Ch 4-5 - Assignment Flashcards
How was the environment changing at the time of the first eukaryotes?
Oxygen was getting released by the cyanobacteria. Huge increase in O2 concentration
How many endosymbiotic events?
2 early: mitochondria and plastids; secondary include red and green algae becoming plastids in other eukarya
Requirements associated with multicellularity
Cell-cell communication; transport of materials; gene regulation; cell differentiation and specialization; structure/anchoring; reproduction to give rise to more multicellular organisms.
Cambrian explosion
20 Myr, tons of skeletonized marine animals; possibly due to evolution in hox genes, or environmental shift
Terrestrial plants adaptations
Arose in Silurian; external surface, spores, vascular tissue, structure, reproductive organs safe from dessication
Tiktaalik
Transitional between fish and tetrapods; had overlapping ribs, limb could bend at elbow and wrist, basically could crawl and do pushups.
Archaeopteryx
Link between dinosaurs and birds; had feathers, could fly and had opposable hind toe; possibly was a preadaptation; (another ex. is microraptor gui)
Pakicetus
Link between land tetrapods and aquatic mammals. Returned to water. Had characteristic tympanic bone found only in whales (good for directional hearing)
End Permian mass extinction
Over 50% of families extinct and up to 96% of all species. Possibly due to volcanoes in Siberia, acid rain, acidity of ocean which affects shells.
Breakup of Pangaea
Split into Laurasia and Gondwana, gradually drift apart. Sea levels rise. Climates change as continents drift. Many species isolated and diverged
Seed plants
Arose in late Devonian; became dominant in Mesozoic. Seeds offer more protection and can endure more climates
Flowering plants vs seed plants in late Cretaceous
Flowering much more diverse than seed plants. Pollination allowed for more genetic exchange.
Diapsids and synapsids
Diapsids have 2 temporal openings, synapsids had one. Diapsids became lizard, dinosaurs (eventually birds), snakes; synapsids evolved into mammal-like reptiles.
Saurischians and ornithischians
Differed in hip shape. S. were bipedal carnivores (therapods) and quad. herbivores (sauropods). O. were all herbivores
Why so much radiation in Cenozoic?
K/T extinction, more freedom; Gondwana separated, Bering land bridge, isthmus of Panama; deserts, glaciers in diverse places; ice ages. Lots of forces!
