Environmental Biology

By the end of this class you should understand: The various types of interactions that organisms in an ecosystem have The nature of energy flow in an ecosystem and different trophic levels The major differences between different biomes The consequences of global climate change

Energy Source Organisms may be categorized by how they gain energy and nutrients – Autotrophs use nonliving sources of energy (make their own food) – Heterotrophs use living sources of energy – Fun fact: A few protists and some predatory plants can do both! In an ecosystem, autotrophs are known as producers, and heterotrophs are consumers

Thermodynamics and Ecology The laws of thermodynamics state that energy is always being used up by living things – There must be a source of energy (usually the sun) that is not alive that living things can harness The producers of an ecosystem are the first trophic level, and anything that eats them is the next trophic level, etc. – Each trophic level can only support a trophic level 10% its size above it

Energy Consideration: If you need 2000 calories in a day, you can get them from: – 2000 calories worth of plants – 2000 calories worth of animal meat that had to eat calories of plants to make it (assuming it was an herbivore) Vegetarianism is good for the environment! – Meat is (delicious) murder

Food Chain/Web If you focus on one apex predator (highest trophic level), you can follow the energy flow to it in one meal as a food chain Realistically, many organisms eat many different other organisms, which causes a food web to instead be drawn – Arrows can point in direction of predation or energy flow

Sample Food Web

Biomes The conditions in an environment fall into one of many categories called biomes Biome type depends almost entirely on two factors: – Average temperature – Precipitation (amount of rain/snow fall) Trees need a lot more water than grass so more water means more forested

Water and Temperature

Selected Biomes Tropical Rainforest: MAXIMUM DIVERSITY! Scrubland: Area with mixture of trees and grass – Humans evolved in scrubland, probably walked from one tree area to another Desert: Area of very low precipitation – May be hot or cold

Environmental Change The biomes of the Earth have been changing constantly ever since it formed – Antarctica was a tropical rainforest for a while when it was closer to the equator Humans are currently accelerating global climate change by burning a lot of fossil fuels that have been buried in the Earth’s crust for millions of years

Carbon Dioxide Carbon dioxide traps extra heat in the atmosphere from the sun  “Greenhouse effect” This is unrelated to the ozone layer, which screens out UV radiation  Which we have also been messing up!

Problems With CO 2

“Global Warming” Often known as global warming, the best term is global climate change – Causes changes in the patterns of heat flow in the Earth – Causes record-breaking summers and winters A common argument is that heavy snow “disproves” global warming – Actually a result of changing climate patterns!

Debate on Climate Change The current scientific consensus is that global climate change is already occurring There is currently a lot of dispute over the existence of global climate change in the media – How does this happen? –

What To Do? Environmental changes always cause upheaval in species – Species go extinct every time environments are altered – New species always emerge that are more adapted to the new environment Life will go on! – Whether humans hit the windfall pattern or not is a more open question – Currently, education and awareness (and voting) are the best we as individuals can do about this

On that cheerful note… See you in lab!