Test #1 Flashcards
What does q represent?
the frequency of another allele
means they are found nowhere else in the world
endemic
the transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes
gene flow
offspring that result from an interspecific mating
hybrids
characterizes a species by body shape and other structural features
morphological species concept
is the same as species
biological species concept
views a species in terms of its ecological niche
ecological species concept
the existence of biological factors (barriers) that impede members of two species from interbreeding and producing viable, fertile offspring
reproductive isolation
Even if hybrids are vigorous, they may be sterile. If the chromosomes of the two parent species differ in number or structure, meiosis in the hybrids may fail to produce normal gametes. Since the infertile hybrids cannot produce offspring when they mate with either parent species, genes cannot flow freely between the species
reduced hybrid fertility
a change in the nucleotide sequence of an organism’s DNA
mutation
a severe drop in population size: the population has passed through a “bottleneck” that reduces its size
bottleneck effect
a process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits
natural selection
What are the conditions for Hardy-Weinberg Equilibrium?
no mutations, random mating, no natural selection, extremely large population size, and no gene flow
allos-other, patro-homeland; gene flow interrupted when a population is divided into geographically isolated subpopulations
allopatric speciation
are remnants of features that served a function in the organisms ancestors
vestigial stuctures
share similar function, but not common ancestry
analogous
What was Cuvier’s belief on evolution?
that the older the stratum, the more dissimilar its fossils were to current life from; and that from one layer to the next, some new species appeared while others disappeared
occurs when conditions favor individuals exhibiting one extreme of a phenotypic range, thereby shifting a population’s frequency curve for the phenotypic character in one direction or the other
directional selection
in north america, the geographic ranges of the western spotted skunk and the eastern spotted skunk overlap, but the western skunk mates in late summer and the eastern skunk mates in late winter
example of temporal isolation
the process by which one species splits into two or more species
speciation
What is genetic variation depend on?
originates when mutation, gene duplication, or other processes produce new alleles and new genes
example of geographic variation; a graded change in a character along a geographic axis
cline
a region in which members of different species meet and mate, producing at least some offspring of mixed ancestry
hybrid zone
the independent evolution of similar features in different lineages
convergent evolution
mate choice, individuals of one sex are choosy in selecting their mates from the other sex
intersexual selection
What does p represent?
the frequency of one allele
speciation occurs in populations that live in the same geographic area
sympatric speciation
a species may originate from an accident during cell division that results in extra sets of chromosomes
polyploid
to species that occupy different habitats within the same area may encounter each other rarely, if at all, even through they are not isolated by obvious physical barriers, such as mountain ranges
habitat isolation
defines a species as the smallest group of individuals that share a common ancestor
phylogenetic species concepts
differences in the genetic composition of separate populations
geographic variation
chance events can also cause allele frequencies to fluctuate unpredicatably from one generation to the next, especially in small populations
genetic drift
Courtship rituals that attract mates and other behaviors unique to a species are effective reproductive barriers, even between closely related species. Such behavioral rituals enable mate recognition–a way to identify potential mates of the same species
behavioral isolation
Three main topics of Natural Selection
- individuals do not evolve 2. can amplify or diminish only those heritable traits that differ among the individuals in a population 3. environmental factors vary from place to place and over time
What has to happen for evolution to occur?
genetic variation
the geographic distribution of species
biogreography
underlying skeletons of the arms, forelegs, flippers, and wings that represent variations on a structural theme that was present in their common ancestor
homologous structure
species that breed during different times of the day, different season, or different years cannot mix their gametes
temporal isolation
What are the four effects of genetic drift?
significant in small populations, can cause allele frequencies to change at random, can lead to a loss of genetic variation within populations, and can cause harmful alleles to become fixed
which stated that mechanism of change are constant over time
uniformitarianism
evolution on its smallest scale and as a change in allele frequencies in a population over generations
microevolution
when a few individuals become isolated from a larger population, this smaller group may establish a new population whose gene pool differs from the source population
founder effect
blue-footed boobies, inhabitants of the Galapagos, mate only after a courtship display unique to their species; part of the “script” calls for the male to high-step, a behavior that calls the female’s attention to his bright blue feet
example of behavioral isolation
the average percentage of loci that are heterozygous
average heterozygosity
the fitness of a phenotype depends on how common it is in the population
frequency-dependent selection
similarity resulting from common ancestry, but not necessarily similar function
homology
What was Aristotle’s belief on evolution?
