Anthropology 102 EXAM 2

How is Tay-Sachs an example of partial dominance?

One allele expresses itself a little if you have a dominant and recessive allele i.e Tt

How is color blindness an example of an x-linked disorder? (sex-linked trait)

• Color blindness comes from sex chromosomes 

• Mother and father must past down colorblind trait

How is male pattern baldness an example of a sex-influenced disorder?

• Baldness trait is inherited based on sex 

• Based on environment

What does it mean when genes are linked? Can linkage be broken down?

• Two genes in same chromosome 

• Crossing over can break linkage

How might you recognize polygenic traits?

Many genes have a single affect i.e height

What is Pleiotropy?

One gene has many effects

Point Mutations

when a single base in a gene is changed

Insertion Mutation

Change in Genetic Code by adding one or more base pairs in DNA

Deletion mutation

the loss of one or more base pairs in dna

What Makes a mutation good, bad, or neutral?

Bad: reduces chances of survival and reproduction

Neutral: nothing happens

Good: increases chance of survival, creates variation

Directional selection

pushes for greater or lesser frequency of given trait in a population

Artificial selection

Human driven selection over past 150 years i.e domestication of dogs

Stabilizing selection

Maintains a phenotype by selecting against deviations

 Fisher’s Runaway Sexual Selection

• Pairing of female preference and male trait

• on same chromosomes after crossing over = linkage

Zahavi’s Handicap principle

If they can survive with handicap, they have great genes

Honest signaling

Possession of a trait that indicates good health and genes

Microevolution

• Short term evolutionary change

• change in allele frequencies from one generation to next

Macroevolution

• Long term evolutionary change

• biological evolutionary over many generations and the origin of higher taxonomic categories

5 forces of evolution

• natural selection 

• Sexual selection 

• Gene flow 

• Genetic drift 

• Mutation

Gene flow

• Movement of alleles to a new population = migration 

 - Carry genes with them 

- mate in the new population 

- increases variation in new population 

- exchange creates a larger gene pool

            - decreases variation in both populations

Genetic drift

• Change in allele frequency across time due to chance 

   - Powerful in small populations 

   - few mating events 

   - change loss of alleles 

   - reduces variation 

Founder effect

a subset of a larger population carries a subset of the populations alleles

Bottleneck

• population increase after a reduction results in a subset of alleles 

  • bottleneck severely reduces population size and genetic diversity 

Variations within and between populations

Gene flow: within - increase between - decrease 

Genetic drift: within - decrease between - increase 

Mutation: within - increase between - increase 

Natural Selection: Within - increase or decrease between -increase and decrease 

Calculate genotype, allele and phenotype frequencies

2 alleles: A, B 

3 Genotypes: AA, AB, BB

Population: AB, AA, BB, BB, AA, AB, AA, AB

Genotype NN Frequency

AA      3      3 / 8 = 0.3753 

AB      3      3 / 8 = 0.3753 

BB      2       2 / 8 = 0.252 

Sum    8        1

5 assumptions of Hardy Weinberg equilibrium

1. No natural selection - survival is random 

2. No sexual selection - mating is random

3. No gene flow - no migration 

4. No genetic drift - population is very large 

5. No mutation

Biological species concepts

• A group of interbreeding natural populations that are reproductively isolated from other such groups 

  • capable of producing viable offspring 

Ecological Species Concept

A set of organisms exploiting or adapted to a single niche

Evolutionary Species Concept

• Evolutionary lineages with their own unique identity 

  • used by paleontologist 

  • species based on morphological differences

Mate Recognition Species Concept

• Define species by unique traits or behaviors that allow species to identify each other for mating

Anagenesis

• single species undergoes gradual change and transform over time 

Cladogenesis

• Branching evolution involving the splitting of species 

• Why all monkeys didn't become human

• What's causing splitting? (allopatric specification)

Allopatric specification

Production of new species through the splitting of existing through the spitting of existing ones due to geographic barrier

Parapatric speciation

• Populations with adjacent ranges separated by environmental gradient. 

• Para (next to)

Gradualism

geometrical change, linear, constant change

 Punctuated Equilibrium

-long periods of equilibrium punctuated by rapid changes

How is extinction important to the evolution of species?

