Transcript CH 7 SEC 3

CH 7 SEC 3
EVOLUTION OF SPECIES
GOAL/PURPOSE

STUDENTS KNOW THE ROLE OF
GENETIC VARIATION AND EXTINCTION
HAS PLAYED IN THE FORMATION OF
LIFE OVER THE HISTORY OF EARTH
AND HOW WE ARE TODAY!
VARIETY OF SPECIES
HOW MANY MILLIONS OF SPECIES
EXIST?
 1.5 MILLION TO???

 KEY- OVER TIME, DIFFERENT
ENVIRONMENTS AND GENETIC
VARIATION HAVE PRODUCED,
THROUGH NATURAL SELECTION, THE
VARIETY OF ORGANISMS THAT EXIST
TODAY.
CONT’D
 HABITAT- IS THE SPECIFIC
ENVIRONMENT THAT PROVIDES THE
THINGS AN ORGANISM NEEDS TO
LIVE, GROW, AND REPRODUCE
 KEY-A NEW SPECIES CAN FORM
WHEN A GROUP OF ORGANISMS
REMAINS ISOLATED FROM THE REST
OF ITS SPECIES LONG ENOUGH TO
EVOLVE DIFFERENT TRAITS.
CONT’D
 GRAPHIC ISOLATION- IS
WHEN SOME MEMBERS OF A SPECIES
BECOME CUT OFF FROM THE REST
OF THE SPECIES (SEE GALAPAGOS
ISLANDS)
 http://video.nationalgeographic.com/video/
places/parks-and-nature-places/coastsand-islands/ecuador_galapagos/
INFERRING SPECIES
RELATIONSHIPS
 KEY- SCIENTIST HAVE COMBINED
THE EVIDENCE FROM DNA, PROTEIN
STRUCTURE, FOSSILS, EARLY
DEVELOPMENT AND BODY
STRUCTURE TO DETERMINE THE
EVOLUTIONARY RELATIONSHIPS
AMONG SPECIES
EXTINCTION OF A SPECIES
 EXTINCT- WHEN NO MEMBERS OF A
SPECIES ARE ALIVE (WOOLLY MAMMOTHS)

WHAT MAKES A SPECIES EXTINCT?
 KEY- EXTINCTION IS CAUSED BY A
CHANGE IN A SPECIES ENVIRONMENT. THE
MEMBERS OF THE SPECIES MAY NOT HAVE
ADAPTATIONS THAT ALLOW THEM TO
SURVIVE AND REPRODUCE IN THE
CHANGED ENVIRONMENT
EXTINCTION

http://www.brainpop.com/science/ourfragil
eenvironment/extinction/preview.weml
THERE ARE MANY WAYS
EXTINCTION CAN HAPPEN…
A
NEW DISEASE
 LOSS OF FOOD SOURCE
 PREDATORS KILL THEM OFF
 HUMAN IMPACT
 OVER HUNTING
 DESTRUCTION OF ENVIRONMENT
 CLIMATE CHANGE
 CATASTROPHIC EVENTS
Cont’d
 Climate Change- has been the leading
cause of extinction
 EX- an area that was once warm and moist
becomes cool and dry
 Resulting- in plants dying and the animals that
feed on those plants dying as well or becoming
extinct
 KEY- SOME ORGANISMS IN A SPECIES MAY
HAVE TRAITS THAT HELP THEM SURVIVE IN
A CHANGED ENVIRONMENT.
HORSESHOE CRABS HAVE
SURVIVED MANY CLIMATE
CHANGES
HORSESHOE CRAB
RECENTLY EXTINCT ANIMALS
http://listverse.com/2009/07/25/10recently-extinct-animals/
 http://www.youtube.com/watch?v=0Kwzg8
WmSEU
 http://news.discovery.com/videos/why-tellme-why-mass-extinction.html

REVIEW QUESTIONS
WRITE THE QUESTION AND ANSWER
 1. IDENTIFY 2 FACTORS THAT
ACCOUNT FOR DIVERSITY OF
SPECIES.
 2. HOW CAN ISOLATION LEAD TO THE
FORMATION OF A NEW SPECIES?
 3. WHAT CAUSES EXTINCTION?
