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Unit 4 Biology Review of AS2
Transcript of Unit 4 Biology Review of AS2
Change over time
"A group of the same species living in particular geographical region at a given time"
Variation in populations
Types of variation:
Monomorphic (one form): a population with no variation of a particular trait
Polymorphic (many forms): a population with two or more variations of a particular triat
Monogenic: a trait controlled by one gene
Polygenic: a trait controlled by more than one gene
How many genes?
How many phenotypes?
No change in allele frequencies from generation to generation
Subject to change due to "change agents"
Block mutations (parts of chromosomes)
- Chromosomal mutations (whole chromosomes)
Environment selects for most 'fit' phenotype
Genetic drift - founder effect
Chance events that can dramatically change allele frequencies - particularly in small populations
The movement of individuals between populations - may change frequency rapidly
Analysing gene pools
"the change over time in one or more inherited traits found in populations of individuals"
How do we know its happended...?
Amino acid sequence
Patterns of evolution
Closely related species become more dissimilar over time in response to selection pressures
Over time selection pressures may act on distantly related species to produce superficial similarities
Evidence: Homologous structures
Evidence: Analogous structures
"when a variety of different species evolve from a single ancestral species"
Anything transmitted genetically
adaptation for bipedalism
skull features including brain size/ function
Transfer of non-genetic information. Faster than biological evolution
Also non-genetic tranfer of information. Ability to create and use items in environment. Developed because of bipedalism
p + q = 1