HBIO 200 Chapter 1-6 Flashcards
Evolution
A change in gene frequency in a population over multiple generations
Natural Selection
Differential reproductive success among individuals in a population from one generation to the next; based on traits that help them survive through adaptations
Charles Darwin 3 observations & 2 deductions
3 Observations:
1. All organisms has the capacity for tremendous population growth
2. Animal populations remain constant/similar over generations
3. No two offsprings from the same parent look alike
2 Deductions:
1. Struggle for existence since more offsprings are produced than can possibly survive
2. Some variations are advantageous, these tend to survive; others don’t
Species
A group of organisms that can interbreed to produce fertile offspring
Population
A group of individuals within a species that live in the same location and interact and interbreed with each other
Forces of Evolution
- Mutation
- Natural Selection
- Sexual Selection
- Gene Flow
- Genetic Drift
Mutation
Change in structure of DNA causing genetic variation
Sexual Selection
Intra-sexual Competition: One sex competing against one another for a female. Eg. Male deers fight against each other and the one with stronger antlers win and stay and has the rights to choose the female
Inter-sexual mate choice: Female chooses male based on their traits. Eg. Female peacock chooses male based on the brightness of their plumage
Gene Flow
The movement of genes from one population to another due to interbreeding
Founder Effect
A small population that has similarity in phenotype and genotype starts a new population; reduces diversity of the population
Genetic Drift
Random change in allele frequency due to chance events
Bottleneck Effect
A random event reduces a significant number of individuals in a population; reduces genetic variation
Directional natural selection
An extreme trait is favored such that the allele frequency shifts towards one direction
Eg. Giraffe’s neck
Disruptive natural selection
Extreme values of a trait in either directions are favored over intermediate values
Eg. Oysters
Stabilizing natural selection
Population mean stabilizes on a non-extreme trait value
Eg. Bird eggs
Gene
A section of the DNA that contains hereditary information AND codes for a specific characteristics or traits of an individual
Allele
Variation of a gene
Heterozygous
2 different alleles
Locus
The physical location of the gene on a chromosome
Homozygous
2 identical alleles
Genotype
the DNA of an individual
Phenotype
the physical expression of the gene
Epigenetics
does not change the genetic code but the phenotype due to different expressions of the genes
Sickle Cell Anaemia
A homozygous disease;
Occur mostly in places with serious malaria since the one copy of the gene of sickle cell anaemia has a survival advantage of Malaria
