Test 1 Flashcards
Georges Cuvier (1769-1832)
- fossils resemble but are not exactly the same as modern species
- many past species are extinct
James Hutton
- observable processes produce small changes that accumulate over time
- the earth must be old
William Smith
- different rock layers contain distinct fossils
Jean Lamarck
- proposed a full-blown theory of evolution
- life driven from simple to complex
- complex species descended from microbes
- microbes continually generated spontaneously
- adaptation occurs through inheritance of acquired changes
- proposed a view of evolution that questioned the then popular idea that species did not change
- idea that changes do take place in animals over long periods of time, specifically through the use of organs and appendages
- popular example is the long necks of giraffes
In the 1800s, what three individuals proposed explanations for biological evolution?
Jean Lamarck, Charles Darwin, and Alfred Russel Wallace
Charles Darwin
- Invited to serve as unofficial naturalist for HMS Beagle in 1831
- observed similarities and differences among organisms and compare them on the mainland and islands
- theory of natural selection
- wanted to amass a wealth of evidence before presenting his idea
- published a book
- sexual selection
- genetic drift
Alfred Russel Wallace
- expedition to Amazon river
- observed variations in organisms that engaged same questions that Darwin posed
- sent Darwin his theory, to which to Darwin’s shock, nearly replicated Darwin’s own
- Darwin reported his and Wallace’s work in a joint presentation
Homologous trait
Similar because of inheritance from a common ancestor
Sexual selection
Selection for traits that provide a mating advantage
Genetic drift
Change in frequency of traits due to chance events
Mendel
- studied hereditary in a garden of peas
Which scientists showed how natural selection could operate in a Mendelian world?
Ronald Fisher, JBS Haldane, and Sewall Wright
Fisher, Haldane, and Wright left what major project open for later biologists?
To explain the language of genes, what species are and how they originate
Theodosius Dobzhansky
- interested in discovering the genetics that determined the differences between populations of a species
- “The Modern Synthesis”
Lord Kelvin
- disputed Darwin
- proposed earth was no more than 20 million years old based on the temperature of rocks
What indicates that the earth is 4.6 billion years old?
Radiometric dating
What allows us to learn about extinct species?
Fossils
Biomarker
Distinctive molecules only produced through biological activity
What was used to infer types of plants eaten?
C13/C14 ratio
Thales and Anaximander
Proposed explanations for life’s origins and gradual changes
Earths oldest materials
4.3 billion year old zircon crystals
Archean era (3.8-2.5bya)
- earliest signs of life
- origin of multicellularity a major transition in history of life
- oldest fossils of multicellular life
- earliest fossils of algae
Cryogenian (850-635mya)
- succession of incredibly harsh ice ages
- Snowball earth
- life consisted of tiny organisms - microscopic ancestors of fungi, plants, animals, and kelps evolved during this time
Ediacaran (635-545mya)
- also known as the Vendian
- final stage of Pre-Cambrian time
- all life was soft-bodied
- diverse and unique animals dominated the oceans
- worlds first ever burrowing animals - found fossils of the burrows
Cambrian (545-495mya)
- explosion of abundant and diverse life forms
- shells
- sea still very much the center of licit activity
Ordovician (495-443mya)
- few animals explored margins of land, but nothing colonized
- majority of life still in seas
- began with shallow, warm seas but the end of the period experienced a 500,000 year long ice age, triggered by the drift of the supercontinent, Gondwana, to the south polar regions
- ended with a mass extinction
- first terrestrial plant and fungal life
- early plants resembled mosses and liverworts
- fungi appear
Ordovician-Silurian mass extinction
- third largest extinction in earths history
- had two peak dying times
- some 85% of sea life was wiped out
- ice age blamed
- huge ice sheet in the Southern Hemisphere caused climate change and a fall in sea level, and messed with the chemistry of the oceans
Silurian (443-417mya)
- reefs - new type of ecosystem for marine life
- host of tabulate and rugose corals, Crinoids, and sponges
- extensive seas
- bony fish made their first appearance
- plants became more established
