Evolution
- Created by: elshuntt
- Created on: 09-04-18 10:55
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- Evolution
- Evidence for evolution
- Theory of evolution
- Theory - a set of idea to explain why something is true (different to a hypothesis)
- Types of evidence for evolution
- Fossils
- Distribution of species
- Ring species
- Body Plans
- Homeobox & Hox Genes
- Molecular Biology
- Genome
- Evolution - we've all descended from a common ancestor
- The more recently separated the closer the species and releatedness
- therefore their base sequences are more similar
- Proteins
- Genome
- Homo-logy of Structures
- similarities in bone structure
- Theory of evolution
- Genetic Diversity and Adaptation
- Genetic Diveristy
- The number of different alleles of a gene in a population
- Natural Selection
- Individuals of a population that are best suited to their environment survive and reproduce more, therefore the beneficial alleles are more likely to be passed on to the next generation.
- Results in species being better adapted to their environment
- changes in allele frequency over time
- A variation of alleles exist in a population resulting in mutations
- Selection for individuals with beneficial allele
- This leads to differential reproductive success
- Changes allele frequency over a long period of time.
- This leads to differential reproductive success
- Selection for individuals with beneficial allele
- A variation of alleles exist in a population resulting in mutations
- Types of adaptations
- anatomical
- physiological
- behavioural
- Selection Pressures
- Directional Selection
- Usually a change in environmental conditions
- Individuals with an extreme type of characteristic are more likely to survive and reproduce
- With the presence of diases the organisms with an allele for antibiotic resistant will increase in offspring and antibiotic resistance will increase
- Stabilising Selection
- Individuals with characteristics of either extreme are less likely to survive and reproduce
- e.g. human birth weight
- Very heavy babies are more likely to die due to complications
- Very light babies are more likely to die due to high surface area to volume ratio = cold
- Babies in the middle range are more likely to survive, thus the population remains stable.
- Directional Selection
- Genetic Diveristy
- changes in allele frequency over time
- A variation of alleles exist in a population resulting in mutations
- Selection for individuals with beneficial allele
- This leads to differential reproductive success
- Changes allele frequency over a long period of time.
- This leads to differential reproductive success
- Selection for individuals with beneficial allele
- A variation of alleles exist in a population resulting in mutations
- Varation
- Intraspecific
- Individuals of the same species have the same genes but different alleles (variation in their phenotypes)
- Interspecific
- Individuals of different species have different genes and live in different environments (variation in their phenotypes)
- Continuous
- variation is smooth (non-discrete)
- Represented in a line graph
- Discontinuous
- Individuals fall into distinct groups with no intermediates
- controlled by a single gene with a few alleles
- represented on a bar chart e.g. blood group
- Genetic Causes
- Mutation
- Meiosis (crossing over or random assortment)
- Random fertilisation (e.g. blood group)
- Inherited factors - genetic variations resulting in evolution
- BOTH
- Most variation is a result of both environemtal and gentic variation
- e.g. height
- GENETIC: tall parents tend to have tall children
- Childhood mutation
- e.g. height
- Most variation is a result of both environemtal and gentic variation
- Environmental Causes
- Environmental changes that change phenotype
- Can change over a lifetime
- e.g. accent
- BOTH
- Most variation is a result of both environemtal and gentic variation
- e.g. height
- GENETIC: tall parents tend to have tall children
- Childhood mutation
- e.g. height
- Most variation is a result of both environemtal and gentic variation
- Intraspecific
- Convergant Evolution
- organism that are not closely released can independently evolve very similar anatomy and behaviour because they become adapted to similar niches/habitats
- Evolution of Resistance
- Insects have evolved resistance to pesticides and herbicides
- Bacteria has evolved resistance to antibiotics
- Antibiotics and pesticides form a strong directional selection pressure
- only individuals with rare mutations will survive and reproduce - passing on resistant alleles
- resistant alleles will increase in frequency so a high proprtion of organisms become resistant
- Consequences
- Crops are ruined; harder to control/maintain; spread of disease (malaria)
- Resistant infection - become life threatening
- Evidence for evolution
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