BIO240 Lecture Terms Essay

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Taxonomy: identification & classification of organisms following the rules of nomenclature
Phylogeny: study of evolutionary history of a (group of) species
Systematics: study of phylogeny (study of biodiversity in evolutionary context)
Binomial: each species has a two-part name
Genus (genera): first part of the name within the name of a species
Specific epithet: second part of the name within the name of a species
Taxon (taxa): taxonomic unit at any level

Microevolution: reflected in character state changes; change in gene frequency within a population due to mutation, selection (natural & artificial), gene flow, and genetic drift of an allele within a population from gen. to gen.
Macroevolution: origin of new taxonomic groups (new species, etc.); evolution on a scale of separated gene pools; change that occurs at or above the level of species

Classify species into higher taxa based on overall similarity. Overall similarity must be based on homologous characters not analogous characters

Homology: similarity in characters resulting from common ancestry
Analogy: similarity in characters resulting from convergent evolution
Cladogram: (phylogentic diagram) constructed from a series of dichotomies; shows ancestral relations between organisms to represent the evolutionary tree of life
Clade: (branch) group consisting of an organism and all its descendants

Monophyletic: a taxon that includes ancestral species and all its descendants
Good taxonomic hypotheses are based on monophyletic groups

Paraphyletic: a taxon that includes the ancestor and some but not all of its descendants

As a general rule, the more homologous parts that two species share, the more closely related
Also, the more complex two structures are, the less likely that they evolved independently

Apomorphic: a derived character
Pleisiomorphic: a primitive (original) character
Whether primitive or derived is a relative distinction

Heterotroph: organism that cannot synthesize own food and is dependent on complex organic substances for nutrition
Autotroph: an organism capable of synthesizing its own food from inorganic substances using light or chemical energy
Derived Character: (synapomorphy) trait that evolved in the ancestor of a group and is present in all its descendants
Parsimony: the use of the simplest route of explanation available
Speciation: keystone process in origination of diversity of higher taxa
Anagenesis: accumulation of changes associated with the transformation of one species into another
Cladogenesis: (branching evolution) the budding of one or more species from a parent species; promotes biological diversity by increasing the # of species

Morphological Species: individuals with similar overall morphologies (form/structure of an organism) belong to the same species (emphasizes overall similarity)
Problems: does not address relatedness (heritage), convergent evolution

Biological Species: set of actually or potentially interbreeding populations (possible genetic exchange); species based on interfertility (interbreeding), not physical similarity
Problems: does not work for asexual organisms, fossils

Evolutionary Species: group of organisms that shares an ancestor; individuals that share a common ancestor belong to the same species
Problems: what prevents similar organisms from interbreeding? What inhibits genetic exchange?

Reproductive Isolation: if two creatures cannot reproduce fertile offspring of both sexes, then they are in different species (prevent members of two diff. species that mate from producing offspring)

No single barrier may be completely impenetrable to genetic exchange, but many species are genetically sequested (isolated) by multiple barriers

Prezygotic barriers: impede mating between species or hinder fertilization of ova if members of diff. species attempt to mate. (includes habitat, behavioral, temporal, mechanical, gametic, and geographical isolation)