Zoology - Chapter 4, 5, & 7 review

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Organic Evolution


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Environmental Science


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92 Terms

Organic Evolution

Population change overtime.

Natural Selection

Theoretical process by which gene variation and the environment lead to significant changes in a population because individuals with gene variations more suited to the environment survive longer and reproduce more.

Theory of Inheritance

the theory that organisms develop new traits as needs arise and pass these acquired traits down to their offspring (wrong) (Lamarck)

Adaptive radiation

the formation of a new species from an ancestral species caused by the availability of a new habitat.


occurs when an inheritable phenotype increases the likelihood of an animal to survive and successfully reproduce.


a measure of the capacity for successful reproduction in a given environment compared to other of the same species.


a change in the frequency of alleles in population over time.


Large-scale changes that result in an extinction or formation of a new species


the study of the geographic distribution of plants and animals.


the study of the fossil record.


evidence of plants and animals from the past that has become a part of the earth's crust.

Convergent Evolution

When unrelated species have similar adaptations (Analogous)

Analogous Structures

Similar structures due to convergent evolution.

Homologous Structures

Similar structures due to shared ancestry.

Comparative Anatomy

The study of structural similarities in living or fossilized animals and homologies that show evolutionary relationships.

Homeotic Genes

Determine identity of body regions in early embryos.


refers to evolutionary relationships among species.

Phylogenic Tree

shows lines of descent from an ancestral species to modern descendants.


represent individuals, populations or species.


represent evolutionary connection between nodes.


groups of individuals of the same species that occupy a given area at the same time and share a common gene pool.

Gene pool

the sum of all the alleles for all traits in a sexually reproducing population.

Population Genetics

the study of the genetic events in gene pools.

Hardy-Wienberg Theorem

States that mixing of alleles in meiosis and their recombination don't alter allele frequencies across generations, given several factors.

  • large population

  • Random sexual reproduction

  • no migration

  • no mutation

  • no natural selection

Genetic Drift

Chance events effecting gene frequencies in a population (Neutral evolution)

Founder Effect

a type of genetic drift caused by the separtation of a few individuals from a bigger population, creating their own population. They do not carry the same gene frequencies as the larger population so this new population will likely have less genetic variation.

Bottleneck Effect

A form of genetic drift that takes place when an event dramatically decreases the size of a population resulting in decreased genetic variation even as populations regrow.

Gene Flow

Changes in gene frequency caused by immigration or emigration of individuals.

Mutation Pressure

a measure of the tendency of gene frequencies to change through mutation.

Selection Pressure

the tendency for natural selection to occur

Directional selection

occurs when individuals with one phenotypic extreme are at a disadvantage compared to all others causing a decrease in that extreme.

Disruptive Selection

Occurs when both phenotypic extremes are at an advantage to those with the intermediate phenotype.

Stabilizing Selection

Occurs when both phenotypic extremes are at a disadvantage and leads to a decrease in phenotypic range.

Balanced Polymorphism

occurs when different phenotypes are maintained at relatively stable frequencies.


a group of populations in which genes are actually or potentially exchanged through interbreeding.


The formation of a new species.

Reproductive isolation

when populations cannot reproduce with one another

Premating isolation

prevents mating altogether, via impenetrable barrier or changes in courtship behavior.

Postmating Isolation

prevents successful fertilization.

Allopatric Speciation

Occurs when subpopulations become geographically isolated.


Small local populations, not isolated.

Parapatric Speciation

relative isolation of a deme can make its members experience different selection pressures that can ultimately result in speciation. (No certain cases)

Sympatric Speciation

Occurs within one population when individuals become reproductively isolated.

Phyletic gradualism

evolution occurs gradually over millions of years.

punctuated equilibrium

long periods of stasis interrupted by brief periods of change.

Mosaic Evolution

occurrence within a population of different rates of evolution in various structures or functions.


study of evolutionary relationships among and diversity of organisms. (Taxonomy)


Assignment of distinctive names to each species.


any grouping of animals that share a particular set of characteristics.