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The formation of a new species.

Macroevolution

The gradual change in allele frequency within a population.

Microevolution

When characteristics of a population change because individuals with certain inherited traits survive specific local environmental conditions and pass down those traits to their offspring.

Natural selection

When a mutation enables an organism to survive in its environment better. Mutations that were once a disadvantage could become an advantage. A trait that is beneficial in one environment may be harmful in another.

Selective advantage

Any factor in the environment that influences the survival and reproduction of individuals with certain traits, leading to changes in the frequency of those traits within a population over time.

Selective pressure

Used to produce a particular plant or animal variety that expresses a desirable trait. For example, breeding dogs, horses… (it may select for unhealthy traits as well as desirable ones).

Artificial selection

A variation in a population that can cause natural selection. If the trait is beneficial, it is more likely to be passed on to the next generation and over time create a population where the common trait is the original mutation.

Mutation

A visible or invisible difference among some members of a population. It can be an advantage, a disadvantage, or have no effect on an individual. These variations occur through sexual reproduction, crossing over, or through mutations. A variation can become an adaptation if it is advantageous to the organism, becoming more common within a population and eventually becoming an adaptation.

Variation

Believed life existed in a perfect and unchanged form.

Plato and Aristotle

Noted similarities between humans and apes, speculated about a common ancestor. Suggested that the Earth was older than 6000 years old.

LeClerc

Discovered remains of a prehistoric fish that did not live during her time. Her discoveries led people to question if all forms of life came into existence at the same time.

Mary Anning

Considered the father of paleontology. Discovered that each layer of rock is characterized by a unique group of fossil species. He believed in CATASTROPHISM, the idea that catastrophic events were violent enough to have killed numerous species each time they occurred.

Cuvier

UNIFORMITARIANISM, states that geological processes operate at the same rate today as they always did. Suggested that the Earth was millions of years old. Slow, subtle processes could happen over a long period of time and result in substantial changes.

Charles Lyell

Believed in the inheritance of acquired characteristics. (not true)

Lamark

Developed the theory of evolution by natural selection.

Darwin

Independently reached conclusions similar to Darwin’s.

Russel Wallace

Supply and demand in population.

Malthus

Indicate the approximate age of the rock in which they are found.

Index fossils

Uses measurements of certain radioactive isotopes to calculate the absolute age in years of rocks and minerals.

Radiometric dating

Show intermediary links between groups of organisms.

Transitional fossils

The study of past and present geographical distribution of different types of organisms.

Biogeography

Same origin, different function.

Homologous structures

Different origin, same function.

Analogous structures

Were functional in ancestors but have no current function.

Vestigial structures

Embryos of different groups of organisms show similar stages of embryonic development.

Comparative embryology

How closely species are related by comparing sequences in amino acids, RNA, DNA, or chromosomes as a whole.

Molecular Biology

Geographical elements that physically prevent interbreeding and result in speciation because they keep populations physically separated.

Geographic barriers

Keep populations reproductively isolated.

Biological barriers

Behavioral isolation

Prezygotic barriers

Temporal isolation

Prezygotic barriers

Mechanical isolation

Prezygotic barriers

Habitat isolation

Prezygotic barriers

Gametic isolation

Prezygotic barriers

Genetic incompatibility of interbred species. Stops development of hybrid zygote during development.

Hybrid inviability

Can mate and produce hybrid offspring, offspring are sterile.

Hybrid sterility

First-generation hybrids mate and offspring are either sterile or weak.

Hybrid breakdown

A new species results from accumulated changes within a population over time. The old species is gradually replaced.

Transformation

One or more species arise from a parent species that continues to exist. The diversification of a common ancestral species into a variety of species that are differently adapted is called adaptive radiation.

Divergence

When the evolution of one species depends on the evolution of the other.

Co-evolution

A process where two or more related species become more dissimilar over time as they adapt to different environmental conditions or ecological niches.

Divergent evolution

When unrelated species independently evolve similar traits due to similar environmental pressures.

Convergent evolution

Evolution happens at a slow and steady pace with the accumulation of small gradual changes that result in large changes.

Gradualism

Long periods of stasis interrupted by periods of rapid change.

Punctuated equilibrium

The transfer of genetic material, such as alleles or genes, between populations of the same species through interbreeding or migration.

Gene flow

An inheritable mutation can affect the entire gene pool. The more genetic variation, the greater the chance a variation will provide a selective advantage in changing the environment.

Mutations

Unable to predict which males will mate with which females. Preferred phenotypes. Inbreeding: closely related individuals breed together.

Non-random mating

Change in allele frequencies in small breeding populations due to chance events. Founder effect: a few individuals start a new isolated population. Not much diversity. Bottleneck effect: quick reductions in populations lead the gene pool to lose diversity.

Genetic drift

Favors genotype on one extreme over the other.

Directional selection

Favors intermediate phenotype.

Stabilizing selection

Favors extremes of a range of phenotypes.

Disruptive selection