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EVOLUTION H.E.KRON-WHRHS-SCI DEPT EVOLUTION -CHANGE IN THE GENE POOL OF A POPULATION OVER TIME SUGGESTS THAT EXISTING SPECIES ARE DERIVED FROM PREVIOUS ONES BY DESCENTORGANISMS NOW ON EARTH SHARE A COMMON ANCESTRY IS A UNIFYING THEME IN BIOLOGY & PROVIDES A FRAMEWORK FOR THE ORGANIZATION OF DIVERSE SPECIES INTO A LINKED PATTERN. A SLOW PROCESS! (AS A RULE IT OCCURRENCE CANNOT BE DEMONSTRATED DIRECTLY.) LAMARCK-INHERITANCE OF ACQUIRED CHARACTERISTICSORGANISMS ADAPT TO THEIR ENVIRONMENT AND PASS THESE CHANGES TO THEIR OFFSPRING USE/DISUSE: SALAMANDER-ON LAND, LEGS COULDN’T TRAMPLE THRU TALL GRASS, BEGAN USING THEIR BELLIES & LEG MUSCLES WASTED AWAY FROM DISUSE LEGLESS SALAMANDERS EVOLVED WHAT’S WRONG WITH THIS IDEA? DARWIN’S THEORY OF NATURAL SELECTION: FROM HIS BOOK - ORIGIN OF SPECIES. NEW SPECIES CAME ABOUT BY NATURAL SELECTION: OVERPRODUCTION STRUGGLE FOR EXISTENCE VARIATION SURVIVAL OF FITTEST 4 COMPONENTS: VARIATION COMPETITION FITNESS ADAPTION VARIATION: INDIVIDUAL MEMBERS OF A POP. WITHIN A SPECIES HAVE HERITABLE DIFFERENCES THESE TRAITS PASSED ON TO NEW GENERATIONS THESE VARIATIONS ARE RANDOM COMPETITION: RESOURCES ARE FIXED: EXP-FOOD & SHELTER POP. GROWS TO LIMIT REPRODUCTION EXCEEDS SURVIVAL INDIVIDUALS MUST COMPETE FITNESS: SOME INDIVIDUALS HAVE TRAITS THAT MAKE THEM BETTER AT SURVIVAL THE FITTEST SURVIVE TO PRODUCE & CARE FOR THEIR OFFSPRING FITNESS IS LINKED TO THE ENVIRONMENT ADAPTION: POP. WITH BEST TRAITS OVERPOPULATE & REPLACE LESS FIT RESULTS IN A NEW POP WITH THE BEST TRAITS ADAPTION IS THE END RESULT OF N. SELECTION: EXP- COAT COLOR, RUNNING SPEEDS, BODY COVERINGS. CONCERNS PHENOTYPE OCCURS WHEN GENES ARE INHERITED MICROEVOLUTION VS MACROEVOLUTION DIVERSITY VS COMPLEXITY MICROEVOLUTION: ANIMALS & PLANTS ADAPT TO CHANGING ENVIRONMENTS INVOLVES SMALL CHANGES DOES NOT CREATE NEW SPECIES CREATES “DIVERSITY” NOT COMPLEXITY EXP: MICROEV-SUPPOSE A WHITE BIRD IS BORN AMONG A POP OF BROWNS. NS FAVORS WHITE IN WINTER & BROWN IN SUMMER. Why? An inherited variation increases an organism’s chance of survival in a particular environment. THE WHITE BIRD IS NO MORE COMPLEX THAN THE BROWN! BEFORE INDUSTRIAL REVOLUTION THERE WERE PEPPERED MOTHS. AFTER, % OF BLACK MOTHS INCREASED DRAMATICALLY. WHY? Environment changes & moths adapted-black is no more complex than peppered! MACROEVOLUTION: evol. that creates a new species. CHANGES ARE SMALL & LARGE Difference between a wolf & dog=small Difference between a starfish & alligator=large EXP: THAT CREATES “COMPLEXITY” Descendants of a lizard evolved into birds with wings & feathers. Birds are more complex than reptiles. EXP: THAT CREATES “DIVERSITY” Descendants of the wolf evolved into dogs; Huskies, Labs etc. A Lab is no more complex than a wolf. NATURAL SELECTION DOES NOT GUIDE EVOLUTIONARY TRANSITIONS WHICH RESULT IN GREATER COMPLEXITY-THEY DEPEND ON “CHANCE” SINCE OBSERVABLE PROCESSES ONLY CREATE “DIVERSITY” THEY SHOULD NOT BE EXTENDED TO EXPLAIN THE ORIGIN OF “COMPLEXITY" Modified Sci Method is based more on speculation than science-c/o-inability of science to test “Macroevolution” THE EVOLUTION OF COMPLEXITY REQUIRES NEW GENES: GENES ARE CHEMICALS GENES DETERMINE TRAITS OF PLANTS & ANIMALS NEW GENES ARE REQUIRED