Population Genetics Flashcards
Define Population
a freely interbreeding group of individuals
Define Gene Pool
the sum total of genetic information present in a population at any given point in time
Define Phenotype
A morphological, physiological, biochemical or behavioural characteristics of an individual
Define Genotype
the genetic constitution of an individual
Define Locus
A site on a chromosome, or the gene that occupies the site
Define Gene
A nucleic acid sequence that encodes a product with a distinct function in the organism
Define Allele
a particular form of a gene
Define Gene Frequency
the relative proportion of a particular allele at a single locks in a population (number between 0 and 1)
Define Genotype Frequency
The relative proportion of a particular genotype in a population (number between 0 and 1)
What is the point of population genetics ?
it studies the distribution of genetic variation within a species over both space and time
What is polymorphic ?
the gene is question will occur in a number of different forms
What is the Hardy-Weinberg Equilibrium ?
p^2 +2pq+q^2 = 1
What are the 6 assumptions of the Hardy-Weinberg Equilibrium ?
- mating is random
- population size is very large
- there is no migration.
- there’s no mutation
- natural selection doesn’t affect the alleles
- all members of the population breed
What are the 2 results of the Hardy-Weinberg equilibrium conditions being met?
- frequencies of alleles at a locus will remain constant from generation to generation
- genotype frequencies can be predicted from allele frequencies
What causes Hardy-Weinberg disequilibrium ?
- genetic drift, mutation, mating choice, migration and natural selection
What is a population bottleneck?
Occurs when a population undergoes a severe decrease in size
What are the 3 broad categories of mutation?
- good/advantageous that increase fitness
- bad/deleterious that decrease it
- indifferent/neutral that aren’t affected by selection with small effects
What was Darwin’s first observation?
- The forms of certain living creatures seemed to be adapted to their specific needs
What is Darwin’s 2nd observation?
- Some species were known to have died out altogether - to have become extinct
What is Darwin’s 3rd observation?
- Darwin’s research voyage on the Beagle had persuaded him of the uneven geographical distribution of life forms throughout the world
What is Darwin’s 4th observation?
- Many creatures possess ‘rudimentary structures’ which have no apparent or predictable function
What are the 2 components of Darwin’s theory of evolution ?
- species are not immutable, but change, or adapt, over time
- agent that produces the changes is natural selection
What does the term adaptation mean in evolutionary biology ?
- processes by which adaptive traits are acquired
- trait that enhance survival and reproduction success of their bearers
What is Darwinian Fitness ?
- an individual that is better at surviving/reproducing is more fit –> fitness is relative
What are the 3 types of natural selection?
- directional
- Stabilising
- Disruptive
Describe stabilising selection
the extremes are selected against, genetic diversity decreases and the population mean stabilises on a particular trait value
Give an example of stabilising selection
- human birth weight is a key example
- selective pressures apply to babies born with a low birth weight and a high birth weight
What is kin selection ?
- refers to strategies that occur in evolution that favour the reproductive success of an organisms relatives, even at a cost of their own survival and/or reproduction
Why is time a constraint of evolution?
as evolution is defined as heritable allelic changes over time, if sufficient time doesn’t pass evolution may not happen
Why is inherent genetic variation a constraint of evolution ?
- the inherent genetic variation limits the possible allelic combinations that can be observed in the offspring
- genetic variability is a large constraint
