AP Biology Unit 8 Review
Terms in this set (65)
English natural scientist who formulated a theory of evolution by natural selection (1809-1882)
Change in a kind of organism over time; process by which modern organisms have descended from ancient organisms.
French naturalist who proposed that evolution resulted from the inheritance of acquired characteristics (1744-1829)
Use and disuse was the concept that body parts that are used extensively become larger and stronger, while those that are not used deteriorate.
The inheritance of acquired characteristics stated that modifications acquired during the life of an organism could be passed to offspring.
A classic example is the long neck of the giraffe. He reasoned that the long, muscular neck of the modern giraffe evolved over many generations as the ancestors of giraffes reached for leaves on higher branches and passed this characteristic to their offspring.
He thought that evolutionary change was driven by the innate drive of organisms to increasing complexity.
Natural selection Observations by Ernst Mayr
Observation #1: All species have such great potential fertility that their population size would increase exponentially if all individuals that are born reproduced successfully.
Observation #2: Populations tend to remain stable in size, except for seasonal fluctuations.
Observation #3: Environmental resources are limited.
Inference #1: Production of more individuals than the environment can support leads to a struggle for existence among the individuals of a population, with only a fraction of the offspring surviving each generation.
Observation #4: Individuals of a population vary extensively in their characteristics; no two individuals are exactly alike.
Observation #5: Much of this variation is heritable.
Inference #2: Survival in the struggle for existence is not random, but depends in part on inherited traits. Those individuals whose inherited traits are best suited for survival and reproduction in their environment are likely to leave more offspring than less fit individuals.
Inference #3: This unequal ability of individuals to survive and reproduce will lead to a gradual change in a population, with favorable characteristics accumulating over generations.
Darwin's interest in the geographic distribution of species was further stimulated by the Beagle's visit to the Galapagos, a group of young volcanic islands 900 km west of the South American coast.
Darwin was fascinated by the unusual organisms found there.
After his return to England, Darwin noted that while most of the animal species on the Galapagos lived nowhere else, they resembled species living on the South American mainland.
He hypothesized that the islands had been colonized by plants and animals from the mainland that had subsequently diversified on the different islands.
After his return to Great Britain in 1836, Darwin began to perceive that the origin of new species and adaptation of species to their environment were closely related processes.
For example, clear differences in the beaks among the 13 species of finches that Darwin collected in the Galapagos are adaptations to the specific foods available on their home islands.
Selection by humans for breeding of useful traits from the natural variation among different organisms
structures that do not have a common evolutionary origin or structure but are similar in function
Structures in different species that are similar because of common ancestry.
Same structure and common ancestor, different function
Process by which unrelated organisms independently evolve similarities when adapting to similar environments
when two or more species sharing a common ancestor become more different over time
study of the distribution of organisms around the world
evolutionary change within a species or small group of organisms, especially over a short period.
large-scale evolutionary changes that take place over long periods of time
The smallest unit that evolution occurs
All the genes, including all the different alleles for each gene, that are present in a population at any one time
principle that allele frequencies in a population will remain constant unless one or more factors cause the frequencies to change
Extremely large population size. In small populations, chance fluctuations in the gene pool can cause genotype frequencies to change over time. These random changes are called genetic drift.
No gene flow. Gene flow, the transfer of alleles due to the migration of individuals or gametes between populations, can change the proportions of alleles.
No mutations. Introduction, loss, or modification of genes will alter the gene pool.
Random mating. If individuals pick mates with certain genotypes, or if inbreeding is common, the mixing of gametes will not be random.
No natural selection. Differential survival or reproductive success among genotypes will alter their frequencies.
A change in the allele frequency of a population as a result of chance events rather than natural selection.
when natural selection maintains stable frequencies of two or more phenotypes in a population, a state called balanced polymorphism.
Greater reproductive success of heterozygous individuals compared to homozygotes; tends to preserve variation in gene pools.
In some situations, individuals who are heterozygous at a particular locus have greater fitness than homozygotes.
