SBI3U1 Unit 3: Evolution - Test Review

Key concepts and terms for the Unit 3 Evolution test.

Adaptations and Variations

Traits that enhance survival and reproduction, arising from differences within a population.

Artificial Selection

The process by which humans selectively breed organisms for desired traits.

Natural Selection

The process by which organisms better adapted to their environment tend to survive and reproduce more successfully.

Lamarck's Theory

The idea that organisms can pass on acquired characteristics to their offspring (inheritance of acquired characteristics).

Fossils

Preserved remains or traces of ancient organisms.

Biogeography

The study of the geographic distribution of organisms.

Anatomy

The study of the structure of organisms.

Embryology

The study of the development of embryos.

DNA

The genetic material containing the instructions for the development and functioning of all known living organisms.

Homologous Structures

Structures in different species that have a similar underlying anatomy due to common ancestry.

Analogous Structures

Structures in different species that have similar functions but different underlying anatomies, due to convergent evolution.

Darwin's Theory

Descent with modification through natural selection.

Descent with Modification

The process by which species accumulate differences from their ancestors as they adapt to different environments over time.

Radiometric Dating

A method used to date rocks and other materials by measuring the decay of radioactive isotopes.

Stabilizing Selection

Natural selection that favors intermediate variants by acting against extreme phenotypes.

Directional Selection

Natural selection that favors one extreme phenotype over the other.

Disruptive Selection

Natural selection that favors both extreme phenotypes over intermediate phenotypes.

Genetic Drift

Random changes in allele frequencies in a population.

Founder Effect

Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population.

Bottleneck Effect

Genetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population.

Speciation

The process by which new species arise.

Pre-zygotic Isolating Mechanisms

Reproductive isolation that occurs before the formation of a zygote, preventing mating or fertilization.

Post-zygotic Isolating Mechanisms

Reproductive isolation that occurs after the formation of a zygote, resulting in hybrid zygotes that are not viable or fertile.

Sympatric Speciation

The formation of new species in populations that live in the same geographic area.

Allopatric Speciation

The formation of new species in populations that are geographically isolated from one another.

Gradualism

A model of evolution in which species evolve gradually over long periods of time.

Punctuated Equilibrium

A model of evolution in which species evolve rapidly over short periods of time, followed by long periods of stasis.

Adaptive Radiation

The diversification of a group of organisms into forms filling different ecological niches.

Divergent Evolution

The process by which related species evolve different traits due to different environmental pressures.

Convergent Evolution

The process by which unrelated species evolve similar traits due to similar environmental pressures.

Coevolution

The process by which two species evolve in response to each other.

Cladogram

A branching diagram showing the cladistic relationships between a number of species.

Derived Trait

A trait that is present in a group of organisms but not in their common ancestor.

Synapomorphy

A shared derived trait that is used to define a clade.

Variations

Differences in traits among individuals of a population.

Mutations

Changes in the DNA sequence that can be neutral, harmful, or beneficial.

Fossil Record

The totality of fossilized artifacts and their placement within the earth's rock strata.

Vestigial Structures

Structures that have lost their original function in a species.

Transitional Fossils

Fossils that show intermediate stages of evolution between ancestral forms and their descendants.

Immutable

Unchanging over time.

Survival of the Fittest

The principle that individuals with traits best suited to their environment are more likely to survive and reproduce.

Radioisotopes

Unstable isotopes that decay over time, used in radiometric dating.

Half-life

The time it takes for half of the atoms in a radioactive sample to decay.

Macroevolution

Evolution on a large scale, encompassing the evolution of new species and higher taxonomic groups.

Microevolution

Evolution on a small scale, encompassing changes in allele frequencies within a population.