Glossary of Terms


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z #

Select the first letter of the word from the list above to jump to appropriate section of the glossary. If the term you are looking for starts with a digit or symbol, choose the '#' link.


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Adaptation
Change in form or function of a species to allow it to survive as environment changes (extinction without ability to adapt)

analogous structures
structures with a similar function,  that evolved independently.  Not present in the common ancestor.  E.g., wings of birds and bats are analagous.  They arose as a result of convergent evolution.

asymmetry
no central axis or point--found in most protists and many sponges [fig 16.7]
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bilateral symmetry [fig. 16.9]
a single plane of symmetry.  only the sagittal plane divides the body into mirror (right and left) halves

Binomial nomenclature
Species of animals are assigned unique scientific names.  A species name always consists of two parts:  the Genus and specific epithet.   The genus name is always first and capitalized.  The specific epithet is second and not capitalized.   Following Linnaeus, who used Latin for species names, the genus and/or species name is italicized or underlined.  More from xrefer

biogeography
the scientific study of the distribution of plants and animals

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- C -

Cellular Respiration
Transformation of sugar molecules to CO2 and H2O and ATP.  Occurs in the mitochondria of eucaryotes.

character
recognizable attribute; anything that has a genetic basis that can be measured.

clade
monophyletic group defined by one or more synapomorphies

cladistics
Phylogenetic Systematics: common descent is the only criterion used in classifying organisms; system developed by Willi Hennig

Classification
ordering organisms into groups. More from xrefer

control
The part of a scientific experiment to which the experimental variable is not applied, but which is similar to the experimental group in all other respects.   Controls are repetitions of the experiment that lack the disturbance (but are subjected to the same procedures).

control group
In scientific experiments, there are experimental and control groups.  In the control group all variables are held constant.  The control group is subjected to the same actions or procedures as the experimental group except that the independent variable being tested is omitted.  This is done in order to determine whether any effects of the experimental treatment are due to that treatment and not to the actions involved in providing the treatment.

controlled experiment
controlled situation- Directly overseeing all element of an experiment (usually in a lab environment)

convergent evolution
similar features that evolved independently from different ancestors, usually as a result of adapting to a similar environment.

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Evolutionary Taxonomy
classification using common descent and morphological distance; shared structural and functional characters are used to define taxa (e.g. Class Reptilia)

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fossil
any evidence of past life.  includes shells, skeletons, tracks, trails, and biochemicals.

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Homeostasis
Maintenance of internal conditions within the body within certain boundaries (eg, blood, water, and temperature)

homologous:
A homologous character state is inherited from common ancestor (e.g. ostrich and robin wings; bones in [analogous] bird, bat, & pterosaur wing).  Homology is determined by position relative to other structures; development (embryological tissue, pattern of ontogeny) & evolution

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- M -

Metabolism
All chemical and energy transformations that occur in cells as repair and growth occur

monophyletic
entire phylogeny; latest common ancestor plus all and only all its descendants [fig 16.3]

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Numerical Taxonomy
measures overall similarity of taxa; relationships are displayed using phenograms; similarities may be the result of convergence, not homology.

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paleontology
the study of ancient life, based largely on fossils

paraphyletic
The most recent common ancestor of all members of the group, but not all descendents.   One or more descendent groups have been excluded; can not be defined strictly by synapomorphies; includes only part of phylogeny; e.g. Class Reptilia.

Photosynthesis
Transformation of CO2 and H2O to sugar molecules 
Solar Energy - Ultimate source of energy for all life on earth

polyphyletic
descendants of unrelated ancestors; convergent evolution; does NOT contain the most recent common ancestor of all members of the group: Requires at least two separate origins

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- R -

radial symmetry
body divided into mirror halves by more than two planes; usually sessile, freely floating, or weakly swimming organisms; includes cnidaria [fig. 16.8], ctenophores, secondarily in some echinoderms.

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synapomorphy
shared derived character states: reflect common ancestry; e.g. amnion, feathers

systematics
scientific study of the kinds and diversity of organisms and of any and all relationships among them

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taxonomy
the theoretical study of classification; rules, etc.  More from xrefer
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vestigial structures
remnants of once useful structures--e.g., hindlimb in boas or whales; human appendix

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Revised: August 18, 2001.
Copyright 1995 by [SomeOrganization].
All trademarks or product names mentioned herein are the property of their respective owners.