FOR THE EVOLUTION OF NEW ORGANS & STRUCTURES NEO-DARWINISM SYNTHETIC THEORY MODERN DISCOVERIES HAVE BEEN INCORPORATED INTO DARWIN’S NATURAL SELECTION THE CELL IS THE SMALLEST UNIT OF LIFEALL LIFE IS COMPOSED OF CELLS LIFE BEGINS WITH THE INFORMATION FOUND IN DNA TO MAKE PROTEINS PROTEINS THAT GENES ENCODE ULTIMATELY DETERMINE THE TRAITS OF AN ORGANISM REPRODUCTION IN HIGHER LIFE REQUIRES MEIOSIS-OFFSPRING INHERIT GENES FROM BOTH PARENTS While NS selects existing variations already in a pop. It does not create new varieties. The ultimate source of new variations would be: Recombinations of existing genes Mutations-altered genes/chr Both of these produce genetic combinations found in earlier generations Recombination/crossing-over: homologous chrs break & reattach onto different chrs. The next generation inherits chrs with new sequences. Sperm & ova can add even greater diversity to a pop’s gene pool! HOW DO NEW SPECIES EVOLVE Today scientists realize that variations arise c/o random changesMutations in existing genes. Point mutation str. Modified irreg. # MUTATION FACTS: Freq. in human sex cells=1/100,000 Humans may have as many as 100,00 genes Most sex cells contain mutations & are common occurrences in healthy people Causes: radiation, chemicals, viruses etc. For mutation to be subject to NS-it must be expressed in the individual’s phenotype. Selection favors mutations that result in adaptive phenotypes and eliminates non- adaptive ones. Even recessive alleles can show up in future generations ENVIRONMENT SELECTS INDIVIDUALS WITH BEST SUITED “GENOTYPES” TO SURVIVE TO ADULTHOOD & TO REPRODUCE. FOR NS TO CAUSE EVOLUTION, IT MUST SELECT FOR OR AGAINST ONE OF THE FOLLOWING 5 COMBINATIONS: 5 GENOTYPE COMBINATIONS EITHER: AA OR aa (BUT NOT BOTH) BOTH: AA OR aa EITHER: AA & Aa OR aa & Aa HETEROZYGOTE: Aa ALL ALLELES: AA, Aa & aa SELECTION AGAINST ONE OF THE HOMOZYGOTES: IF aa IS COMPLETELY SELECTED AGAINST WHILE AA & Aa ARE SELECTED FOR- THE FREQUENCY OF aa CHILDREN WILL DROP DRAMATICALLY. THERE WILL BE A PROGRESSIVE DECREASE IN “a”! EXAMPLES AGAINST “aa”: ALBINISM-homozygous recessive individuals are at a slight selective disadvantage. Can live to adulthood & reproduce. DIABETES-inherited recessive, the selection is more severe. Prior to this century those who inherited usually died in childhood. Since insulin in 1921 it is no longer a killer of children SELECTION AGAINST BOTH HOMOZYGOTES: only Aa would be able to mate! NATURE SELECTING AGAINST BOTH HOMOZYGOTES: Malaria found in Africa c/o plasmodiaparasites that feed on RBC. People who produce norm RBC are good hosts & easily get the disease & death In African malarial zones there is an inherited condition of the sickle-cell trait. “aa” have a resistance to malaria c/o deflated RBC’s are poor hosts. However these kids die in childhood from sickle cell anemia. People who are Aa for sickle-cell trait have good resistance to malaria c/o sickle shaped cells and rarely develop the life threatening anemia. Those who are AA produce normal RBC’s which make excellent hosts for malaria. So in malarial environments nature selects for Aa sicklers. It selects against “aa” sicklers & people who produce normal RBC’s. EVOLUTION IS THE PROCESS BY WHICH GENE POOLS OF A SPECIES WITH