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Chapter 22, 23, 24


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What is Mutation
Mutation is a change in an organism's DNA.
What is Directional selection
is most common during periods of environmental change or when members of a population migrate to some new habitat with different environmental conditions
What is gene flow
A population may gain or lose alleles by gene flow, genetic exchange due to the migration of fertile individuals or gametes between populations.
What is polymorphic
if two or more distinct morphs are each represented in high enough frequencies to be readily noticeable.
What is geographic variation
differences in gene pools between populations or subgroups of populations.
What is nucleotide diversity
Population geneticists measure by comparing the nucleotide sequences of DNA samples from two individuals and then pooling the data from many such comparisons of two individuals
what is Prezygotic barriers
impede mating between species or hinder the fertilization of ova if members of different species attempt to mate.
what is Mechanical Isolation.
Closely related species may attempt to mate but fail to consummate the act because they are anatomically incompatible.
What is balanced polymorphism
This ability of natural selection to maintain stable frequencies of two or more phenotypic forms in a population.
what is Habitat Isolation.
Two species that live in different habitats within the same area may encounter each other rarely, if at all, even though they are not technically geographically isolated
what is Behavioral Isolation.
Special signals that attract mates, as well as elaborate behavior unique to a species, are probably the most important reproductive barriers among closely related animals
what is Reduced Hybrid Fertility.
Even if two species mate and produce hybrid offspring that are vigorous, reproductive isolation is intact if the hybrids are completely or largely sterile.
Natural selection preserves variation by two mechanisms. One such mechanism is heterozygote advantag
heterozygote advantage
A second mechanism promoting balanced polymorphism is ?
frequency-dependent selection
what is Gametic Isolation.
Even if the gametes of different species meet, they rarely fuse to form a zygote.
What is cline
is a graded change in some trait along a geographic axis.
what is the morphologic species concept
characterizes each species in terms of unique set of structural features, remains the way we distin guish most species.
what is Differential growth rates in a human.
The arms and legs grow faster than the head and trunk, as can be seen in this conceptualization of different-aged individuals all resealed to the same height.
what is relative fitness
the contribution of a genotype to the next generation compared to the contributions of alternative genotypes for the same locus.
What is Diversifying selection
occurs when environmental conditions are varied in a way that favors individuals on both extremes of a phenotypic range over intermediate phenotypes
what is punctuated equilibrium
According to this model, species diverge in spurts of relatively rapid change, instead of slowly and gradually.
What is Stabilizing
Stabilizing selection culls extreme variants from the population, in this case eliminating individuals that are unusually light or dark. The trend is toward reduced phenotypic variation and maintenance of the status quo.
Taxonomy is the branch concerned with naming and classifying the diverse forms of life
What is Artificial selection
the breeding of domesticated plants and animals. Humans have modified other species over many generations by selecting individuals with the desired traits as breeding stock.
What is The Founder Effect
The Founder Effect. Genetic drift is also likely whenever a few individuals from a larger population colonize an isolated island, lake, or some other new habitat.
what is homeotic
genes determine such basic features as where a pair of wings and a pair of legs will develop on a bird or how a plant's flower parts are arranged.
what is Differential reproduction
Differential reproduction - whereby organisms with traits favored by the environment produce more offspring than do organisms without those traits
Two main features of the Darwinian view of life:
Two main features of the Darwinian view of life: (1) The diverse forms of life have arisen by descent with modification from ancestral species and (2) the mechanism of modification has been natural selection working over enormous tracts of time.
What is Darwinian fitness
the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals
What is Polymorphism
Polymorphism. When two or more forms of a discrete character are represented in a population, the different forms are called morphs
What is a Species
a group of populations whose individuals have the potential to interbreed and produce fertile offspring in nature
What is Homology
similairty in characteristics resulting from common ancestry.
what is genealogical species concept
defines a species as a set of organisms with a unique genetic history
what is allopatric speciation
speciation takes place in populations with geographically separate ranges.
what is sympatric speciation
speciation takes place in geographically overlapping populations.
What is Anatomical homologies
Descent with modification ( like forelimbs of humans, cats, and bats ). Similarities between species grouped in the same taxonomic category.
what is sexual dimorphism
size difference, usually one in which males are larger than females.
what is Hybrid Breakdown.
In some cases when species crossmate, the first-generation hybrids are viable and fertile, but when these hybrids mate with one another or with either parent species, offspring of the next generation are feeble or sterile, For example, different cotton species can produce fertile.
what is Temporal Isolation.
Two species that breed during different times of the day, different seasons, or different years cannot mix their gametes.
What is homologous structures
the forelegs, wings, flippers, and arms of different mammals.
What is biogeography
the geographic distribution of species
what is the study of fossils.
what is Population Genetics
An important turning point for evolutionary theory was the birth of Population Genetics, which emphasizes the extensive genetic variation within populations and recognizes the importance of quantitative characters.
What is microevolution.
Evolution is a generation-to-generation change in a population's frequencies of alleles. Because such change in a gene pool is evolution on the smallest scale, it is referred to more specifically as microevolution.
The main factors that can act to alter the allele frequencies in a population are?
genetic drift, natural selection, gene flow, and mutation.
wWhat is A Population
A Population is a localized group of individuals belonging to the same species. For now, we will define a Species as a group of populations whose individuals have the potential to interbreed and produce fertile offspring in nature
What is a Gene Pool
The total aggregate of genes in a population at anyone time is called the population's Gene Pool. It consists of all alleles at all gene loci in all individuals of the population.
What is Measuring Genetic Variation
Population geneticists measure genetic variation at both the level of whole genes (gene diversity) and at the molecular level of DNA (nucleotide diversity).
what is speculating each boundary between strata corresponded in time to a catastrophe, such as a flood or drought.
What is the cumulative product of slow but continuous processes.
What is a Population
Population is a group of interbreeding individuals belonging to a particular species and sharing a common geographic area. A population is the smallest unit that can evolve.
waht is Natural selection
Natural selection is differential success in reproduction (unequal ability of individuals to survive and reproduce). Natural selection occurs through an interaction between the environment and the variability inherent among the individual organisms making up a population.
what is endemic
species found nowhere else in the world.
For a population to be in Hardy-Weinberg equilibrium, it must satisfy five main conditions
1)Very large population size, 2) No migration, 3)No net mutations, 4)Random mating, 5)No natural selection.
Most fossils are found in Sedimentary Rocks formed from the sand and mud that settle to the bottom of seas, lakes, and marshes.
Sedimentary Rocks

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