Modern Genetics
Evolution depends on this in heritable traits.
Variation
Different versions of the same gene are called
Alleles
The primary way new alleles form
Mutations
Walrus infants of intermediate birth weight have the highest survival
Stabilizing Selection
A change in allele frequencies in a population over generations
Microevolution
Known as the father of modern genetics for his work with pea plants
Gregor Mendel
The specific position of a gene on a chromosome
Locus
A change of one base pair in a gene
Point mutation
Ground finches evolve larger beaks due to long term diet changes, those with smaller beaks die.
Directional Selection
A change over long periods of time that leads to speciation events
Macroevolution
Darwin understood variation was important but did not know that traits were inherited. He called this phenomenon:
Descent with Modification
A functional stretch of DNA that codes for a product or has a specific regulatory role
Gene
Sexual reproduction reshuffles alleles via
Crossing over, independent assortment, random fertilization
In a certain habitat, both very light and very dark mice survive better than any intermediate colored mice.
Disruptive Selection
The only mechanism that produces adaptive evolution
Natural Selection
a pair of chromosomes (one from each parent) that carry the same genes at the same loci but with variation
Homologous chromosomes
Difference between a diploid and haploid; Significance?
Diploid- two copies of each chromosome; Haploid- one copy of each chromosome. Eukaryotes are diploid/genetic variation/recombination, Prokaryotes are haploid/simplicity
Errors during this process can lead to gene or chromosome duplication/deletion
Crossing over/recombination
The type of selection in which heterozygote advantage plays the greatest role
Balancing Selection
The three mechanisms that cause allele-frequency change.
Natural Selection, Genetic Drift, Gene Flow
Natural selection acts on phenotypes, but evolutionary change is measured as a shift in
Allele frequencies at the genotypic level
The same genotype can produce different phenotypes depending on this
Environment
Only mutations in these cells are passed to offspring and are therefore acted upon by evolution.
Germline cells/Gametes
Peacock tails display increased mating success despite survival costs- the antithesis to natural selection
Sexual Selection
An individual with two copies of the same allele versus one with two different alleles.
Homozygous vs Heterozygous