Topic 10: darwin Flashcards
(31 cards)
What are theories on origin of species pre-Darwin?
- Traditional = earth inhabited by unchanging species
- Aristotle = species are fixed
- Old testament = species individually designed by God = perfect
Give the Scala Naturae
1) God
2) Angels
3) Humanity
4) Animals
5) Plants
6) Minerals
What is Carolus Linnaeus’ theory of species origin?
- Organismal adaptation = evidence God designed each species for specific purpose
What is Lamarck’s hypothesis of evolution?
- Species evolve via use/disuse of body parts = inheritance of acquired characteristics
- Not supported by scientific evidence
Why did Darwin begin researching?
- Doubts about permanence of species
- Went on 5-year world-wide trip
- Interest in geographic distribution of resembling species in different regions of Galapagos
Define uniformitarianism
- Mechanisms of change constant overtime
What influenced Darwin’s ideology?
- Lyell’s principle of uniformitarianism + study of fossils
Describe Darwin’s theory on species origin
- Published in 1859
- Evolution = descent with modification
- Mechanism = natural selection
Define evolution
- Change in inherited characteristics of biological population over generations
2 main points of Darwin’s theory
1) Descent with modifications:
- Current species descend from ancestral species = common ancestor
- Modifications happened over generations
2) Natural selection is mechanism of evolution:
- Individuals with favorable traiys = likely to survive + reproduce = survival of fittest
- Traits accumulate over populations = higher population with better traits
Define natural selection
- Process that occurs = populations’ heritable variation exposed to environmental factors
- Factors favor reproductive success of some over others
What is explained by Darwin’s theory?
- Adaptations of organisms
- Unity + diversity of life
- Evolution is responsible for unity + diversity
Define unity of life
- Similarities between organisms
- All life connected via long evolutionary history
- E.g. related organisms = similar anatomical features
Define diversity of life
- Differences between organisms
Define tree of life
- Natural selection can enable ansestral species = split into 2+ descendant species
Define adaptation
- Evolutionary process = enhance fitness + survival of individual in own environment
- Adaptation + origin of new species = closely linked
Give Darwin’s 2 observations of NS/adaptation
1) Members of population = vary in inherited traits
2) Species produce more offspring than environment can support = many fail to survive + reproduce
Give Darwin’s 2 conclusions of NS/adaptation
1) Differences in reproductive success = individuals with inherited trait with higher probability of surviving + reproducing = more offspring
2) Evolutionary adaptations in populations = unequal ability to survive + reproduce = accumulation of favorable traits over generations
Explain how traits are effected by NS/adaptation
NATURAL SELECTION:
- Doesn’t create new traits
- Selects traits already present in population
ADAPTATION:
- Environmemt determines trait selected/against
- Adaptations vary with different environments
Describe NS/adaptation in thalassaemia
- Thalassaemia allele survives in heterozygous carriers in countries = malaria
- Plasmodium malariae replicates in mosquitoes living in tropical regions
- Infects RBC = digest haemoglobin
- Carriers = lower haemoglobin level = more resistant to infection
- NS favored survival of carriers of allele
- Therefore having single allele advantageous = protect against malaria in endemic region
- Heterozygous carriers have protection against coronary heart disease
What scientific data supports evolution?
- Direct observation
- Homology
- Fossil record
- Biogeography
Describe direct observation of evolutionary change
- NS in response to introduced plant species
- Evolution of drug-resistant bacteria
- Evolution of insecticide-resistant mosquitoes
- Increased survival of thalassaemia carriers when exposed to malaria
Describe the evolution of drug-resistant bacteria
- Bacteria = short generation times = 1-3 hrs
- Rapid adaptive evolution = antibiotic resistance
- E.g. MRSA = pathogenic strain
- E.g. Staphylococcus aureus = penicillin/methicillin resistance 2 years after use
- When exposed to antibiotics MRSA = more likely to survive + reproduce than non-resistant strains
Describe methicillin
- β-Lactam antibiotic
- Binds to + inhibits transpeptidase = responsible for forming peptidoglycan in cell wall
- MecA gene = gene encodes > protein binds to β-Lactam antibiotic
- Transpeptidase = stays active in presence of β-Lactam antibiotic = prevents inhibition of cell wall synthesis
