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164 Cards in this Set
- Front
- Back
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The Scientific Method
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1. Observation
2. Form hypothesis 3. Test hypothesis a. Experimentation b. Comparison 4. Draw conclusions 5. Refine hypothesis 6. Generalization |
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Proximate mechanisms
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How does it work?
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Ultimate causation
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What is it for?
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Adaptation
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any trait that enhances an individual's survival and reproduction
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HOMOLOGY
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similarity by common descent
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VESTIGIAL TRAITS
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homologous structure that is either rudimentary or no longer used
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CONVERGENT EVOLUTION
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independent evolution of traits through similar selection pressures
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ANALOGY
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similarity due to convergent evolution
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LaMarck's evolutionary theory:
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1. Through use and disuse, structures change over an individual's lifetime.
2. These acquired characters are passed on to descendants. |
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Darwin's theory of evolution by natural selection:
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1. More individuals are born than can survive to reproduce.
2. Individuals vary in most traits 3. Individuals with certain traits are more likely to survive and reproduce 4. Variation is at least partly heritable |
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Thus, populations evolve, but individuals do not:
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a. Individuals inherit unmodified traits.
b. Individuals carrying different heritable traits show differential survival and reproduction c. An increasing proportion of individuals carry the favorable trait in the next generation |
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Levels of selection:
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1. Populations evolve through the spread of traits that benefit the INDIVIDUALS that carry them
2. A trait's effect on the survival of a group or species is secondary to its effects on the individual that possesses it |
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Linnaean system
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Kingdom, Phylum, Class, Order, Family, Genus, Species
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Phylogenetic classification
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based on shared, derived homologous traits
Classification may have any number of levels, depending on the history of the lineage |
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ADAPTATION
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any trait that enhances an individual's survival or reproduction
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MORPHOLOGY
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physical characteristic or form of an organism
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TAXON
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a unit of classification
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TAXONOMY
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the classification of life according to type
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PHYLOGENY
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evolutionary history of a group of related taxa
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CLADE
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group of species with common ancestor
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MONOPHYLETIC GROUP
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taxonomic group that includes all descendants of a single common ancestor (e.g. mammals)
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PARAPHYLETIC GROUP
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taxonomic group that is incomplete because it excludes some of the descendants of a particular ancestor (e.g. reptiles)
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POLYPHYLETIC GROUP
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taxonomic group that includes descendants of several different lineages (e.g. pandas)
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Comparative anatomy
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Evolution can be studied by comparing different organisms.
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Homologous structures
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Structures shared by a group of organisms due to common ancestry; these may be modified for different uses (e.g., mammalian forelimbs)
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Analogous structures
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Similar structures perform a similar function, not due to common ancestry but from convergent evolution (e.g., fins and body shape in marine organisms)
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Vestigial structures
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structures that are seemingly non-functional (e.g., snake "legs")
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Comparative embryology
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Closely related taxa undergo similar embryonic development and may therefore retain characteristics that reflect ancestry (e.g., similar embryological stages of fish, frogs, snakes, bird, humans; presence of gill pouches in human embryos).
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GENE
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unit of inheritance; region of DNA that encodes for a single protein molecule
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LOCUS
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location of a gene along the length of the chromosome
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HOMOLOGOUS PAIR
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in diploid organisms, each chromosome is matched by another chromosome that codes for the same genes
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ALLELES
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alternative forms of the same gene
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HOMOZYGOTE
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individual that carries two identical alleles for a particular gene
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HETEROZYGOTE
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individual that carries different alleles for a particular gene
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DOMINANCE
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the ability of a single allele to determine the phenotype of the heterozygote
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SEGREGATION
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separation of homologous pairs at meiosis
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INDEPENDENT ASSORTMENT
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Recombination of non-homologous chromosomes
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DIHYBRID CROSS
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Mating of parents that differ in two different traits
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LINKAGE
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Tendency for genes on the same chromosome to be passed on together. Linkage is highest for genes in adjacent regions of the chromosome.
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GENE MAPPING
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Determination of physical location of genes on each chromonsome.
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POLYGENIC TRAITS
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Where multiple loci affect a single trait
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EPISTASIS
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Where one locus influences the expression of another locus
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PLEIOTROPY
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Where a single locus affects multiple traits
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SEX-LINKED TRAITS
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Traits coded by genes on the sex chromosomes
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HEMIZYGOTE
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Genotype of a haploid, or of a diploid possessing non-homologous sex chromosomes.
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Gene frequency
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The proportion of a particular allele among all alleles at a gene locus.
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Mutation
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A change in the nucleotide sequence whether by substitution, duplication, insertion or deletion.
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Gene flow
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The migration of genes into a population from other populations by interbreeding.