• new species emerge 

  • Opens up ecologic niches that were once occupied 

-increasing diversity 

-mass extinction followed by diversification of surviving species 

phylogeny

• A reconstruction of evolutionary branching sequence.

• Taxonomy related to understanding to phylogeny

Analogous Traits

 similar not from being related to each other i.e butterfly wing and bat wing 

Homologous Traits

similar because shared ancestry i.e bat wing and human arm

Convergent Evolution

Process by which unrelated organisms independently evolve similarities when adapting to similar environments i.e sharks and dolphins

Parallel Evolution

independent evolution of similar traits, starting from a similar ancestral condition

Divergent Evolution

common ancestors but two completely different species

Synapomorphy

• Shared derived traits 

• Found in last common ancestor 

• Shared by all descendents 

• Trait characterizes taxonomic group 

• Most recent trait 

I.e apes are primates without tails

Symplesiomorphy

• shared ancestral traits 

• shared by members of taxonomic group 

• Inherited from a distant ancestors 

• Traits from far far ancestors 

 Why do we say humans are a polytypic species

Lots of type, lots of variation

 What are population and subspecies

Subspecies - sub set of species share geographic range, different phenotypic traits, race 

• Race interchangeable with subspecies, but subspecies needs geographic rage

What do biologists mean by race?

Geographic range

Discrete Traits

• Either you have it or not

  • , i.e tongue rolling, tongue folding, thumb on top, blood type

Continuous traits

• Anything you can measure with tool

  • i.e height, head shape, noes shape, torso length 

Anthopometry

-the scientific study of the measurements and proportions of the human body.

Be comfortable reading an index and understand what indexes are used for:

comparing shape for things of different sizes

 Index as a tool

      • Ratio is a useful for eliminating size confounds/ measuring shape 

Cephalic Index = head width / head length * 100

    • Low value = long, narrow head

   • High value = rounder head

i.e 8/16cm x 100 = 50 

Above what frequency should alleles be, to be considered polymorphic

Polymorphic - if at least two forms with frequencies greater than 1%

No polymorphic/ fixed  - no two forms with frequencies greater than 1% 

Cline

A gradual change in a trait along a geographic axis.

What adaptive explanation has been given to account for clinal distributions in blood type alleles?

A,B - areas  high bacterial diseases/ regions with majority A,B better resist bacterial disease 

O - in areas of high viral diseases/ regions with majority O blood type better resist viral diseases 

Haplotype

Combinations of Alleles

Duffy blood group allele

• Marker of european ancestry 

• it is an allele only from European descent, but when people form Africa and Asia have it (which many do) it expresses gene flow. Racial groups are almost purely cultural

 What does sinodonty tell us about the origin of the people of the new world

It is evidence of gene flow

What do phylogenies of modern humans based on mtDNA tell us about where all

Where did humans come from?

• Short lines on charts reflect recent migration 

• Mtdna tells us that africans line of mtdna implies long residence in one place which could mean that we might have originated in africa 

What do patterns of lactose intolerance tell us about the influence of culture on Biology?

 Lactase production into adulthood

• Dominant allele

• Regulatory function related to timing of

Lactase production

Lactose tolerance found in populations with

long history of diary

• Individuals who drink it could have a

nutritional advantage

• May facilitate calcium absorption in the north

balanced polymorphisms

• A stable polymorphism in a population in which Natural Selection prevents alternate phenotypes from becoming fixed or lost

• Maintenance of variation

Dependent polymorphism

 • Human Leucocyte Antigen System (disease recognition system) 

          • Many linked loci on c’some 6

          • Controls immune response

When an allele is common…

Diseases encounter alleles enough to

evolve counter strategies

When an allele is rare…

Possessors of that allele have better

resistance to infectious diseases

Heterozygous advantage

 • Two Alleles

        • HbA – normal round red blood cell

        • HbS – sickle-shaped

            • Recessive

             • Reduced ability to carry oxygen

Acclimatization

• Short-term changes in physiology in

response to new environmental conditions

• High Altitude Hypoxia – Oxygen

  starvation

  • Headaches

  • Dehydration

  • Difficulty Catching Breath

adaptability

adaptation