ATR 250
Chapter 2:  Evolution- Constructing a Fundamental Scientific Theory

adaptations    Changes in physical structure, function, or behavior that allow an organism or species to survive and reproduce in a given environment.
adaptive radiation    The diversification of an ancestral group of organisms into new forms that are adapted to specific environmental niches
allele    One or more alternative forms of a gene.
blending inheritance    An outdated, disreputed theory that the phenotype of an offspring was a uniform blend of the parents' phenotypes. 
catastrophism    The doctrine asserting that cataclysmic events (such as volcanoes, earthquakes, and floods), rather than evolutionary processes, are responsible for geologic changes throughout Earth's history.
chromosomes    The strand of DNA found in the nucleus of eukaryotes that contains hundreds or thousands of genes.
deoxyribonucleic acid (DNA) A double-stranded molecule that provides the genetic code for an organism, consisting of phosphate, deoxyribose sugar, and four types of nitrogen bases.
dominant   Refers to an allele that is expressed in an organism's phenotype and that simultaneously masks the effects of another allele, if another one is present.
evolutionary biology    A specialty within the field of biology; the study of the process of change in organisms.
fossils    Physical remains of part or all of once-living organisms, mostly bones and teeth, that have become mineralized by the replacement of organic with inorganic materials.
gemmules   As proposed by Darwin, the units of inheritance, supposedly accumulated in the gametes so they could be passed on to offspring.
gene   The basic unit of inheritance; a sequence of DNA on a chromosome, coded to produce a specific protein.
gene flow Admixture, or the exchange of alleles between two populations.
gene pool   All the genetic information in the breeding population.
genetic drift The random change in allele frequency from one generation to the next, with greater effect in small populations.
genotype    The genetic makeup of an organism; the combination of alleles for a given gene.
genus    A group of related species.	
geology   The study of Earth's physical history.
habitat   The specific area of the natural environment in which an organism lives.
Lamarckism    The theory of evolution through the inheritance of features which an organism can pass on acquired during its lifetime.
Mendelian inheritance The basic principles associated with the transmission of genetic material, forming the basis of genetics, including the law of segregation and the law of independent assortment.
modern synthesis    A unified theory of evolution that combines genetics with natural selection. 
mutation    A random change in a gene or chromosome, creating a new trait that may be advantageous, deleterious, or neutral in its effects on the organism.
natural selection The process by which some organisms with environmentally adaptive features survive and reproduce preferentially thereby increasing the frequency of those features in the population.
paleontology    The study of extinct life-forms through the analysis of fossils.
phenotype    The physical expression of the genotype; it may be influenced by the environment.
population genetics   A specialty within the field of genetics; it focuses on the changes in gene frequencies and the effects of those changes on adaptation and evolution.
recessive   An allele that is expressed in an organism's phenotype if two copies are present, but is masked if the 
species    A group of related organisms that can interbreed and produce fertile, viable offspring.
systematics    The study and classification of living organisms to determine their evolutionary relationships with 
taxonomy   The classification of organisms into a system that reflects degree of relatedness.
uniformitarianism   The theory that processes that occurred in the geologic past are still at work today.