vents that sit atop cracks in the ocean floor leading to subterranean chambers of molten rock
Fossils (p. 97)
Skeletons, bones, shells, body parts, leaves, seeds, or impressions of such items that provide recognizable evidence of organisms that lived long ago
Evolution (p. 100)
Change in the genetic makeup of a population of a species in successive generations. If continued long enough, it can lead to the formation of a new species.
Theory of Evolution (p. 100)
widely accepted scientific idea that all life forms developed from earlier life forms.
Microevolution (p. 100)
small genetic changes a population undergoes
Macroevolution (p. 100)
long-term, large-scale evolutionary changes among groups of species
Niche (p. 103)
total way of life or role of a species in a ecosystem. It includes all physical, chemical, and biological conditions a species needs to live and reproduce in an ecosystem
Habitat (p. 103)
Place or type of place where an organism or population of organisms lives.
Genetic Variability (p. 100)
variability among individuals within a species
Gene Pool (p. 100)
Sum total of all genes found in the individuals of the population of a particular species
Alleles (p. 100)
different molecular form found in a particular gene
Mutation (p. 100)
random change in DNA molecules making up genes that can yield changes in anatomy, physiology, or behavior in offspring
Mutagen (p. 100)
chemical or form of radiation that causes inheritable changes (mutations) in the DNA molecules in the genes found in chromosomes
Natural Selection (p. 101)
process by which a particular beneficial gene is reproduced in succeeding generations more than other genes. The result of natural selection is a population that contains a greater proportion of organisms better adapted to certain environmental conditions.
Adaptation (p. 101)
Any genetically controlled structural, physiological, or behavioral characteristic that helps an organism survive and reproduce under a given set of environmental conditions. It usually results from a beneficial mutation.
Artificial Selection (p. 101)
Process by which humans select one or more desirable genetic traits in the population of a plant or animal and then use selective breeding to end up with populations of the species containing large numbers of individuals with the desired traits.
Speciation (p. 104)
formation of two species from one species because of divergent natural selection in response to changes in environmental conditions; usually takes thousands of years
Geographic Isolation (p. 104)
separation of populations of a species for long times into different areas
Reproductive Isolation (p. 104)
long-term geographic separation of members of a parrticular sexually reproducing species
Divergence (p. 104)
process when mutation and natural selection operate independently in two geographically isolated populations and change the allele frequencies in different ways
Extinction (p. 105)
Complete disappearance of a species from the earth. This happens when a species can not adapt and successfully reproduce under new environmental conditions or when it evolves into one or more new species.
Background Extinction (p. 106)
Normal extinction of various species as a result of changes in local environmental conditions.
Mass Extinction (p. 106)
catastrophic, widespread, often global event in which major groups of species are wiped out over a short time compared with normal extinctions
Mass Depletion (p. 106)
period of species loss in which extinction rates are much higher than normal but not high enough to classify as a mass extinction
Adaptive Radiations (p. 106)
Process in which numerous new species evolve to fill vacant and new ecological niches in changed environments, usually after a mass extinction or mass depletion. Typically, this takes billions of years.
Biodiversity (p. 107)
Variety of different species (species), genetic variability among individuals within each species (genetic), variety of ecosystems (ecological), and functions such as energy flow and matter cycling needed for the survival of species and biological communities (functional).