Evolution. Darwin s Journey and Observations

Transcription

1 Evolution Darwin s Journey and Observations

2 Who was Charles Darwin? English naturalist Took a 5 year voyage on the HMS Beagle Voyage s intent was to explore the coast of South America Darwin took many specimens and made many important scientific observations

3 Where did the HMS Beagle go?

4 The Galapagos Islands

5 Galapagos Tortoises Much larger than tortoises found elsewhere Tortoise sizes and shell shapes vary on different islands Islands with a lot of food à large tortoises with dome-shaped shells Islands with less food à smaller tortoises with saddle-shaped shells Why are there different shapes? Height, size, food, and weather!

6 Saddlebacked tortoise Domed tortoise

7 Blue-footed Booby Sea gull with bright blue feet The foot color comes from pigments in their diet the more well-nourished, the bluer they are.

8 Male parades feet in front of female, do a crazy dance, and then give the female one last look at his feet Females continuously evaluate male foot color in mate Evidence for sexual selection Mating Dance

9 The only aquatic iguana found anywhere in the world! Hypothesized that the marine iguana and land iguana came from a common ancestor Marine Iguana

10 What ideas influenced Darwin? Jean Baptiste Lamarck s Theory of Acquired Characteristics Use & Disuse theory Ex: Giraffes Believed that giraffes stretched necks to reach food, then passed that on to offspring

11 What does Lamarck s theory mean? If I dye my hair red, will my babies have red hair? If I NOPE. work out and pump iron all day, every day, will my future children be more muscular? If I spend hours in a tanning bed, will my children inherit darker skin? You can t change your genes!

12 The Theory : Natural Selection The most fit organism survives and reproduces There is a struggle for existence known as competition for food, shelter, and mates Living things reproduce in greater numbers than will survive All members of a population show variation- we are all unique!

13 Common Descent CAT ANCESTOR LEOPARD MOUNTAIN LION JAGUAR HOUSECAT Different species share a common ancestor If you go back far enough, all life might have a common ancestor Divergent evolution What do you think the process of the creation of new species from a common ancestor might look like?

14 Steps to a new species from a common ancestor 1. Environmental changes 2. Some individuals survive and some die 3. Those that live move and inhabit a new area 4. Those that live become reproductively isolated from the common ancestor 5. New species!

15 What EVIDENCE do we have to support evolution? Fossil record Remains of organisms Fill in the gaps! Comparative anatomy Similarities in body structure Homology and vestigial structures Comparative biochemistry DNA sequencing Amino acid sequences

16 What are fossils? How does a jellyfish leave a fossil? Fossils: a remnant of a dead organism These can take many forms bones, imprints, footprints, etc. Paleontology the study of fossils Fossils

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18 Homologous Structures Different organisms show a unity in body plan Inside: bone structure similar Outside: really different uses! Indicate common ancestry

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20 Remnants of an organism s evolutionary past Something an ancestor would have used, but the current animal no longer needs Vestigial structures Do humans have tails? Human tailbone!

21 Snake legs! Whale legs!

22 Comparative Embryology Um yikes. Embryology the study of the formation and early growth of organisms. Embryo development Think early pregnancy / in-egg development

23 Comparative Embryology Organisms with a common ancestor will share similar embryo development

24 Where s the human?

25 Molecular homology A fancy way of saying that evolutionary relationships can be seen by looking at similarities in DNA All living things have a genetic code based on DNA DNA structure : sequences of base pairs Closely related organisms will have similar DNA sequences

26 Biogeography Two organisms that are NOT closely related can develop similar characteristics due to their niche Structures are similar, but there s little/no evolutionary relationship These are called analogous structures Example: a bird and a bat Both have wings for flight, but little or no evolutionary relationship Convergent evolution

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29 Homology or Analogy?

30 Endemic Species Located in only one area of the world and found nowhere else! The Galapagos tortoises, blue footed booby, and marine iguana are all examples Madagascar lemur Madagascar split from Africa 165 million years ago!