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27 Cards in this Set

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  • Back
Define clade.
A group of organisms that includes the most recent common ancestor of all its members and all descendants of that ancestor; every valid clade forms a "monophyletic" group
Define anagenesis.
Change occurring within a lineage.
Define a cladogram.
The pictorial representation of branching sequences that are characterized by particular changes in key morphological or molecular characteristics. (Character states)
Define homology.
Characters that have the same evolutionary origin from a common ancestor, often coded for by the same genes. Homology is the basis for all decision about evolutionary relationships among species.
Define taxon.
Any named group of organisms.
Define monophyletic taxon:
A group of species that evolved from a single ancestor that includes all descendants of that ancestor. Every valid clade must form a monophyletic taxon.
Define apomorphy.
Any derived or specialized character.
Define plisiomorphy.
Any ancestral or primitive character.
Define synapomorphy.
a derived character that is shared by the most recent common ancestor and by 2 or more descendants of that ancestor. In cldistic methodology, synapomorphies define clades; that is, they determine which species are most closely related to each other. Essentially, they are homologous characters that define clades.
Define autamorphy
A derived character possessed by only one descendant of an ancestor and thus of no use in discerning relationships among other descendants.
Define node
A branching point on a cladogram
Define paraphyletic grouping.
A group of species sharing an immediate ancestor but not including all descendants of that ancestor.
Define polyphyletic grouping:
An incorrect grouping containing species that descended from 2 or more different ancestors. Members do not all share the same immediate ancestor, but may resemble each other.
Name the seven basic groupings in the classification scheme.
Kingdom, phylum, class, order, family, genus, species.
What is the difference between analogous and homologous features?
Analogous features are those that have come to resemble each other through convergence whereas homologous are those that are evolutionarily linked to each other.
What types of new evidence would cause scientists to rethink a specie's evolutionary heritage?
New evidence on the early development of a species, new DNA data, discovering characteristics not shared with any existing groups, aquiring new information in general.
Why create an evolutionary tree?
Then one can determine the relationships among the animals.
What are the two basic ways one determines the basis of evolutionary relationships?
homology and polarity, or the the direction of evolutionary change.
Defne planktonic
Forced to drift or wander.
Name the three types of worms
Earthworm, nematode, flatworm.
Describe the tissue layers of an earthworm.
Outer ectoderm surrounding a mesoderm. Mesordem fills in space with organs. Peritonmeum surround the fluid-like coelum which encapsulates the gut, lined with endoderm.
What is another name for earthworm?
Coelomate because it is a prime example of a worm with coelom.
Describe the internal tissue structure of a nematode.
internal gut surrounded by endoderm. This is encompassed by pseudocoel and enclosed by a thin layer of mesoderm and ectoderm.
What is another name for a nemotode?
Pseudocoelomate because of its pseudocoelom.
Describe the internal tissue structure of a flatworm.
a gut surrounded by endoderm, a thicker layer of mesoderm, then ectoderm.
What is another name for a flatworm?
Acoelomate because it lacks coelem.
What are the two different types of cellular cleavage?
Sprial and radial.