THE FACTS ON FILE DICTIONARY OF EVOLUTIONARY BIOLOGY
ENTRIES A TO Z SEE ADENINE GENOTYPIC EFFECT ABC FLORAL MODEL IN EVOLUTIONARY DE GENES THAT BRING ABOUT THE ARRANGEMENT OF PARTS OF A FLOWER IN WHORLS CIRCLES RATHER THAN ALONG AN AXIS WORK ING ON ARABIDOPSIS A SMALL ANNUAL PLANT OF THE BRASSICACEAE MUSTARD FAMILY IT HAS BEEN DISCOVERED THAT THREE CLASSES OF GENES ARE INVOLVED DENOTED A B AND C A GENES ALONE ARE RESPONSIBLE FOR THE OUTER WHORL OF LEAFLIKE SEPALS A AND B GENES TOGETHER REG ULATE THE DEVELOPMENT OF THE NEXT WHORL OF PETALS B AND C GENES CONTROL THE DEVELOP MENT OF THE STAMENS C GENES ALONE DETER MINE THE DEVELOPMENT OF THE INNER WHORL OF CARPELS WHAT IS MOST SIGNIFICANT IS THAT THE GENE LEAFY A HIGHER CONTROL GENE REGU LATES THE ABC SYSTEM SHOWING THAT THE FLOWER PARTS ARE BASED ON A LEAF ARCHETYPE OR BASIC PLAN SEE ALSO RECAPITULATION THE DEVELOPMENT OF LIVING FROM NONLIVING MATTER AS IN THE ORIGIN OF SEE DATING TECHNIQUES THE OLDEST ROCKS KNOWN DATED AT JUST OVER 4000 MILLION YEARS OLD FOUND IN NW CANADA SEE EARTH AGE OF A METHOD BY WHICH OR GANISMS ADAPT AND SURVIVE TEMPORARY BUT RECURRING STRESSFUL ENVIRONMENTS IN WHICH PRIOR EXPOSURE TO A PARTICULAR STRESS LEADS TO THE ORGANISM BEING BETTER ABLE TO COPE THE NEXT TIME IT IS ENCOUNTERED THE FIRST EX POSURE RESULTS IN THE EXPRESSION OF PROTEINS E G HEAT SHOCK PROTEINS THAT HELP THE OR GANISM COPE AND THEREAFTER THESE PROTEINS ARE ONLY EXPRESSED WHEN THE STRESS IS EN COUNTERED EXPRESSING SUCH PROTEINS ALL THE TIME WOULD BE A DRAIN ON RESOURCES SO IT IS AN ADVANTAGE TO BE ABLE TO EXPRESS THEM ONLY WHEN THEY ARE NEEDED DENOTING A CHROMOSOME OR FRAGMENT OF A CHROMOSOME THAT LACKS A STONE AGE TOOLS ESPE CIALLY HAND AXES THEY HAVE BEEN EXCAVATED ALONG WITH EARLY HOMINID REMAINS FOR EX AMPLE THOSE OF HOMO ERECTUS AT OLDUVAI GORGE IN EAST AFRICA AND ALSO WITH HOMO ERGASTER THE USE OF THESE TOOLS IN HUMAN EVOLUTION IS NOT THOUGHT TO BE AS IMPORTANT AS IT ONCE WAS AS IT HAS BEEN DISCOVERED THAT CHIMPANZEES HAVE ALSO USED TOOLS EXTEN SIVELY SEE ALSO OLDOWAN INDUSTRIAL COM PLEX MOUSTERIAN TOOLS UPPER PALEOLITHIC COELOM I E THERE IS NO CAVITY BETWEEN THE DIGESTIVE TRACT AND THE BODY WALL EXAM PLES ARE THE PLATYHELMINTHES AND THE NE MERTINES RIBBON WORMS ACQUIRED CHARACTERISTIC ACQUIRED TRAIT A PHENOTYPIC CHANGE IN THE STRUCTURE OR FUNCTION OF AN ORGAN OR SYSTEM DURING THE LIFE OF AN ORGANISM BROUGHT ABOUT BY THE USE OR DISUSE OF THAT ORGAN OR SYSTEM OR BY ENVIRONMENTAL INFLUENCES MOST ARE THE RE SULT OF DISEASE INJURY STARVATION OR SENES CENCE ACQUIRED CHARACTERISTICS ARE NOT GENETICALLY BASED AND CANNOT BE INHERITED FOR EXAMPLE SPORTSMEN MAY DEVELOP STRONG MUSCLES AND PLANTS GROWING NEAR COASTS SHOW ADAPTATIONS TO THE DRYING EFFECTS OF SEA AIR SEE ALSO LAMARCKISM ANY CHORDATE ANIMAL WITH A NOTOCHORD AND LACKING A BRAIN AND SKULL ACRANIATES INCLUDE THE UROCHORDATA AND SEE RADIAL SYMMETRY SEE PRIMATES PROSIMIANS A PROPERTY OR TRAIT E G PHYSIOLOGICAL STRUCTURAL OR BEHAVIORAL THAT CONTRIBUTES TO REPRODUCTIVE SUCCESS OR FITNESS THE GENES FAVORED BY SELECTION ARE PASSED ON TO SUCCESSIVE GENERATIONS MOST ORGANISMS ARE NOT PERFECTLY ADAPTED BECAUSE OF DEVELOPMENTAL GENETIC AND HIS TORICAL CONSTRAINTS TRADE