sELECTION IS JUST THE ISOLATING OF A PORTION OF A POPULATION IN WHICH A CERTAIN TRAIT OR NUMBER OF TRAITS GROWS TO PROMINENCE IN CONTRAST WITH THE CHARACTERISTICS OF THE POPULATION FROM WHICH IT SPLIT OFF. nATURAL SELECTION IS GENERALLY THOUGHT OF AS TRAITS BEING SELECTED BY THE ENVIRONMENT, AS FOR INSTANCE A PARTICULAR KIND OF BEAK WHICH EVOVLES OVER TIME TO BETTER MAKE USE OF A PARTICULAR KIND OF FOOD THAT IS MORE READILY AVAILABLE IN THE ENVIRONMENT THAN SOME OTHER KINDS. OVER A NUMBER OF GENERATIONS THE PREVANLENCE OF THIS FOOD SOURCE FAVORS THE USE OF A PARTICULAR BEAK SHAPE UNTIL THE BIRD BECOMES CHARACTERIZED BY THAT SHAPE.
ok, i SUPPOSE THAT MUST HAPPDEN SOMETIMES BUT IT DOESN'T SEEM TO BME TO BE THE MOST LIKELY OR MOST COMMON WAY TRAISTS BECOME CHARACTERISTIC OF POPULATIONS. wHAT HAPPENS WHEN A NUMBER OF INDIVIDUALS SPLIT OFF FROM A LARGER POPULATION AND BECOME REPRODUCTIVELY ISOLATED FROM THE LARGER POULATION OVER A NUMBER OF GENERATIONS IS THAT THERE IS A NEW SET OF GENE GREQUENCIES FROM THEAT OF THE EARLIER POPULATION, SO THAT SOME TRAITS ARE MORE PREVALENT AND SOME LESS EXPRESSED IN THE NJEEW THAN IN THE OLD. i THINK WHAT MOST OFTEN HAPPENS IS THAT THE TRAITS DO THE ESLECTING. tHEY FIND WHATEVER IS IN THE ENVIRONMENT THAT BEST SUITS THEM RATHER THAN THE OTHER WAY AROUND. oF COURSE THEENVIRONMENT MAY ALSO CONTRIBUTE TO THE PROCESS BUT PROBABLY A LOT LESS THAN THE THEORY SUPPOSES.
ii'M THINKING OF dARWIN'S FINCHES. tHERE ARE QUITE A FEW DIFFERENT POPULATIONS OF FINCHES WITH DIFFERENT BEAK TYPES, SOME SHORT AND STUBBY, SOMELONG AND NARROW AND EVERYTHING IN BETWEEN. THEY ARE EACH BEST ADAPTED TO PARTICULAR KINDS OF FOODS AVAILABLE IN THEIR ENVIRONEMNTS lONG NARROW BEAKS CAN BPROBE BENEATH BARK TO FIND INSECTS, SHORT STUBBY BEAKS CAN CRACK THE SHELLS AND HUSKS OF NUTS AND SEEDS, AND SO ON AND S FORTH. eACH BEAK TYPE IS FOUND IN THE MOST SUIGTABLE ENVIRONEMTN FOR IT. dSsURVIVAL OF THE FITTEST AND ALL THATL.
bUT THE GENOME DOES ITS OWN THING AND EVRY GENERATION OF SEXUALLY REPRODUCING ANIMALS HAS VARIATIONS ON THE ANIMAL'S TRAITS. wHEN A LONGER NARROWER BEAK HAPPENS TO SHOW UP IN AN INDIVIDUAL THAT ONE WILL NATURALLY FIND ITSELF DIGGING INSECTS OUT FROM THE TREE BARK AND THAT SORT OF THING. iT WILL PASS ON ITS NARROWER BEAK TO ITS OFFSPRING WHICH WILL ALSO GRAVITATE TO THE KIND OF FOOD THAT BEAK DEALS WITH SO WELL. tHEY MAY FIRST WANDER TO THE AREAS OF MORE TREES WITH MOR INSECTS AND GET ISOLATED FROM OTHER FINCHES AND THEN PRPAGAGTE IN A NEW EVIRONMENT AND SO ON. i'D GUESS THIS IS A BETTER SEXPLANATION OF THE VARIETY OF FINCHES THAN NATURAL SELECTION WHICH SEEMS TO ME TO BE AN OAWFULLYH COSTLY WANY OF BRINGING OUT NEW TRAITS , WHICH IS OF COURSE EXPRESSED IN THAT SLOGAN ANYWAY, THE SURVIVAL OF THE FITTEST. THE LESS FIT JUST MAY NOT SURVIVE AT ALL WHERE THEY ARE NOT ADAPTED. bUT IF THE TRAIT SEEKS ITS BEST MATCH IN THE ENVIRONMENT THANEN THE BIRDS JUST GO WHERE THEY BEST FIT AND SPLIT OFF ACCORDING TO THAT PRINCIPLE. FORMING NEW POPULATIONS.
i THINK ALSO OF THE pODmRCARU LIZARDS. THIS WAS AN EXPERIMENT DONE BY SCIENTISTS i DN'T KNOW WHEN. tEN LIZARDS WERE CHOSEN FROM HE LARGE POPULATION OF LIZARDS ON THE MAINLAND, FIVE MALE AND FIVE FEMALE i THINK, AND LET LOOSE ON AN ISOLAND CALLD pOD mRCARU WHERE THERE WERE NO LIZARDS. tEHY WERE LEFT THERE AND THE SCIENTIESTS WHENT AWAY BUT CAME BACK THIRTY YEARS LATER TO SEE HOW THE LIZARDS HAD FARED IN THEIR NEW ENVIRONMENT. THEY FOUND THAT ALL THE LIZARDS ON THE ISOLAND HAD DEVELOPED VERY LARGE HEADS AND STRONG JAWS AND A TOUGHER DIGESTIVE SYSTEM, AND RTHAT THEY ATE A MUST ROUGHER DIET THAN THOSE OF THE ORIGINAL POPULATION ON THE MAINLAND.
