Exam #1 Vocab.

allele

allele

refers to one of any number of alternative forms of the DNA sequence of the same locus

homology

the similarity of characteristics resulting from shared ancestry

blending inheritance

(Darwin) progeny inherits any characteristic as the average of the parents’ values of that characteristic

inheritance of acquired characteristics

(Lamarck) an organism changes during life in order to adapt to its environment, those changes will be passed on to its offspring

polymorphism

the simultaneous occurrence of two or more discrete phenotypes within a population

in simple cases, each phenotype results from a different allele or combination of alleles of a single gene

in complex cases, the phenotypes result from complex interactions between many different genes and the environment

The Modern Synthesis

merges Darwin’s principle of natural selection with Mendel’s discovery of particulate inheritance

hereditary information is encoded in genetic material called genes

merged the fields of taxonomy and paleontology into a unified field of evolutionary biology

indel

a term for an insertion or deletion of bases in the genome of an organism

heterozygosity

the possession of two different alleles of a particular gene or genes by an individual

heritability

the extent to which offspring resemble their parents more than an individual chosen randomly from the population

genetic drift

evolution arising from random changes in the genetic composition of a population from one generation to the next

microevolution

change in the genetic composition of a population through time (generations)

mutation

any change to the genetic sequences of an organism

exaptation

a trait that initially carries out one function and is later co-opted for a new function; bone jaws → ear bones

the original function may or may not be retained

molecular clock

a method used to determine time, based on base pair substitutions; they use the rates of molecular change to deduce the divergence time between lineages in a phylogeny

synapomorphy

a derived form of a trait that is shared by a group of related species

plesiomorphic character states

the ancestral character state for a particular clade

clade

a single “branch” in the tree of life; each one represents as an organism and all of its descendants

paraphyletic group

describes a group of organisms that share a common ancestor, although the group does not include all the descendants of that common ancestor

convergent evolution

similar characteristics that evolve independently between different species

biomarker

molecular evidence of life in the fossil record, these can include fragments of DNA, molecules such as amino acids, or isotopic ratios

fitness

a measure of how well an organism functions in a given environment

igneous rocks

dated through radioactive decay, created by molten lava

sedimentary rocks

dated through ‘bracketing‘ between younger and older igneous formations, created by layers of silt

metamorphic rocks

rocks that arise from the transformation of existing rock to new types of rock in a process called metamorphism

fossilized trackways

a sequence of fossil tracks left by a single organism

phylogenetics

the idea that species are the smallest possible groups whose members are descended from a common ancestor and who all possess defining or derived characteristics that distinguish them from other such groups

homoplasy

describes a character state similarity not due to shared descent, not useful for determining a phylogenetic tree

principle of parsimony

a principle that guides the selection of the most compelling hypothesis among several claude’s; Occam’s Razor

the hypothesis requires the fewest assumptions or steps is usually the best

outgroup

a group of organisms that is outside of the monophyletic group being considered

root of a phylogenetic tree

the oldest point in the tree and corresponds to the theoretical last common ancestor of all taxonomic units included in the tree

polyploidy

more than two paired chromosomes

humans are diploids, any more than this

gene expression

the process by which information from a gene is transformed into a product

transposable elements

also known as "jumping genes," are DNA sequences that move from one location on the genome to another

synonymous substitution

a single base pair change that does not result in an amino acid change

nonsynonymous substitution

a single base pair change that results in a single amino acid change

nonsense substitution

a base pair change that results in a preemptive stop codon, ending the amino acid sequence

frameshift mutation

an insertion of deletion of one or two base pairs that will shift the reading frame of the entire sequence

polyphenic trait

a trait for which multiple, discrete phenotypes can arise from a single genotype, depending on environmental circumstances

quantitative trait

a measurable phenotype that varies among individuals over a given range to produce a continuous distribution of a phenotype

phenotypic plasticity

refers to changes in the phenotype produced by a single genotype in different environments 3

evolutionary coalescence

the process in which the genealogy of any pair of homologous alleles merges in a common ancestor

lineage sorting

alleles of unlinked loci can sort differently into lineages isolated by speciation; loci subject to balancing selection can also sort differently thats the species phylogeny

evolutionary substitution

an allele goes to fixation, which means a population has all the same mutation

mutational saturation

a mutation has acted multiple times upon nucleotides and observed change in sequence is, in fact, less than the historical change in sequence

there are only four base pairs which limits the number of states per character

polygenic trait

similar to quantitative traits, a measurable phenotype that varies among individuals over a given range to produce a continuous distribution of a phenotype, attributed to polygenic effects

epistasis

nonadditive interactions between alleles at loci

multiregional model of human origins

this hypothesis holds that modern humans emerged from populations of "archaic" hominids in Africa, Europe, and Asia that evolved locally but also exchanged genes

out of Africa model of human origins

this hypothesis holds that all living humans descend from a population that first appeared in Africa and subsequently spread throughout that continent and across the remainder of the globe

Neutral theory of molecular evolution

this theory holds that most evolutionary changes occur at the molecular level, and most of the variation within and between species are due to random genetic drift of mutant alleles that are selectively neutral

evolution

the process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth, descent with modification