Biology-Evolution

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Comparative anatomy

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The study of similar morphological features across different species.

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Creationism

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The theory of the origin of life, which states that all life was created in its current form by God in a mass creation event that took place about 6000 years ago.

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Inheritance of acquired traits (Lamarckian Inheritance)

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The passing on of traits acquired during a parent's lifetime to offspring (EX: Giraffe Necks)

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Lamarckism

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The theory of evolution stating that species change over time and that this change occurs through USE AND DISUSE and the inheritance of acquired traits.

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Use and disuse

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The Lamarckian evolutionary idea that if an animal often used a particular trait or characteristic, that trait or characteristic would become more pronounced. Alternately, if a trait went unused, it would become less pronounced.

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Common Descent

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The belief that all present life evolved from a few common ancestors.

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Gradualism

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The Darwinian belief that evolution takes place in innumerable small steps. Led Darwin to believe that the world was much older than previously thought.

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Darwinism

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The theory of evolution proposed by Charles Darwin. It holds that species change over time and that this change comes about through the mechanism of natural selection.

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Natural Selection

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The theory holding that competition exists within species, determining which species live to have offspring, and pass their traits on to those offspring.

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Population Speciation

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The Darwinian belief that there are random phenotypic variations within species that confer advantages selected for by natural selection; these variations can be passed from parent to offspring.

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Analogous trait

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A trait that is morphologically and functionally similar to another, but which arose from a different ancestral condition. Compare with homologous traits

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Area cladogram

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A tree diagram showing the evolutionary relationships between species and the geographical areas in which they are found.

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Fossil record

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The grouping of fossilized remains according to relative and absolute age.

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Homologous traits

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Traits found in different species that are morphologically and functionally similar and that arose from the same ancestral condition. Compare with analogous traits.

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Molecular clocks

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A molecular clock is a molecule that has remained functionally unchanged for a long period of time and that has a constant rate of accumulation of neutral substitutions. See hypothesis of neutral evolution.

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Species richness

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The number of different species that inhabit an area.

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Trace fossils

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Fossilized imprints of objects. For example, fossilized footprints are trace fossils.

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Artificial selection

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Selection by humans for desired traits. Also called domestication or breeding.

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Choice

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sexual selection, the competition for attention from the opposite sex.

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Directional Selection

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When selection pressures favor one extreme of the trait distribution.

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Disruptive Selection

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When the average form of the trait is selected against while either extreme is unaffected.

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Fitness

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The probability that an individual will contribute its genes to the next generation.

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Morphs

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The different physical forms a trait may have. Long necks and short necks are examples of morphs.

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Natural Selection

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The theory holding that competition exists within species, determining which species live to have offspring, and pass their traits on to those offspring.

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Polymorphic

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A trait that exists in several different morphs is polymorphic

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Stabilizing Selection

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When selection pressures favor the average form of the trait.

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Sexual Selection

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The selection of traits based on their role in courtship and mating.

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Gene flow

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The movement of genes through a population or between populations through mating.

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Analogous structures

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A trait that is morphologically and functionally similar to another, but which arose from a different ancestral condition.

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Coevolution

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Evolution that results from the relationships between animals. For example, one animal might prey on another, meaning that only the fastest of the second animal survive, creating a selection pressure. As the second animal gets extremely fast, only the fastest of the first predatory animal can catch enough food to survive, creating selection pressure on the predator to become faster.

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Coevolutionary arms race

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The back-and-forth evolution of defense and offense between predator or parasite and prey that often a can often result in a rapid burst of evolutionary change in both species.

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Convergent evolution

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Pattern of evolution in which two unrelated species gradually become similar to each other through adaptation to a common environment, often resulting in analogous structures. Compare with divergent evolution and parallel evolution.

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Divergent evolution

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Pattern of evolution in which two closely related species gradually become more and more dissimilar. Compare with convergent evolution and parallel evolution.

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Parallel evolution

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Pattern of evolution in which two species maintain the same degree of similarity while each undergoes change along an independent path. Compare with convergent evolution and divergent evolution.

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Species

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The most specific categorization for organisms. The term "species" refers to a group of organisms that shares the same gene pool and can successfully mate. A bulldog and a greyhound are of the same species because they can produce young. A cat and a bulldog, which experience reproductive isolation from each other and therefore cannot produce young, are separate species.