TIME. ALL OF THE SPECIES MAKE UP THEIR GENE POOL. EVOLUTION CHANGES GENE POOLS AND CREATES NEW ONES. THEREFORE NS ONLY PRESERVES GENES THAT OFFER A SELECTIVE ADVANTAGE NS only preserves genes that offer a selective advantage-sometimes called “competitive” advantage. These genes are responsible for beneficial variations. EVOLUTION creates diversity by altering the gene pool. Mutations creates alleles. Alleles are not new genes, but alternate forms of the same gene. Exp: Hb-a protein for transporting O2. If mutations change the DNA encoding process, these changes may alter aa sequence. If the altered genes still encode for Hb-then they are called “alleles”. NATURAL SELECTION: PRESERVES THE BEST ALLELES OPTIMIZES EXISTING GENES BY SELECTING BEST ALLELES MicroEVOL. CONCERNS ORGANISMS ADAPTING TO CHANGING ENVIRONMENTS & NS PRESERVES ALLELES MORE FIT. ENVIRONMENTAL SELECTION: NO EXP: LINGULA Lamp shells found in rock strata 500 mya. Over all this time still looks the same today! Gryphaea-coiled shell similar to oyster 180mya Sea bed changed from rocky to mud. Flat shells only could survive in rocky areas. Curved shells could lift upper valve clear of sea bottom ADAPTIVE LANDSCAPESVISUALIZE FITNESS OF ALLELES Fitness= series of valleys and hills Alleles on hill more fit NS preserves ones on the hill NS optimizes existing genes by sel. most favorable ADAPTIVE LANDSCAPE-APPLIES TO STR & ORGANS: Consider a reptile evolving into a bird. Front legs are preserved by NS. Thus NS fights this transition. If the transition takes place despite NS-then only chance can guide it. Mutations away from optimized legs lower the fitness of a reptile. NS is not driving such a process. GENETIC DRIFT(CHANCE)DETERMINES WHICH GENES SURVIVE. ALLELES FREQUENCY OF A GENE POOL DUE TO CHANCE OR RANDOM EVENTS. CAUSES GENE POOLS OF 2 ISOLATED POP’S TO BECOME DISSIMILAR AS SOME ALLELES ARE LOST & OTHERS FIXED. The net effect of Genetic Drift on a small pop’s gene pool can be rapid. Note the red trait increases dramatically from generation to generation FOUNDER EFFECT-case of gen. drift in which rare alleles occur in higher frequency in a pop “isolated” from general pop. Exp: Darwin’s finches When a pop is started by one or a few who randomly separate from a larger pop-chance may dictate that allele freq. in new pop. may be different from original pop. Island species vary from mainland species BOTTLENECK EFFECT-genetic drift in which a severe reduction in pop. Size results from natural disasters, predation or habitat reduction. Results in severe reduction of the total genetic diversity of the original gene pool. Exp: Cheetah pop. Was probably reduced in the great Ice Age 10,000 ya. Separation causes infertility c/o intense inbreeding=very little gen. Variation. WHEN ARE TWO POP’S NEW SPECIES? - WHEN POP’S NO LONGER INTERBREED THEY ARE THOUGHT TO BE SEPARATE SPECIES. GENETIC DIVERGENCE RESULTS WHEN ADAPTION, DRIFT AND MUTATION ACT ON POPULATIONS. Barriers to gene flow isolate pop’s & lead to formation of a new species. ADAPTIVE RADIATION-the diversification of a species into two or more species as groups adapt to different environments Over time, the pop’s genetically diverge enough so that they can no longer reproduce with each other Models of speciation