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41 terms

Biological Anthropology Test 1

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adaptation
a FEATURE of an organism CREATED by the process of natural selection.
continuous variation
ex: height in humans, birthweight
discontinuous variation
phenotypic variation in which there are a discrete number of phenotypes with no intermediate types. Ex: pea color in Mendel's experiment
stabilizing selection
selection pressuresd that favor average phenotypes. Stabilizing sleection reduces the amount of variation in the population but doesn't alter the mean value of the trait.
directional selection
where a single phenotype is favored, causing the allele frequency to continuously shift in one direction
disruptive selection
driving force behind sympatric speciation extreme values for a trait are favored over intermediate values. E.g.: large nose rather than medium sized nose
diploid
refers to cells that have pairs of homologous chromosomes, where one chromosome of each pair is inherited from each parent. All primates are diploid
homozygous
a diploid organism whose chromosomes have two copies of the SAME allele. Opposite of heterozygous
genotype
the genetic makeup of a trait
phenotype
the shown trait
parapatric speciation
two-step process in speciation where selection causes the differentiation of geographically separate, isolated populations of a species and the populations become reproductively isolated as well
chromosomes
carries genes and appears during cell division
homologous traits
structural similarities derived from two species with independent ancestors. Eg. a bat's wing and a human's hands
natural selection
the process that produces adaptation
mitosis
the process of division of normal body cells through which new diploid cells are created
meiosis
the process of cell division in which haploid gametes (eggs and sperm) are creatred
morphology
the form and structure of an organism
polygenic
many genes?
pleiotropy
genes that influence multiple traits
microevolution
evolution of populations within a species
macroevolution
evolution of new species, families, and higher taxes
mutation
a spontaneous change in the chemical structure of DNA
sympatric speciation
a hypothesis that speciation can result from selective pressures favoring different phenotypes within a population without geographic isolation as a factor
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
allele
one of two or more alternative forms of a gene
reproductive isolation
a relationship between two populations in which there is no gene flow between them
balanced polymorphism
a steady state in which two or more alleles coexist in a population.
founder effect
occurs when a new colony is started by a few peope from the original population. Not much diversity, usually mutations.
bottleneck effect
occurs when a population endures a natural disaster and alleles are greatly reduced in diversity
gradualism
opposite of punctuated equilibrium
punctuated equilibrium
where there are specific, extreme changes in evolution. Like a square like tree
allopatric speciation
speciation that occurs when two or more populations of a single species are geographically isolated from each other and then diverge to form two or more new species
phylogeny
the evolutionary relationships among a group of species. diagrammed as a family tree
adaptive radiation
the process in which a single lineage diversifies into a number of species
genes are carried on
chromosomes
what's a nucleotide composed of?
a phosphate-sugar base
What are the differences between DNA and RNA
DNA is double stranded while RNA is single stranded, DNA has only a nucleus but RNA can have a nucleus or a cytoplasm, the main ingredient in DNA is Thymine while in RNA it's Uracil.
genetic drift
the change in frequency of a gene do to randomness
gene flow
the transfer of alleles of genes from one population to another
cladogenesis
where two somewhat related species eventually form a new species
anagenesis
a gradual transformation of one species to another