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Gregor Mendel
Developed laws of inheritance; peas
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Mendel's Model
- 1. Trait variation is due to alternative versions (alleles) of heritable factors (genes)
- 2. for each character an organism inherits 2 alleles
- 3. dominant alleles mask recessive alleles
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law of segregation
two alleles for a heritable character segregate during gamete formation and end up in different gametes
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law of independent assortment
different alleles of different loci sort independently
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Eugenics Movement
breeding "better" humans. forcibly sterilize people
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diploid cell
2 sets of chromosomes
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Thomas Hunt Morgan
fruit fly experiments provided frist strong evidence genes are chromosomal
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transform
change phenotype and genotype
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Hershey & Chase
used bacteriophage to show that viral DNA can program cells
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Franklin & Wilkins
made x-ray diffraction images of DNA
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Watson & Crick
used Franklin&Wilkins's x-ray images to deduce the double helix
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character
heritable feature that varies among individuals
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trait
each variant for a character (purple color)
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phenotype
appearance or observable traits
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monohybrid
heterozygous for one character
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dihybrid
heterozygous for two characters
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quantitative characters
when either-or classification is impossible b/c the characters vary in the population; a continuum
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polygenic inheritance
an additive effect of two or more genes on a single phenotypic character
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Linneaus
developed classification system to reveal divine order of life; father of taxonomy
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Cuvier
found diff fossils in diff strata and inferred extinction
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Hutton & Lyle
found earth's features explained by processes currently operating; implied earth is >>>6000 yrs
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Erasmus Darwin
evolution from a common ancestor, competition and sexual selection responsible for species change. vague ideas of transmutation
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Lamarck's theory
developed comprehensive theory of evolution that included discredited theory of inheritance of acquired characters
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Alfred Russell Wallace
independently described an evolutionary system almost identical to Darwin's
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Darwin's Theory
- 1. members of a population often vary greatly in their traits
- 2. individuals inherit traits from parents
- 3. all species are capable of producing many more offspring than their environment can support
- 4. owned to lack of food or other resources many of these offspring don't survive
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homologous characters
similarities due to common ancestry. homologous structures with very diff functions
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vestigial traits
historical remnants of traits important for ancestry (things that have reduced or have no function; due to ancestors who did have use for them, i.e. appendix in humans)
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molecular homology
genetic code due to descent from common ancestors rather than individual creation
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point mutation
single-base substitutions caused by error in DNA synthesis or repair
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insertions/deletion
caus addition/loss of amino acids, frame shifts or truncated proteins
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gene duplications
duplications of short stretch of DNA caused by unequal crossovers during meiosis or strand slippage during DNA replication
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chromosome inversion
breaks in 2 places, flips and reanneals
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polyploidization
organism have more than 2 sets of chromosomes
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random genetic drift
changes in allele frequencies within populations which result from chance variation in individual survival and reproduction
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gene flow
consists of genetic addiction/subtractions resulting from movement of fertile individuals or gametes
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stabilizing selection
selection against both extremes
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directional selection
selection against an extreme
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disruptive selection
selection against intermediate phenotype
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sexual selection
natural selection for mating success can result in sexual dimorphism, sexually selected traits may be bad for survival
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diploid
containing two complete sets of chromosomes, one from each parent
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balancing selection
occurs when natural selection maintains two or more forms in population, leads to a state called balanced polymorphism
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anagenesis
transforms one species into another
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cladogenesis
splitting of the gene pool, giving rise to one or more new species
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prezygotic barriers
- impede mating or hinder fertilization if mating occurs
- 1. habitat isolation
- 2. temporal isolation
- 3. behavioral isolation
- 4. mechanical isolation
- 5. gametic isolation
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postzygotic barriers
- prevent the hybrid zygote from developing into a viable fertile adult
- 1. reduced hybrid viability (genes of diff parent species may interact and impair hybrid development)
- 2. reduced hybrid fertility
- 3. hybrid breakdown
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autopolyploid
extra chromosome sets derived from one species
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allopolyploid
has chromosome sets derived from two diff species
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adaptive radiation
the evolution of diversely adapted species from a common ancestor upon introduction to new environmental opportunities
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macroevolution
evolutionary change at or above the species level
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microevolution
evolution within a species
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allometry
changes in the relative growth rates of diff body parts
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paedomorphosis
sexually mature adults with juvenile morphology
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homeotic genes
control body plans by controlling the developmental fate of groups of cells
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hox genes
the products of one class of homeotic genes, which provide positional info
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exaptation
many characters evolved for purposes other than those for which they are currently used
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phylogeny
the evolutionary history of a species or group of related species
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systematics
scientific system for classifying organisms
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taxonomy
the science of naming and classifying living things
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phylogenic systematics
classification of organisms by their order of branching on an evolutionary tree
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monophyletic
ancestor and all its descendents
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paraphyetic
ancestor and some of its descendents
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polyphyletic
descendents w/o common ancestor
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homoplasies
analogous structures/molecular sequences that evolved independently
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cladistics
reconstruct phylogeny
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orthologous genes
genes are a single copy gene in the genome and are homologous between species
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paralogous genes
result from gene duplication, thus are found in more than one copy of the genome
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Neutral theory
- Kimura
- states much evolutionary change in genes and proteins has no effect on fitness and not influenced by darwinian selection
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proximate
"how" questions about behavior
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ultimate
"why" questions about behavior
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ethology
the study of behavior
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fixed action patterns (FAPs)
sequence of unlearned behaviors that are largely unchangeable
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sexual selection
selection for mating success, may oppose natural selection, may lead to sexual dimorphism
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ecosystem services include
pollination, nutrient cycling, purification of air and water, detoxification and decomposition of wastes, moderation of weather extremes
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inbreeding depression
breeding w/close relatives increases the chance the parents will share the same deleterious recessive alleles
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factors reducing Effective population size (Ne)
- 1. fluctuations in population size over time
- 2. inbreeding
- 3. overlapping generations
- 4. unequal family sizes
- 5. unequal sex ratios
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Malthus
believed that resources can only support a limited population
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Empedocles
natural theory of struggle among species
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Aristotle
created Scala Natura, believed hierarchy of organisms was fixed
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maladaptive evolution
harmful allele fixation
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convergent evolution
organisms evolve structures that have similar (analogous) structures or functions in spite of their evolutionary ancestors being very dissimilar or unrelated.
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H-W assumptions
- 1. random mating
- 2. infinitely large population
- 3. no natural selection
- 4. no genetic drift
- 5. no migration
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analogous structures
features of different species that are similar in function but not necessarily in structure and which do not derive from a common ancestral feature and which evolved in response to a similar environmental challenge.
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allopatric speciation
gene flow impeded by physical/geographic barrier, selection and drift lead to reproductive isolation
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sympatric speciation
takes place in geographically overlapping populations, can occur through chromosome changes or through non-random mating
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