Botany: Plant Evolution
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species change over time; "descent with modification", genetic change in population.
Characteristics of Natural Selection
- -Variation in population's traits
- -Hereditary traits
- -More offspring produces than survive
- -"fit" individuals are more likely to survive and reproduce.
- Darwin and Wallace came up with it
- it occurs at a POPULATION level
- acts only on phenotype
- Also know as selective breeding.
- Evolution created by humans
Can be passed from parents to offspring. Does not include somatic changes as Lamark suggested.
An organism's ability to survive in it's habitat
An evolutionary modification that improves an organism's chances of survival and reproductive success.
- Remains/traces of organisms in layers of rock.
- formed by slow decay under sediment
- fossil record is biased
- radioactive isotope dating is used to predict age.
comparison of the structural details of any given organ found in different organisms
similarities in related species because of a common ancestor. Same structure, could have different functions.
Ex. Whale flipper and horse leg.
similarities that arise through convergent evolution. Same function, could be different function.
Ex. Insect and bird wings.
Evidence for Evolution
- comparative anatomy
- biochemistry and molecular biology
the study of the geographic distribution of living organisms and fossils.
Evidence of Evolution: areas that have been isolated for a long time have unique flora and fauna.
- Amino acids in common proteins (ex cytochrome c)
- sequence of nucleoties in DNA more similar in related species.
a group of individuals of the same species living in one area.
the total genes present/available in the population
the number of times an allele appear in a population
Hardy-Weinberg Principle: Definition
the matematical prediction that allele and genotype frequencies do not change from generation to generation in the abscence of microevolutionary processes.
(p^2) + 2pq + (q^2) = 1
Hardy-Weinberg Principle: Conditions
- Random mating
- No mutations
- Large population
- No migration
- No natural selection
4 Agents of Evolutionary Change
- Genetic Drift
- Gene flow
- Natural Selection
- must occur in gametes to be inherited.
- Increases potential for adaptation.
- increases variation
- may be positive or negative
movement of individuals (animals) or pollen/seeds (plants) into or out of a population
mating across populations provides access to more alleles.
- production of random evolutionary changes in small breeding populations
- decreases genetic variation within the population.
- Makes population more susceptible to extinction.
Modes of Selection
Directional, Stabilizing, and Disruptive
genetic drift that results from a small population colonizing a new area.
Population becomes smaller, limiting the variation in the population.
Biological Species Concept
a species consists of one or more populations whose members interbreed in nature to produce fertile offspring.
the differentiation of populations into two distinct species
- speciation that occurs when one population becomes geographically separated from the rest of the species.
- clines on mountains.
when a population forms a new species within the same geographic region at it's parent species. In plants, it often involves polyploidy organisms.
the elimination of a species
Types of Extinction
- Background extinction: occurs in response to gradual changes in the environment over long time periods.
- Mass extinction: numerous species/genera/families go extinct at once in a relatively short time. Has occured 5-6 times in Earth's history.
- Antropogenic Extinction: extinction caused by humans.
the possession of more than two sets of chromosomes
When polyploidy occurs along with sexual reproduction between individuals of two species. Creates polyploid offspring
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