OFFS BETWEEN COMPETING DEMANDS AND BECAUSE IT TAKES TIME FOR BETTER ADAPTATIONS TO DEVELOP OR GANISMS THAT HAVE BECOME HIGHLY ADAPTED TO ONE ENVIRONMENT ARE THEN OFTEN NOT SO ADAPTABLE AS LESS SPECIALIZED ORGANISMS AND ARE AT A DISADVANTAGE IN A CHANGING ENVI RONMENT ADAPTATION VERSUS ADAPTABILITY SEE ADAPTIVE EVOLUTION NATURAL SELECTION TION OF THE ADAPTIVE VALUE OF A CHARACTER ADAPTIVE EVOLUTION EVOLUTIONARY CHANGE THAT IS NOT RANDOM BUT IN WHICH AN ORGAN ISM BECOMES INCREASINGLY ADAPTED TO ITS EN VIRONMENT ADAPTIVE EVOLUTION SHOWS A STRONG CORRELATION BETWEEN REPRODUCTIVE SUCCESS AND HERITABLE VARIATION AND IS DRI VEN BY NATURAL SELECTION COMPARE NEUTRAL ADAPTIVE LANDSCAPE SEE ADAPTIVE TOPOG A BEHAVIOR IN A POPULA TION THAT FAVORS AN INCREASE IN THE NUMBER OF OFFSPRING PRODUCED EVEN IF SUCH A BE HAVIOR IS ONLY PARTLY GENETICALLY DETER MINED IT WILL SPREAD THROUGHOUT THE POPU LATION IF CIRCUMSTANCES CHANGE SO THAT IT NO LONGER PROVIDES ANY SURVIVAL OR REPRODUC TIVE ADVANTAGE THE BEHAVIOR WILL CONTINUE TO BE EXHIBITED IT WILL CEASE ONLY IF IT BE COMES POSITIVELY DISADVANTAGEOUS IN THE THE GRADUAL FORMA TION THROUGH EVOLUTION OF A NUMBER OF DIF FERENT VARIETIES OR SPECIES FROM A COMMON ANCESTOR EACH ADAPTED TO A DIFFERENT ECO LOGICAL NICHE WHEN A SPECIES DEVELOPS A NEW CHARACTERISTIC IT MAY BE ABLE TO IN HABIT A DIFFERENT NICHE FOR EXAMPLE WHEN REPTILES DEVELOPED FEATHERS AND EVOLVED INTO BIRDS THEY WERE ABLE TO INHABIT AN ENORMOUS NEW NICHE THERE ARE FOR EXAM PLE OVER TWICE THE NUMBER OF BIRD SPECIES COMPARED TO THOSE OF MAMMALS THERE ARE ALSO SEVERAL MILLION SPECIES OF INSECTS A CLASSIC EXAMPLE OF ADAPTIVE RADIATION IS IL LUSTRATED BY THE FINCHES OF THE GAL PAGOS ISLANDS INVESTIGATED BY CHARLES DARWIN KNOWN AS DARWIN S FINCHES THERE ARE SPECIES DARWIN SUGGESTED THAT THE FINCHES INHABITING THE NORTHERNMOST ISLANDS WERE GEOGRAPHICALLY ISOLATED FROM THOSE ON THE OTHER ISLANDS AND EVOLVED INDEPENDENTLY THE COMMON ANCESTOR IS THOUGHT TO BE A SEED EATING GROUND FINCH WHICH EVOLVED INTO TWO GROUPS GROUND FINCHES AND TREE FINCHES THE GROUND FINCHES EVOLVED INTO SIX MODERN SEED EATING SPECIES AND THE TREE FINCHES EVOLVED INTO EIGHT MODERN SPECIES ONE SEED EATING AND THE OTHER SEVEN INSECT ADAPTIVE TOPOGRAPHY ADAPTIVE LAND SCAPE FITNESS SURFACE A GRAPH OF THE MEAN FITNESS OF A POPULATION AGAINST GENE OR GENOTYPE FREQUENCY PEAKS CORRESPOND TO GENOTYPIC FREQUENCIES AT WHICH THE AVER AGE FITNESS IS HIGH VALLEYS CORRESPOND TO GENOTYPIC FREQUENCIES AT WHICH THE AVERAGE FITNESS IS LOW SEE GENE MUTATION ADDITIVE GENETIC EFFECT A PHYLOGENETIC TREE IN WHICH THE DISTANCE BETWEEN ANY TWO POINTS IS THE SUM OF THE LENGTHS OF THE BRANCHES ALONG THE PATH CONNECTING TWO POINTS SEE PHYLOGENY SEE ALSO NEIGHBOR SYMBOL A A NITROGENOUS BASE FOUND IN DNA AND RNA IT IS ALSO A CON STITUENT OF CERTAIN COENZYMES E G NAD AND FAD AND WHEN COMBINED WITH THE SUGAR RIBOSE IT FORMS THE NUCLEOSIDE ADENO SINE FOUND IN AMP ADP AND ATP ADE NINE HAS A PURINE RING STRUCTURE ADENOSINE ADENINE NUCLEOSIDE CLEOSIDE FORMED FROM ADENINE LINKED TO D RIBOSE WITH A GLYCOSIDIC BOND ADENOSINE TRIPHOSPHATE ATP IS A NUCLEOTIDE DERIVED G FORTIS SEEDS G DIFFICILIS SEEDS ADAPTIVE RADIATION ILLUSTRATED BY DARWIN S FINCHES