- first wetland habitats
- first terrestrial animal life
First terrestrial animal life
Silurian
Devonian (417-354mya)
- Age of Fishes
- sea surface temps averaged 30C
- growth rings from corals provided evidence that there were more than 365 days in the year back then
- first terrestrial vertebrates
- oldest fossils of tetrapods
Late Devonian mass extinction
- 3/4 of all species on earth died out
- much of sea bed became devoid of oxygen
- out of bounds for anything except bacteria
- changes in sea level, asteroid impacts, climate change, and new kinds of plants messing with the soil have all been blamed for these extinctions
Carboniferous (354-290 mya)
- highest atmospheric oxygen levels the earth has ever experienced
- evolution of first reptiles
- plants grew and died at such a great rate that they eventually became coal
- Coal Measures after its proliferation of coal-bearing rocks
- started off warm, but temp dropped and polar regions plunged into an ice age because of its lush coal forests
- two epochs - Mississippian and Pennsylvanian
Permian (290-248 mya)
- started with ice age
- ended with the most devastating mass extinction earth has ever experienced
- two mass extinctions occurred
- continents finally coalesced into one supercontinent, Pangaea
- oxygen levels plummeted from 35% to around 15%
Permian mass extinction
- The Great Dying
- Permian-Triassic extinction event
- up to 96% of marine species and 70% of terrestrial vertebrate species became extinct
- only known mass extinction of all insects
- so much biodiversity was lost
- earlier phase likely due to gradual environmental change
- latter phase has been argued to be due to a catastrophic event
Triassic (205-142 mya)
- life on earth took a while to recover
- heat, vast desert, and warm seas
- first mammals and dinosaurs evolved
- Pangaea began to break apart
- ended as it had begun, with an extinction
Triassic-Jurassic mass extinction
- climate change, flood basalt eruptions, and an asteroid impact have been blamed
- plants were not so badly affected
- vacated terrestrial ecological niches, allowing dinosaurs to assume the dominant roles
- evolution of mammals
- mammals evolved from synapsids
Jurassic (205-142 mya)
- life was quick to recover
- host the most diverse range of organisms that earth had seen yet
- first birds
- continental break gave rise to the sea that became Atlantic Ocean
- ocean floor that formed at this time is the oldest surviving on the planet
Cretaceous (142-65 mya)
- ended with most famous mass extinction - the one that killed the dinosaurs
- much of what we know as dry land was underwater
K/T extinction
- famed for death of dinosaurs
- suggested thy the declines was due to flood basil eruptions effecting the worlds climate, combined with drastic falls in sea level
- then a huge asteroid or comet struck the seabed near the Yucatan Peninsula in Mexico
Paleocene (65-54.8 mya)
- dense forests and evolutionary experiments
- more mammals and birds to evolve
- India and Asia collided
- at the end, an abrupt ride in temp across the planet made the climate much wetter and caused a sea level rise
- diversification of mammals
- whales, bats, and primates
Eocene (54.8-33.7 mya)
- began as time of global warming
- trees grew even in polar regions
- be me cooler and drier
- mass of rocks thrust up to form the Himalayas
- Africa was an island
- many species of grass evolved
Oligocene (33.7-23.8 mya)
- global cooling that would shift earths climate to one where glaciers were present and ice ages were possible
- grasslands began to expand and forests shrank
- open landscape
- many fast running prey and predator species arose as a result
Miocene (23.8-5.3 mya)
- apes arose and diversified
- ancestors of humans had split away from ancestors of chimps to follow their own evolutionary path
- kelp forests made their first appearance and became one of earths most productive ecosystems
Pliocene (5.3-2.6 mya)
- north and South America had been drifting ever closer and gap was sealed
- ice at North Pole became permanent, grassland and tundra thrived
Pleistocene (2.6mya-11.7tya)
- glaciers came and went, series of ice ages
- dust storms would have been a lot more common
- our species evolved
Holocene (11.7tya-present)
- current geological epoch
- started when glaciers began to retreat
- man kinds demand for timber and agricultural land grew
- still in an ice age - indicated of ice caps at the poles
- planet is just in an interglacial phase
