Introduction to Evolution and Genetics Flashcards Preview

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Flashcards in Introduction to Evolution and Genetics Deck (38)
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What creates variation in a population

mutation, recombination and gene flow


What processes influence variation in a population

selection and genetic drift


Who was the first to advocate for evolution

Jean-Baptiste de Lamarck


What was Lamarck's theory of evolution

Lowly forms of life arise spontaneously from inanimate matter
They progress towards greater complexity
Environment alters the needs of the organisms
Use and disuse alter morphology
This is transmitted to the next generation


What were Darwin's main ideas

All organisms have descended with modification from a common ancestor
the chief agents of modification is natural selection on individual variation


What did Darwin study to develop his theory

Fossil record
Geographic distribution of species
Comparative anatomy
Studies on domestic animals


What were the initial problems with Natural Selection?

Peeps were ready to accept biological evolution, but thought the struggle for existence was at the species level, not the individual


Popular misconceptions about evolution

There is no “higher goal”
No progress from “lower” to “higher” life forms
Natural selection acts at individual level
Evolution and natural selection are amoral
The “law” of natural selection cannot be used to justify the class struggle, capitalism, etc


What was the blending problem for natural selection

How can traits values segregate and not merge to a mean value with no variation?
Mixing paints on a paint pallet


Who solved the blending problem but introduced another

Gregor Mendel in 1900
Heritable traits were thought to be discontinuous


What is the modern synthesis of evolution

Populations contain genetic variation that arises spontaneous and at random
This variation is subject to random fluctuations
Natural selection favours certain variants that increase fitness
Genetic variation can be exchanged between populations (gene flow) and occasionally between species
Recombination shuffles variation and generates new genotypes
Over time, genetic changes accumulate so that populations become reproductively isolated


How does biodiversity and genetic complexity increase?

Duplication and divergence


How does duplication and divergence increase biodiversity and genetic complexity

Duplication does not increase genetic information but it does give substrate for selection and drift leading to divergence


How does symbiosis increase biodiversity and genetic complexity

Origin of eukaryotic life, but also evolution of chromosomes (linking genes), associations between plants and fungi, animals and algae


How does epigenesis increase biodiversity and genetic complexity

Heritable changes in gene expression or cellular phenotype not due to changes in the DNA


What is Kumura Neutral Theory

Most intraspecific variability at the molecular level is neutral and variation in maintained by the input of new mutations balanced by the loss due to drift
Few DNA polymorphisms in a species are due to positive or balancing selection


What is the process of epigenetic regulation

Not all adaptive evolution occurs through mutations and changes in the DNA code
Heritable changes occur in gene expression
Modifications are DNA methylation and histone modification
Changes may remain through cell divisions and across generations (i.e. heritable)


How much needs to die to be class as a mass extinction

75% taxa


What is the current extinction rate?

Estimated 1000-fold increase over ‘background extinction rate (not yet 75%)


What has been affected by the sixth extinction

extinction of megafauna in the late Pleistocene, but currently most taxa


What is the cause of the sixth extinction

human population size expansion, loss and fragmentation of habitat, pollution, over exploitation, climate change


How do we slow the extinction rate on a global scale

Reducing pollution and greenhouse gas emission and protection of the ozone layer


How do we slow the extinction rate on a local scale

Protecting habitat, life-style changes (food, recycling etc.)


How do we slow the extinction rate on a species level

Protecting species in situ
Ex situ conservation in zoos
Reintroduce animals (plants) when habitat is restored and safe


What are the risks of captive breeding

Inbreeding depression
Loss of genetic variation
Outbreeding depression (hybridisation)
Adaptation to captive environment
Accumulation of new deleterious mutations


How to minimise the risks of captive breed

breeding with wild individuals
be aware of local adaptations
maximise migration regime?
purging regime = removing deleterious mutations through inbreeding


What is the main concern over captive population size

Too large, you get too much adaptation to captivity, too small and there is too much inbreeding depression


When doing breeding experiments, why would you limit the amount of offspring, from each individual

By equalising the reproductive ability of everyone you reduce the effects of selection


Why does deleterious alleles arise in captivity

inbreeding and all ill animals get medicine


What were the main conclusions of Oosterhout et al 2007

During reintroduction
Many fish died from parasites (epidemics)
Inbreeding Regime - lowest survival
Outbred guppies from the largest natural population - had the highest survival