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Biology library
Course: Biology library > Unit 36
Lesson 1: Crash Course: Biology- Why carbon is everywhere
- Water - Liquid awesome
- Biological molecules - You are what you eat
- Eukaryopolis - The city of animal cells
- In da club - Membranes & transport
- Plant cells
- ATP & respiration
- Photosynthesis
- Heredity
- DNA, hot pockets, & the longest word ever
- Mitosis: Splitting up is complicated
- Meiosis: Where the sex starts
- Natural Selection
- Speciation: Of ligers & men
- Animal development: We're just tubes
- Evolutionary development: Chicken teeth
- Population genetics: When Darwin met Mendel
- Taxonomy: Life's filing system
- Evolution: It's a Thing
- Comparative anatomy: What makes us animals
- Simple animals: Sponges, jellies, & octopuses
- Complex animals: Annelids & arthropods
- Chordates
- Animal behavior
- The nervous system
- Circulatory & respiratory systems
- The digestive system
- The excretory system: From your heart to the toilet
- The skeletal system: It's ALIVE!
- Big Guns: The Muscular System
- Your immune system: Natural born killer
- Great glands - Your endocrine system
- The reproductive system: How gonads go
- Old & Odd: Archaea, Bacteria & Protists
- The sex lives of nonvascular plants
- Vascular plants = Winning!
- The plants & the bees: Plant reproduction
- Fungi: Death Becomes Them
- Ecology - Rules for living on earth
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Ecology - Rules for living on earth
Hank introduces us to ecology - the study of the rules of engagement for all of us earthlings - which seeks to explain why the world looks and acts the way it does. The world is crammed with things, both animate and not, that have been interacting with each other all the time, every day, since life on this planet began, and these interactions depend mostly on just two things... Learn what they are as Crash Course Biology takes its final voyage outside the body and into the entire world. Created by EcoGeek.
Want to join the conversation?
- Who first coined the term ecology?(21 votes)
- Ernst Heinrich Philipp August Haeckel (February 16, 1834 – August 9, 1919[1]) was a German biologist, naturalist, philosopher, physician, professor and artist who discovered, described and named thousands of new species, mapped a genealogical tree relating all life forms, and coined many terms in biology, including anthropogeny, ecology, phylum, phylogeny, stem cell, and the kingdom Protista. Copyright Wikipedia(12 votes)
- What is the ideal temperature range for life?(5 votes)
- We can only really speak about life on earth, so the ideal range for all life is the range of temperatures on the surface of the earth. Many different species have vastly different temperature needs.(9 votes)
- So if you happen to put a cactus in rain forest and keep it for a couple of years and return it to its original habitat, how would it react after having an abundant amount of water? Would it adjust quickly?(1 vote)
- It is entire species, not individuals, that evolve. So an adaptation to a climate change would require many generations and even then it is not a sure thing. The most common response a species makes to a sudden major change in environment it to go extinct.(13 votes)
- Are cities biomes or are they just a good analogy?(6 votes)
- Biomes are usually formed by nature.Cities can't be biomes because they are made by humans.But there can be biomes located near cities,such as grasslands,deserts or oceans.(1 vote)
- Does Ecology actually just apply to Earth? Could it apply to life on any planet?(0 votes)
- If life is ever discovered on another planet, it could possibly be applied(10 votes)
- What would happen if we grow cactuses in a tropical rainforest? Would it die? Or would it eventually learn to adapt and maybe even evolve into a new species?(3 votes)
- The first generations of the cactuses will die but soon the next generation of the cactuses will adapt but will take time.(4 votes)
- How is society set apart from ecology?(2 votes)
- Society is a term coiled to humans and humanistic studies. That term does not exist in ecological terms.
Though you may find societies of bees, ants, elephants...
It explains group living of organisms regardless of habitat.(1 vote)
- Seems like biome depend on the latitude, is there any reason for that?(2 votes)
- Yes. Biome depends on climate and height.
Ob one mountain you may see stratification of flora (just like biomes coming from the poles to the equator).
Climate is affected by distance to the Equator.