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Genetic drift
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The random change in frequency of alleles in a population, especially when population size is suddenly reduced to a few individuals.
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Natural selection
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Differential survival and reproduction of individuals carrying particular heritable traits.
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RELATIVE FITNESS
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The contribution of one genotype to the next generation compared to alternative genotypes at the same locus.
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SELECTION COEFFICIENT
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Difference in relative fitness between two genotypes.
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DIRECTIONAL SELECTION
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One allele is favored over another, resulting in the virtual elimination of the inferior allele.
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Factors permitting the coexistence of alternative alleles:
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1. Alternatives are selectively neutral
2. Stabilizing selection: heterozygote advantage (overdominance) 3. Disruptive selection: heterozygote disadvantage 4. Frequency-dependent selection: an allele confers a selective advantage only when rare |
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HARDY-WEINBERG THEOREM
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Predicts the frequency of genotypes in a population, assuming:
1. Individuals mate at random with respect to genotype 2. Gene frequencies remain constant 3. Individuals carry only two alternative alleles, A and a AA = p2 Aa = 2pq aa = q2 |
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PREADAPTATION
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Structure that served a particular function at one time, but subsequently performs different or additional function
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STASIS
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Absence of morphological change during a species' history
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Levels of selection:
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1. Populations evolve through the spread of traits that benefit the INDIVIDUALS that carry them
2. A trait's effect on the survival of a group or species is secondary to its effects on the individual that possesses it |
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Basic premises of evolutionary theory:
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1. More individuals born than can survive to reproduce.
2. Individuals vary in most traits 3. Individuals with certain traits are more likely to survive and reproduce 4. Variation is at least partly heritable 5. Large spans of time have been available for change |
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SEX
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Fusion of genes from more than one individual
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ASEXUAL REPRODUCTION
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reproduction without sex (e.g. by mitosis)
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SEXUAL REPRODUCTION
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1. Isogamy: fusion between gametes of equal size
2. Anisogamy: fusion of sperm and egg |
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THE TWO FOLD-COSTS OF SEX IN DIPLOIDS:
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At meiosis, females throw away half their genetic material to produce a haploid egg
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Advantages of sex in haploids:
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1. Conjugation allows the selfish spread of genes by imposing them on other individuals
2. Transformation allows for chromosome repair |
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Advantages of sex in diploids
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1. Elimination of mutations by segregation and independent assortment
2. Sex allows the acquisition of alleles that confer resistance to disease In diploids, sex must confer a two-fold advantage to overcome the costs of meiosis |
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MONOGAMY
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one male with one female
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POLYANDRY
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several males mate with the same female
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POLYGYNY
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several females mate with the same male
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SEXUAL SELECTION
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selection of traits that influence mating success
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Tenets of sexual selection:
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1. Female reproduction is limited by amount of resources she can convert to eggs or young
2. Male reproduction is limited by the number of matings he can obtain |
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Intra-sexual competition
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a. Direct combat (greatest with polygyny)
b. Sperm competition (greatest with polyandry) |
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Female choice
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a. On basis of male providing resources (more sons & daughters)
b. On basis of male genetic quality (better sons & daughters) c. On basis of male attractiveness (sexy sons, choosy daughters) |
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ALTRUISM
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Where the behavior of one individual increases the fitness of another individual at some cost to itself
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COOPERATION
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Where two or more individuals benefit by working together
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KINSHIP
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Proportion of genes shared by common descent
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INCLUSIVE FITNESS
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An individual's own fitness plus the effects of its behavior on the fitness of its close genetic relatives
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EUSOCIALITY
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Social system in which sterile workers raise the offspring of a small number of reproductives
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RECIPROCITY
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Where two individuals exchange altruistic acts based on previous interactions. Individuals show an initial tendency to cooperate, but only continue to cooperate if their partner had also been cooperative.