fIRST OF ALL THEY DIDN'T EXPECT THAT MUCH CHANGE IN SO SHORTG A TIME BECAUSE OF COURSE THEY WERE THINKING IN TERMS OF EVOLUTION WITH ITS MILLIONS OF YEARS SO THIS SHOULD MAKE IT CLEAR THEY AWERE WITNESSING SIPLY THE PROLIFERATION OF A PARTICULAR VARIATION THAT WAS BUILT INTO THE LIZARD GENOME AND JUST HAPPENED TO BE MORE PREVALENT IN THE TEN LIZARDS THEY RANDOMLY SELECTED TO PULATE THE ISOLAND. THAT TRAIT INCREASED FROM GENERATION TO GENERATION JUST BASED ON PRINC8IPLE SOF GENETIC INHERITANCE, NHOT ANY PRESSURE FROM THE ENVIRONMENT. tHERE WAS ALL THE SAME KIND OF FOD ON THE ISLLAND AS ON THE LMAINLAND BUT AS THE LIZARDS DEVELOPED THE ABILITYT TO EAT THE ROUGHTER TOUGHER FOOD IT BECAME THEIR MAIN SOURCE OF DIET. tHAT'S THE BEST EXPLANATION OF IT IT SEEMS TO BME.
iFtHERE IS SUPPOSEDLY NO SUCH THING AS RACE AND HAT'S TRUE ENOUGH IN SOME IMPORTANT SENSE, BUT IT'S A SCIENTIFIC TERM THAT DESCRIBES THE VARIETIES OF LIVING THINGS FOUND IN NATURE, OR THAT'S HOW IT WAS ORIGINALLY USED. yOU COULD TALK OF A RACE OF RACCOONS AND SO ON. wENEVER A NUMBER OF INDIVIDUALS SPLIT OFF FROM THE MAIN POPULATION AND INBRED WITH ONE ANOTHER IN ISOLATION FROM THE GREATER POPULATION A WHOLE PECULIAR SET OF TRAITS WILL EMERGE TO DEFINE THE NEW POPULATION IN SDISTINCTION ROMT HE ORIGINAL, AHND THAT'S TRUE OF PEOPLE AS WELL AS ANIMALS. aSIANS LOOK DIFFERENT FROM eUROPEANS BECAUSE THEYVE DEVELOPED SEPARATELY FROM EIACH OTHER FOR HUNDREDS OF YEARS. THAT'S ALL A REACE IS.
aNYAY, YES SLECTION IS THE AGENT OF CHANGE OF "EVOLUTION" IN THE SIMPLE SENSE BUT IT INVOLVES THE ELIMINATION OF OTHER TRAITS IN THE PROCESS OF DEVELOPING ITS OWN TRAIT PICTURE IN A NEW POPULATION. THERE IS CONSEQUENCTLY A TREND TOWARD REDUCTION IN GENETIC DIVERISTY. tHERE IS NOT AN INCREASE. MANY TRAITS CHARACTERISTIC OF THE NEW POULATION MAY BECOME FIXED OR HOMOZYGOUS THROUGHT THE WHOLE GROUP, TAT'S A LOSS OF THE ALLELES FOR HETEROZYGOSITY. THIS IS JUST A TGREND IN LARGE POPULATIONS BUT IN SMALL PULATIONS IT CAN BECOME CRUCIAL AS WITH ENDANGERED SPECIES AND PUREBRED AHIMALS WHICH DEVLEOP GENETIC DISEASES. iN THE ORIGINAL CREATED WORLD WHICH HAD NO DISEASES OR DEATH SUCH GENETIC FACTS WOULD NOT THREATEN THE ANIMAL BUT IN THIS FALLEN WORLD THEY ARE DEFINITELY THREATENEED. BUT THE POINT i'M TRING TO MAKE IS SIMPLY THAT IT'S AT THESE EXTREMES THAT THE NORMAL TREND OF EVOLUTION IS SHOWN AND IT'S AN IELIMINATION AND A REDUCTION, NOT AN INCRESE, AND THAT IS SIMPLY NOT WHAT EVOLUTION NEEDS IN ORDER TO CONTINUE. iN FACT AT THESE EXTREMES NO FURTHER CHANGE OR EVOLUTION IS POSSIBLE AT ALL, IT'S COME TO AN END.
mUTATION ALWAYS COMES UP AT THIS POINT IN THE CONVERSATION. BUT WHAT DOES MUTATION DO? aLL IT DOES IS CHANGE THE SEQUENCE OF EXISTING GENES, MOREST FREQUENTLY MAKING NO CHANGE IN THE TRAIT GOVERNMENTED BY THE GENE, BUT OFTEN BRINGING ABOUT SOME SORT OF DISEASE, AND ONLY VERY VERY RARELY IF AT ALL BRINGING ABOUT ANYTHING USEFUL TO THE CREATURE. AND WHAT IF A MUTATION OCCURS IN THE CHEETAH SAY THAT IS ACTUALLY ENEFICITAL. wLL IT WOULD HAVE TO BE IN THE REPRODUCTIVE SYSTEM AND IT WOULD HAVE TO BE PASSED ON TO ALL ITS OFFSPRING AND IT WOULD ACT JUST LIKE ANY OTHER GENE. TO BE SELECTED IT WOULD DISPLACE OTHER GENES AND SO ON. a MUTATION IS JUST ANOTHER GENE IN THE END IF IT IS AT ALL USEFUL AND MOSTLY IT ISNIT.
