Biological Anthropology Ecam #1

adaptation

a feature of an organism created by the process of natural selection

natural selection

the process that produces adaptation

morphology

the form and structure of an organism

equilibrium

a steady state in which the composition of the population does not change

stabilizing selection

selection pressures that favor average phenotypes

trait

a characteristic of an organism

character

a trait or attribute of the phenotype of an organism

species

a group of organisms classified together at the lowest level of taxonomic hierarchy

stasis

a state or period of stability during which little or no evolutionary change in a lineage occurs

fecundity

the biological capacity to reproduce

independent assortment

the principle that each of the genes at a single locus on a pair of homologous chromosomes is equally likely to be transmitted when gametes are formed

recombination

the creation of new genotypes as a result of the random segregation of chromosomes and of crossing over

crossing over

the exchange of genetic material between homologous chromosomes during meiosis

regulatory gene

a DNA sequence that regulates the expression of a structural gene

biochemical pathway

any of the chains of chemical reactions by which organisms regulate their structure and chemistry

combinatorial control

the control of gene expression in which more than one regulatory protein is used and expression is allowed only in a specific combination of conditions

spliceosome

an organelle that splices the mRNA in eukaryotes after the introns have been snipped out

ncRNA

molecules of RNA that do not code for proteins

micro RNA

short segments of RNA that are involved in the translation of mRNA into protein and gene expression

lcRNA

RNA molecules that are longer then 200 nucleotides

modern synthesis

an explanation for the evolution of continuously varying traits that combines the theory and empirical evidence of both Mendelian genetics and Darwinism

canalized

the quality of being very insensitive to environmental conditions during development, resulting in similar phenotypes in a variety of environments

pleiotropic effect

a phenotypic effect created by a gene that influences multiple characters

correlated response

an evolutionary change in one character caused by the selection on a second, correlated character

genetic drift

random change in gene frequencies due to sampling variation that occurs in any finite population

fixation

a state in which all the individuals in the population are homozygous for the same allele at a particular locus

microevolution

evolution of populations within a species

macroevolution

evolution of new species, families, and higher taxa

biological species concept

the concept of species as a group of organisms that have the potential to reproduce with one another and produce fertile offspring, and that are reproductively isolated from other such groups

gene flow

the introduction of genetic material from one population or species to another through the successful reproduction of migrating individuals

anagenesis

a form of speciation where a single lineage evolves, with a daughter species replacing its parent species without branching

cladogenesis

a form of speciation where a single ancestral lineage branches into two or more descendant lineages

allopatric speciation

speciation that occurs when two ore more populations of a single species are geographically isolated from each other and then diverge to form two or more new species

character displacement

the result of competition between two species that causes the members of different species to become morphologically or behaviorally more different from each other

reinforcement

the process in which selection acts against the likelihood of hybrids occurring between members of two phenotypically distinctive populations, leading to the evolution of mechanisms that prevent interbreeding

parapatric speciation

a two-step process of speciation in which selection causes the differentiation of geographically separate, partially isolated populations of a species and later the populations become reproductively isolated as a result of reinforcement

sympatric speciation

the hypothesis that speciation can result from selective pressures favoring different phenotypes within a population without positing geographic isolation as a factor

niche

the way of life of a particular species

adaptive radiation

the process in which a single lineage diversifies into several species, each characterized by distinctive adaptations

derived trait

a trait that appears later in the evolution of a lineage or clade

ancestral trait

a trait that appears earlier in the evolution of a lineage or clade

out-group

a taxonomic group that is related to a group of interest and can be used to determine which traits are ancestral and which are derived

molecular clock

the hypothesis that genetic change occurs at a constant rate and thus can be used to measure the time that has elapsed since two species shared a common ancestor

fossil calibration

the method of calculating the divergence time between species and the yearly mutation rate, as determined by the amount of genetic dissimilarity between the species and an out-group species whose divergence time from the two species is known from the fossil record

cladistic taxonomy

a system for classifying organisms in which patterns of descent are the only criteria used

evolutionary taxonomy

a system for classifying organisms that uses both patterns of descent and patterns of overall similarity