Offspring that results from the mating of individuals from two different species or from two true-breeding varieties of the same species; an offspring of two parents that differ in one or more inherited traits; an individual that is heterozygous for one or more pairs of genes.

Layered rock that results from the activities of prokaryotes that bind thin films of sediment together.

A feature of an organism that is a historical remnant of a structure that served a function in the organism’s ancestors.

Which of the following could provid the best data for determining the phylogeny of very closely related species?

Structures in different species that are similar because of common ancestry.

The formation of new species in populations that are geographically isolated from one another.

Genetic drift resulting from a drastic reduction in population size. Typically, the surviving population is no longer genetically representative of the original population.

The scientific discipline concerned with naming and classifying the diverse forms of life.

A process in which individuals with certain inherited traits are more likely to survive and reproduce than are individuals that do not have those traits.

A method for determining the absolute ages of fossils and rocks, based on the half-life of radioactive isotopes.

Which concept of species would be most useful to a field biologist identifying new plant species while exploring in a tropical forest?

In the fossil record, long periods in which a species undergoes little or no morphological change (equilibria), interrupted (punctuated) by relatively brief periods of sudden change.

According to the biological species concept, species are defined by their

The evolution of similar features in different evolutionary lineages, which can result from living in very similar environments.

What prevents horses and donkeys from hybridizing to form a new species?

A definition of species in terms of ecological niche, the sum of how members of the species interact with the nonliving and living parts f their environment.

The supercontinent that formed near the end of the Paleozoic era, when plate movements brought all the landmasses of Earth together.

Major divisions in the geologic record are marked by

A change in the pool of a population due to change. Effects of genetic drift are most pronounced in small populations.

If you were using cladistics to build a phylogenetic tree of cats, which would be the best choice for an outgroup?

Natural selection that maintains stable frequencies of two or more phenotypic forms in a population.

Which of the following is an example of a POSTzygotic reproductive barrier?

Descent with modification; the idea that living species are descendants of ancestral species that were different from present-day once’s; also, the genetic changes in a population from generation to generation.

The transfer of alleles from one population to another as a result of the movement of individuals or their gemetes.

An organism that has more than two complete sets of chromosomes as a result of an accident of cell division.

Ancient photosynthetic prokaryotes were very important in the history of life because they

A definition of species as the smallest group of individuals that shares a common ancestor, forming one branch on the tree of life.

Period of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill new or vacant ecological roles in their communities.

Biologists have found more than 500 species of fruit flies on the various Hawaiian Islands, all apparently descended from a single ancestor species. This example illustrates

Natural selection that favors intermediate variants by acting against extreme phenotypes.

Natural selection in which individuals on both extremes of phenotypic range are favored over intermediate phenotypes.

The evolution of a new species.

A scientific discipline focused on classifying organisms and determining their evolutionary relationships.

Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool is not reflective of that of the original population.

A change in the genetic information of a cell; the ultimate source of genetic diversity.

If an allele is recessive and lethal in homozygous before they reproduce,

An evolutionary novelty that is unique to a particular clade.

Natural selection in which individuals at one end of the phenotypic range survive and reproduce more successfully than do other individuals.

A scientific discipline that uses nucleic acids or other molecules in different species to infer evolutionary relationships

Evolutionary change above the species level, encompassing the origin of a new group of organisms through a series of speciation events and the impact of mass extinctions on the diversity of life and its subsequent recovery.

An inherited character that enhances an organism’s ability to survive and reproduce in a particular environment.

The similarity between two species that is due to convergent evolution rather than to descent from a common ancestor with the same trait.

In a cladistic study of evolutionary relationships, the group of taxa whose evolutionary relationships are being determined.

A group of populations whose members have the potential to interbreed and produce viable, fertile offspring.

A reproductive barrier that prevents hybrid zygotes produce by two different species from developing into viable, fertile adults. Includes reduced hybrid viability, reduced hybrid fertility, and hybrid breakdown.

The animals and plants of India are very different from the species in nearby Southeast Asia. Why might this be true?

In a cladistic study, a taxon or group of taxa known to have diverged before the lineage that contains the group of species being studied.

A geographic region in which members of different species meet and mate, producing at least some hybrid offspring.

A change in a population’s gene pool over generations.

Adaptive radiations may be promoted by all of the following except one. Which one?

Similarity in characters resulting from a shared ancestry.

An approach to systematics in which common descent is the primary criterion used to classify organisms by placing them into groups called claves.

Which of the following factors would not contribute to allopathic speciation?

A group of individuals belonging to one species and living in the same geographic area.

The study of biological structures, functions, and heredity at the molecular level.

The formation of new species in populations that live in the same geographic area.

A reproductive barrier that impedes mating between species or hinders fertilization if mating between two species is attempted. Includes temporal, habitat, behavioral, mechanical, and ga,ethic isolation.

All copies of every type of allele at every locus in all members of the population.

A character shared by members of a particular clade that originated in an ancestor that is not a member of that clade.

Natural selection is sometimes described as “survival of the fittest.” Which of the following best measures an organism’s fitness?

A swim bladder is a gas-filled sac that helps fish aintain buoyancy. Evidence indicates that early fish gulped air into primitive lungs, helping them survive in stagnant waters. The evolution of the swim bladder from lungs of an ancestral fish is an example of

Definition of a species as a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring but do not produce viable, fertile offspring with members of other such groups.

A definition of species in terms of measurable anatomical criteria.

The study of the past and present distribution of organisms.

The existence of biological factors (barriers) that impede members of two species from producing viable, fertile offspring.

When hybrids produced in a hybrid zone can breed with each other and with both parent species, and they survive and reproduce as well as members of the parent species, now would predict that