TRACING EVOLUTIONARY HISTORY

TRACING EVOLUTIONARY HISTORY

• MACROEVOLUTION– THE MAJOR CHANGES IN THE HISTORY OF LIFE– THE FOSSIL RECORD CHRONICLES (PROVIDES A

TIMELINE) FOR THE EVOLUTION OF LIFE– GEOLOGICAL TIME SCALE• PROVIDES A SEQUENCE OF FOSSILS AND AN OVERVIEW

OF MACROEVOLUTION OVER MILLIONS OF YEARS

TRACING EVOLUTIONARY HISTORY

• THE ACTUAL AGES OF ROCKS AND FOSSILS MARK GEOLOGIC TIME– RADIOMETRIC DATING• BASED ON THE MEASUREMENT OF CERTAIN

RADIOACTIVE ISOTOPES• EXAMPLE???

TRACING EVOLUTIONARY HISTORY

• CONTINENTAL DRIFT HAS PLAYED A MAJOR ROLE IN MACROEVOLUTION– “PANGEA” UNTIL PRESENT

– EXPLAINS THE DISTRIBUTION ACROSS GREAT GEOGRAPHICAL BARRIERS

TRACING EVOLUTIONARY HISTORY• PLATE TECTONICS PLAY A MAJOR ROLE IN

MACROEVOLUTION– FORCES WITHIN THE EARTH THAT FORCE THE MOVEMENT OF

EARTH’S CRUST– CAN RESULT IN VOLCANOES AND EARTHQUAKES, WHICH CAN

LEAD TO MASS EXTINCTIONS– MASS EXTINCTIONS ARE ALMOST ALWAYS FOLLOWED BY HUGE

DIVERSIFICATION OF LIFE-FORMS– EXAPTATIONS

• REFERS TO A STRUCTURE THAT EVOLVED FOR ONE CONTEXT, BUT LATER WAS ADAPTED TO ANOTHER FUNCTION (SUCH ADAPTATIONS ARE KEY FOR DIVERSIFICATION AFTER MASS EXTINCTIONS)

TRACING EVOLUTIONARY HISTORY

• PHYLOGENETIC TREES STRIVE TO REPRESENT EVOLUTIONARY HISTORY

TRACING EVOLUTIONARY HISTORY

• PHYLOGENY EVOLUTIONARY HISTORY OF A GROUP OF ORGANIMS

• PHYLOGENETIC TREES DIAGRAMS THAT TRACE EVOLUTIONARY HISTORY AS BEST AS CAN BE DETERMINED– BASED ON PHENOTYPIC AND GENETIC

SIMILARITIES!!

TRACING EVOLUTIONARY HISTORY

• CLASSIFICATION, OR TAXONOMY, IS BASED ON PHYLOGENY– BINOMIAL

NOMENCLATURE IS THE RESULT OF PHYLOGENETIC STUDIES

TRACING EVOLUTIONARY HISTORY

• PHYLOGENETIC TREES ARE BASED ON PHENOTYPIC AND GENETIC SIMILARITY– PHENOTYPIC SIMILARITY• HOMOLOGOUS STRUCTURES VS ANALOGOUS

STRUCTURES– CONVERGENT EVOLUTION

VS DIVERGENT EVOLUTION

TRACING EVOLUTIONARY HISTORY

• PHYLOGENETIC TREES ARE BASED ON PHENOTYPIC AND GENETIC SIMILARITY– GENETIC SIMILARITY IS BASED

ON AMINO ACID, DNA, AND RNA SEQUENCES

– MORE SIMILAR SEQUENCES SUGGEST MORE COMMON ANCENSTRY

TRACING EVOLUTIONARY HISTORY

• PHYLOGENETIC TREES ARE BASED ON PHENOTYPIC AND GENETIC SIMILARITY– ***MITOCHONDRIAL DNA IS USED FOR

ORGANISMS BELIEVED TO BE MORE RECENTLY RELATED***

– IN ADDITION, THERE IS BELIEVED TO BE A “MOLECULAR CLOCK”• A RELATIVELY CONSTANT RATE OF GENETIC CHANGE,

THAT SUGGESTS A TIMELINE OF EVOLUTION

TRACING EVOLUTIONARY HISTORY

• CLADOGRAMS VS PHYLOGENETIC TREES– CLADOGRAM A

PHYLOGENETIC TREE BASED ON CLADISTICS

– CLADES EVOLUTIONARY BRANCES THAT CONSIST OF AN ANCESTRAL SPECIES AND ALL OF ITS DESCENDANTS

TRACING EVOLUTIONARY HISTORY

• CLADOGRAM OF ALL LIFE!!– IT’S A WORK IN PROGRESS!– 3 DOMAIN SYSTEM – WHAT ABOUT THE 5 -

KINGDOM SYSTEM??

TRACING EVOLUTIONARY HISTORY• YOU KNOW, ALL THIS TALK ABOUT ORGANISMS CHANGING IS

ALL WELL, AND GOOD…BUT UUMM, WHERE DID THE VERY FIRST LIVING THINGCOME FROM? I MEAN, DID IT JUST FALL OUT OF THE SKY?HOW CAN YOUHAVE EVOLUTIONWITHOUT LIFE TOBEGIN WITH?NEXT CHAPTER THE ORIGIN OF LIFE!!!