Chapters 19 and 21: Descent with Modification and Evolution in Populations

On the Origin of Species

Charles Darwin's book explained how various species evolve over time and only those favored by the environment can survive and reproduce

Evolution

A change in allele frequency in a population over time

Descent with modification

The concept that Earth's many species are descendants of ancestral species that were different from the present-day species

Charles Lyell

Effectively discredited the long-standing view that the earth's surface had been formed by short-lived cataclysms, such as biblical floods and earthquakes-his principle: uniformitarianism: same geological processes that are at work today slowly formed the earth's surface over an immensely long time

Jean-Baptiste Lamarck

This man developed the first concept of evolution after his studies of biology by hypothesizing offspring inherited characteristics acquired by the parent.

George Cuvier

Studied fossils and determined that species have gone extinct, as they exist in the fossil record but not anymore in living form.

Paleontology

The study of fossils

Charles Darwin

The most influential biologist of all time; formulated the mechanism of evolution (natural selection)

HMS Beagle

The ship Charles Darwin sailed upon during a 5 yr trip to map the coast of S. America, Darwin studied a wide variety of plants and animals

Artificial selection

The selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits

Natural selection

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits

Phenotype

Observable characteristics (appearance/behavior) of an individual resulting from the interaction of its genotype with the environment.

Genes

DNA segments that serve as the key functional units in hereditary transmission and determine traits.

Adaptation

Inherited characteristic of an organism that enhances its survival and reproduction in a specific environment

Microevolution

Evolutionary change below the species level; change in the allele frequencies in a population over generations

Population

A group of individuals of he same species that live in the same area and interbreed, producing fertile offspring

Genetic variation

Differences among individuals in the composition of their genes or other DNA segments

Gene pool

The aggregate of all copies of every type of allele at all loci in every individual in a population. The term is also used in a more restricted sense as the aggregate of alleles for just one or a few loci in a population

Gene flow

The transfer of alleles from one population to another, resulting from the movement of fertile individuals or their gametes

Genetic drift

A process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next. Effects of genetic drift are most pronounced in small populations

Founder effect

Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population

Bottleneck effect

Genetic drift that occurs when the size of a population is reduced, as by a natural disaster or human actions. Typically, the surviving population is no longer genetically representative of the original population

Relative fitness

The contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals in the population

Directional selection

Natural selection in which individuals at one end of the phenotypic range survive or reproduce more successfully than do other individuals

Disruptive selection

Natural selection in which individuals on both extremes of a phenotypic range survive or reproduce more successfully than do individuals with intermediate phenotypes

Stabilizing selection

Natural selection in which intermediate phenotypes survive or reproduce more successfully than do extreme phenotypes

Sexual selection

A for of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates

Sexual dimorphism

Differences between the secondary sex characteristics of males and females of the same species