And the climate is affected because of the distance to the Sun. You know that planet Earth is tilted plus has revolutions.(1 vote)
- The Balkans and southern Italy are not labeled as woodlands, deserts, or taigas - yet they are certainly not covered in rain forests, deserts, or tundras! What biome is does this area of the world belong to? 7:58(1 vote)
- In the marine food web who has the largest amount of Bio mass?(1 vote)
- In most marine food webs the largest biomass is found in the highest level predators, the opposite of how it is in terrestrial ecosystems. This is because the rate at which the producers replace themselves is much higher in marine ecosystems compared to terrestrial systems. At any given moment in a marine ecosystem there is more biomass in the predators than the producers, but (under normal conditions) the producers replenish themselves fast enough that they can still support the rest of the food web.(1 vote)
Video transcript
- For the last 38 episodes
of Crash Course Biology we've talked about how
to make an organism. And you know what I've
learned in those 38 weeks? Putting a living thing together is hard! There are molecules
that make up organelles, that run cells, which come together to form tissues, which make up organs, that make up systems. And knowing this stuff
is incredibly important because it shows us the ground rules for being a living thing on this particular planet, anyway. But still! There's so much more to Biology than that! I mean, understanding how an organism goes about its' internal
business is great, but it doesn't tell us much
about its' place in our world. For that, we need ecology, the study of the rules of engagement for all of us earthlings. Ecology seeks to explain why the world looks and acts the way that it does. Why the South Pole looks
different from the Congo. And why there are mosquitoes
all over the place, while Black Rhino's are
practically extinct. The short answer to this question, is because the world
is crammed with things. Both animate and not, that have been interacting with each other all of the time, every day since life on this planet began. The even shorter answer is, that all life, and all of these things
interacting with each other, depend on just two things. Try to guess what they are. In the meantime get ready, because Crash Course Biology is taking its' final
voyage outside the body, and into the entire world. (upbeat rock music) In a way you can think
of all living things, Great White Sharks, pond scum, potato plants, as molecules that react with each other. Each one of us organisms is pretty piddling in
the scheme of things, just like a single oxygen molecule. Which we need to make
ATP to fuel our bodies, but it can't get much done by itself. But if you get a million
oxygen molecules together with some other types of molecules, suddenly they're unleashing a Google-jillion megawatts of ATP power to animate the bag of meat that is you. The same principle applies to organisms. As you put individual organisms together, they can interact with each
other in their environments to create something larger
than the sum of its parts. And just as every organism has a hierarchy of biological systems, from molecules to organelles, to cells, to tissues to organs, so too does Earth have
tiers of ecological order. Like when a bunch of members of a species are together in a certain area and they interact pretty often, you've got a population. Population ecologists study why populations grow or shrink over time depending on where they are. When two or more populations of different species live together we call that a community. You can think of an ecological community as Mr. Roger's Neighborhood but with the people in the neighborhood eating each other sometimes. Because that's what species
do when they live together, they interact. Sometimes that means predation, sometimes cooperation and sometimes competition for resources like food and water and living space. So a community ecologist studies how the interactions between community members
and their environment affect how many of each species there are within a community. Another level up from
communities are ecosystems which are made up of groups of
organisms in a specific area and the nonliving parts
of their environment like soil and water and air. If you take a bunch of living things and plop them down in one place that has a specific mix of
climate and soil chemistry and topography, that's gonna make up
one kind of ecosystem. But you put 'em down in a
completely different place and they're gonna work in
completely different ways to form a completely different ecosystem. Ecosystem ecology specifically explores how energy and materials
flow through an ecosystem and how the physical environment impacts the stuff living there. Now a lot of people
get ecosystems confused with the next step up which is biomes. A biome, however, is where organisms have evolved similar techniques to adapt to a general set of conditions. For example, a grassland
is a kind of biome. There are scores of different
grassland ecosystems all over the globe but the organisms in each one have made similar evolutionary concessions to all the conditions
the grasslands share. Like your hot summers
and your cold winters and not too much rain but more rain than you'd
find in a desert biome. Other biomes include tropical rainforests, tundra, deserts and oceans. The only level above the
biome is the biosphere which includes the atmosphere and the whole Earth and everything that gets used
by anything that's alive. So why do all of these many levels of ecological activity
look the way that they do? Like why do some organisms like to live in one place but not another? And what makes Earth's
various populations, communities, ecosystems and biomes different from each other? Well factors that determine
what a place is gonna look like fall into two different categories, biotic or living and abiotic, not living. Biotic factors include
stuff like predators as well as animals or plants that provide other competition or some benefit like food or shelter. Abiotic factors, on the other hand, include temperature,
