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
- Australopithecines
- 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)
- Hominids
- 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
- Anthropoids
- monkeys, apes, humans
- Prosimians
- most primitive primates: lemurs, tassiers
- Polygenic
- 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
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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
- Neanderthals
- 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
- Microevolution
- any change in the allele frequencies using a population
- Mutations
- 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
- Primates
- hands and feet adapted for grasping; binocular vision
- Macroevolution
- 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
- Uniformitariansim
- Lyell: Geologic processes have been changing phases and has existed in the past
- Temporal Isoluation
- Breeding at different times of the day (prezygotic)
- Diploidy
- 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
- Polymorphism
- 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
- Cline
- gradual change in phenotype over a geographical range
- Mutation
- 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
- Biogeography
- 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