Evolution and Genetics: A Comprehensive Guide

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Gene Pool

The gene pool is the sum of all genetic information carried by all the individuals of a population.


Mutations are the ultimate source of all genetic variation, and are the result of random changes in DNA sequences.

Gene Flow

Gene flow is the movement of genes from one population to another. It occurs when individuals migrate from one population to another, thus bringing their genes with them.

Genetic Drift

Genetic drift is a random process where certain alleles are removed from the population by accidental events. It is more likely to affect small populations than larger ones.

Founder Effect

The Founder Effect occurs when a small group of individuals establishes a new population far from existing populations. Because this group is so small, it creates a genetic bottleneck (populations bottleneck).

Adaptive Radiation

An Adaptive Radiation is when one species rapidly evolves into many descendent species.

Which individual has the greatest fitness?

The individual who has the most offspring and then dies.

How old is the Earth?

4.6 billion years old.

Directional Selection

This occurs when individuals at once extreme of a phenotype range are favored, while other individuals are selected against. Example: Dark moths are favored when the trees are covered in soot.

Disruptive Selection

This occurs when individuals at both extremes of a phenotype range are favored, while individuals with intermediate phenotypes are selected against. Example: Plainfin Midshipmen (fish) have very large and very small males. Large males defend the eggs, while small males sneak in and fertilize the guarded nests.

Artificial Selection

This occurs is when humans select the traits that will allow an individual to reproduce and pass its genes to the next generation. This can lead to very rapid evolution of a population. Example: Many breeds of dogs have evolved through this process.

Sexual Selection

This occurs when members of the opposite sex determine which traits will increase the chance of an individual being able to reproduce. This may decrease an individual’s chance of survival, but this is balanced out by the increased chance of reproduction. Example: a peacock’s large, vibrantly colored tail feathers are favored by peahens… and tigers.

Which of the following kingdoms is made up of mostly single celled organisms some of which are autotrophic, some are heterotrophic, and some are both?


Which of the following kingdoms is made up of multicellular, heterotrophic organisms which have complex sensory structures which allow them to respond rapidly to their environments?


Which of the following kingdoms contains multicellular organisms which use photosynthesis?


Which of the following kingdoms contains multicellular heterotrophs which reproduce using spores?



Change over time

Biological Evolution

Change in the genetic makeup of a population from generation to generation

Evolution applies to everything, while biological evolution only applies to living organisms.


An inheritable change in phenotype which provides an advantage for survival and/or reproduction in a specific environment

Fill in the blanks in the statement below. Homologous structures are adaptations which evolved from the same underlying structure which was inherited from a common ancestor. These structures have evolved different functions to adapt to different environments. Examples of these structures include a whale’s fin, a bat’s wing, and a human hand. Vestigial structures have also evolved from the same underlying structure, but have been reduced and no longer have a function. Examples of these structures include a whale’s kind limbs, and a snake’s legs.


The formation of a new species
speciation occurs when two populations are geographically isolated.
Sympatric  speciation occurs when two populations are not geographically isolated.

List the three ways in which an adaptive radiation can occur. Mass Extinction, Colonization of a new habitat, Evolution of a novel trait which confers a significant competitive advantage.
List the levels of the Linnean hierarchy from the broadest category to the most specific. Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

List the three domains of life. Eukarya, Bacteria, Archaea

Fill in the blanks in the statement below. A autotroph is an organism which can make its own food. A heterotroph is an organism which must consume other organisms to get energy and nutrients

Explain how Darwin’s theory of evolution by natural selection was influenced by two other people. Lamarck- Provided a hypothesis for a mechanism behind evolution in living things. It was wrong, but it was one of the first explanations Lyell- Wrote “Principles of Geology.” Proposed that changes occurring today also occurred in the past. Lyell applied this to the Earth, but Darwin applied it to living things. Wallace- Came up with the idea of natural selection at the same time as Darwin. He pushed Darwin to publish his theory.

Explain how natural selection causes populations to evolve. The environment chooses which traits provide an increased chance of reproduction. These traits are passed down to the next generation, therefore increasing the chance of those individuals reproducing. Eventually, the majority of the population will possess these beneficial traits.

Explain how one of the following provides evidence for evolution: Fossils- Show physical changes in bone structure over time. Fossils from different time periods can be compared to see how groups of organisms have changed. Similar structures can be used to determine ancestry. DNA sequencing- DNA bases act as traits which can change from generation to generation. DNA sequencing can be used to construct phylogenetic trees and determine how organisms are related to eachother. The more similar the DNA from two organisms is, the more closely related they are.Development of an Embryo- In early embryonic stages, all animals look the same. As the embryos develop they begin to look different. The longer two embryos look the same, the more closely related they are.

Use the biological species concept to explain why a horse and a donkey are different species even though they can produce offspring (mules) The biological species concept states that two individuals are the same species if they can reproduce and create viable offspring. A horse and a mule can reproduce, but their offspring the mule is infertile. Therefore the offspring of the pairing is not viable, and the two cannot be considered the same species.

Use the ecological species concept to explain why polar bears and grizzly bears are different species even though they can produce offspring (grolar bears) The ecological species concept states that two organisms are the same species if they share adaptations for the same environments. Grizzly bears and polar bears can both produce viable offspring and are therefore considered the same species by the biological species concept, but they have very different adaptations for very different environments. Polar bears have white fur, thick fat, and long noses for surviving and hunting seals on the polar ice, while grizzlys have brown fur, long claws, and short noses for an omnivorous diet in forested habitats. Because they have different adaptations for different environments they are not considered the same species by the ecological species concept.

Explain why biodiversity is important. High biodiversity is an indicator of a healthy environment. When more species are present in an area, that area is less prone to large losses of species, or changes in the habitat. If one species is eliminated it is much more likely that another species will be able to fill the same role. In a habitat with few species, if one species goes extinct then it is less likely that the vacant role can be filled which can cause drastic changes to the environment and the other species in it.

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