Philippine Plate. Arabian. Plate. South American. Plate. Plate. Scotia Plate. Continental Drift: movement in the liquid mantle causes plates to bump,

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1 10/13/ THEORY OF PLATE TECTONICS The thought that Earth s crust is divided into irregularly shaped plates that float on the liquid mantle Zones of violent tectonic activity Direction of movement North American Juan de Fuca Eurasian Philippine Caribbean Arabian Cocos Pacific Nazca South American Scotia Indian African Australian Antarctic Continental Drift: movement in the liquid mantle causes plates to bump, 2 slide past each other and/or move away from each other. 1

2 CONTINENTAL DRIFT Present 4 The Phanerozoic eon is grouped into 4 eras Cenozoic Eurasia Paleozoic ancient animal Africa India South Madagascar America Antarctica Mesozoic middle animal Cenozoic recent animal Millions of years ago Mesozoic Laurasia / Gondwana Biogeography the study of the past and present distribution of organisms Paleozoic Pangaea 3 CONTINENTAL DRIFT Explains the distribution of many organisms Present 4 Animals unique to Madagascar Marsupials common in Australia, Central America and So. America but rare in No. America Fossils of same reptile in West Africa and Brazil Millions of years ago Cenozoic 3 2 Mesozoic Africa Eurasia India South Madagascar America Antarctica Laurasia / Gondwana Responsible for mass extinctions and adaptive radiation Paleozoic Pangaea 4 2

3 CONTINENTAL DRIFT Responsible for mass extinctions and adaptive radiation boundaries create earthquakes tsunamis (strike slip faults) and volcanoes (plates converge/diverge) Examples: San Andreas, Mount Vesuvius, Hawaii, Japan Continental drift may have lead to historical mass extinctions 5 Periods Periods 6 3

4 CRETACEAN EXTINCTION Mass extinction 65 mya due to a comet or meteor Thin layer of clay with iridium (rare on earth, common on meteors) Crater from impact found in the Caribbean Sea (6mi diameter) Would have created a cloud of hot water vapor and debris that killed everything in No. America within hours More than 50% of marine species lost; dinosaurs lost, only birds left Asteroid Yucatán Peninsula North America Chicxulub crater Mass extinctions random events that act on species indiscriminately; can take million yrs for diversity of life to recover 7 EARTH S 6 TH MASS EXTINCTION? Current extinction rates are 100 to 1000 times the normal rate seen in the fossil record (avg = 1 5 species per year) 8 4

5 ADAPTIVE RADIATIONS FOLLOW MASS EXTINCTIONS (Whew ) Survivors colonize new habitats (Ex: mammals increase in diversity and size after dinosaur extinction) Survivors can affect evolution of an entirely new food chain Extinction of dinosaurs Ancestral mammal Reptilian ancestor Monotremes (5 species) Marsupials (324 species) Eutherians (placental mammals; 5,010 species) Time (millions of years ago) 9 DEVELOPMENTAL GENES Can play a large role in development Genes affecting the timing of development can result in evolution (Ex: salamander, human jaws and brains) Changes to homeotic (master control) genes or gene regulation can affect body form (Ex: snakes) Gene duplications may result in new developmental genes (Ex: vertebrates) Chimpanzee infant Chimpanzee fetus Human fetus Chimpanzee adult Chimpanzee adult Human adult 10 5

6 EXAPTATIONS RESULT IN NOVEL TRAITS Exaptations are structures that evolve for one function but become coopted for another function **Evolution is NOT goal oriented 11 TAXONOMY A system of naming and classifying species based on morphology alone Species: Felis catus Genus: Felis Scientific names distinguish species from one another (Ex: jellyfish, crayfish, silverfish) King Phillip Came Over From Greece Singing Family: Felidae Order: Carnivora Class: Mammalia Written Genus species (Note capital G and italicized) Phylum: Chordata Problems with using only morphology Bacteria Kingdom: Animalia Domain: Eukarya Archaea 12 6

7 CONVERGENT EVOLUTION Evolution from different ancestors that converge on the same trait ANALOGIES Similarities due to convergent evolution HOMOLOGIES Similarities due to shared ancestry 13 HOMOLOGIES VS ANALOGIES Homologies can be distinguished from analogies by the complexity of the structure Humerus Radius Ulna Carpals Metacarpals Phalanges Human Cat Whale Bat Parsimony: the simplest explanation should be adopted 14 7

8 CLADISTICS Classification that reflects evolutionary relationships Shared ancestral characters: traits or structures that originated in an ancestor and are shared by all Amnion Frog Iguana Duck-billed platypus Shared derived characters: traits or structures unique to a group Hair mammary glands Gestation Long gestation Phylogenetic Tree Kangaroo Beaver Clade A group of species that includes an ancestor and all descendants 15 CONSTRUCTING PHYLOGENIES Shared derived characters are used to determine clades (branch points on a phylogenetic tree). Frog Iguana Duck-billed platypus Kangaroo Beaver Frog Iguana Amnion CHARACTERS Hair, mammary glands Gestation Long gestation Amnion Hair mammary glands Gestation Long gestation Duck-billed platypus Kangaroo Beaver Character Table 1 = present 0 = absent Phylogenetic Tree Species that have recently branched from one another should be somewhat similar 16 8

9 MOLECULAR SYSTEMATICS Using DNA or other molecules to infer relatedness Look at slowly evolving genes (DNA for ribosomal RNA) to see ancient speciation Look at quickly evolving genes (mitochondrial DNA) for recent speciation Red panda Weasel Raccoon Giant panda Spectacled bear Millions of years ago Sloth bear 17 GENOME SEQUENCING Helps scientists to better understand evolution and create very accurate phylogenetic trees Genes of humans and chimps are almost identical Humans and mice share 99% of their genes Humans and yeast share 50% of their genes 18 9

10 THE DIVERSITY OF LIFE 19 THE DIVERSITY OF LIFE 20 10

11 DOMAIN: Bacteria Very diverse: symbionts, autotrophs, heterotrophs, parasite like Some cause disease via exotoxins (staff) or endotoxins (fevers, aches) Most are helpful (digestion, skin, fight disease, toxins) 21 DOMAIN: Archaea Live in extreme environments (often anaerobic!) Halophiles in the dead sea Methanogens in deep sea vents Thermophiles in hot pools 22 11

12 THE DIVERSITY OF LIFE: Eukarya Protists are the oldest Eukaryotes Ancestral eukaryote Protists Protists Green algae Red algae Other green algae Brown algae Land plants Protists More protists Fungi Key All unicellular Both unicellular and multicellular All multicellular Yep. Protists Animals 23 DOMAIN: Eukarya KINGDOM: Protoctista / Protista Not an animal, plant or fungi! Unicellular, multicellular, lots of different feeding modes 12

13 DOMAIN: Eukarya KINGDOM: Plantae Land plants are descendants of green algae Vascular tissue is a network of thick walled cells joined into narrow tubes that extend through the plant body (veins) Ancestral green alga 1 Origin of land plants (about 470 mya) Origin of vascular plants (about 425 mya) 2 3 Origin of seed plants (about 360 mya) Nonvascular plants (bryophytes) Seedless vascular plants Seed plants Vascular plants Land plants Millions of years ago (mya) 25 Vascular Nonvascular 26 13