relate to geographic subdivisions: Allopatric-barrier Parapatric-adj. Pop’s Sympatric-coexist Founder Effectsmall isolated pop on edge VARIATION & SPECIATION VARIATION CAN BE MEASURED IN DIFF WAYS-HUMANS CAN BE TALL/SHORT, SKINNY/FAT ETC. (VARIATION IS A DISTRIBUTION OF AVG & EXTREMES) NATURAL SELECTION IS A PROCESS OF SURVIVAL AND REDRODUCTION THAT LEADS TO IN ALLELE FREQ. OVER TIME AS THOSE INDIVIDUALS MOST “FIT” SURVIVE AND LEAVE MORE OFFSPRING THREE PATTERNS STABILIZING SELECTION-favors the intermediate phenotype. Extremes in variation are selected against. Infants weighing less that 5 lbs have higher rates of infant mortality. DIRECTIONAL SELECTIONfavors one or the other of the extremes. Insecticide resistance with DDT after yrs of use lost its effectiveness on insects. Resistence to DDT is a gen. Trait only those resistant survived & reproduced. DISRUPTIVE SELECTIONfavors individuals at both extremessel. against middle of the curve causing 2 or more distinct phenotypes. African butterflies have 2 distinct phenotypes both resemble brightly colored but distasteful butterflies of other species. Each one gains protection from predation although they are quite edible. DISRUPTIVE-favors both extremes HARDY-WEINBERG THEOREM: IDEA DEVELOPED TO DETERMINE IF A POP. WAS EVOLVING. AUTHORS SET UP A SERIES OF PARAMETERS WHICH DO NOT EXIST IN NATURE TO BE FOLLOWED WHEN DETERMINING THE ALLELE FREQUENCIES OF ANY POP. EVOLUTION WILL NOT OCCUR IF: NO NATURAL SELECTION NO MUTATIONS POP. MUST BE A LARGE SIZE RANDOM MATINGS POP. MUST BE ISOLATED-NO GENE FLOW SINCE IT IS HIGHLY UNLIKELY THAT ANY OF THESE CONDITIONS WILL OCCUR IN THE REAL WORLD, EVOLUTION IS THE INEVITABLE RESULT F O S S I L S F O S S I L S FOSSIL EVIDENCE Remains of living things that existed long ago F O S S I L S PETRIFICATION IMPRINTS CASTS FREEZING TAR PITS AMBER BUT THERE ARE MISSING LINKS BETWEEN EVERY MAJOR GROUP OF PLANTS AND ANIMALS STUDY OF FOSSIL RECORDS HELPS BUILD A HISTORICAL SEQUENCE OF BIO EVOLUTION OF COMPLEX ORGANISMS FROM SIMPLE ONES. Sequence of snail shells oldest on left & youngest on the right dated from 10 mya to 3 mya Horse evolved from 5-toed browser to 1-toed grazer F O S S I L S DARWIN BELIEVED THAT OVER TIME THAT SPECIES EVOLVED C/O GRADUAL IN FREQ. OF TRAITS. THEORY OF PUNCT. EQUILIBRIUM HAS BEEN DEVELOPED TO EXPLAIN RATES OF THAT OCCUR AT AN UNEVEN TEMPO. PE IN NATURE OCCURS C/O ABRUPT IN THE WORLD’S CLIMATE & ENVIRONMENTS. SPECIATION OCCURS RAPIDLY FOLLOWED BY LITTLE OR NO FACTS: Darwin recognized that the fossil record is not continuous Most transitional forms have yet to be found Missing links undermine the entire theory of evolution With PE idea, the fossil record can no longer be used to disprove evolution B I O G E O G R A P H I C A L DISTRIBUTION OF ORGANISMS Animals & plants are most closely related to those in nearby regions B I O G E O G R A P H I C A L TWO HYPOTHESES: RELATED FORMS EVOLVE IN ONE PLACE & SPREAD OUT TO OTHER REGIONS SAME TYPE OF ADAPTION IN GEOGRAPHICAL REGIONS SEPARATES ORGANISMS GRADUAL ISOLATION BY NEW LAND FORMS, WATER, HIGHWAYS, VOLCANO, EQ, RIVERS. Ice Age-one body of water & one species of fish. Dries up in diff. areas. Fish pop isolated. Fish diverged & could no longer interbreed even if brought