certain “affinities” among organisms; life-forms could be arranged on a ladder, or scale of increasing complexity
Strains of cultivated rice have accumulated different mutant recessive alleles at two loci in the course of their divergence from a common ancestor. Hybrids between them are vigorous and fertile, but plants in the next generation that carry too many of these recessive alleles are small and sterile. Although these rice strains are not yet considered different species, they have begun to be separated by postzygotic
example of hybrid breakdown
inherited characteristics of organisms that enhance their survival and reproduction in specific environments
adaptations
The hybrid offspring of a male donkey and a female horse is a mule, which is robust but sterile. A “hinny”, the offspring of a female donkey and a male horse, is also sterile.
example of reduced hybrid fertility
a difference between the two sexes in secondary sexual characteristics
sexual dimorphism
describing these periods of apparent stasis punctuated by sudden change
puncuated equilbria
may contribute to reproductive isolation after the hybrid zygote is formed
postzygotic barriers
differences among individuals in the composition of their genes or other DNA segments
genetic variation
the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals
relative fitness
originates when mutation, gene duplication, or other processes produce new alleles and new genes
What is genetic variation depend on?
What are the three mechanisms that contribute to shuffling?
crossing over, independent assortment of chromosomes, and fertilization
various mechanisms can change a sterile hybrid into a fertile polyploid
allopolyploid
as descent with modification; a change in the genetic composition of a population from generation to generation
evolution
two species of garter snakes occur in the sam geographic areas, but one live mainly in water while the other is primarily terrestrial
example of habitat isolation
is an individual that has more than two chromosome sets that are derived from a single species
autopolyploid
separates certain closely related species of aquatic animals, such as sea urchins. Sea urchins release their sperm and eggs into the surrounding water, where they fuse and form zygotes. It is difficult for gametes of different species, such as the red and purple urchins shown here, to fuse because proteins on the surfaces of the eggs and sperm bind very poorly to each other.
example of gametic isolation
impeding members of different species from attempting to mate, by preventing an attempted mating from being completed successfully, or by hindering fertilization if mating is completed successsfully
examples of prezygotic barriers
occurs when conditions favor individuals at both extremes of a phenotypic range over individuals with intermediate phenotypes
disruptive selection
if individuals who are heterozygous at a particular locus have greater fitness than do both kinds of homozygotes
heterozygote advantage
new layers of sediment cover older ones and compress them into superimposed layers of rock
strata
the shells of two species of snails in the genus spiral in different directions: moving inward to the center, one spirals in a counterclockwise direction, the other in a clockwise direction. As a result, the snails’ genital openings are not aligned, and mating cannot be completed
example of mechanical isolation
Sperm of one species may not be able to fertilize the eggs of another species. For instance, sperm may not be able to survive in the reproductive tract of females of the other species, or biochemical mechanisms may prevent the sperm from penetrating the membrane surrounding the other species’ eggs.
gametic isolation
the genes of different parent species may interact in ways that impair the hybrid’s development or survival in its environment
reduced hybrid viability
meaning selection within the same sex, individuals of one sex compete directly for mates of the opposite sex
intrasexual selection
What is an example of biogeography?
continental drift
some first-generation hybrids are viable and fertile, but when they mate with one another or with either parent species, offspring of the next generation are feeble or sterile
hybrid breakdown
matting is attempted, but morphological differences prevent its successful completion
mehanical isolation
What was Lamarck’s view on evolution?
found what appeared to be several lines of descent, each a chronological series of older to younger fossils leading to a living species; thought that evolution happens because organsims have an innate drive to become more complex
block fertilization from occurring
prezygotic barriers
the broad pattern of evolution above the species level
macroevolution
acts against both extreme phenotypes and favors intermediate variants
stabilizing selection
humans have modified other species over many generations by selecting and breeding individuals that possess desired traits
artificial selection
What was Linnaeus’s belief on evolution?
developed two-part format for naming species
is a group of individuals of the same species that live in the same area and interbreed, producing fertile offspring
population
Some salamander subspecies of the genus live in the same regions and habitats, where they may occasionally hybridize. But most of the hybrids do not complete development, and those that do are frail.
example of reduced hybrid viability
a form of selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates
sexual selection
occurs when natural selection maintains two or more forms in a population
balancing selection
differences in DNA sequence that do not confer a selective advantage or disadvantage
neutral variation
