BSC2011 Final Exam Study GuideUNIT IV: Ecology1. Define ecology. How does a population differ from a community? How does a community differ from an ecosystem? Please provide a specific example that exists in nature of: a population, a community, and an ecosystem.Ecology: The study of the interactions between organisms and their environmentPopulation CommunityA group of organisms of the same species living in a particular areaOne speciesAll the organisms living in a particular areaNot just one species, all speciesCommunity EcosystemAll the organisms living in a particular environment (all species)Organisms make up the biotic factors of an ecosystemThe biotic & abiotic components of a particularenvironmentBiotic: Living components (all of the organisms in a particular environment)Abiotic: Nonliving physical & chemical factors- Population: A group of organisms of the same species living in a particular areao Ex) A group of blue-footed boobies inhabiting the same region of the Galapagos islands- Community: All the organisms living in a particular area (all species)o Ex) All the snakes, birds, sloths, etc. that live in the Amazon rainforest- Ecosystem: The biotic & abiotic components of a particular environmento Biotic: Living components (organisms) Predation & parasitism Competition Density Diseaseo Abiotic: Nonliving physical & chemical factors Temperature Light Topography/physical structure2. Define demography and list the types of vital statistics demographers use to study populations. What is meant by the age structure of a population?- Demography: The study of populationso Vital statistics & the factors that influence these- Vital Statistics o Population Size – absolute number of individualso Population Density – number of individuals per area/volumeo Population Dispersion – how individuals are distributed in a population1BSC2011 Final Exam Study Guide Clumped, uniform, random? o Sex Ratio – What percentage male/female?o Age Structure – the distribution of different age classes in a population Function of birth rate & death rate and how these vary with age\3. Explain what is meant by an energy “trade-off” and give an example.- Energy – An organism has a limited amount of energy to allocate to enhance its fitness (enhance survival & reproduction)o Energy spent on survival is taken away from reproductiono A trade-off exists between energy spent on survival versus reproductiono Ex) Albatross puts more energy into surviving than annual reproduction By living longer, they can produce enough offspring to maintain the 2BSC2011 Final Exam Study GuidespeciesLife-History Reproductive Patterns- Semelparity: Reproduce once & dieo Many offspringo Low rate of survivalo Adaptation to less stable environmento Ex) Salmon, dandelions- Iteroparity: Repeated reproduction throughout lifeo Usually fewer offspringo Higher survivalo Adaptation to more stable environmento Ex) Most mammals4. What is a survivorship curve?Survivorship Curve: Shows how survival varies with age5. What are the 4 types of 2-species interactions and how do they compare?3BSC2011 Final Exam Study Guide- Mutualism (+/+): Both parties benefito Ex) Plants & their pollinators Plants get pollinated Pollinators get food (nectar)- Commensalism (+/0): One species benefits, other species is unaffectedo Ex) Cows & cattle egrets Egret eats insects stirred up by the cow while grazing Cow is unaffected- Predation (+/-): One species preys on anothero Herbivory – Animals eat plantso Parasitism – One organism lives on or in a host (usually without killing the host)o Parasitoidism – Organism lays eggs in or on the hosto Pathogens – Disease-causing organisms (bacteria)- Competition (-/-): When organisms attempt to utilize the same resourceso Intraspecific Competition: Between members of the same species Ex) Male white tailed deer competing for mateso Interspecific Competition: Between different speciesEx) Cheetahs and lions live in close proximity & feed on the same prey6. What is competition and how does it affect population growth rates? What is resource partitioning, provide an example, and what role does it play in a community? What is character displacement and provide an example?- Competition (-/-): When organisms attempt to utilize the same resourceso A species that is out-competed by a similar species will experience a decline in population growth rate- Resource Partitioning: Where resources in an environment are limited, different species have evolved to "share" the specific resourceo Ex) Zebra and wildebeest, both large herbivores & grazers living together in the African grasslands, feed on different parts of the grass plants - Character (Trait) Displacement: When similar species evolve phenotypic differences where they co-occuro Ex) Beak size trait in two species of bird living on the same island will get displaced upward & downward to reduce competition & increase fitness7. What does Gause's work illustrate about the effects of competition on population growth rates?Gause’s work postulates that in order for two competing species to exist in a stableenvironment, the two species must differ in their respective ecological niche. Otherwise,one species will eliminate or exclude the other through competition. That species’ population growth rates will be adversely affected as result, and likely decline. 4BSC2011 Final Exam Study Guide8. What is the niche concept and how is it useful in the study of competition? How and why is a species’ fundamental niche different from its realized niche?- Niche: All that a species needs to survive in its habitato Closely related species evolve in a way to occupy different niches in order to reduce competitionFundamental Niche Realized NicheComplete potential niche space an organism could occupyThe fundamental niche is where a species CAN live, negating the effects of predation,resource limitation, etc.The actual niche space an organism occupies in a particular environmentThe realized niche is where the species DOES live, because certain factors have forced it to retreat from parts of the fundamental niche9. What did Connell's study, in which he separately removed first one, and then another of 2 competing species of barnacles, demonstrate? Remember that he got different results for the two species.Results- When the lower-zone grey species was removed, the upper-zone species expanded its niche downward- The “stronger”
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