IE: sickle cell anemia (recessive - sickle cell disease, dominant - malaria)
Frequency dependent selection
selection in which the fitness of a phenotype depends on how common the phenotype is in a population
Unity of life
the descent of all organisms from an ancestor that lived in the remote past
Diversity of life
adaptation of populations of organisms to different ways of life and environments
Descent with modification
principle that each living species has descended, with changes, from other species over time
All organisms are related through descent from a common ancestor that lived in the remote past.
Over evolutionary time, the descendants of that common ancestor have accumulated diverse modifications, or adaptations, that allow them to survive and reproduce in specific habitats.
Similarity in characteristic traits from common ancestry
remnant of a structure that may have had an important function in a species' ancestors, but has no clear function in the modern species.
Genetic drift that occurs when a few individuals become isolated from a larger population and form a new population whose gene pool composition is not reflective of that of the original population.
When a new population is started by only a few individuals who do not represent the gene pool of the larger source population
Genetic drift resulting from the reduction of a population, typically by a natural disaster, such that the surviving population is no longer genetically representative of the original population.
when the numbers of individuals in a large population are drastically reduced by a disaster.
Movement of alleles into or out of a population due to the migration of individuals to or from the population.
the contribution an individual makes to the gene pool of the next generation relative to the contributions of other individuals
contribution of a genotype to the next generation compared to the contribution of alternative genotypes for the same locus.
Consider our wildflower population.
a type of natural selection in which one extreme phenotype is favored over all others
most common during periods of environmental change or when members of a population migrate to a new habitat with different environmental conditions.
natural selection in which individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle of the curve
when environmental conditions favor individuals at both extremes of the phenotypic range over those with intermediate phenotypes.
Natural selection that favors intermediate variants by acting against extreme phenotypes
favors intermediate variants and acts against extreme phenotypes.
A form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates.
results in sexual dimorphism marked differences between the sexes in secondary sexual characteristics not directly associated with reproduction.
Males and females may differ in size, coloration, and ornamentation.
marked differences between the sexes in secondary sexual characteristics not directly associated with reproduction.
Males and females may differ in size, coloration, and ornamentation.
A direct competition among individuals of one sex (usually the males in vertebrates) for mates of the opposite sex.
direct competition among individuals of one sex (usually males) for mates of the opposite sex.
Selection whereby individuals of one sex (usually females) are choosy in selecting their mates from individuals of the other sex; also called mate choice.
or mate choice occurs when members of one sex (usually females) are choosy in selecting their mates from individuals of the other sex.
differences in DNA sequence that do not confer a selective advantage or disadvantage
have negligible impact on fitness, and thus natural selection does not affect these alleles.
the state of being diploid, that is having two sets of chromosomes
an individual that has more than two chromosome sets that are all derived from a single species
Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers
the formation of a new group of organisms or higher taxon by evolutionary divergence from an ancestral form.
group or level of organization into which organisms are classified
Some first-generation hybrids are fertile, but when they mate with another species or with either parent species, offspring of the next generation are feeble or sterile
mating is attempted, but morphological differences prevent its successful completion
Pattern of evolution in which long stable periods are interrupted by brief periods of more rapid change
The process by which the female lays eggs and the male fertilizes them once they are outside of the female
The formation of new species in populations that are geographically isolated from one another.
Formation of new species
polyploidy resulting from contribution of chromosomes from two or more species
Form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding
Biological species concept
Species is a group of populations whose members have the potential to produce fertile offspring.
Ecological species concept
A definition of species in terms of ecological niche, the sum of how members of the species interact with the nonliving and living parts of their environment.
Sperm of one species may not be able to fertilize eggs of another species
The theory that evolution occurs slowly but steadily
Barriers that impede mating or hinder fertilization.
Reduce hybrid fertility
Hybrids survive, Sterile
Separation of species or populations so that they cannot interbreed and produce fertile offspring
species evolves into a new species without any barriers that separate the population
An evolutionary pattern in which many species evolve from a single ancestral species
form of reproductive isolation in which two populations reproduce at different times
Morphological species concept
defines a species by structural features
Process in which eggs are fertilized inside the female's body
single species evolves into a different species
Barriers that prevent the hybrid zygote from becoming a fertile adult.
condition in which an organism has extra sets of chromosomes
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