Bio 104 test 1
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What is artificial selection?
When humans have modified other species by selecting and breeding individuals with desired traits.
Explain descent with modification
The outcome of natural selection: modifications accumulated from generation to generation that can ultimately result in new species.
Change in allele frequencies in a population over time.
- • #1: Members of a population often vary greatly intheir traits
- • #2: Traits are inherited from parents to offspring
- • #3: All species are capable of producing moreoffspring than the environment can support
- • #4: Owing to lack of food or other resources, manyof these offspring do not survive
Describe at least four lines of evidence forevolution by natural selection
- Direct observations of evolution
- The fossil records
Define adaptation in biology
Heritable traits that increase an individual's fitness.
Mechanism of evolution theorized by Darwin and Wallace. Individuals whose heritable traits enable them to survive in their environment and successfully produce offspring which themselves survive and reproduce well will contribute a greater proportion of their genes to the next generation, leading to changes in allele frequencies through time.
Genetic variation refers to diversity in gene frequencies.
- Changes to allele frequencies within species or populations.
- consists of adaptations that evolve within a population, confined to one gene pool
refers to evolutionary change above the species level, this is the cumulative effect of many speciation and extinction events. Reproductive isolation.
Genetic changes in a population due to random processes, (catastrophe) such as a founder event, in which only a few individuals (and their specific subset of the genes in a population) start a new population.
Type of genetic drift. A subsample of the original population has different allele frequencies from the parent population.
A form of genetic drift that occurs as a result of a rapid decrease in the gene pool of a population; usually associated with a rapid decrease in effective population size, that decreases genetic diversity and potentially decreases population fitness because negative alleles may accumulate
Mechanism of evolution involving the transfer of alleles between populations
Explain why the majority of point mutations are harmless
A single mutation on a strand of DNA can still produce the same amino acid when transcribed into RNA, then translated by the ribosome.
Maintains genetic variation in the formof hidden recessive alleles
favors individuals at one end of the phenotypic range
favors individuals at both extremes of the phenotypic range
favors intermediate variants and acts against extreme phenotypes
is competition among individuals of one sex (often males) for mates of the opposite sex.
often called mate choice, occurs when individuals of one sex (usually females) are choosy in selecting their mates
Why Natural Selection Cannot Fashion Perfect Organisms?
- 1. Selection can act only on existing variations
- 2. Evolution is limited by historical constraints
- 3. Adaptations are often compromises
- 4. chance: natural selection and the
biological species concept
- is a group of populations whose members have the potential to interbreed in nature andproduce viable, fertile offspring; they do not breed successfully with other populations.
- Only used for sexual creatures.
morphological species concept
defines a species by structural features
Ecological species concept
views a species in terms of its ecological niche
phylogenetic species concept
defines a species as thesmallest group of individuals on a phylogenetic tree
Gene flow is interrupted or reduced when a population is divided into geographically isolated subpopulations.
Allo = Other site
Example: A flood creates a river with two different ecosystems on both sides.
Sympatric (same country) speciation:
Takes place in geographically overlapping populations. Example: birds living together but recognizing only certain mating calls.
Hybrid zones. What are 3 outcomes of them.
It is a region in which members of different species mate and produce hybrids
- When closely related species meet in a hybridzone, there are three possible outcomes:
- – Reinforcement or strengthening of reproductive barriers
- – Fusion or weakening of reproductive barriers
- – Stability or continued formation of hybrid individuals
is the accumulation of differences between groups which can lead to the formation of new species, usually a result of diffusion of the same species to different and isolated environments which blocks the gene flow among the distinct populations allowing differentiated fixation of characteristics through genetic drift and natural selection.
Example: Darwin's Finches
describes the independent evolution of similar features in species of different lineages. Convergent evolution creates analogous structures that have similar form or function, but that were not present in the last common ancestor of those groups.
Example: Bats, birds, and insects have all evolved wings separately.
Smooth, gradual evolutionary change.
Species traits relatively constant, interrupted by brief, sudden, and abrupt strong selective pressures. Most of the time evolution is in stasis.
Evolutionary process by which populations diverge to form new species. Affected by environment.
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