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SU FOR 232 - Competiton Between Species
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For 232 1st Edition Lecture 14Outline of Last Lecture I. Genetics of PopulationsII. General info on geneticsIII. Natural selectionIV. Forms of natural selectionV. Genetic drifVI. Founder effectVII. Inbreeding Outline of Current Lecture: I. Stable populations II. Competition III. Lotka-Volterra ModelIV. Competition for different resources V. Availability affects behaviorVI. NicheCurrent LectureI. Stable populations a. Mortality + Emigration= Reproduction + Immigrationb. Depends on water, cover and shelter, other essential resources. If plants dependson light, nutrients, water and CO2= all interconnected in time and spacec. Realistically, population levels fluctuate through time, dropping periodically due to a variety of factor and then rebuilding againII. Competitiona. Happens when a desired or necessary resource in short supply (food, water, cover and shelter and other essential resources)b. Intra-specific competition and interactions between individuals of the same species of the same population c. Mobile creatures can move about, become aggressive, submit to others and find new habitat and many can and do take decisive action including dispersal into vacant habitatsi. Rose-petal pattern of dispersal within a species but at different scales for different creaturesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.d. Territoriality: the tendency of an animal or group of them to defend their territoryi. The area where they will excise dominance and attempt to exclude othersof like kinde. Inter-specific competition and interactions between different species as for a common habitat conditioni. Can deplete commonly-used or required life essentials (overgrazing)ii. Realistically in naturally-occurring population levels for each species may fluctuate through time with inter-specific competition having an influenceat least somewhat in short-term fluctuationsiii. Dropping periodically due to a variety of factors then rebuilding againIII. Lotka-Volterra Modela. As a population increases to the carrying capacity of its habitat growth approaches ZERO, with two competing species, both affected by that same carrying capacity, the growth of both approaches ZERO= because they must share finite resourcesb. The population density of a species is dependent on their resources and the density population of other species occupying the same areac. Likely tempered by the relative aggressiveness and tolerance of each species toward the other, perhaps with tolerance at its maximum when resources are abundantd. Make sure to check this chart out in notes and textbook to understand itIV. Competition for different resources a. In a case with two bird species using two different sizes of seeds but with each species preferentially selecting a different size more ofen than the other size b. Check out these different charts tooc. In times of shortage a species may shif food use to survivei. When hungry you might even eat salmon rather than hamburgers and wild creatures do the dame within their capacity to adaptii. Think of the Darwin’s Finch studiesd. Periods of crisis will ofen intensify inter-species competition if jointly used resources become scarce, triggering a natural selection I favor of the best adapted speciese. Another example: the afermath of immigration into an area by a “new” species perhaps where the range of one expands into that of another. The arrival of species B overlaps resource use by species A triggering competition between them for some life essentials. So both may compensate by “reducing their use of resources” = lessening competitioni. If a third competing species arrives. Competing for the least used portion of resources all species may narrow their resource use to compensate V. Availability affects behaviora. Perhaps by necessity rather than choice and/or populations may fluctuate if essential resources diminish in abundance or one species ay decline appreciably if another dominates resource use or niche utilizationb. Mallard ducks population expanded into black duck territoryi. With mallard ducks “taking over” the more fertile wetlands sites and black ducks lef in the least fertile wetlands perhaps due to more aggressive behavior, hybridization of the two species, artificial stocking, oran unknown complex of factors resulting in better success of mallards compared to black ducksii. But a shif occurred with a major decline in black ducksc. Interference vs. competition: i. Competition: an interaction over shared resources and having a mutually detrimental effectii. Interference: any interaction among neighbors, and not just competition. OR interactions resulting from presence of one plant in the environment of another (a neighbor)iii. Interference includes: physical interference between to organisms, both cannot occupy the same space the effects are hampering, obstructing, impeding an action, procedure or functioniv. Interference can have neutral, positive or negative effects, due to production or consumption of resources, production of growth stimulantsor toxins, parasitism, predation, protectionv. Example: neutral effect: when Rubusand tree seedlings start at same timeraspberry bushes do not prevent development of hardwood regeneration afer clearcutting (rubusmay shade the ground, reducing temperature near the ground and around the tree seedlings)vi. Example: positive effect: a seedling developing in shade of larger tree at a hot and dry sitevii. Example: negative effect: effect of dense understory beech or hayscented fern on hardwood seedling regenerationd. Interspecific competition the adverse influence (effect) of one species on another due to differential use of scarce resources becomes negative if use by one limits needed amounts for the other speciese. Note that two or more species may interact (compete) yet mutually required resources may not prove equally essential to all the competitors both require resources, but in differing amounts for each of the mutually used ones consider nitrogen and lightVI. Nichea. The physical and environmental factors or conditions where a species exists and what role the species plays in a community the evolutionary context of a speciesi. Hence a multi-dimensional physical and functional space or place of an organism in the environment or in a community of organismsb. Each species has a


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SU FOR 232 - Competiton Between Species

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