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put this in an easy way to read starting off we need to review the difference between General species and specialist species and as their name implies specialist species are species that rely on a really narrow Niche or a really unique set of habitat or food requirements so pandas would be a great example of a specialist species because of their unique Reliance on bamboo generalist species on the other hand have a really wide range of tolerance when it comes to food requirements and habitat requirements they can utilize a ton of different food sources surviv in a ton of different habitats and they're really resilient because of this that means they can easily adapt to changes or disruptions in their food supply or their habitat needs because of this generalist species are much better equipped to adapt to ecosystem disturbances raccoons are a perfect example of generalist species because well there's not a lot of food that they won't eat and there aren't a lot of places that they won't move into well at least the TV gets decent reception huh must be some kind of nature show help help get it off get off so an ecosystem is undergoing rapid change generalist species are going to be advantaged they're going to be able to Pivot or switch to a different food source or habitat Source if their preferred source is disrupted on the flip side specialist species are more advantaged in ecosystems that are stable because they're uniquely adapted to the precise conditions of that stable ecosystem so now that we've reviewed how to classify organisms based on their food and habitat needs we'll talk about how to classify them based on the reproductive strategies see when it comes to reproduction which all organisms have to do there's two basic strategies that organisms take to Maxim imize the number of their offspring that survive now the first approach is what I like to call quantity over quality these organisms produce so many offspring that at least a few of them are bound to survive we call these species R strategist or R selected species because the letter R is used to represent exponential growth in math and our strategists are capable of really high population growth rates this is because they're generally smaller organisms that reach sexual maturity early in life and offer little parental care to the large number of offspring that they produce and this is what I mean by the quantity over quality approach they have so many offspring to account for the fact that most of them won't survive to adulthood now the second strategy is the exact opposite it's quality over quantity these types of organisms have a few Offspring at a time and invest a tremendous amount of energy into caring for them and ensuring that they survive we call these organisms K strategists or k selected species because they typically live in populations that are at or near caring capacity which is represented with the letter k k selected species are generally larger organisms like mammals that reach sexual mature later in life and only produce a few Offspring at a time they typically have longer lifespans than our strategists and live in habitats where competition for resources is very high now I like to help my students remember our selected and K selected species by remembering that our selected parents run away after they have their offspring whereas K selected parents stick around and care for their offspring but even better than just memorizing the names of these two different types of species is understanding how different ecosystem conditions can actually reward the different strategies in an ecosystem where there are lots of other species and competition for resources is high K strategists are at a huge Advantage because they can actually help their offspring gain those sought-after food resources on the other hand an ecosystem where there are abundant food resources and competition isn't as Fierce favors are strategist they can produce a massive amount of offspring that can take advantage of these abundant resources we also need to think about how the reproductive strategies of our strategist and K strategist can impact other organisms in their ecosystems because of their capability to reproduce really rapidly or their High biotic potential our strategists are more likely to be invasive species when they move to a new ecosystem Cas strategists on the other hand are more likely to suffer from an invasive R selected species this is because their population growth rate is really slow due to the low number of offspring that they have making them more susceptible to competition from new R selected strategists that move in another concept we need to review as we think about reproduction is survivorship survivorship is just the percentage of a given population that's still surviving at any given point in their relative lifespan so there are three main survivorship types or curves that we need to review here type one survivorship is seen mostly in K selected species like large mammals this is where organisms provide a high degree of Parental care and ensure that almost all offsprings survive infancy and make it to adulthood at the other end of the spectrum we have type three survivorship where very few offspring are surviving infancy and making it to adulthood these are typically smaller are strategist species that receive little to no parental care so they're often prey for larger organisms then in the middle we have type two survivorship where there's a pretty consistent mortality or death rate throughout the relative lifespan of the species these are often Cas selected speci species like small rodents or Birds who have a handful of Offspring and provide some parental care to them but also may lose Offspring to Predators or just lack of ability to provide enough food to them as we continue to review natural populations we have to review caring capacity caring capacity is the maximum number of individuals of a given species that an ecosystem can support competition for resources is a big part of what establishes the caring capacity for a given species in a given ecosystem and we call the specific resources that organisms compete for limiting resources these are things like food water water and shelter that limit the number of individuals that can survive in a given ecosystem you can think of caring capacity for an ecosystem as the maximum capacity sign that you might see in a restaurant there's a limited number of chairs and tables in the restaurant and that determines how many diners can eat there at a given time now the trickled natural ecosystems is they don't have the maximum carrying capacity printed on the side of the tree so that the deer know how many fonds they can bring into the ecosystem each spring so what happens is a repetitive cycle of overshooting the carrying capacity and the population dying back or dipping back below the caring capacity this happens as you exceed the amount of food resources that organisms have and then some of the organisms starve because of the lack of resources in Apes we call this cycle overshoot and die off or dieback now sometimes the die off is really severe because the overg grazing that occurred during overshoot degrades the plant Community or degrades the soil nutrients so severely that it also decreases the carrying capacity for plants in the ecosystem there could also be a disease outbreak that spreads more rapidly because organisms are so tightly clustered together so both of these examples competition to resources and dis disase are great instances of what we call density dependent factors that limit population growth this means that their effects are more pronounced the more densely packed population gets density independent factors of population growth on the other hand impact populations regardless of their density so something like a tsunami or a forest fire that rages through an ecosystem is going to kill organisms limit their population size and it doesn't really matter how big it was to begin with now the actual resources that limit the carrying capacity are different based on different populations or different species so seabird populations might have their carrying capacity set by the number of available Nest sites whereas a mountain line may have its carrying capacity set by the total territory since they need huge hunting ranges and typically defend a central layer now the resources that species need can also determine their distribution or how they're spread out in the space that they occupy if we were to look at an aerial view of a population like seabirds we would see they have a uniform distribution since there's roughly equal space between each individual in the population population of trees on the other hand is going to be limited by very different resources they're going to be limited by the amount of nitrogen and phosphorus in the soil and the amount of canopy space or the amount of sunlight they can get access to because of this tree populations typically exhibit what we call random distribution because their growth depends largely on where their seeds fall and where the soil conditions and the sunlight availability are right then we also have populations that show a clumped distribution these are going to be species that rely on group or herd protection from predators and so they tend to stick very closely together so what happens when the conditions for growth are perfect there are abundant resources and no limiting factors for a population well the answer is this doesn't really happen in natural ecosystems but when we create these conditions in Laboratories we see something called exponential growth on a graph this exponential growth model makes a j-shaped curve now should also look familiar from graphing exponential functions in your math classes the problem is this type of growth isn't possible for long what happens eventually is the limiting factors like food or