Lecture 16: The evolutionary Impact of Genetic Variation Flashcards
What is Variation
These are differences in a population
Heredity
offspring tend to look more like their parents than distant relatives
There is such a thing as heritable variation, the differences in the genetic makeup of a parent that transfers to its offspring. What does this mean simply and where does it come from?
Heritable variation means that no two siblings will have identical genetic makeup.
this stems from three things:
1. mutations
2. segregation and independent assortment (Mendel’s law)
3. recombination
Mutation
a stable change in DNA that occurs at a low rate
What are the possible effects of mutations
deletion
beneficial
neutral
what the types of mutation
insertion/deletion
point mutations (1 wrong base)
chromosomal re-arrangements (The sequence of chromosomes have been flipped)
T/F, Mutation rates are higher in men
true
G6PD deficiency in humans
Mutation in humans which can cause severe anemia due to red blood cell but it can also protect against malaria
What type of mutation is G6PD?
2 amino acid replacements (point mutations)
Preformationism
the idea that only 1 parent contributes to inheritance
Theory of blending inheritance
it was thought that offspring are the creation of equal blends of both parents
What was the issue of blending inheritance in relation to natural selection?
It assumes that homogenized populations, so it doesn’t account for heritable variation
What were the differences between the predictions of blending inheritance theory on the outcome of Mendel’s experiment and the actual data
It was thought that the combination of the 2 different peas would produce a diluted colour of both parents but what ended up happening is that in the first generation all the peas were yellow and in the second generation, only one pea was green
What were the conclusions of Mendel’s experiment
inheritance is determined by discrete genes
each organism carries two copies of each gene and each allele and exhibit dominance or recessivity
sperm/egg come together to make offspring
offspring inherit only gamete from each parent randomly
Which parts of the conclusion made the central parts of Mendel’s law
Reproductive organs (sperm/egg) fuse together to make offspring and that offspring inherit one gamete from each parent randomly
_______ plus ______ of chromosomes generate diversity
segregation and independent assortment
Why exactly generates diversity?
the independent random assortment of chromosomes in segregation during meiosis
Genotype
genetic constitutions of an organism
phenotype
physical attributes
genome
the entire genetic makeup/dna of an organism
polymorphism
the existence of variant forms within a population
discrete/discontinuous traits
contraints where there are only 2 allele options.
In Mendel’s experiments, peas were either smooth or rough
Continous/complex traits
multiple possibilities of genetic outcomes
Evolutionary Synthesis
Includes the principles of DNA, natural selection, genetics, and biogeography
Quantitative Genetic Inheritance
Relation between gene number and phenotypic variability
What affects quantitative traits
complex polygenic inheritance and environmental inheritance
Discrete Variation
mandelian genetics
genes of major effect, dominance and recessiveness
spread of alleles and change in allele frequency
Continuous Variation
Quantitative genetics
many genes each with alleles of small effect
important environmental affects
selection response as change in average trait value
