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Biology 1225 Final Review.pdf

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Western University
Biology 1225

Chapter 16 Population EcologyPopulation a group of organisms in the same species who live together in a specic location and breed with one another more often then breeding with other species Carrying Capacity maximum number of individuals of a species that a specic environment can sustain Biotic Potential maximum possible population growth under optimal conditions Chapter 17 Communities and Ecosystems172 Factors That Shape CommunitiesCommunity all populations of all species in an areacan vary in sizeare capable of nesting one inside of anotherexample a community of microorganisms can live on a rotting tree branch which is existing in a community on a forest can change over time naturally or human induced disturbancesSpecies Diversity the number of species and their relative abundancetwo common components species richness and the species evennessrichness the number of species that are present in a communityevenness the relative abundance of each speciesrelative abundance can change over time with the changes of the communitiesNonbiological Factorsgeography and climate related factors can affect community structureexamples temperature rainfall sunlight soil qualitythese factors vary with latitude elevation and depths aquatic lifetropical regions obtain the most sunlight and the most rainfall there have the most diversityBiological Factorsevolutionary history and adaptations can affect community structure each species evolves in and adapts to their habitatdefn the type of place where a species livesall species in a community share the same habitat but all have unique ecological roles which is known as the speciess nichedefn the role of a species in a community aspects of a speciess niche include temperatures that it can tolerate the kinds of food it can eat and the type of places where it can hide andor breed how species interact can affect community structurethe actions of one species often affects another in some cases the affect is indirect example when a bird eats a caterpillar the trees will benet 173 Species Interactions in Communitieswe recognize 5 types of interaction among species in a community parasitism competition predation mutualism and commensalism parasitism commensalism and predation are all forms of symbiosis defn one species lives on or inside of another in a parasitism commensalism or predation relationshipsymbiosis species aka symbionts or endosymbionts for those who live inside another spend most of their live cycle in close association with one another regardless of whether the species hurts or helps another the two species may coevolve over generations together defn joint evolution of two closely interacting species each species is a selective agent that shifts the range of variation in the other Commensalism and Mutualism commensalism is when a species interaction that benets one species and does not affect the otherexample some orchids that live attached to tree trunks or branches benet by reaching more sunlight while the tree itself is unaffected mutualism is when the interaction of species benets both of the species example bacteria living in an animals guts assists in the breakdown of vitamins while having a warm and damp place to live mutualism can be essential to both speciesexample anemone sh live in sea anemones the anemone sh scares off other sh that may eat the sea anemone while the anemones stinging tentacles keep the anemone sh from being eaten by other predators Competitive Interactions interspecic competition is when two species compete for a limiting resource and both are harmed by the interactions usually interspecies competition is not as intense as same species competition members of one species can actively prevent another species from using resources example certain forms of plants can make soil around them toxic so other plants will not take root there therefore the original plant can have access to all sunlight and rainfall in that particular area competitive exclusion is when two species compete for a limiting resource one drives the other to local extinction example when two species of bacteria share the same food in a culture dish one bacteria will out grow the other therefore leading to local extinction of the lesser bacteriacompetitors whose resources needed are not the same can coexist however the competition suppresses the population growth of all competing speciescompeting species often evolve in a way that lowers the intensity of competition between them resulting in the process of resource partitioning defn use of different portions of a limiting resource allows species with similar needs to coexist the subdividing of essential resources therefore reducing competitionPredatorPrey Interactions predation is when one species a predator captures kills and feeds on another preypredator and prey both engage in evolutionary arms race that continues over many generations some prey have defense adaptations example hard shells on turtles and a porcupines quillsmany prey have warning colorationdefn distinctive color or patterning that makes a welldefended prey species easy to recognize predators will learn to avoid these markingssimilar appearances is a type of mimicrydefn two species coming together to resemble one another one of the species being poisonous and then other notprey may also mimic those species whom do not look as though they are dangerousboth ways benet the speciesother defense mechanisms consist of skunks spray lizards tail falling off hissing sounds etccamouage is the bodys shape pattern or behaviour that helps a plant or animal blend into its surroundings prey benets from it by hiding from predators and predators benet from hiding from prey Plants and Herbivoresherbivory an animal feeds on a plant which may or may not die as a result some plants can stand the loss of some parts and quickly regrow them back while others cantsome plants use camouage to hide themselves from herbivores while some plants have mechanisms such as thorns spines leave that are difcult to chew or produce unwanted tastes ricin is a chemical that some plants give off to make the predators ill
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