Midterm 1: ch 1-4 Flashcards Preview

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Flashcards in Midterm 1: ch 1-4 Deck (34):
1

adaptations

A feature of an organism created by the process of natural selection.

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natural selection

The process that produces adaptation. Natural selection is based on three postulates: (1) the availability of resources is limited; (2) organisms vary in the ability to survive and reproduce; and (3) traits that influence survival and reproduction are transmitted from parents to offspring.

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morphology

The form and structure of an organism

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fecundity

The biological capacity to reproduce.

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hidden vatiation

Variation in genotypes for the same phenotypes

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genetic drift

Random change in gene frequencies due to sampling variation that occurs in any finite population. Genetic drift is more rapid in small populations than in large populations.

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gene flow

The movement of genes from one population to another, or from one part of a population to another, as the result of interbreeding

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fixation

A state that occurs when all of the individuals in a population are homozygous for the same allele at a particular locus.

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pleiotropy

Occurs when one gene influences two or more seemingly unrelated phenotypic traits

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polygenic trait

One whose phenotype is influenced by more than one gene

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monogenic trait

One whose phenotype is influenced by one gene

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Hardy-Weinberg equilibrium

The unchanging frequency of genotypes that results from sexual reproduction and occurs in the absence of other evolutionary forces such as natural selection, mutation, or genetic drift.

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environmental variation

Phenotypic differences between individuals that exist because those individuals developed in different environments.

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canalized (traits)

Describing traits that are very insensitive to environmental conditions during development, resulting in similar phenotypes in a wide range of environments

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plastic (traits)

Describing traits that are very sensitive to environmental conditions during development, resulting in different phenotypes in different environments

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microevolution

Evolution of populations within a species.

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macroevolution

Evolution of new species, families, and higher taxa.

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biological species concept

The concept that species are defined as a group of organisms that cannot interbreed in nature.

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ecological species concept

The concept that natural selection plays an important role in maintaining the differences between species, and that the absence of interbreeding between two populations is not a necessary condition for defining them as separate species

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allopatric speciation

Speciation that occurs when two or more populations of a single species are geographically isolated from each other and then diverge to form two or more new species.

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sympatric speciation

A hypothesis that speciation can result from selective pressures favoring different phenotypes within a population, without positing geographic isolation as a factor

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adaptive radiation

The process in which a single lineage diversifies into a number of species, each characterized by distinctive adaptations.

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phylogeny

The evolutionary relationships among a group of species, usually diagrammed as a “family tree.”

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taxonomy

A branch of biology that is concerned with the use of phylogenies for naming and classifying organisms.

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analogous (trait)

Similarity between traits that is due to convergent evolution, not common descent.

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homologous (trait)

Similarity between traits that is due to common ancestry, not convergence.

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ancestral trait

A trait that appears earlier in the evolution of a lineage or clade. Ancestral traits are contrasted with derived traits, which appear later in the evolution of a lineage or clade.

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derived trait

A trait that appears later in the evolution of a lineage or clade. Derived traits are contrasted with ancestral traits, which appear earlier in the evolution of a lineage or clade.

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neutral theory

A theory postulating that genetic change is caused only by mutation and drift.

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genus

A taxonomic category below family and above species. There may be several species in a genus, and several genera in a family.

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family

A taxonomic level above genus but below order. A family may contain several genera, and an order may contain several families.

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superfamily

The taxonomic level that lies between infraorder and family. An infraorder may contain several superfamilies, and a superfamily may contain several families

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cladistic taxonomy

A system for classifying organisms in which patterns of descent are the only criteria used.

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evolutionary taxonomy

A system for classifying organisms that uses both patterns of descent and patterns of overall similarity