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SELFISH GENES
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1. Meiotic drivers -- genetic elements that cause one allele to be disproportionately common in the gametes
2. Transposons -- segments of DNA that jump from one chromosome to another and occasionally from one individual to another 3. Viruses -- segments of DNA or RNA that operate as separate individuals |
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REPRESSOR
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protein that suppresses expression of a specific gene
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RESTRICTION ENZYME
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enzyme that recognizes and breaks DNA that is foreign to the cell
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LYMPHOCYTE
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white blood cell that manufactures "antibodies" which combat foreign molecules ("antigens")
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CYTOPLASM
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contents of the cell outside the nucleus In reproduction, cytoplasmic elements are inherited solely from the mother
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MORPHOSPECIES
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set of individuals with the same physical appearance
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BIOLOGICAL SPECIES
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set of individuals with the potential to interbreed successfully
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CRYPTIC SPECIES
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subset of morphospecies that is genetically distinct and does not interbreed
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Prezygotic barriers
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fertilization does not occur
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Postzygotic barriers
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eproductive failure after fertilization
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Patterns of speciation
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1. Allopatric speciation (Allo = other, patric = homeland)
2. Sympatric speciation (Sym = same) |
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NONDISJUNCTION
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both members of a homologous pair end up in same gamete
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POLYPLOIDY
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More than two copies of each chromosome in the same individual
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AUTO-POLYPLOIDY
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origin of polyploidy by fusion of two diploid gametes
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MICROEVOLUTION
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Changes in allele frequency due to mutation, drift, gene flow and selection
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MACROEVOLUTION
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Large-scale patterns and rates of change in the major taxonomic groupings
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Molecular structure of life:
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1. Machinery of heredity ("genotype") is composed of nucleic acids (DNA & RNA)
Nucleic acids are long chains of nucleotide bases 2. Physical structures of the body ("phenotype") are composed of proteins Proteins are long chains of amino acids |
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Possible sequence in the origin of life:
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1. Nucleotides and amino acids were abundant on the ancient planet
2. Single nucleotides ("monomers") can be linked together to form chains ("polymers") of RNA on crystals of clay 3. RNA is capable of self-replication and of synthesizing proteins 4. Proteinoids self-assemble to form droplets ("microspheres" or "protobionts") 5. Certain proteins (enzymes) improve self-replication rates of RNA 6. RNA that synthesized its own microsphere could monopolize its own enzyme 7. DNA is more stable than RNA and serves as the data storage system |
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DNA HYBRIDIZATION
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comparison of whole genomes of two species by estimating degree of bonding between single-stranded DNA obtained from each species
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MOLECULAR CLOCK
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estimate of time since two species shared a common ancestor based on degree of genetic difference, assuming that rate of change has been constant
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The prokaryotes belong to two kingdoms:
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A. ARCHAEBACTERIA - restricted to extreme environments similar to early earth
B. EUBACTERIA - all other bacteria, spirochaetes, cyanobacteria, etc. |
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Origins of the endosymbiotic organelles
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Mitochondria were free-living aerobic, heterotrophic eubacteria
Chloroplasts were free-living autotrophic cyanobacteria |
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The eukaryotes comprise four kingdoms:
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1. Protista - eight major taxonomic groups including:
a. Protozoa - unicellular heterotrophs b. Eukaryotic algae - unicellular autotrophs c. Slime molds - single/multi-cellular heterotrophs 2. Fungi - multicellular heterotrophs (descent from red algae or slime molds) 3. Plants - multicellular autotrophs (descent from green algae) 4. Animals - multicellular heterotrophs (descent from protozoa) |
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AUTOTROPHIC NUTRITION
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organism produces its own organic nutrients from sunlight or other inorganic sources
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EUKARYOTES
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Organisms with cells containing a nucleus and organelles
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HETEROTROPHIC NUTRITION
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organism acquires organic nutrients by eating the products of other organisms
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ORGANELLES
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Unit within the cytoplasm of the cell that performs a specialized function
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MITOCHONDRIA
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site of cellular respiration
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CHLOROPLAST
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site of photosynthesis (conversion of CO2 and H2O to organic compounds by sunlight)
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PROKARYOTES
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Organisms with cells lacking a nucleus
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SYMBIOSIS
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Where two different organisms live in direct contact
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MUTUALISM
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both species benefit
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COMMENSALISM
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one species benefits, the other is unaffected
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PARASITISM
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one species benefits at the other's expense
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Large-scale classification of animals has been based on:
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1. Symmetry: radial vs. bilateral
2. Gut: open vs. closed; if closed, whether lined with mesoderm ("coelomate") 3. Segmentation |
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Chordates
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1. Hemichordates: acorn worm
2. Urochordates: sea squirts 3. Cephalochordates: lancelets 4. Vertebrates: fish, amphibia, reptiles, mammals |
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CILIA
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numerous short cellular appendages specialized for locomotion
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FLAGELLA
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long cellular appendages specialized for locomotion (one per cell)
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COELOM
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body cavity lined with mesoderm
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MESODERM
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middle layer of early embryo that develops into the notochord, muscles, kidneys, heart
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NOTOCHORD
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flexible rod located between the gut and the nerve cord
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SKELETONS
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1. Hydrostatic - fluid held in a closed body compartment that provides a rigid frame
2. Exoskeleton - hard encasement on the surface of an animal that provides points of muscle attachment 3. Endoskeleton - hard skeleton buried in the soft tissues of an animal. |
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Time line in human evolution:
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Bony fishes: 450 million years
Amphibia: 350 million Reptiles: 300 million Mammals: 190 million Placental mammals: 90 million Primates: 65 million Apes: 35 million Hominid: 6 million |
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Major innovations from the fishes to the primates:
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1. Lungs in Fishes
2. Paired walking appendages in Amphibia 3. More efficient lungs and waterproof skin in Reptiles 4. Extensive maternal care, endothermy, and large brains in Mammals 5. Larger brains in Primates |
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ENDOTHERMY
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utilization of metabolic energy to maintain constant body temperature
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ECTOTHERMY
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utilization of external energy (e.g. sunlight) to maintain temperature
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HOMINID
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all members of the human lineage since divergence from the apes, including the genus Australipithecus ("southern ape") and the genus Homo
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EVOLUTIONARY TIME
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time spans long enough for changing gene frequencies to produce conspicuous changes in morphology or behavior.
