EVOLUTION & SPECIATION

VOCABULARY REVIEW EVOLUTION – CHANGE OVER TIME NATURAL SELECTION - INDIVIDUALS BETTER ADAPTED TO THE ENVIRONMENT ARE ABLE TO SURVIVE & REPRODUCE. A.K.A. “SURVIVAL OF THE FITTEST”

NEW VOCABULARY POPULATION – GROUP OF INDIVIDUALS OF SAME SPECIES THAT INTERBREED GENE POOL – COMMON GROUP OF ALL GENES PRESENT IN A POPULATION

Variation in Populations 2 processes can lead to this: Mutations - change in DNA sequence Gene Shuffling – from sexual reproduction

Nonrandom mating: inbreeding and assortive mating (both shift frequencies of different genotypes)

Natural Selection: differential success in reproduction; only form of microevolution that adapts a population to its environment

Evolution of Populations Occurs when there is a change in the types of genes in a gene pool

Conditions needed for Genetic Equilibrium

SPECIATION THE FORMATION OF NEW SPECIES AS NEW SPECIES EVOVLVE, POPULATIONS BECOME REPRODUCTIVELY ISOLATED REPRODUCTIVE ISOLATION – MEMEBERS OF 2 POPULATIONS CANNOT INTERBREED & PRODUCE FERTILE OFFSPRING.

3 ISOLATING MECHANISMS…….. BEHAVIORAL ISOLATION- CAPABLE OF BREEDING BUT HAVE DIFFERENCES IN COURTSHIP RITUALS (EX. MEADOWLARKS) GEOGRAPHICAL ISOLATION – SEPARATED BY GEOGRAPHIC BARRIERS LIKE RIVERS, MOUNTAINS, OR BODIES OF WATER (EX. SQUIRREL) TEMPORAL ISOLATION – 2 OR MORE SPECIES REPRODUCE AT DIFFERENT TIMES.

Tigon Result of male tiger and female lion mating in captivity. Offspring are infertile. Separated both geographically and ecologically.

Liger Result of male lion and female tiger mating in captivity. Offspring are infertile.

SPECIATION IN DARWIN’S FINCHES SPECIAITON IN THE GALAPAGOS FINCHES OCCURRED BY: - FOUNDING OF A NEW POPULATION, - GEOGRAPHIC ISOLATION which led to -- REPRODUCTIVE ISOLATION and CHANGES IN THE NEW POPULATION’S GENE POOL due to COMPETITION.

Big Question!!! How did life arise on the big blue planet?? Scientists attempt to answer this question scientifically.

Big Bang Theory A cosmic explosion that hurled matter and in all directions created the universe 10-20 billion years ago Evidence it explains why distant galaxies are traveling away from us at great speeds Cosmic radiation from the explosion can be observed The Big Bang theory probably will never be proven; consequentially, leaving a number of tough, unanswered questions.

What was early earth like? Earth was Hot!! Little or no oxygen Gasses in atmosphere: Hydrogen cyanide (poison to you!) Hydrogen sulfide Carbon dioxide Carbon monoxide Nitrogen water

So how did the earth get oxygen? Some of that oxygen was generated by photosynthetic cyanobacteria Some came from the chemical separation of water molecules into oxygen and hydrogen.

Others evolved ways of using oxygen for respiration Oxygen drove some life forms to extinction Others evolved ways of using oxygen for respiration

How did life begin? Miller and Urey’s Experiment Passed sparks through a mixture of hydrogen methane ammonia and water This produced amino acids – the building blocks of life

Miller’s experiment suggests that lightning could have produced amino acids