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62 Cards in this Set

  • Front
  • Back


- Genetic change in a population of organisms over time (generations)

- Darwin proposed that natural selection was the mechanism of evolution


Any peculiarity of structure, physiology or behavior that promotes the likelihood of an organism's survival and reproduction in a particular environment


- Enters a population through mutation

- Without variation, a population cannot evolve

- Selection, artificial or natural, can only work on variation that exists in a population


- The preserved remains, tracks, or traces of once-living organisms

- Created when organisms become buried in sediment

- Most fossils are skeletons

- Contains the most direct evidence of evolution

Sedimentary Rock

- Organisms are fossilized when they are buried in sediment

- We don't have fossil remains of many organisms because they were never buried in sediment

Molecular Clock

A mechanism for determining the relatedness of organisms by comparing the number of differences in crucial organic molecules


- A backbone made of bony segments called vertebrate (found in animals)

- All vertebrate embryos, including humans, have pharyngeal pouches (these develop into gill slits in fish) and a rudimentary tail (in humans all that remains of this tail is the coccyx

- Similar bone structure is seen in different species of vertebrates


- Formed by the division of the fertilized egg

- All vertebrates have similar embryos, indicating that the instructions for early development are critical and have not evolved major differences

Homologous Structure

- A human arm and a bat wing are “homologous

- Have different functions but similar structures as a result of descending from a common ancestor

- Homology due to descent from a common ancestor is the result of “divergent” evolution

Analogous Structure

- Similar structures due to parallel evolution

- When organisms evolve in the same environment, they may evolve structures that have similar functions

Vestigial Organ

- Organs that are genetically determined, but have lost much of their ancestral function in a given species, but have nonetheless retained those processes through evolution

- Examples include the human appendix and the pelvis of a whale

Convergent Evolution

- Parallel evolutionary adaptations to similar environments

- Results in analogous structures


- A permanent change in the dna of an organism

- Occurs in DNA

- Will lead to alterations in a protein


The movements of individuals or alleles into or out of a population

Allele Frequency

Refers to how many people in a population carry a particular allele

Genetic Drift

- Random loss of alleles which can cause drastic changes in a small population

- If only a few members of the population carry certain alleles, and they die or are lost or fail to reproduce, then these alleles are lost from the population

Founder Effect

Occurs when a few individuals leave one population and become the foundation of a new population

Nonrandom Mating

- Individuals mate with each other preferentially in a nonrandom way

- Occurs in populations where, either by choice or geographic isolation, there is little mating outside the population

- Can cause an unusually high allele frequency for specific alleles in a population

Natural Selection

A natural process whereby the conditions in the environment determine which organisms survive and reproduce

Artificial Selection

Intentional selection of breeding partners based on desired characteristics


A group of organisms that can breed successfully in nature and produce fertile offspring


- Consists of all the organisms in an area that are of the same species

- In a population, more individuals are produced than can survive

- Members of a population compete for limited resources

Isolating Mechanism

- Make it difficult/impossible for organisms of same species to breed

- Over time (with unique processes of natural selection occurring in different groups) this leads to speciation


- Involves successive change: first, local populations become increasingly specialized

- If they become different enough, natural selection may act to keep them that way

Reproductive Isolation

- Populations whose members do not mate with each other or who cannot produce fertile offspring

- Belong to different species

Prezygotic Isolating Mechanism

Mechanisms that prevent the formation of a zygote (fertilized egg)

Geographic Isolation

Members of a species are physically separated and cannot breed

Ecological Isolation

Members of a species in an area are localized to a particular part of the habitat, and so do not breed

Behavioral Isolation

Courtship and mating rituals may differ and prevent breeding

Temporal Isolation

Different breeding seasons prevent breeding

Mechanical Isolation

Structural differences between organisms prevent them from breeding

Sickle-Cell Anemia

- Hereditary disease

- The sickle cell allele causes abnormal red blood cells

- Homozygous for the sickle cell allele – usually die

- Heterozygous – make enough normal red blood cells (normal hemoglobin) to function

- Very common in parts of Africa

Stabilizing Selection

Selects the heterozygote advantage (heterozygotes are resistant to malaria)

Disruptive Selection

- Acts to eliminate the intermediate phenotype

- The intermediate phenotype is less able to survive

Directional Selection

- Acts to eliminate one extreme

- Genes for this extreme become less available... phenotypic range shifts

What type of evolution is a MAJOR EPISODE OF EXTINCTION?


What type of evolution is THE APPEARANCE OF A NEW SPECIES?




What is a trait that gives an organism a survival advantage over other organisms?


How do most adaptations arise?

As random, spontaneous mutations

How does the theory of punctuated equilibrium differ from the theory of gradualism when considering the pace of evolution?

Punctuated equilibrium proposes that evolutionary events occur in spurts, while gradualism proposes that evolution is a gradual, ongoing process

Which theory includes the idea that there may be long periods of time without evolution?

Punctuated equilibrium

What are the preserved remains of dead organisms called?


Fossils are created when an organism becomes buried in .....


Which layer of rock is the oldest in sedimentary rock?

The bottom layer

How does sedimentary rock allow the dating of fossils?

Determines the age of the rock

What is a molecular clock?

A mechanism for determining the relatedness of organisms by comparing the number of differences in crucial organic molecules

In a molecular clock, will organisms that are closely related have A FEW or MANY AMINO ACID DIFFERENCES in their proteins?


Did organisms that are closely related diverge RECENTLY or DISTANTLY?


What types of structures are similar in structure but not in function?


What types of structures are similar in function but not in structure?


What types of structures are a result of covergent evolution?


What term describes organs that are remnants of a useful organ in a previous ancestor?


The wing of a bat and the arm of a human are ______________.


The flippers of penguins and dolphins are ______________.


The human appendix is an example of a ____________________.

Vestigial organ

What is the definition of a mutation? Does a mutation occur in DNA or in proteins?

A permanent change in the DNA of an organism; a mutation occurs in DNA, but will lead to alterations in a protein

List 4 mechanisms that can cause a change in the allele frequency of a population

- Migration

- Genetic drift

- Nonrandom mating

- Selection

The movement of individuals into or out of a population is called _____________


List and describe two types of genetic drift

- Founder effect occurs when a few individuals leave a population and become the foundation for a new population

- Bottleneck effect occurs when many individuals in a population die and a few individuals survive to form the basis of the next generation

The amish community marries preferentially within their own community, limiting their gene pool and increasing the allele frequencies of several negative traits. This behavior is called ________________

Nonrandom mating

How does artificial selection differ from natural selection? Which type of selection has had the greatest influence on evolution?

- Artificial selection occurs when organisms are intentionally chosen for breeding because of their traits; in natural selection organisms with advantageous traits are not chosen, but have a better chance to survive and therefore to reproduce.

- Natural selection