lec 1.3+2.1 Flashcards
What are the five key processes of ecology?
Abiotic requirements, biotic interactions, evolution, dispersal and stochasticity
What are abiotic requirements? What was the example used in class?
1) Certain species can only tolerate certain abiotic conditions. Eg. moisture, temperature, salinity, pH etc.
2) Aedes Aegypti mosquitoes like it warm so if Canada gets warmer with climate change, it will be able to survive here and yellow fever will become contractible here
What are biotic interactions?
Competition from the other species in an environment. Eg. Herbivores, predators, competitors, parasites and pathogens
Abiotic and biotic interactions can act on the same species. What is the lecture example of this?
Both temperature and competition determine distribution of semibalanus balnoides (barnacles)
What is evolution? What was the example used in class?
1) Where a species is found is usually where it evolved.
2) there is no polar bears in Antartica because they evolved from grizzles in the north (arctic) and they cannot disperse through the tropics to get to the southern hemisphere even if Antartica has the correct abiotic requirements
What is Dispersal? What were the two examples used in class?
1) Ability or capacity for movement short, distances .
Ability of a species to move affects where it is found/can live.
2) Plants dispersal occurs by seed movement
whales move thousands of kilometres in a year (they migrate)
What is migration?
Type of dispersal dependent on seasonal variation and includes a round trip
What is stochasticity? What was the example given in class?
1) Random changes in the relative abundance of species
2) Monarch butterflies having small population so any random event such as there forest having less fir trees results in less monarchs which can threaten extinction
When is stochasticity particularly important when looking at certain populations?
In organisms with small population sizes. Random extinction can happen if populations reach really low levels eg.monarch butterflies
How does stochasticity affect a species dispersal?
Stochasticity means that even if an area is theoretically suitable for a species, randomness can prevent it from being found there.
What is evolution defined as?
Change in allele frequencies in a population overtime
If frequency of an allele is 40% in a population and goes to 70% what is that known as?
Gene evolving a population
What are mutations?
A source of new alleles
What are the three main causes of evolution?
Natural Selection, Genetic Drift and Gene Flow
What is Natural Selection? Why does it happen? What was the example in class?
1) When individuals with certain alleles [heritable traits] survive and reproduce more successfully than other individuals
responsible for “modification” part of descent with modification
2) Some traits are only beneficial in specific conditions and individuals with those advantageous traits leave more offspring
3) bacteria vs. antibiotic resistance bacteria
What is Gene Flow? When does it usually happen?
1) Transfer of genetic material (alleles) from one population to another through migration, reproduction or hybridization
2) When individuals from from one population move to another and interbreed introducing new genetic variations
What are two common effects of gene flow?
1) Populations become more similar
2) New alleles can be introduced into a population ( similar to mutations)
What is genetic drift? When does it have a stronger impact?
1) Random change in allele frequencies in a population due to chance events
2) Has stronger effect on small populations where chance events can lead to significant genetic changes over time
What are the four main affects of genetic drift on small populations?
1) allele frequencies fluctuate at random; some may disappear, others are fixed
2) genetic variation of a population is reduced
3) frequency of harmful alleles can increase
4) chance event may lead to allele fixation in one population and loss from another
What are the two main consequences of genetic drift? Give an example of one using hatching rate.
1) Loss of genetic variation reduces the ability of the population to respond to changing environmental conditions (even if the population increases in size)
2) Increase of harmful alleles can reduce survival and reproduction
Eg. As habitat is lost population size goes down so more harmful alleles are fixed by chance and hatching rate goes down
What is recombination? How is different to mutations? How are they similar in terms of evolution?
Recombination: offspring have combinations of alleles that differ from parents therefore producing different genotypes within a population
Mutation: Provides the raw material on which evolution is based; recombination rearranges raw material into new combinations
3) Both contribute new genotypes/ allele combinations to a population
What is a common mutation is east asians?
ALDH2, when drinking alcohol elevated acteyl aldehyde is not processed quickly and basically gives them like an allergic reaction (toxin)
What are the three selections dependent on phenotype?
Directional, Stabilizing, and Disruptive
What is Directional Selection? How does it impact a graph? What was the example used in class?
1) Individuals at one phenotypic extreme are favoured
2) Pushes statistics/peak to one side
3) In medium ground finches drought favoured large beak size for cracking hard seeds as fish not avalible
