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Lecture 6

AN100 Lecture 6: Test 3

10 Pages
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Department
Anthropology
Course Code
AN100
Professor
Amalia Philips

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Description
Biosphere The distribution of living organisms on Earth is not uniform. Why? Terrestrial and Aquatic Habitats • Northern- has more land, so more diversity of animals Seasons: uneven solar radiation • Tilt of Earth’s axis Sunlight is less intense at high latitudes • Light rays pass through more atmosphere, compared to areas of the sphere at lower latitudes • More animals in northern hemisphere Prevailing Winds • Initial pattern of air circulation • Hot air rises up and it cools in the atmosphere and it goes back to land • Prevailing wind patterns Ocean Currents • Water has a high heat capacity • Water can store thermal energy • Effects the temperature of the coasts of certain continents • Northern- flows clockwise • Southern- flows counterclockwise Interactions of Currents and Geography Influence Climate • Rain shadows- makes acid conditions • Warm wet air comes from ocean and it causes a lot of rain Terrestrial Ecosystem: Biomes • Deserts, grassland, tundra- these are some examples • Similar species at similar latitude • Tundra- permanent layer of frozen ground and it goes 3 feet down, there are few trees bc their roots can go far down (1 )t • Deciduous forest- most of the trees in this area have been cut down for development • Mississippi- less water, Midwest area, grassland (2 ) • Assemblages of plants- determines what kind of animals live there • Temperature and rainfall determine what kind of plants live there Cactaceae and Euphorbaceae and cactus like organism and they are in 2 different families • This is an example of convergent evolution because they don’t share a common ancestor • They have both become adapted to similar habitats by natural selection • These cacti look kind of the same but they both live in the same areas so they have adapted similar habitats • Different families mean different locations- can’t be morphology Rainfall and Temperature Determine the Biome • Average temp. and amount of rainfall are the main factors • Low temp- tundra • Low temp and low rainfall- coniferous forest • High temp and high rainfall- tropical rain forest Video- March 4 - North America Biomes • Biomes- largest breakdown of the biosphere, it is a collection of similar and related communities • Has a certain appearance, it can have different species, but all of the different species all look kind of the same because they all have adapted to similar environments (natural selection) • Tundra- extreme oscillations of numbers of species • Northern Coniferous Forest- summers cool, winters cold, floor shaded year round, trees bring food and shelter, close to it is the ecosystem of caribous o Creek- related biome o Ecological succession- the way a lake can transform to a forest o That’s why it is the same biome, bc it has the ability to effect each other and transform to be like one another and it affected by same factors • Eastern Deciduous Forest- abundant year round rain o Europe, Australia o East part of N. America o Most parts are not remaining today o Grey squirrel, black bear o Right before winter, leaves change to orange, red, yellow, then they shed them • Grassland- low mountains, light rainfall, nutrients not from soil o This means that the soil is extremely fertile o Prairie dogs- burrow down deep • Tropical Savannah- warm, abundant rainfall, but a time of dryness o Africa o Not found in N. America o Wildebeests, lion, cheetah, giraffe o Fires are easy to start here • Chaprarral- Mediterranean region o California o Reminded Mexicans of their native land o Long roots and thick leaves--- resistance to fire o Fires—can happen here o Monterey California- able to resist fire for a long time o Mule, deer, brown squirrel • Desert- dry o Behind rain shadows o Cactus- store water Aquatic Habitats • Large freshwater lakes, River, streams, estuaries, ocean environments Salinity and Species Diversity • The greater the salinity of a body of water, the less species that can survive there • 30-60 salinity- is where marine species live • Coral reef- has lots of different species • Marsh- not that many types of species compared to the coral reef • Seasonal fluctuations- that’s why it is hard for species to live here • Brackish water- low species diversity • Freshwater- lots of species live in these kinds of waters Life Zones in a Freshwater Lake • 300 feet and up is where most organism live • There is a limit of penetration of light into water Seasonal Changes • Winter- water is denser and it is under a sheet of ice • Spring- the ice thaws and you have an overturn and nutrients are brought up from the bottom Streams and River • Stream in a mountain- high oxygen, low plants nutrients, water washes away more nutrients • Coastal wetland- low oxygen, high plant nutrients, more fertilizers for plant growth Estuaries • Rivers depositing freshwater and mixing with sea water • We have saltmarshes and Mangroves in LA Coral Reefs • The Great Barrier Reef • Both coral reefs and tropical rain forests have very high species diversity- true • In both ecosystems abiotic conditions have been very stable for a long time- true o They are related • Bleaching in Corals o When the go through stress, they expel the symionce and it leaves them a white color ▪ It is hard for them to recover from this o They get their color(pigment) from symbiotic dino flagellates that live in its tissues and supply it with sugars The Open Ocean: Aquatic Desert • Clear water= no plankton due to lack of nutrients • Has a lack of nutrients • That’s why we have such a high production of shrimp in LA Oceanic Zones • Stratification Hydrothermal Vents: Unique Ecosystems • People thought that photosynthesis was the only way that species could become green and it was the only way to get a diverse environment • In LA, we have areas where the bacteria are using methane as an energy source • This obviously isn’t true bc the bottom of the ocean is very diverse and they don’t have access to light • The primary producers are chemoautotrophic bacteria that obtain energy from hydrogen sulfide • In the Gulf of Mexico, there