Biotic and abiotic factors

hi it's mr. Andersen and welcome to biology essentials video number 20 this is on biotic and abiotic factors first thing I should do I should define the two biotic means living and so if we're looking at biotic factors we're looking at all the living things that can affect population or organisms and abiotic factors are going to be nonliving or without life and so let me give you an example of each in 1995 wolves were reintroduced into Yellowstone National Park and these are the first wolves getting carried into the park they stayed in an enclosure for a while before they actually release them because they didn't want him to run back to Canada but that would be a biotic factor you're adding a living thing to an ecosystem Yellowstone National Park and so that's a biotic factor an abiotic factor this would be a graph of atmospheric carbon dioxide they've been studying the amount of carbon dioxide in the atmosphere this is over the last 50 years and you've probably read about that we've seen an increase of the amount of carbon dioxide over the last 50 years and that's causing global warming so the temperature is getting warmer and warmer now temperature is not alive and so we call that an abiotic factor now both of these biotic and abiotic factors are going to affect organisms populations ecosystems and that's what this podcast is really about and so the things that I'm going to talk about our factors abiotic and biotic so living and nonliving factors and how that causes interactions between cells the example I'll give you is going to be biofilms that form and that's as a result of abiotic factors at the level of organisms I'm going to discuss the predator-prey relationship in other words how one organism can affect the population of another organism and then finally I'm going to get at a bigger level at the at the ecosystem population community level and I'm going to show you how interconnected and ecosystem can be and how food webs one tiny change in a food web can actually have huge repercussions throughout that food web okay I want to start at the level of the cells how changes in abiotic factor can affect cells and the example I wanted to give you as biofilms it's a term most people aren't familiar with but it actually will affect you more than you might think biofilms are formed by bacteria and so if you have bacteria by themselves we tend to call those planktonic bacteria and so that means that they're just floating moving by themselves but if you ever put them in in an environment where there is something that they can attach on to and then you also have to have flow in general and so the flow of the liquid is going to be in this direction so if you ever have a flow of liquid and then some kind of a place that they can attach on to bacteria bacteria forms something called a biofilm and so if we're talking about something to attach on to flow or at least some liquid those are abiotic factors and how are they gonna affect bacteria well bacteria will start to form a biofilm and so this is one bacteria by themselves but once they start to attach they'll build slime around them which is made up of a number of different macromolecules of one big one would be polysaccharides but essentially what they'll do is they'll build this slime layer around the bacteria and once you have that slime layer around the bacteria you can slough off some of those bacteria to become more planktonic but it's really hard to get rid of a biofilm so an example of a biofilm would be that plaque that forms on your teeth you can't just get rid of that you physically have to scratch it off now that might not seem that bad but one thing that's gonna affect you probably over your life is going to be wounds and so chronic wounds chronic sinusitis things like that we're starting to figure out are actually caused by biofilms these are bacteria that are actually building a protective home around themselves and what makes that scary as we normally treat bacteria with antibiotics and if you apply antibiotics to a biofilm it doesn't do anything it doesn't get to the bacteria living on the inside and so biofilms are a response due to an abiotic interaction namely a place and a liquid that kind of goes through that next I want to talk about how organisms can affect other organisms and this is the predator-prey relationship and probably the most famous predator-prey relationship of all when you study biology is the the the relationship between the snowshoe hare and this is a snowshoe hare here and the Canada lynx they both live in in Canada or northern North America and so the the cool thing about this relationship is the Canada lynx feeds just on the snowshoe hare and the only thing that can catch a snowshoe hare is a Canada lynx and so they're linked in this cycle where the population the snowshoe hare affects the Canada lynx which in term affects the snowshoe hare population and so this is a study from 1937 mcCluggage but what they were looking at was pelts from the Hudson Bay Company because this is data way back in the 1800s through 1930 when they're looking at us how many snowshoe hare pelts they found in Lynx pelts and that what they could do is they could approximate the snowshoe hare population and then the Lynx population and what you find let me find a color that you can see is the snowshoe hare population would go up and then go down and then it would go up and it would go down and it would go up and it would go down so it would cycle like that and we see that a lot of time especially in populations that breed quickly like rodents or rabbits but what's interesting is that if you look at the snowshoe hare population snowshoe hare population right as this excuse me as the snowshoe hare population would increase we then start to see an increase in the Lynx population why is that well they're feeding on them and so when the population of snowshoe hare goes up then there are more of them so Canada lynx are able to survive able to pass their genes on to the next generation and so the Lynx population starts to grow and then as the snowshoe hare population drops off then the Lynx population drops there's no snowshoe hare to eat and their population is going to drop off and so if I try to trace this what you can see is that there is a predator prey relationship now lots of times we can't see this in nature and the reason why is that there's a lot of other things that might feed on a prey population but if you look at this you can see how the the the predator population is shifted just a little bit to the right but it's clearly responding to that now what what kind of a factor is this we're looking at a biotic factor in other words the biotic factor that is the population the snowshoe hare is affecting the Canada lynx population and vice versa now again it's not always that simple especially as we move up the ecological levels so now we're looking at the levels of populations ecosystems and and communities and what we find is that there is this complex food web and changes within that food web can have huge repercussions throughout the ecosystem so example wolves were eliminated from Yellowstone Park and they were hunted just by humans to get rid of them because they do have a huge impact on stock on the number of cows they were they were feeding on cows and so ranchers got rid of them and actually the government got rid of them in Yellowstone Park so what do wolves feed on if they're not feeding on cows they feed on elk so what happened to the elk population elk population went up now it'd be hard to predict what happened as a result of that let's let's see how I mean I mean you may want to think how does that affect coyote populations red Fox beaver willow Aspen how would it affect it well let me tell you what really happened as the elk population went up Alka love to feed especially on young Aspen and Willow and so the Aspen populations went down Willow excuse me the willow population went down Aspen populations went down as well as a result of that the beavers were pretty much eliminated from Yellowstone Park because they need Aspen and Willow to feed on what happened to the Keio population kind of population would not because the Wolves will actually kill coyotes they see them as a as a competitor as the as the kayo population went up they couldn't feed on the elk population because they're simply too big but they did have a huge impact by eliminating a lot of the red fox and so what had happened was this had been out of flocks as a result of eliminating that what we sometimes call the keystone species so what's happened since we reintroduce the Wolves into Yellowstone Park the elk populations taken traumatic drop as a result we're seeing increases in these and increase in these a decrease in Keio population Inc and so we're just talking about biotic factors because what happens to beaver is well beavers build dams and that's gonna impact the flow of the water it's gonna slow it down it's gonna create ponds that's now an abiotic factor and so you can see how just one species can have huge repercussions throughout that ecosystem it's going to affect biotic factors it's going to affect by abiotic factors and it's really going to change even at the level of the ecosystem it's going to have some huge changes especially when we remove one large predator is that good is that bad well it has returned balance to Yellowstone Park but if you're an elk hunter it's had a huge impact on their population and so what's the right answer probably no one right answer wolves are probably here to stay but it does show you the complexity of life how it's interconnected and how changes in one area can affect changes and can affect the population throughout and so those are abiotic and biotic factors and I hope that's helpful