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ENV100Y5 Lecture Notes - Lecture 6: Population Ecology, Convergent Evolution, Selective Breeding

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magentabear247
21 Feb 2018
School
UTM
Department
Environment
Course
ENV100Y5
Professor
Barbara Murck

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Document Summary

Populations evolve over time and populations may diverge and form new species. Evolution: change in the genetic composition of a population. Variants of a given gene are called alleles. From any given gene (locus), there may be one, a few or many variants in a population. Migration: arrival of an individual changes genetic composition of a population, interbreeding changes future generations. Random drift: random events remove alleles from a population. Natural selection: some variants more likely to survive than others, there is genetic variation in populations, population is going to change, adaptations are traits that help you survive. Migration, drift, mutation, and selection are all agents of evolution. Adaptations are traits that help you survive and reproduce. Humans can be unintentional agents of natural selection. Convergent evolution: similar adaptations in unrelated species (shark, dolphin, reptile) Changes in the environment provoke changes in adaptations. Directional selection: drives a feature in one direction. Disruptive selection: traits diverge in two or more directions.

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Related Questions

Which of the following is most likely as a population goes through a bottleneck?

Heterozygosity decreases because genetic distance increases.

Genetic diversity increases because mutation rate increases while the population is going through the bottleneck

. Genetic diversity decreases because some alleles can be lost as the number of individuals dwindles

. The proportion of individuals that are heterozygous increases because there are fewer individuals.

2)What is meant when it says that genetic drift produces "non-adaptive" evolution?

Sometimes natural selection can favor a trait that is good for the current conditions, but when conditions change it is no longer helpful.

Evolution is just a genetic change in a population. If genes are lost from a population due to chance (i.e. genetic drift), that may not be adaptive, meaning the remaining organisms are no more fit.

Evolution isn't perfect, and sometimes it makes mistakes.

Which statement about evolution by natural selection isfalse?

Natural selection allows organisms with higher fitness toreproduce more successfully.
Natural selection favors those traits that confer higherfitness in the environment.
Natural selection is a random change in characteristics of apopulation over generations.
Evolution by natural selection affects populations oforganisms, not individual organisms.

An organism's fitness depends on its _____.

ability to survive and reproduce
ability to swap genetic material with other organisms
physical size
ability to mutate
population

Consider the heavily armored stickleback fish population thatcolonized the lake. If all the individuals in that population weregenetically identical, what do you predict would happen when theycolonized the freshwater lake?

The population would increase, as it has increased foodresources.
The population would evolve through natural selection to bebetter adapted to its environment.
The population would decrease due to more juvenile fish beingeaten.
No answer text provided.

Which of the following are adaptations?

Thicker beaks on finches that allows them to eat large seeds,when large seeds are the most abundant.
Less armor on stickleback fish in freshwater that allows themto grow faster to avoid predation.
More armor on stickleback fish in the ocean that prevents themfrom being eaten by larger predators.
None of the above.
All of the above.

In 1908 Hardy and Weinberg published papers showing that the binomial or multinomial could be applied in genetics to predict the frequencies of genotypes when allele frequencies where known. The formal algebraic proof of this Hardy-Weinberg Equilibrium Law assumes that there is no mutation in the population. This assumption is necessary, because a. organisms reproduce sexually and litter or family sizes vary. b. populations will exhibit random sampling changes in allele frequency. c. populations are not infinite and the Hardy-Weinberg proof is only a very crude approximation when natural selection is acting. d. populations are not closed and reproduce both sexually and asexually so an infinite size population is required to preserve genetic variation. e. allowing alleles to change would alter their frequencies.