Taxonomy
the branch of biology concerned with identifying, naming, and classifying species.
Binomial
a two-part Latinized name of a species; for example, Homo sapiens
Genus
in classification, the taxonomic category above species; the first port of species' binomial; for example, Homo
Natural selection
a process in which organisms with certain inherited characteristics are more likely to survive and reproduce than are organisms with other characteristics; unequal reproductive success.
Evolutionary adaptations
modification resulting from natural selection that suits organism to their environment
Fossil record
the ordered sequence of fossils as they appear in rock layers, marking the passing of geologic time
Homology
similarity in characteristics resulting from a shared ancestry.
Vestigial structures
a structure of marginal, if any, importance to an organism. vestigial structures are historical remnants of structures that had important functions in ancestors.
Evolutionary tree
a branching diagram that reflects a hypothesis about evolutionary relationships between groups of organisms.
Artificial selection
the selective breeding of domesticated plants and animals to promote the occurrence of desirable traits in the offspring
Gene pool
all the alleles for all the genes in a population at any one time.
Hardy-Weinberg equilibrium
the condition describing a non-evolving population (one that is in genetic equilibrium)
Microevolution
a change in a population's gene pool over a succession of generations.
Genetic drift
a change in the gene pool of a population due to change.
Bottleneck effect
genetic drift resulting from a drastic reduction in population size. typically, the surviving population is no longer genetically representative of the parent population.
Founder effect
the genetic drift resulting from the establishment of a new, small population whose gene pool represents only a sample of the genetic variation present in the parent population.
Gene flow
the gain of loss of alleles from a population by the movement of individuals of gametes into or out of the population
Directional selection
natural selection that acts in favor of the individuals at one end of a phenotypic range.
Disruptive selection
natural selection that favors extreme over intermediate phenotypes
Stabilizing selection
Natural selection that favors intermediate variants by acting against extreme phenotypes
Sexual selection
A form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates.
Macroevolution
evolutionary change above the species level. examples of macro evolutionary change include the origin of a new group of organisms through a series of speciation events and the impact of mass extinctions on the diversity of life and its subsequent recovery
Speciation
an evolutionary process in which one species splits into two or more species, the most basic process in macroevolution.
Biological species concept
the definition of a species as a population or group of populations whose members have the potential in nature to interbreed and produce fertile offspring.
Prezygotic barriers
a reproductive barrier that impedes mating between species or hinders fertilization of eggs if members of different species attempt to mate.
Postzygotic barriers
a reproductive barrier the operates if interspecies mating occurs and forms hybrid zygotes.
Allopatic speciation
The formation of a new species as a result of an ancestral population's becoming isolated by a geographic barrier.
Sympatric speciation
The formation of new species in populations that live in the same geographic area
Geologic time scale
a time established by geologist that reflects a consistent sequence of geologic periods, grouped into four divisions: Precambrian, Paleozoic, Mesozoic, and Cenozoic
Radiometric dating
a method for determining the age of fossils and rocks from the ratio of radioactive isotope to the nonradioactive isotopes of the same element in the sample.
Biogeography
the study of the past and present distribution of organisms.
Paedomorphosis
the retention in the adult of features that were juvenile in ancestral species.
Systematics
a discipline of biology that focuses on classifying organisms and determining their evolutionary relationships.
Phylogenetic trees
a branching diagram that represents a hypothesis about evolutionary relationships between organisms.
Convergent evolution
the evolution of similar features in different evolutionary lineages, which can result from living in very similar environments.
Analogy
the similarity between two species that is due to convergent evolution rather than to descents from a common ancestor with the same trait.
Cladistics
the study of evolutionary history; specifically, an approach to systematics in which organisms are grouped by common ancestry.
Clade
an ancestral species and all its descendant - a distinctive branch in the tree of live.