Chapter 16: Evolution

16-1 Darwin’s Voyage of Discovery

Voyage of the Beagle

•1831, Darwin set sail on ______

•Ship’s naturalist -observer/collector of plants, animals, & fossils

•Left from England, sailed around South America, across Pacific, around Africa, and back to England

•______

•______– change of populations of organisms over time

•Darwin noted 3 patterns of biodiversity:

______– different, yet ecologically similar animal species inhabited separate, but ecologically similar, habitats around the globe (rheas, ostriches and emus)

______– different, yet related animal species occupied different habitats within a local area (tortoise shell shape - Galapagos)

______– fossils of extinct animals were similar to living species

16-2 Ideas That Shaped Darwin’s Thinking

Darwin was influenced by:

•James Hutton - proposed that layers of rock form very ______

–Some rocks move up, while others are buried to create ______

______

–Natural forces such as ______shaped the landscape

–These processes happen very slowly over millions of years

•Charles Lyell – said earth was ______

-Earth changed over time due to geologic forces (volcanoes, earthquakes, wind, erosion, etc.)

-Darwin reasoned that if Earth changed, those who lived on it ______.

•Jean-Baptiste de Lamarck suggested that organisms acquired traits ______to adapt to their environment and passed those acquired traits onto their offspring.

•WRONG – ______

______

•Thomas Malthus – an economist that said the human population was limited by the ______.

-Darwin reasoned that the same limits could apply to organisms in nature.

Natural Variation and Artificial Selection

•Natural Variation – ______.

•Farmers depend on natural variation for ______.

–Only the largest hogs would be bred.

•Artificial Selection – ______.

16-3 Darwin Presents His Case

•Darwin published his findings in 1859 in a book entitled ______

______.

•He was motivated to publish his book in 1859 because Alfred Wallace had independently come up with the same conclusions

Adaptations vs. Variations

•Variations – differences that exist within a population ______

______

•Ex: length of your thumb

•Adaptations –______because that trait improves fitness

•Ex: an opposable thumbs

•Sources of variation:

• – individual genes change

•Ex: ATC  AGC

• – during meiosis, chromosomes get mixed up (crossing over) in making eggs & sperm

• – which sperm fertilizes which egg – determined by chance

•Three types of adaptations:

• – ______of an organism

•Ex: long tongue to get food, sharp teeth

• – ______an organism takes

•Ex: migration, tracking prey, storing nuts, growing toward light

• – ______

•Ex: venom, ink of octopus, protein in web, respiration rate, digestive enzyme, blood clotting

CamouflageMigrationSnake Venom

•______

•Natural selection - the process by which environment acts on a population, determining which organisms are most “fit.” Those organisms who are most “fit” survive and reproduce more often than those who are not.

•Fitness – reproductive success (“survival of the fittest”)

Common Descent

•Darwin noticed similarities between species seen on mainland and island chains

•Thought similarities could be explained by – species came to ______as the species adapted to its new environment.

16.4 Evidence of Evolution

•______

•Anatomy

•______structures

•______

Fossil Evidence

•Fossils - the remains of past life

•Ex: shells, bones, teeth, imprints

•Tell us ______

•Record is incomplete – many organisms leave no fossils behind

Anatomical Evidence

•All vertebrate forelimbs contain ______–suggests they evolved from a common ancestor.

•Homologous structures - structures that are similar because they ______

______

•Ex: frog, lizard, bird, whale, cat, bat, and human forelimbs

•Analogous structures - ______

•Ex: bird wing & insect wing

•Vestigial structures – ______

______but may have been used by its ancestors.

•Ex: human appendix, python leg bone

Embryology –______at certain stages of development, ______they are thought to be.

Biochemical Evidence

•Universal genetic code – ______

______in proteins

•All organisms have certain organic molecules in common.

1.Hemoglobin - carries oxygen in blood

2. ______- protein for cell respiration found in almost all living cells

3. ______– control development

Direct observation – We’ve seen evolution occur in cases like:

•The Grant’s studies of finches on Daphne Major in the Galapagos

•Bacteria becoming resistant to antibiotics

•Insects that become resistant to pesticides