Pt. 2 Bio Final

the process by which one species splits into two or more species; responsible for diversity of life

changes over time in allele frequencies in a population

the broad pattern of evolution over long time spans

defines a species as members of populations that actually or potentially interbreed in nature, not according to similarity of appearance; appearance is helpful in identifying species, but it doesn't define species; species are identified by the ABSENCE of gene flow

prevents the formation of new species because of the existence of biological factors (barriers) that impeded members of two species from producing viable, fertile offspring; block gene flow between species and the formation of hybrids

block fertilization from occurring; (1) impede members of different species from attempting to mate (2) preventing an attempted mating from being completed successfully (3) hindering fertilization if mating is completed successfully

contribute to reproductive isolation once the zygote is formed; ex: developmental errors may reduce survival/problems after birth leave offspring infertile or unable to survive long enough to reproduce

2 species that occupy different habitats wihtin the same area may see each other rarely even if they aren't separated by geographic barriers; pre

species that breed during different times of day, seasons, or years can't mix gametes; pre

courtship rituals that attract mates and other behaviors unique to a species are reproductive barriers; such rituals allow for mate recognition (a way to identify potential mates of the same species); pre

mating is attempted, but morphological differences prevent its successful completion; pre

sperm of one species may not be able to fertilize the eggs of another species (ex: it cannot survive in reproductive tract of female); pre

the genes of different parent species may interact in ways that impair the hybrid's development or survival in its environment; post

when hybrids are sterile; meiosis can fail to produce normal gametes if the two parent species differ in chromosome number or structure; post

when 1st generation hybrids are fertile and stable, but their offspring with either one another or a parent are feeble or sterile (steeble); post

characterizes a species by body shape and other structural features; can be applied to both asexual and sexual organisms

views a species in terms of its ecological niche

defines a species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life

gene flow is interrupted when a population is divided into geographically isolated subpopulations

speciation occurs in populations that live in the same geographic area; less common than allopatric; can occur if gene flow is reduced by factors such as polyploidy, habitat differentiation, and sexual selection

an individual that has more than two chromosome sets that are all derived from a single species

an organism that has two sets of chromosomes, each from one parent; are usually only fertile when reproduction is asexual

a region in which members of different species meet and mate, producing at least some offspring of mixed ancestry

when natural selection strengthens prezygotic barriers because hybrids are less fit than members of their parent species; formation of hybrids is reduced; because of this, barriers of reproduction between species should be stronger for sympatric species than for allopatric species

periods of apparent stasis punctuated by sudden change

the evolutionary history of a species or group of species

a discipline focused on classifying organisms and determining their evolutionary relationships; used to construct phylogenies

the first part of the binomial naming system is the genus and is where the species belongs; the second part is called the specific epithet and is unique for each species within the genus

the named taxonomic unit at any level of the hierarchy

the evolutionary history of a group of organisms can be represented in a branching diagram

a classification based entirely on evolutionary relationships; it only names groups that include a common ancestor and all of its descendants

groups of organisms that share an immediate common ancestor and are therefore each other's closest relatives

means that a branch point within the tree represents the last common ancestor of all taxa in the tree

a branch point from which more than two decendant groups emerge; indicates that evolutionary relationships among the descendant taxa are not yet clear

a similarity due to convergent evolution; a bat wing is ANALOGOUS to a bird's wing

analogous structures that arose independently (from the Greek "to mold in the same way")

shared nucleotide bases in organisms that are otherwise very different; coincidental matches

uses DNA and other molecular data to determine evolutionary relationships

biologists place species into groups called clades, each of which includes an ancestral species and all of its decendents

a taxon (group of organisms) which forms a clade, meaning that it contains all the descendants of the possibly hypothetical closest common ancestor of the members of the group

a group which consists of an ancestral species and some, but not all, of its decendents

includes taxa with different ancestors

a character that originated in an ancestor of the taxon; (ex: in mammals, the backbone)

an evolutionary novelty unique to a particular clade (ex: in mammals, hair)

a species or group of species from an evolutionary lineage that is known to have diverged before the lineage that includes the species we are studying (ingroup)

it is important to first investigate the simplest explanation that is consistent with the facts

given certain rules about how DNA changes over time, a tree can be found that reflects the most likely sequence of evolutionary events

we can predict (using parsimony) that features shared by two groups of closely related organisms are present in their common ancestor and all of its descendants

homologous genes that are found in different species because of speciation; widespread and can extend over huge evolutionary distances

result from gene duplication, so they are found in more than one copy in the same genome

a yardstick for measuring the absolute time of evolutionary change baseed on the observation that some genes and other regions of genomes appear to evolve at constant rates

much of evolutionary change in genes and proteins ahs no effect on fitness and therefore is not influenced by Darwinian selection

the movement of genes between organisms in different domains; the process in which genes are transfered form one genome to another through mechanisms such as exchange of transposable elements and plasmids, viral infection, and PERHAPS fusion of organisms