together. REPROD. ISOLATION Inability of formerly interbreeding to reproduce offspring. Early and late frog breeding times have been selected against c/o predators CONVERGENT EVOLUTION Unrelated species become similar in appearance as they adapt to same kind of environment. MANY DIVERSE ORGANISMS SHOW C ANATOMICAL SIMILARITIES O M P Bat wing A N A T O M Y Bird wing Pterodactly wing Human arm HOMOLOGY-SIMILAR STRS IN DIFFERENT SPECIES OFTEN DESPITE DIFF FUNCTIONS C FORM FOLLOWS FUNCTION O IF 2 SPECIESHAD A COMMON M ANCESTOR THEYSHOULD P HAVE MAINTAINED “BUT A MODIFIED” THE SAME N COMPONENT PARTS, BONES, A MUSCLES ETC. T O HOMOLOGOUS STR’S = M PHYSIOLOGICAL STR’S THAT Y HAS BEEN ADAPTED FOR A NEW FUNCTION. C VESTIGAL STR’S - REMAINS O OF STR’S THAT WERE M FUNCTIONAL IN SOME P ANCESTOR. ARE OFTEN A HOMOLOGOUS TO ORGANS N THAT ARE USEFUL IN OTHER A SPECIES. T O M Y Human tail bone is homologous to functional tails of other primates C O M P A N A T O M Y ANALOGY-SIMILAR FUNCTION BUT DIFFERENT STRUCTURES EXP: BIRD WINGS & INSECT WINGS=FLIGHT BUT DIFFERENT STR’S & VARIATIONS. NEARLY ALL ORGANISMS USE THE B SAME BIOCHEMICAL MOLECULESI DNA, ATP & ENZYMES O C H E M I C A L COMPARISON OF BASES BETWEEN CHIMP AND HUMAN= 99.125% SIMILARITY E EARLY STAGES OF M DEVELOPMENT OF EMBRYOS B SHOW PECULIAR SIMILARITY R Y O L O G Y SUGGESTS COMMON ORIGIN PURPLE-SULFUR BACTERIA P R E C A M B R I A N T I M E STROMATOLITES-BACT COMMUNITIES CS P A L E O Z O I C E R A CAMBRIAN EXPLOSION SHOWS NUMEROUS FAMILIES OF PALEOZOIC FAUNA BRACHIOPODS TRILOBITE SMALL MARINE INVERTEBRATES PLUS CORALS ECHINODERMATASPINY-SKINNED & RADIAL SYMMETRY AGRIOCRINUSFOSSIL SOFT BODIED & UNMINERALIZED PARTS OUR OWN PHYLUM WAS C REPRESENTED BY A SMALL A SLIVER-LIKE THING THE M PIKAIA - FOUNDER OF B PHYLUM CHORDATA? R I A N CAMBRIAN S I L U R I A N Plants evolved from algae c/o chlorophyl & starch storage- moss first land plants but still need H2O First vascular land plant- cooksonia-no leaves, flowers or seeds but probably S root hairs and sporangia(420mya) i l u r i a n D FIRST LAND ANIMALSE Myriapods, centepedes, millipedes V O N I A N P E R Worms with appendages TETRAPOD EVOL. FROM FISH D OUT OF H2O. FISH HAD SERIES E OF BONES ARRANGED LIKE V O ARMS/LEGS. N I A N P E R TETRAPOD ANTHRACOSAUR TETRAPOD AMPHIBIAN-TRANSITION FORM BETWEEN FISHES & AMPH. WITH NOTOCHORD SPINE & RIBCAGE ICHTHOSTEGAAMPH. BELIEVED TO BE FIRST LAND VERT. DERIVED FROM LOBE FINNED FISH DEVONIAN DROUGHTS MAY HAVE BEEN CAUSE FOR NS TO FAVOR THOSE FISHES WHO VENTURED OUT TO PARCHED EARTH COELACANTH-LOBE FINNED RHIPIDISTIANS LUNGFISH-EXTINCT AMPHIBIANS VERT. ADULTS USE LUNGS LARVAE-LONG TAILS USED GILLS COLD-BLOODED & EGGS LAID IN H2O HAVE EXISTED 350MYA OLDEST GROUP OF TERRESTRIAL VERTEBRATES PTERPLAX ANDRIAS C A R B O N I F E R O U S FERN-ALLOPTERIS (307MYA) FERNS GYMNOSPERMS P E R M I A N REPTILES REPTILE-DIMENTRODON REPTILE-HYLONOMUS FERN-LYGINOPTERIS 307MYA FERN-GLOSSPTERIS FERN-CALAMITESSPORE-BEARING CLUB MOSSLEPIDODENDRON-LEAF SCARS ON TRUNK-100FT ACROSS & 3FT DIA. CARBONIFEROUS LAND PLANTS AND INSECTS POST PERMIAN EXTINCTION-GYMNOSPERMS BECAME ABUNDANT. HAVE SEEDS FROM P SEEDLESS ANCESTORS - HELPED TO DISPERSE O & ENCASED SPERM PONDEROSA S T P E R M I A N 2455 YRA ARISTATA CONES 2455 YRA LEBACHIA-OLDEST