Chapter 18 and 19

1.       Analogous structure  Body parts that once differed in evolutionarily distant lineages.

2.       Asteroid              Rocky, metallic body.

3.     Comparative morphology   Scientific study of comparable body parts of adults of major lineages.

4.       Derived trait      A novel feature that evolved but once

5.       Fossil   Physical evidence of an organism that lived in the distant past.

6.       Fossilization       How fossils form.

7.       Geologic time scale   Time scale for the Earth's history with major subdivisions

8.       Gondwana    Paleozoic supercontinent; with other land masses, it formed Pangea.

9.     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.

10.  Homologous structure:  Of separate lineages, comparable body parts that show underlying similarity even when they may differ in size, shape.

11.   Lineage: Line of descent.

12.   Morphological convergence      Macroevolutionary pattern. In response to similar environmental pressures over time, evolutionarily distant lineages evolve in similar ways.

13.   Morphological divergence          Macroevolutionary pattern; genetically diverging lineages undergo change from body form of a common ancestors.

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

15.   Plate tectonics theory  Theory that great slabs (plates) of the Earth's outer layer float on a hot, plastic mantle.

16.   Stratification      Stacked layers of sedimentary rock.

17.   Theory of uniformity     Early theory that the earth's surface changes in gradual, uniformly repetitive ways

18.   Adaptive radiation          Macroevolutionary pattern; burst of genetic divergences from a lineage that gives rise to many species.

19.   Adaptive zone  Minimum amount of energy required to get a specific reaction going, with or without the help of an enzyme.

 20.   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.

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

22.   Archipelago        Island chain some distance away from a continent.

23.   Biological species concept          Defines a species as one or more populations of individuals that are interbreeding under natural conditions, producing fertile offspring.

24.   Cladogenesis     Speciation pattern in which a lineage splits and isolated populations undergo genetic divergence.

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

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

27.   Extinction           Irrevocable loss of a species.

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

29.   Genetic divergence        Gradual accumulation of differences in gene pools of populations or subpopulations of a species after a geographic barrier arises and separates them.

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

31.   Hybrid zone       Where adjoining populations are interbreeding and producing hybrid offspring.

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

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

34.   Punctuation model of speciation   Idea that most morphological changes occur in a brief span when populations start to diverge.

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

36.   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.

37.   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.

38.   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.