Lecture 1: Ecological and Evolutionary Genetics

Question 1

Genome Transmission

Answer 1

• Some parts of genome are uniparentally inherited(mt, Y) and some are biparentally(autosomes, X)
• Some parts present in all members(mt, X, autosomes), and others in half(Y)
• Areas of low recombination inherited as a unit, while recombination will break up areas of high recombination to be inherited independently

Question 2

How to use genome data

Answer 2

• Use regions of genome that are inherited biparentally to infer contributions of both parents
• Use uniparentally inherited genomes to track specific contributions of one parent
  
  • mt tracks maternal
  • Y tracks paternal
• Use genetic markers to understand evolutionary process
• Use data about behavior and ecology to understand patterns in genetic data

Question 3

Elephant social system

Answer 3

• Females live with natal group with 2-20 maternal kin
• Males leave natal group at adolescence and do not join other social groups
• Males attracted to females in heat and can be seen within their natal group
• Male reproductive lifespan is long

Question 4

Do male elephant avoid inbreeding

Answer 4

• Hypothesis 1: Males have evolved inbreeding avoidance because inbreeding depression is severe
• Hypothesis 2: Selection has not led to inbreeding avoidance because inbreeding depression is weak

Question 5

Litmus test: Do males behave in way to avoid inbreeding

Answer 5

• Observe elephant behavior
• Quantify mating behavior and test whether they are directed away from kin
• Extract DNA to see if offspring created from inbreeding or not
• Results: Elephants avoid kin

Question 6

Elephant mating behavior

Answer 6

• Male reproductive success is skewed and should create strong cost of inbreeding avoidance
• Despite costs, males avoid inbreeding
• Fight with other males for mating
• Females also have behavior to avoid inbreeding

Question 7

Gene flow and differentiation

Answer 7

• Genetic differentiation: differences between populations in allele frequencies
• Genetic variation: amount of variation within populations
• Gene flow erode differences between populations
• Restricting gene flow lead to accumulation of genetic differences
• Gene flow increases genetic variation

Question 8

How do barriers effect genetic structure in coyotes

Answer 8

• Null hypothesis: Natural and human barriers have no effect on coyote patterns of genetic variation
• Hypothesis 1: Barriers lead to genetic differences between coyote population
• Hypothesis 2: Barriers lead to slight genetic differences between coyote populations

Question 9

Genetic differentiation in coyotes

Answer 9

• Fst: measurement metric for genetic differentiation
• Fst range from 0(pan-mixia) to 1(complete genetic differentiation)
• Fst in coyotes was 0.08

Question 10

Do cultural forces affect human genomes

Answer 10

• Patrilocality: females move to location of male partner
• Matrilocality: Males move to location of female reproductive partner
• Predictions:
  - Matrilocality: Y chrom variation is higher, Y chrom differentiation lower, mtDNA variation lower, mtDNA differentiation higher. Not much gene flow in females
  
  • Patrilocality: Y chrom variation lower, Y chrom differentiation higher, mtDNA variation higher, mtDNA differentiation lower. Not much gene flow in males

Question 11

Human differentiation with better markers

Answer 11

• Correlation between Y chromosome and mtDNA
• Gene flow among populations similar for males and females
• Similar rates of divergence for Y chromosomes and mtDNA