: Ectrodactly and lissencephaly (cerebral cortex is smooth).  

Natural selection working on traits:

Deleterious traits are obvious--you can weed out the phenotype in the population.

Hard to weed out all recessive allele between phenotype is same for homozygous  and heterozygous genotype.  

Recessive trait might not be manifested in population.  

**Natural selection works on the phenotype.  

Eugenics: Breed individuals with preferable genes. Take out people with unwanted  phenotypes.  

Adaptation in which individuals tend to avoid incest. Incest avoidance that  recognizes the recessive alleles.  


2 separate alleles, they are functioning genes, if you are heterozygous, you  experience both alleles.  

Ex) Chicken, heterozygous have peppered color feathers.  

Ex) Blood type, A, B, AB, O -- markers, immune system rejects blood types different  than your blood type.  

Rhesus factor: RH+ is the presence of antigens. 2 loci, they have dominant allele  and the recessive. 1 loci- Ce, 2nd loci- D. Just need either big C or big D to RH+. RH- = ce d/ ce d.  

There are many combinations.

Antigens, if immune messes up, it might attack you.  

How many Loci are there:

Bacteria had 1200 genes.  

Yeast has 5k.  

Human: have 20k genes. Most of the time, in most of your cells, most of the genes  are turned off.  

Rice: 38k genes.  

Do all loci have multiple allele: very few are hetero.


Genes are vital in making us how we are. Natural selection narrows our genes. But if your mutation rate is too high, it will be disastrous when you need to adapt.  

Human genome: Once you sequence it, it was thought it would determine who you  are. But that's not true. Most of your genome does nothing (junk genome). Also  because there is a gene - environment relation. There is not a fixed response to the  environment. Phenotypic plasticity (Genetic-environmental adaptation)  

Hypotheses: Why is there junk DNA: Back up files, genes with mutation will turn on,  or when coding genes, everything is unraveling, you have to get to the right place,  junk DNA separates the important genes (like blank space between chapters in a  book).

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