Vocabulary#3

     allopatric speciation: Speciation model. A physical barrier arises, separates populations or subpopulations of a species, ends gene flow, and favors divergences that end in speciation.

 

       anagenesis: Speciation pattern; changes in allele frequencies and morphology accumulate within an unbranched line of descent.

 

      archipelago: Island chain some distance away from a continent.

 

      biological species concept: Defines a species as one or more populations of individuals that are interbreeding under natural conditions, producing fertile offspring, and are isolated reproductively from other such populations.

 

       cladogenesis: Speciation pattern in which a lineage splits and isolated populations undergo genetic divergence.

 

     dosage compensation: Any mechanism that balances gene expression between the sexes during critical early stages of development.

 

      evolutionary tree: Treelike diagram; a branch point means divergence from a shared ancestor and branches signify separate lines of descent.

 

      extinction: Irrevocable loss of a species.

 

       gene flow: Microevolutionary process; alleles enter and leave a population as an outcome of immigration and emigration, respectively.

 

       genetic divergence: Gradual accumulation of differences in gene pools of populations or subpopulations of a species after a geographic barrier arises and separates them; thereafter, microevolution occurs independently in each.

 

       gradual model of speciation: Idea that species arise by many small morphological changes that accumulate over great spans of time.

 

       hybrid zone: Where adjoining populations are interbreeding and producing hybrid offspring.

       mass extinction: Catastrophic event or phase in geologic time when entire families or other major groups are irrevocably lost.

 

      parapatric speciation: Idea that neighboring populations can become distinct species while maintaining contact along a common border.

 

      punctuation model of speciation: Idea that most morphological changes occur in a brief span when populations start to diverge; speciation is rapid, and the daughter species change little for the next 2-6 million years or so.

 

      reproductive isolating mechanism: Heritable feature of body form, functioning, or behavior that prevents interbreeding between two or more genetically divergent populations.

 

      speciation: The formation of a daughter species from a population or subpopulation of a parent species by way of microevolutionary processes. Routes vary in their details and duration.

 

      species: One kind of organism. Of sexually reproducing organisms, one or more natural populations in which individuals are interbreeding and are reproductively isolated from other such groups.

 

      sympatric speciation: A speciation event within the home range of an existing species, in the absence of a physical barrier. Such species may form instantaneously, as by polyploidy.

 

 

Vocabulary#2

analogous structure: Body parts that once differed in evolutionarily distant lineages but converged in structure and function as responses to similar environmental pressures.

as   asteroid: Rocky, metallic body, a few to 1,000 kilometers across, hurtling through space.

 

co  comparative morphology: Scientific study of comparable body parts of adults or embryonic stages of major lineages.

 

      derived trait: A novel feature that evolved but once and is shared only by the descendants of the ancestral species in which it evolved.

 

]--  fossil: Recognizable, physical evidence of an organism that lived in the distant past.

 

      fossilization: How fossils form. An organism or evidence of it gets buried in sediments or volcanic ash; water and dissolved inorganic compounds infiltrate it; then chemical changes and pressure from accumulating sediments above transform it to stony hardness.

 

<!   geologic time scale: Time scale for the Earth's history with major subdivisions corresponding to mass extinctions.

 

<!   Gondwana: Paleozoic supercontinent; with other land masses, it formed Pangea.

 

<]   half-life: The time it takes for half of a given quantity of any radioisotope to decay into a different, and less unstable, daughter isotope.

 

]      homologous structure: Of separate lineages, comparable body parts that show underlying similarity even when they may differ in size, shape, or function; outcome of morphological divergence from a shared ancestor.

 

       lineage: Line of descent.

 

]--   morphological convergence: Macroevolutionary pattern. In response to similar environmental pressures over time, evolutionarily distant lineages evolve in similar ways and end up being alike in appearance, functions, or both.

 

]-    morphological divergence: Macroevolutionary pattern; genetically diverging lineages undergo change from body form of a common ancestor.

 

<    Pangea: Paleozoic supercontinent upon which the first terrestrial plants and animals evolved.

 

<    plate tectonics theory: Theory that great slabs (plates) of the Earth's outer layer float on a hot, plastic mantle. All plates are slowly moving and have rafted continents to new positions over time.

<!   stratification: Stacked layers of sedimentary rock, built up by gradual deposition of volcanic ash, silt, and other materials over time.

 

]--   theory of uniformity: Early theory that the earth's surface changes in gradual, uniformly repetitive ways. Has since been replaced by plate tectonics theory.

 

<    adaptive radiation: Macroevolutionary pattern; burst of genetic divergences from a lineage that gives rise to many species.

 

       adaptive zone: Minimum amount of energy required to get a specific reaction going, with or without the help of an enzyme. Reactions differ in the amount required.