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ECOLOGICAL TIME
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time spans measured in months or years.
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POPULATION ECOLOGISTS
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study the size, structure and distribution of populations of particular species.
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COMMUNITY ECOLOGISTS
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study the relationships between different species coexisting in a single habitat.
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ECOSYSTEMS ECOLOGISTS
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study the interaction between species through the overall flow of energy and the cycling of materials in the physical environment.
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Population size depends on:
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Birth, Immigration, Death, Emigration
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Human population growth can be decreased by:
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1. Improved contraception
2. Lowering preferred family size 3. Increasing age of first reproduction |
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LIFE HISTORY
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age-specific rates of growth, reproduction, and survival
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ITEROPARITY
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repeated breeding
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SEMELPARITY
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explosive breeding
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SENESCENCE
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physiological deterioration of the body from in-built processes
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EXTRINSIC MORTALITY
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death due to predation, accident, or the environment
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Fitness is the product of survival and reproduction.
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1. High adult mortality favors rapid breeding.
2. Traits that increase reproduction can spread even if they increase mortality. 3. Damaging reproductive traits are most likely to spread if their effects on survival are delayed until old age. |
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COEVOLUTION
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the joint evolution of two closely interacting species, such that when one species changes, the other also evolves
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COMPETITION
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demand by two organisms for the same limiting resource
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INTERFERENCE COMPETITION
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one species prevents another from gaining access to the resource
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EXPLOITATION COMPETITION
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one species is better able to extract the resource
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COMPETITIVE EXCLUSION
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one species drives another to extinction
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CHARACTER DISPLACEMENT
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divergence in the characters of two overlapping species because of competition for the same resources
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PARASITE
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organism that feeds on the living tissue of its host
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VIRULENCE
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extent to which parasite damages the host
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Ecosystem
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all the organisms in a given area as well as the non-living ("abiotic") factors with which they interact.
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Biome
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one of the world's major communities, classified according to the predominant vegetation and characterized by adaptations to the local environment.
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Trophic structure
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the different feeding relationships in an ecosystem that determine the route of energy flow and the pattern of chemical cycling.
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Nutrient cycling
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movement of vital chemicals between the physical environment and living organisms
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Carbon cycle
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he conversion of atmospheric CO2 to carbohydrates by the process of photosynthesis, and the return of CO2 back into the atmosphere by respiration and decomposition
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Nitrogen fixation
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conversion of atmospheric nitrogen into ammonia and nitrates by bacteria
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Primary productivity
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the amount of light energy converted to chemical energy by the autotrophs of an ecosystem.
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Trophic levels:
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Producers - organisms capable of producing organic energy from sunlight = autotrophs
Consumers - organisms that acquire organic energy from food = heterotrophs Primary consumers - organisms that eat plants Seconday consumers - organisms that eat primary consumers Detritovores - organisms that eat dead organic matter |
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Food chain
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the pathway along which food is transferred from trophic level to trophic level.
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Food web
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the interconnected feeding relationships in an ecosystem
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ENDEMISM
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being restricted to a particular geographical location
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INBREEDING DEPRESSION
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the loss in fertility and viability of offspring born to parents that are close genetic relatives
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INCIDENCE
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the presence of a particular species in a certain area
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ISLAND BIOGEOGRAPHY
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patterns of species richness as a function of island size and location
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SPECIES DIVERSITY
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the number and relative abundance of each species in a biological community
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SPECIES RICHNESS
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the number of species living in a biological community
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Habitat destruction increases extinction rates by:
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1. Outright loss of habitat of endemic species
2. Habitat fragmentation a. Small populations are subject to higher risk by chance events (floods, fires, epidemics, etc.) b. Small populations are subject to inbreeding depression |
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Value of biodiversity:
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1. Alternative forms of food
2. New medicines 3. Greater resilience in the face of natural disaster |
