Basic Biology

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EVOLUTION

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Genetic change in a Population or species over generations

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Mimic

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to imitate or copy

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fossil record

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ordered sequence of fossils as they appear in the rock layers, marking the passing of geologic time

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Biogeography

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the geographic distribution of species

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Comparative anatomy

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comparison of body structures between different species

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Homology

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similarity due to a common ancestor

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Comparative embryology

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comparison of anatomical structures that appear during early stages of development
Similar stages indicate relatedness

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Natural selection

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Individuals with traits best suited to the local environment generally leave a larger share of surviving, fertile offspring

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Population

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a group of individuals of the same species living in the same place at the same time
smallest biological unit that can evolve

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Microevolution

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Evolutionary changes in a population’s genetic makeup from generation to generation

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Genetic drift

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A change in the gene pool of a small population due to chance

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Bottleneck effect

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– drastic reduction in population size
E.g. earthquake, flood, fire, etc.
Reduces genetic diversity

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Founder effect

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random change in the gene pool that occurs in a small colony of a population
May result in high frequency of inherited disorders

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Gene flow

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Gain or loss of alleles from a population by the movement of individuals or gametes into or out of the population

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Mutation

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changes in an organism’s DNA
Relatively rare
original source of genetic variation

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Fitness

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the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals.

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Directional selection

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shifts the overall makeup of the population by favoring variants of one extreme

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Disruptive selection

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favors variants of opposite extremes over intermediate individuals.

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Stabilizing selection

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calls extremes variants from the population.

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Macroevolution

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evolutionary change on a ground scale

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Speciation

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origin of new species

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Species

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population or group of populations whose members have the potential to interbreed with one another in nature to produce fertile offspring

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Prezygotic

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(before zygote formation)
Prevent mating or fertilization between species

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Postzygotic

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(after zygote formation)
Mechanisms that operate should interspecies mating actually occur (hybrid zygote)

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Allopatric speciation

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speciation – formation of new species as a result of an ancestral population’s becoming isolated by a ______________ barrier

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Sympatric speciation

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speciation – formation of new species ____________ a geographic barrier

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Exaptation

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a structure that has evolved in one environmental context and later becomes adapted for a different function in a different environmental context

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Taxonomy

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the identification, naming, and classification of species

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Systematics

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the study of the diversity and relationships of past and present organisms

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Ambiguous

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Common names

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Phylogeny

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evolutionary history of a species.

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Biogenesis

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life-from-life”
Life arises by the reproduction of preexisting life

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Pathogen

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something that causes disease or illness

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Exotoxin

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poisonous proteins secreted by bacterial cells

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Plant

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an autotrophic (producer), multicellular eukaryote that makes organic molecules via

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Terrestrial

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(land-dwelling

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Mycorrhizae

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root-fungus; helps plant absorb water & minerals

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Symbiotic

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relationship [direct contact]

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Lignin

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– a chemical that hardens cell walls

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Xylem

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dead cells; allow for transport water & nutrients

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Phloem

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live cells; distribute sugars from leaves to other parts of the plant

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Mechanisms of microevolution

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Natural selection
Genetic drift
Gene flow
Mutation

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Spore

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haploid cell that develops into multicellular organism without fusing with another cell

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pollen

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Plant sperm

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fruit

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ripened, thickened ovary of a flower, containing seed(s)

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seed

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plant embryopackaged with food supply within protective coating

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fungus

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a heterotrophic (consumer) eukaryote that digests food externally and absorbs the resulting small nutrient molecules

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mycelium

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feeding network made up of hyphae

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hyphae

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threads of cytoplasm surrounded by plasma membrane and cell wall

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animal

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a eukaryotic, multicellular, heterotrophic organism that obtains nutrients by ingestion (eating) and digests its food within its body.

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invertebrate

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animals without backbones

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vertebrate

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animals with backbones