Key Terms Bi164 Exam 2

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anisogamy

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female choice, eggs much larger than sperm

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Batemann's principle

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female reproductive system typically limited by resources, males by access to mates

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sexual dimorphism

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difference between males and females (size, shape, etc.)

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runaway selection

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selection goes to far and offspring cannot survive (Irish elk)

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adaptation

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structure or function that arises because of selection

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exaptation

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structure whose current function isn't its original function

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contingency

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restricted by available variation (testis duct much longer than needed, no optimality)

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homology

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refers to structures that have same evolutionary origin

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analogy

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refers to structures with the same function

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Species Definition

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Morphological species concept - species is a group of organisms that look alike

Biological species concept - species is a group of interbreeding individuals reproductively isolated

Phylogenetic species concept - species is an evolutionary unit (clade) defined by some diagnostic (unique) feature

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Allopatric model of speciation

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begins with physical isolation either dispersal or vicariance

vicariance - any abiotic change that isoaltes members of a species

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Sympatric model of speciation

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can have speciation w/o isolation, disruptive selection, very rare.

- plants often double their ploidy 2n to 4n offspring: instantaneous sympatric speciation

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cladistics

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technique to allow us to recreate probable evolutionary pathways

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phylogeny

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evolutionary pathway

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primitive (plesiomorphic)

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close to what ancestor looked like, no evolutionary change

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derived (apomorphic)

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moved away from ancestry, evolutionary change from ancestral condition

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outgroup

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species just outside of the group of organisms being studied

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principle of parsimony

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we accept provisionally the phylogenetic tree (cladogram) with fewest evolutionary changes

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monophyletic group

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taxonomic group, includes ancestor and all descendant species; desirable for our taxonomy

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paraphyletic group

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group that includes the ancestor and some, but not all of descendant species

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reversal

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when a trait changes from its evolved form and goes back to the original

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polyphyletic group

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some descendent species, but not ancestral species

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convergence

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two species of different families converge and have similar characteristic(s)

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4 Types of Fossils

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1.) intact - pollen preserved intact
2.) compression - sediments accumulated on top
3.) cast
4.) permineralized - hardens into stone

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molecular clock

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point mutations occur at a reasonably constant rate, allow us to track things like AIDS

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phyletic gradualism

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macroevolution occurs very slowly over long periods of time

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punctuated equilibrium

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idea that macroevolution isn't gradual but happens in spurts

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quantam speciation

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speciation occurs in a jump

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convergent evolution

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same changes take place among species that aren't related (same climates, different parts of the world)

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biogeographic hotspots

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vast amount of diversity in place

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incipient species

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not quite speciation, but on the way there

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ring species

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species interbreed along a line, but will not at end of circuit

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radiation

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an explosion of species (often seen on islands)

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endemic

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found nowhere else in the world

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first biomolecule

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thought to be RNA because it has a great template and catalytic function

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primary/secondary embosymbiosis

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cell that ingests another cell to help it survive (how there came to be mitochondria)