Chapter 14

mid-mesozoic

2nd dramatic chapter in history of continental drift began during the _____ era.

prezygotic barriers

___ ___ include temporal isolation, habitat isolation, behavioral isolation, mechanical isolation, and gametic isolation.

fossil record

___ ___ is the sequence in which fossils appear in rock state and an archive of macroevolution

prezygotic barriers

___ ___ prevent mating or fertilization between species.

reproductive barrier

a ___ ___ is anything that prevents individuals of closely related species from interbreeding.

polyploidy

a species may originate from an accident during cell division that results in an extra set of chromosomes, a condition called ___.

natural selection

affects individual organisms but individuals do not evolve

mutation

animals and plants avg. about one ___ in every 100,000 genes per generation

evolutionary trees

are hypothesis reflecting our current understandings of patterns of evolutionary descent

homologous structures

are one of the best sources of information for phylogenetic relationships

vestigial structures

are remnants of features that served important functions in an organisms ancestor

vertebrate embryos

at some point in their development, all ___ have a tail posterior to the anus, and structures called pharyngeal pouches

gene pool

at the population level, biologists focus on the ___ which consists of all copies of every type of allele

geological isolation

basically, allopatric speciation requires some type of ___ ___, sympatric speciation does not.

homologous structures

both anatomical and molecular can be used to determine the branching sequence of an evolutionary tree

homology

can also explain observations about embryonic development that are otherwise puzzling

polyploidy

can arise from a single parent species.

disruptive selection

can lead to a balance between two or more contrasting phenotype forms in a population

artificial selection

darwin learned that ____ has two essential components: variation among individual and heritability

stabilizing selection

favors intermediate phenotypes, occurs in relatively stable environments, and is the most common.

multicellular organisms

in ___ only mutations in cells that produce gametes can be passed to offspring and effect a pop. gen. variability

prokaryotes

in ___, mutations can quickly generate genetic variation in a population

sexual selection

in a common type of ___, individuals are choosy in selecting their mates

reproduce sexually

in organisms that _______, most of the genetic variation in a population results from the unique combo of alleles that each individual inherits

secondary sexy structures

in some species, ___ may be used to compete with members of the same sex for mates

natural selection

in the process of ____, individuals whose traits better enable them to obtain food, escape predators, or tolerate physical conditions will survive and reproduce more successfully and pass adaptive traits to offspring

postzygotic barriers

include reduced hybrid viability, reduced hybrid fertility, and hybrid breakdown.

convergent evolution

involves superficially similar structures from different evolutionary branches that result from natural selection shaping analogous adaptations

natural selection

is NOT goal-directed; it does not lead to perfectly adapted organisms

genetic drift

is a change in the gene pool of a small population due to chance

sexual dimorphism

is a distinction in appearance between males and females not directly associated with reproduction or survival

sexual selection

is a form of natural selection in which individuals with certain traits are more likely than others to obtain mates

the bottleneck effect

is an example of genetic drift and results from a drastic reduce in population size

gene flow

is another source of evolutionary change and is genetic exchange with another population, may result in the gain or loss of alleles, and tends to reduce gen. diff. between populations.

macroevolution

is evolutionary change above the species level and includes the impact of mass extinctions on the diversity of life and its subsequent recovery

relative fitness

is the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals

artificial selection

is the selective breeding of domesticated plants and animals to promote the occurrence of desirable traits in the offspring

mutation

is the ultimate source of the genetic variation that serves as raw material for evolution

mutation

new alleles originate by ___, a change in the nucleotide sequence of DNA

speciation

occurs with the evolution of representative barriers between the isolated population and its parent population

natural selection

only ___ consistently leads to adaptive evolution that results in a better fit between organisms and their environment

genetic

only the ___ component of variation is relevant to natural selection

postzygotic barriers

operate if interspecies mating occurs and hybrid zygotes form

homologous genes

organisms as dissimilar as humans and bacteria share _____ inherited from a very distant common ancestor

bottleneck

passing through a "___" decreases the overall genetic variability and results in a loss of individual variation

continental drift

process called ____, movements in the mantle cause the plates to move

evolution

refers to generation-to-generation changes in population

directional selection

shifts the overall makeup of a population by selecting in favor of one extreme phenotype

analogy

similarity due to convergence is called ___

allopatric speciation

species can form by ___ ___, in which the initial block to gene flow is a geographic barrier that physically isolations the splinter population.

sympatric speciation

species can form by ___ ___, without geographic isolation.

exaptations

structures such as feathers that evolve in one context but become co-opted for another function are called ___

biological species concept

the ___ ___ ___ cannot be applied in all situations, including asexual organisms and fossils.

biological species concept

the ___ ___ ___ defines a species as a "group of population whose members have the potential to interbreed with one another and produce fertile offspring."

geologic time scale

the ___ ___ ___ divides Earth's history into consistent sequence of geologic periods.

cretaceous

the ___ extinction occurred at the end of the cretaceous period, included the extinction of all dinosaurs except birds.

permian

the ___ mass extinction occurred at about the time pangaea formed, claimed about 96 marine species.

founder effect

the ____ is likely when a few individuals colonize an isolated habitat, represent genetic drift in a new colony, and explains the relatively high frequency of certain inherited disorders in some small human pop.

speciation

the diversity of life evolved through ____, the process in which one species splits into two or more species.

biogeography

the history of continental merges and separations explains many patters of ____, the study of the past and present distribution of organisms.

homeotic genes

the master control genes, program development by controlling changes in an organisms form as it develops from a zygote into an adult.

radiometric dating

the most common method geologist use to learn the ages of rocks and the fossils they contain is ___ ___, a method based on the decay of radioactive isotopes.

paedomorphosis

the retention in the adult of body structures that were juvenile features in an ancestral species.

heritability

the transmission of a trait from parent to offspring

theory of plate tectonics

where the continents and sealers form a thin outer layer of solid rock divided into giant, irregularly shaped plates that float atop the mantle, a mass of hot, viscous material