RELATIVE OF CONIFERS BRISTLECONE GHOST 4776 YRA EUPARKERIA-BELIEVED TO BE RELATIVES OF ARCHOSAURS THE CROCODILES, DINOSAURS, AND BIRDS. SEEM TO BE BIPEDAL FOR SHORT DISTANCES TRIASSIC-245-208mya-middle M animals-reptile like mammals & E S dinosaurs O Z O I C JURASSIC-208-146mya-more dinosaurs and first mammals appear CRETACEOUS-146-65mya-first flowering plants. Extinction of E R dinosaurs & modern birds A appear=life as it now exists on earth. M TRIASSIC E Pangaea S Hot & dry O Z Seasonality O strong I Small dino’s C ferns, cycads E R A Gymnosperms JURASSIC CRETACEOUS breaks apart almost like today warm/moist warm, high sea level no polar ice later sea levels down flooded plains greater extremes archaeopteryx dino’s flourish flying pterosaur angiosperms large dino’s ants & butterflies Major extinction at end of this era DINOSAURS EVOLVED FROM ARCHOSAUR REPTILES-THEIR CLOSEST RELATIVES ARE CROCODILES Dinos evolved upright stance & warm blooded which allowed for continuous locomotion. Cladistically birds are dinosaurs. Transitional fossil-mix of reptilian & avian C R E T A C E O U S T O T E R T I A R Y Angiosperms evolved from gymnosperms. Closest relatives are the Gnetophytes=outcrops of the flowering plants. ANGIOSPERMS ARE THE DOMINATE FLORA OF THE WORLD(3/4 OF ALL LIVING PLANTS ARE ANGIOSPERMS)DEVELOPED FRUITS & FLOWERS FOR POLLEN AND SEED DISPERSAL EXTINCTION-DECREASE IN BIOLOGICAL DIVERSITY. 99.9% OF ALL SPECIES THAT EVER EXISTED ARE NOW EXTINCT! WHY? ENVIRONMENTAL CHANGE: LIVING: competition, new parasites, new predators, new prey defenses. NON-LIVING: climate, soil, pH, salinity. Extinction occurs after a species has been reduced to a very limited distribution or has become specialized in its food, habitat or behavior patterns EXAMPLES: Everglades kite feeds on a certain snail who’s pop was reduced by swamp draining. Ivory-billed woodpecker was eliminated by destruction of southern forests Sea cows swim slowly along shorelines and were easy targets for whalers in Pacific NW-went extinct. Will our species become extinct? Nuclear winter-cooling effects of a large number of explosions results in dust or particles in the air blocking sunlight. Global nuclear war could produce temperatures of less than -40 C in 80 days-most crops and some humans would not survive. Comets and asteroids-impacts would throw up large clouds of particulate. Impact on other species due to: Habitat destruction by man Introduction of competing & predatory species & parasites by man Overexploited resources by humans. ACKNOWLEDGEMENTS www.axel-and-alice.com/ghbc //bioweb.cs.earlham.edu/9-12/evolution www.talkorigins.org www.fieldmuseum.org/exhibits www.xs4all.nl/~steurh www.time-travel.com/cenozoic //fp.bio.utk.edu/darwin www.infoplease.com //teamwork.icdavis.edu //bioserve.latrobe.edu.au/vcebiol //depts.washington.edu/vert //ald.zen.uni-breman.de www.gpc.peachnet.edu/~pgore //library.thinkquest.org/19926 //geology.wr.usgs.gov //biocrs.biomed.brown.edu.Books www.ucmp.berkeley.edu/vertebrates //darwinsmistake.com www.life.umd.edu/classroom/bsci124 www.sprl.umich.edu/glc //daphne.palomar.edu/wayne/ww060/ //fig.cox.miami.edu/faculty/Tom/bil160 www.zoomdinosaurs.com www.sc2000.net/~czarembra www.kean.edu/~biology www.truman.edu/academics/ss