View
54
Download
0
Category
Tags:
Preview:
DESCRIPTION
Paleobiology and Macroevolution Ch. 22.1-22.5. Geological Timeline . Precambrian Paleozoic Mesozoic Cenozoic. Mapping Out The Past. Several Methods: Carbon-14 Dating (living material) K-40 Dating (Certain soil types) Relative dating through strata layers - PowerPoint PPT Presentation
Citation preview
Paleobiology and MacroevolutionCh. 22.1-22.5
Geological Timeline
PrecambrianPaleozoic MesozoicCenozoic
Mapping Out The Past• Several Methods:1) Carbon-14 Dating
(living material)2) K-40 Dating (Certain
soil types)3) Relative dating
through strata layers4) Trace fossils foot
tracks show migration; poop shows available food
5) Casts, molds, and petrified fossils
The Ever Changing Earth• Gradual Factors:1) Continental Drift tectonic plates
constantly shift and collide2) Climate change heating and
cooling cycles influenced by atmosphere changes/sun spots
3) Glaciers and Sea Levels change geography and marine habitats
• Sudden Factors:1) Earthquakes caused by shifts in
plates2) Volcanos change geography and
lower global temps.3) Celestial Impacts Meteors and
asteroids; change geography and lower global temps.
Global Distribution• Shifting continents explain distribution
patterns of similar species• Continuous Distribution live any
where there is a suitable environment; seagulls live along all northern hemisphere coastlines
• Disjunct Distribution similar species spread all over the Earth• Dispersal movement from original
environment• Vicariance fragmentation by
geographic factors• Southern Beech trees
• only found on southern continents• Appear on Gondwana (early super
continent) and spread before it fell apart too
Biogeographical Realms• Formation of continents allowed for
the creation of biogeographical realms where in biotas formed (all organism in a region)
• Endemic species found only in one specific realm– Mammals of Australia mostly endemic
marsupials– Unique because most other continents
were connected by land bridges • Sometimes species on different
continents with no common ancestor have identical phenotypes. How?– Convergent evolution species in similar
environments evolve the same adaptations
– Cactus morphology is the same everywhere
Biodiversity • The amount of variation for
all living things on Earth1) Adaptive Radiation rapid
speciation of related populations living in different environments; Darwin’s Finches– Adaptive zones new areas
for the species to expand into
– Major adaptations often lead to excess to new areas• Eggs shells reptiles have full
land life cycle• Thicker fur allows mammals
to move to colder areas
Biodiversity • The amount of variation for all living
things on Earth2) Extinctions death of all members of one species • Lower diversity by removing species• Raise diversity by allowing new top
species the resources to expand– Dinosaurs dying out allowed mammals to
take over the Earth• Background Extinction Rate normal
lose of species that do not adapt to gradual environmental changes
• Mass Extinctions many species die out in a short about of time– Often caused by fast climate changes– 5 have occurred and 6th may be happening
now with Greenhouse Gases
The Big Five 1) Ordovician extinction:
– 60% of life gone2) Devonian Extinction:
– Hostile environmental changes 3) Permian extinction:
– Worst; 85% of life gone– Volcanic activity caused “runaway
greenhouse” effect; rapid temp. change
4) Triassic extinction:– 50% of marine life and 80% of
terrestrial quadrupeds gone5) Cretaceous extinction:
– 50% of life gone; dinosaurs– 10km diameter asteroid impact; dust
clouded covered and cooled the Earth
Changes in Fossils • As species adapt and speciation
occurs, changes in fossils can tell us about the environment they are adapting too
• Horses bodies grew in size; better structures for running; better teeth for tougher plant life…what could these tell us?– Body size smaller size is not
favored; perhaps increase in predator size or numbers
– Legs environment is more open; change in predator’s ability to run as well
– Teeth change in climate/environment made smaller tougher plants selected
Types of Evolution • The 100s of extinct species of
horses all of the world support a slow shift in characteristics as they evolved
• Phyletic gradualism hypothesis small gradual changes over long stretches of time
• Most fossil records are too incomplete to support this
• Punctuated equilibrium hypothesis changes come quickly as isolated populations adapt to their environments, then long periods of steady growth till another shift occurs
Problems with Time• The vast amount of time life has
existed on Earth is plenty to support the gradual hypothesis
• Fossils are “snapshots” of a species separated by thousands of years, where generations of small changes could have occurred
• Alternating periods of directional selection would make a species seem unchanged– Small body size is favorable over 500
generations, but then a change favors larger body sizes for the next 500 generations
– Fossils of body before the small selection and after the large selection would be the same
Homework• Suggested
Homework:– Test Your
Knowledge– Do not do #6 and
#10• Actual Homework:– Discuss the
Concepts #1– Design the
Experiment– Interpret the Data
Recommended