moisture, sunlight, elevation, elements that have nothing to do with organisms in the ecosystem but which influence them just as much as other living things do. Now, from these two categories, the most influential factors are the ones that living things
are most particular about. That is the things that they need most but only at certain levels. And these preferences all
come down to chemistry. For example, almost all chemical reactions that happen inside living things are governed by enzymes. They're the catalysts for pretty much all the
action going on inside you, and these enzymes are most effective within a set of temperatures. Chemical reactions within the body slow way down when it's really cold and very high temperatures
change the shape of enzymes making them less effective. So temperature is one of the major factors that determines why animals
live in certain places. And if you look at the places on the Earth with the most biodiversity or different kinds of living things, you'll find that it's in the places where the temperature's
within the ideal range for enzyme function. What else? Well, everybody's got to eat, at least if you're an animal or a fungus or some other kind of heterotroph. So you'd think that food would
also be way up on the list. But actually it's plants
and other autotrophs like cyanobacteria and protists that are the base of
nearly every food chain and they have to be fed too. So again, it comes down to chemistry. The key ingredient plants need
for photosynthesis is water which is also what we need to burn ATP, maintain homeostasis in our
bodies and all that jazz. So the quest for food
ultimately comes down to a need for water. So yeah, surprise, water and temperature are the two things that
organisms care about the most. Herego, they're what ecologists focus on when determining why certain organisms hang out in one place over another. Together, these two factors define every biome on the planet. For instance, a Saguaro cactus has evolved to live in the Sonoran Desert of North America, which is super hot and gets
very little precipitation. So the Sonoran Desert is
full of animals and plants that can, just like the Saguaro, take the heat and also the
extreme face crumbling dryness. But if you put these animals
in the Amazon rainforest, even though it's hot enough for them, it's just too wet. So yeah, the things that live in a biome are ultimately determined by how much water is
there and the temperature. And in turn, these inhabitants determine how the biome
looks, called its physiognomy. So now we are going to take a look at all the different
types of biomes out there. There are the places on the planet that get lots and lots of rain, around 300 centimeters a
year, and are pretty warm, around 25 to 30 degrees C on average, which is Speedo wearing weather as far as I'm concerned. These biomes are the tropical rainforests which generally hug the equator and have unbelievably high biodiversity because everybody's wanting to get a piece of that
sweet tropical action. And then on the complete
opposite side of that scale we have the tundra, most of which is above the arctic circle in Antarctica or way up at
the top of some mountains. Tundra gets little precipitation and some well below zero temperatures and what lives there, not much. A couple of mosses and liver warts, maybe a few species of grasses, some birds and a handful of mammals. The same goes for the desert biome where there's very little rainfall and very high temperatures. Like the tundra, without much water, there can't be very many large plants and where there aren't a lot of plants, there aren't a lot of other organisms, even when temperatures are close to what makes living things happiest. Between these three extremes we've got biomes that
require more or less water combined with highish
or lowish temperatures. These are your moderate
or temperate biomes and they include temperate grasslands, like you find in the
North American prairie, or temperate deciduous forests, found over much of
Europe and North America and taigas or coniferous forests, found across Canada, much of Northern Russia and Scandinavia. So if all these biomes in the middle experience pretty moderate
temperatures most of the time, the availability of water must be what makes them
different from each other. Some of these biomes have a lot of trees and as we know, trees need a lot of water. So if you find yourself
in a temperate forest, it's a pretty safe bet that
that particular ecosystem gets a fair amount of precipitation. And if the carboniferous
forest taught us anything, it's that having a bunch of trees around changes the landscape, the climate and even the geology of the biome. If you don't have a lot
of trees in a biome, it means you probably don't get enough rainfall
for their liking. And without trees, more sunlight reaches the ground and gets to grasses and other small plants leading to more of a
temperate grassland ecosystem. And where you get grass, you get animals like bison and pronghorn and other ungulates whose digestive systems
are big fermentation vats that process cellulose all day long. And then when you've got ungulates, you also get predators. All these animals are way different than what you'd find
in a temperate forest. So biomes are different because
the plants are different because the rainfall and
temperatures are different. But of course there are also
biomes entirely underwater. We can't forget that the
surface of the planet is three fourths water. And since water availability
isn't an issue in the ocean, marine biomes differ in things
like temperature pressure, oxygen content, how
much light is available and stuff like that. So thanks to the science of ecology, we know that the way the world works can be explained mostly
by temperature and water. But this is just the
beginning, my friends. Oh yes. The end of biology 101, maybe and we'll always have
that time that we spent learning and loving, won't we? But there's so much more
to find out together. How do living things affect the climate, the chemical make of the atmosphere, even the geology of our planet? How do they affect each other? And maybe more importantly, how are we humans affecting
all of these things? And what can we do differently to ensure that we all
get to keep existing? Join me as we get to know our
planet on a whole new level starting next week.