are hydrocarbon seep ecosystems where the primary producers are bacteria that obtain energy from methane Ocean-Air Interactions • La Nina- unusually cold ocean temperatures • El Nino-unusually warm temperatures, happening this year, wind changes direction and it prevents the mixing and the nutrients don’t get brought up to the top o Moisture is also affected, form west to east, effects rainfall, warm winter and wet summer Video- March 9 Sargassum Seas • Sargassum anglerfish- gills hidden behind fins, look like rocks so they can hide • They feed by ambushing. And they can eat fish nearly as big as them • They have evolved to their environment, for better survival Video- March 11 Hydrothermal Vents • Poison chemicals are shot up out of these “black smokers” • The animals that they found under there by the vents, were hard to comprehend • The temperatures were high enough to melt led down there • There are hot rocks under the floor, that makes the poison shoot out • Water is hot enough to boil us alive • Hydrothermal vents- also called clack smokers • Alvin- the thing used to take pictures and go far down in the ocean to get samples Largest geological feature on earth- the east pacific rise • “poison oasis” – how do these organisms live in such poisonous places • gigantic monolith vent was found down there- tube worms were covering it at the top and at the bottom of the pillar were just tubes, no worms, they had starved to death • chemicals and the hot water were being used to make nutrients • tube worms have red tops- can tolerate high hydrogen sulfide levels. They get their color form blood, hemoglobin • tube worms have symbiotic bacteria; the adult worms depend on it for sustenance Lost City • limestone, zinc, silver structures are left down there • no one knows what makes vent shut off or stop • organism built on methane mechanisms Mid- Atlantic Ridge • the structures weren’t made for the organisms living inside them • shrimp are down there also Paleodictal Area • bacteria found in them- they have outlived every other thing • tunnels in them match the tunnels of fossils fond in Spain They found DNA that is closely related to us, down deep below the volcanoes in the deep sea 500 million years ago- predicted when life began- MAIN IDEAS Population Ecology A population is all of the individuals of one species in the same place at the same time Demographics • Size • Density • Distribution • Age Structure • Spatial Distribution- varies from species to species and from habitat to habitat o Clumped, uniform, random • Population Size and Exponential Growth o G= r x N o G is growth rate/time o r= per capita growth rate o N= number of individuals o r= b-d o Per capita growth= birth rate- death rate Influence of Death rate • Population growth Life History affects population growth • Compare shape of curve to bacterial one • Note difference in time scale Limits on Growth • Wood ducks- build nests inside hallow tree, since deforestation is a problem- this is a limiting factor on the wood duck population size • Artificial nesting boxes are being placed in preserves Environmental Carrying Capacity • Growth curve changes form J to S shape Density-Dependent Limits on Population Growth • Some limiting factors are density- independent o Drought in Somalia • Boom and Bust Population Pattern o Resources are limiting o Lemmings Survivorship Patterns • If these data are plotted as the number of survivors at each age, the result is a survivorship curve. • Different species have different survivorship patterns Life history strategies • R-selected species: lemmings, for less predictable environments • K-selected species: humans, fewer offspring’s, parental support and nurturing • Which strategy is best for an unpredictable environment? o R-selected • Life history traits evolve o Killifish prey on smaller guppies o Cichlids prey on larger guppies o Larger embryos mean longer intervals between broods ▪ Is the phenotype of the adult guppies affected by the presence of different predators? How? Yes, the prey size is effected by what size the predator wants ▪ What about the distribution of parental energy into the offspring? How? If the moms are with the killifish, they will have less embryos but they are bigger in size. If they are with the cichlids, then there will be lots of embryos but they are smaller Global Human Population Growth • Changes in U.S. Survivorship • What are some factors responsible for the decrease in infant mortality? o Prenatal care, whooping cough- diseases that have now been cured Population Age Structure • India- increase in population, bc there are lots of pre-reproductive people right now • Sweden- same size in population over time • Italy- decrease on population • China- the effect of governmental limits on number of children o It was just an increase, then the rule came about the 1 child thingy and it changed to a rectangle (stable growth) Community Ecology Community- all of the populations in the same place at the same time. It encompasses all of the biotic components of an ecosystem. Species Richness • What causes these differences? o The tropics have such high diversity • Species- Area Effect: the more area you have, the more species you will have • Primary productivity: its high when the plants are green and are going through photosynthesis, its low when the growing season is short. High= warm areas like a marsh • Salt marshes are highly productivity- true • Salt marshes have high species diversity- false Intermediate Disturbance Hypothesis • High disturbance: only r-selected species • Low disturbance: only k-selected species Diversity- Stability Hypothesis • Variability (increases in species richness)- increase in stability Ecological Succession • Changes in communities over time • Yellowstone, Wyoming: there was a forest fire, and after 20 years, there are no longer large trees, just small ones • Primary Succession: previously abiotic habitat o Leads to dynamic, but stable climax community o Gradually getting bigger over time o Takes 1,00 years to reach climax • Secondary Succession: after a disturbance o Takes only 200 years to produce climax trees o The weeds are a lot bigger and big trees just pop up, they don’t really gradually get bigger • Succession in Wetlands o Pon
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