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27 Cards in this Set
- Front
- Back
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Define clade.
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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
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Define anagenesis.
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Change occurring within a lineage.
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Define a cladogram.
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The pictorial representation of branching sequences that are characterized by particular changes in key morphological or molecular characteristics. (Character states)
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Define homology.
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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.
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Define taxon.
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Any named group of organisms.
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Define monophyletic taxon:
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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.
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Define apomorphy.
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Any derived or specialized character.
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Define plisiomorphy.
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Any ancestral or primitive character.
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Define synapomorphy.
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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.
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Define autamorphy
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A derived character possessed by only one descendant of an ancestor and thus of no use in discerning relationships among other descendants.
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Define node
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A branching point on a cladogram
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Define paraphyletic grouping.
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A group of species sharing an immediate ancestor but not including all descendants of that ancestor.
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Define polyphyletic grouping:
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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.
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Name the seven basic groupings in the classification scheme.
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Kingdom, phylum, class, order, family, genus, species.
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What is the difference between analogous and homologous features?
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Analogous features are those that have come to resemble each other through convergence whereas homologous are those that are evolutionarily linked to each other.
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What types of new evidence would cause scientists to rethink a specie's evolutionary heritage?
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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.
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Why create an evolutionary tree?
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Then one can determine the relationships among the animals.
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What are the two basic ways one determines the basis of evolutionary relationships?
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homology and polarity, or the the direction of evolutionary change.
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Defne planktonic
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Forced to drift or wander.
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Name the three types of worms
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Earthworm, nematode, flatworm.
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Describe the tissue layers of an earthworm.
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Outer ectoderm surrounding a mesoderm. Mesordem fills in space with organs. Peritonmeum surround the fluid-like coelum which encapsulates the gut, lined with endoderm.
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What is another name for earthworm?
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Coelomate because it is a prime example of a worm with coelom.
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Describe the internal tissue structure of a nematode.
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internal gut surrounded by endoderm. This is encompassed by pseudocoel and enclosed by a thin layer of mesoderm and ectoderm.
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What is another name for a nemotode?
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Pseudocoelomate because of its pseudocoelom.
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Describe the internal tissue structure of a flatworm.
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a gut surrounded by endoderm, a thicker layer of mesoderm, then ectoderm.
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What is another name for a flatworm?
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Acoelomate because it lacks coelem.
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What are the two different types of cellular cleavage?
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Sprial and radial.
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