Chapter 15-1: The Puzzle of Chapter 15-1: The Puzzle of LifeLife’’s Diversitys Diversity

Essential Questions:Essential Questions:What was Charles DarwinWhat was Charles Darwin’’s s contribution to science?contribution to science?What patterns did Darwin observe in What patterns did Darwin observe in the Galapagos Islands?the Galapagos Islands?What contemporary ideas shaped What contemporary ideas shaped DarwinDarwin’’s thinking?s thinking?

Voyage of the Voyage of the HMS BeagleHMS Beagle – 1831 - – 1831 - 18361836

DarwinDarwin’’s observationss observations Patterns of diversityPatterns of diversity

Plants/animals seemed well-suited to their Plants/animals seemed well-suited to their environmentenvironment

Similar environments on different continents Similar environments on different continents had diff. animals/plantshad diff. animals/plants

Living organisms & fossilsLiving organisms & fossils Some fossils resembled animals alive todaySome fossils resembled animals alive today Some fossils unlike anything alive todaySome fossils unlike anything alive today

The Galapogos IslandsThe Galapogos Islands TortoisesTortoises

Low islands hot & dry, sparse vegetation: Low islands hot & dry, sparse vegetation: tortoises had long neckstortoises had long necks

High islands wetter, lush vegetation: High islands wetter, lush vegetation: tortoises had short neckstortoises had short necks

Shells varied in particular ways from island Shells varied in particular ways from island to islandto island

FinchesFinches Beak shape different on different islandsBeak shape different on different islands

The journey homeThe journey home Darwin wondered if animals living on Darwin wondered if animals living on

different islands were once members of the different islands were once members of the same speciessame species

Chapter 15-2: Ideas that Chapter 15-2: Ideas that shaped Darwinshaped Darwin’’s thinkings thinking

An ancient, changing EarthAn ancient, changing Earth Hutton: theory of geological change: Hutton: theory of geological change:

uniformitarianismuniformitarianism Lyle: Lyle: Principles of GeologyPrinciples of Geology: explain past : explain past

in terms of presentin terms of present

LamarckLamarck’’s Theory of Evolutions Theory of Evolution Tendency toward perfectionTendency toward perfection Use and disuse: giraffe reaching for Use and disuse: giraffe reaching for

vegetation could stretch out neckvegetation could stretch out neck Inheritance of acquired traitsInheritance of acquired traits Evaluating LamarckEvaluating Lamarck’’s theorys theory

Behavior doesnBehavior doesn’’t affect genes, so rejectedt affect genes, so rejected But, first theory attempting to explain how But, first theory attempting to explain how

species might change over timespecies might change over time

Population growthPopulation growth Thomas Malthus – 1798Thomas Malthus – 1798

If human pop. continued to grow unchecked, If human pop. continued to grow unchecked, at some point not enough food/space at some point not enough food/space availableavailable

War, famine, disease only things that have War, famine, disease only things that have checked the pop.checked the pop.

Darwin:Darwin: This is true of all living thingsThis is true of all living things Many more organisms are born than can Many more organisms are born than can

possibly survivepossibly survive Therefore, a Therefore, a struggle for existence struggle for existence goes on goes on