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Biology Ch. 22-24, 34 (Campbell, et al)


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Conditions for H/W Equillibrium
Very large population size, no migration, no net mutations, random mating, no natural selection
First bipedal ancestral organisms, small cranial capacities (450 cc), large teeth & faces, no evidence of stone tools, Lucy & Lactore
Theory of Natural Selection
Organisms whose collection of traists make them the most successful will likely pass their traits on to their offspring
Reduced Hybrid Fertility
sterile hybrids (i.e., horse + donkey = sterile mule)
Common ancestor (5-7 mya)
Hardy-Weinburg Theorem
The frequency of alleles and genotypes in a popluation's gene pool will remain the same if only acted upon by sexual recombination and random fertilization
monkeys, apes, humans
most primitive primates: lemurs, tassiers
multiple alleles affect a trait
Homo Habilis
2.5 mya, cranial capacity = 700cc, evidence of stone tools
Allopatric Speciation
Takes place in geographically isolated populations
Sexual Recombination
rsponsible for the bulk of genetic variation
Applications of the H/W Equation
1.) If H/W Equillibrium exists, a population is not evolving
2.) Usefal in data prevalence to harmful alleles
Gradualism model
Species diverge at a slow, gradual pace over long spans of time
Stabilizing Selection
The extremes are selected against
Multiregional hypothesis
Homo sapiens evolved from H. erectus in seperate geographic parts of the world
lived from about 600,000 - 30,000 ya, evolved from H. erectus in Europe, heavily built, much different from us; same brain size as H. sapiens sapiens
Genetic drift
change in allele frequencies due to random chance (bottleneck effect: sever reduction in size causes limited pool; founder effect: freq. in a colony is diff. than of a parent's)
Directional Selection
One of the extremes is selected for good
Descent with Modification
All organisms share a common ancestor; similar species whare a more recent ancestor; we belong to a tree of life, with some branches blooming and others dying
Out of Africa Hypothesis
H. sapiens first evolved in Africa, and then dispersed through Europe and Asia, replacing existing H. erectus populations
Biological species concept
a population whose members have the potential to produce fertile offspring is a species
any change in the allele frequencies using a population
heritable changes in DNA that will affect allele frequencies
Punctuated Equillibrium Model
Species diverge in spurts of rapid change; Evolution taking place rapidly
Gene flow
the flow of alleles in and out of a population as a result of migration
Homo erectus
1.8 mya, cranial capacity = 1000cc, sophisticated stone tools, use of fire and hunting, first hominid to leave Africa
Sexual Selection
secondary sexual characteristics are enhanced because they increase the chane of mating
Diversifying Selection
both extremes are favored over the intermediate
Adaptive radiation
Evolution of many species from a single common ancestor
Galapagos Finches
The diversity in beak shape played an important role in Darwiin's discovery
3 Summations of Darwin's Ideas
Natural Selection is this differential success in reproduction, and its product is adaptation; Natural Selection occurs b/o the enfironment and the variability in the population; Variations in a population arise by chance, but natural selection is determined by reproductive success
Non-random mating
Certain genotypes will be selected over another
hands and feet adapted for grasping; binocular vision
Evolution w/ new taxonomic groups (i.e. reptiles ---> birds)
Gametic isolation
Failure of gametes to fuse during fertilization (prezygotic)
Gene Pool
Pool of genees for a opulation; sum of all alleles of a population
Lyell: Geologic processes have been changing phases and has existed in the past
Temporal Isoluation
Breeding at different times of the day (prezygotic)
harmful recessive traits can be masked in a diploid organism
Evolutionary fitness
Darwinian Fitness: measures the contribution an individual makes to the next generation's genepool; Relative fitness: red v. white (80 v. 20 per cent, etc)
Limitations to the biological species concept
Existence of fertile hybrids, doesn't account for organisms taht reproduce asexualy, can't distinguish extinct species based on fossil evidence
Habitat Isolation
Living in different areas (prezygotic)
Contributions from Malthus
"Essay on Principles of Population" : Organisms produce more offspring than can survive (population regulation)
Evidence for evolution
Biogeography, fossil record, comparative anatomy, comparative embryology, molecular biology, field studies
multiple forms for a particular trait
Distinct variations
two alleles (B or b)
Artificial Selection
Choosing traits in plants or animals to perpetuate (i.e. Dog Breeds)
Reduced Hybrid Viability
failure to develop into a healthy adult
Behavioral isolation
Courtship rituals
gradual change in phenotype over a geographical range
Only if it occurs in gametes; rare and random events that may result in a new allele; few mutations that are beneficial will be selected for
Geographic variation
environment will influence which traits are selected for and against
Natural Variation
alleles that are not selected for or against will persist and will add to the variation
Comparative Anatomy
homologous structures (similar structures with different functions)

vestigal structures (those no longer used or needed)
Heterozygous Advantage
If the heterozygous genotype has an advantage, both the R and r alleles will be preserved (i.e., sickle cell anemia)
Sympatric Speciation
Takes place in geographically overlapping populations
Mechanical Isolation
anatomical incapability
Modern Synthesis
unifying theme in biology; it includes genetics, anatomy, etc.
Fossil Record
Largely incomplete record of fossils
Frequency dependant selection
the genotype that is most prevalent becomes selected against
the study of geographical distribution of organisms
Adaptive Evolution
results from a combination of chance events that produce new genetic variation (sexual recombination and mutation) and natural selection that propogates some variations over the others
Population genetics
The study of the genetics for the particular population in individuals
Theory of Acquired Characteristics
Lamarck proposed a law of use and disuse by which acquired characteristics explained evolution (disproved by Mendel)
Field Studies
watching natural selection take place
Molecular Biology
Similarities in nucleotides, genetic code, and proteins

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