Log in
HomeStudy Guides420,000CA160,000

BIOL 2050 Study Guide - Midterm Guide: Genetic Drift, Natural Selection, Genotype

63 views11 pages
tanturtle350
14 Jul 2015
School
York University
Department
Biology
Course
BIOL 2050
Professor
lorti

For unlimited access to Study Guides, a Grade+ subscription is required.

Document Summary

The theory of evolution by natural selection is a process that results in the evolution of organisms over time. Organisms possessing certain heritable characteristics that make them better suited to an environment tend to survive, reproduce and increase in number. Consequently, they are able to pass on their necessary genotypic (genetic) qualities to later generations. Natural selection, along with gene flow, genetic drift and mutations are the major mechanisms of change which drive evolution. Although natural selection often decides which organisms survive and procreate, the real number of individuals that remain to pass on their favoured traits are usually determined by several external factors. Decreased availability of food, loss of habitat, exposure to diseases, changes in weather patterns and increased contact with predators are some of the many selective pressures which influence the process of natural selection in a species.

Get access

Grade+
$40 USD/m
Billed monthly
Grade+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
10 Verified Answers

Related Documents

BIOL 2050 Chapter Notes - Chapter 6: Frequency-Dependent Selection, Trophy Hunting, Allele Frequency
sapphirehound938
BIOL 2050 Lecture Notes - Lecture 7: Genetic Drift, Adaptive Radiation, Overfishing
graywolf909
BIOL 2050 Lecture Notes - Lecture 8: Genetic Drift, Overfishing, Gene Flow
graywolf909

Related Questions

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.

Question 5

Which of the following is FALSE:

Natural selection has foresight, and can mold organisms in accordance with environments in the far future. This is why organisms have a good "fit" to their environments long after they have arisen through speciation.
Selection is an undirected process that can only ever work with the materials at hand.
Human beings have foresight because they possess brains that can think about possible outcomes and the consequences of actions. This is different to a process like natural selection.
The fact that natural selection has no foresight does not mean that it is incapable of producing beings that have foresight.

Question 6

The wings of bats, birds and flying insects are examples of:

Convergently evolved traits (at least in terms of their basic functionality).
Homologous traits.
Plesiomorphies.
None of the above.

Question 7

The effect of a trait depends on the environment because:

Organisms decide to change their behavior every so often to evade predators.
It is only ever in the context of an environment that these traits can exist, and whether they assist the organism or inhibit it will depend on the particularities of that environment in which it must interact.
Sexual selection will not tolerate wasteful and extravagant displays.
The environment is changing too fast for the organism to keep up with in terms of its conscious appreciation of it, so it must rely on its traits to do the work.

Question 8

Which of the following is TRUE:

Natural selection is not random; mutation is random; speciation is necessarily driven by natural selection.
Natural selection is not random; mutation is random; speciation is not necessarily driven by natural selection.
Natural selection is random; drift is random; speciation is not necessarily driven by natural selection.
Natural selection is not random; mutation is random; speciation must occur through the evolution of pre-zygotic barriers to mating.

Question 9

Heritability is:

The same as inheritance.
Another way of stating the degree to which a trait is genetic (for example, you could say that the color of your skin is "80 percent genetic and 20 percent environmental")
The proportion of variance of a trait in a population that is attributable to genetic variance in that population.
Present in populations, but not necessary for evolution by natural selection.

An adaptation or adaptive trait is a trait/characteristic that has evolved in a population of organisms which provides a functional advantage. Adaptations increase the biological fitness of a population. Fitness is defined as the ability to survive and pass genes on to subsequent generations. For the purposes of this assignment, you are to choose an adaptive trait common to more than one species. For example, birds and bats both have wings. Write a 2-3 page (500 – 750 words, 12 point font) paper including the following elements. Be sure to compose your work with your own words. Do not copy and paste from any source. Describe what makes this trait an adaptation. Briefly describe how the trait evolved; e.g., mutation, genetic drift, migration and/or natural selection. Be sure to support your answer with evidence. What is the difference between homologous and analogous traits? How does your trait of choice fit either of these descriptions? What is convergent and divergent evolution? Describe whether the trait is a result of convergent or divergent evolution. Use in-text citation and provide source references for at least 3 sources. The textbook can be one source. When citing articles or other types of documents, follow standard guidelines as introduced on "Citing references in scientific research papers".