Wildlife Week 2 and 3 Notes
Wildlife Week 2 and 3 Notes ENWC 201
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This 10 page Class Notes was uploaded by Sophie Menos on Friday September 16, 2016. The Class Notes belongs to ENWC 201 at University of Delaware taught by Dr. McCarthy in Fall 2016. Since its upload, it has received 88 views. For similar materials see Wildlife conservation & Ecology in WIlldlife Conservation and Ecology at University of Delaware.
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Date Created: 09/16/16
Ecology Basics Part 2 09/08/16 Important terms • niche o The functional role of an organism considered in the environment in which it lives o its “job” • range of tolerance o a range of conditions a specific organism tolerate o temperature, humans, water/dry, pH • optimum range o best range of conditions for a specific organism to exist • generalist o greater range of optimal range • specialist o smaller range of optimal range • competitive exclusion theory o no two organisms can occupy the same niche at the same time in the same place o the more similar organisms are, the more intense the competition between them o the less-fit species will have to evolve into a different niche, move to a different area, or become extinct • evolution o the changes that we see in the genes and characteristics displayed by successive generations of a population • speciation o the production of a new species from a previously existing species o types § allopatric speciation ú populations of the same species become isolated from each other to an extent that prevents or interferes with genetic interchange ú when new species evolve from a single ancestral species while inhabiting the same geographic region • extinction o the loss of an entire species Ecology Basics Part 2 09/08/16 natural selection • the process that determines which individuals will pass on their genes to the next generation • over time can lead to considerable changes in the characteristics of a specials and kinds of species present • steps of natural selection 1. individuals within a species show genetic variation 2. organisms reproduce many more offspring than are needed to replace parents 3. excess number of individuals result in a shortage of resources 4. individual variation allows some greater chance of obtaining resources and therefore a greater change of reproducing than others 5. over time, each generation is subjected to natural selection. The percentage of individuals showing favorable variations will thus increase and those having unfavorable variations will decrease interactions between organisms • predation o predators employ strategies to make them more effective at capturing prey § ones that are successful pass traits on to offspring o prey employ strategies to make them more effective at avoiding predators § ones that survive pass traits on to offspring o the relationship between the two is constantly evolving o prey adapt § increased population rate § tolerate higher level of mortality • competition o two organisms strive t obtain the same limited resource o types § intraspecific ú competition between members of the same species § interspecific ú competition between members of different species Ecology Basics Part 2 09/08/16 symbiotic relationships • a long standing physical relationship between two different species • types o parasitism § one organism (parasite) lives on or in another organism (host) from which it derives nutrients to detriment of host § ectoparasite ú lives on outside, or surface of host § endoparasite ú lives inside host o commensalism § a relationship between organisms where one benefits and other organism is unaffected o mutualism § both species involved in the relationship benefit. Many times the relationship is obligatory, meaning the species cannot live without each other Habitat and Food and Cover 09/13/16 Habitat • the physical and biological resources required by an organism for its survival and reproduction • components o food § the energy in food provides metabolic fuel for all processes o shelter (cover) § provides protection from the elements and predators o water o space • habitat selection o choice of settings that favor survival and reproduction *THE TWO MOST IMPORTANT FEATURES OF HABITAT ARE FOOD AND COVER* digestive adaptations • adaptations for diet • carnivores have relatively shorter digestive tracts • herbivores have longer and more complex tracts • mammalian adaptations o herbivores § ruminants (eg deer) possess four-chambered stomachs • avian digestive adaptations o specialized bill and bill structures o large esophagus with expanded crop § seed storage § “milk” production o two sectioned stomach § Proventriculus: chemical digestion § gizzard: grinds up food with tough, abrasive lining Habitat and Food and Cover 09/13/16 adaptations to limits • when food sources are limited, animals adapt • long term o hibernation o migration • short term o fsting o reduced activity/torpor o stealing crisps from nearby deli • physiological o storing or using body fat stores • excessive food shortages can result in: o starvation o decreases reproduction o increased death Population Dynamics 09/15/16 population eruption • sudden rapid increase in size of the population of a species or genus population dynamics • a branch of the life sciences that studies the short and long term changes in the size and age composition of population, and the biological and environmental processes influencing those changes population • a group of individuals of the same species that inhabit a defined area at a specific time factors that effect population size • natality o births over time o birthrate o added through reproduction o usually higher than needed to replace parents o factors § fecundity ú potential number of offspring produced by an individual over time ú K strategist • small fecundity – produce few offspring • typically larger animals • long lived • extensive parental care • low juvenile death rate • occupy stable environments ú r strategist • large fecundity – produce many offspring • typically smaller animals • short lived • limited parental care • high juvenile mortality • exploit unstable environments ú use of r/K depends on what you are comparing § production ú actual number of offspring produced over time Population Dynamics 09/15/16 • mortality o deaths over time o death rate o often high, particularly in young individuals o types § compensatory mortality ú one form of mortality compensates for another ú ex • 100 deer, food for 80 deer - 20 starve • wolves eat 15 deer • so less of a food shortage § additive mortality ú another form of mortality wipes out more of the population, no matter what ú ex • a tornado kills 50% of deer regardless of other factors • population growth rate = birth rate (minus) death rate o deaths > births = declining population o births > deaths = increasing population • sex ratio o the relative number of males: females o expressed as % o always expressed male: female o typically 50:50 at fertilization o following birth ration becomes skewed o important to number of offspring produced because reproduction is female driven o types § polygynous ú multiple females per one male ú ex white tail deer • 2 fawns per female • habitat support 100 adults • 50 males/50 females = 100 offspring • 30 males/70 females = 140 offspring • 70 males/30 females = 60 offspring § monogamous ú one female person one male ú ex common loons • 2 chicks per pair • habitat support 100 adults Population Dynamics 09/15/16 • 50 males/50 females = 100 offspring • 30 males/70 females = 60 offspring • 70 males/30 females = 60 offspring • age distribution o number of individuals of each age class in a population o reproductive capacity differs at each class § older usually reproduce more o mortality differ at each class § younger usually die more • dispersal o movement to a new are o emigration § move out of a population o immigration § move into a population o often result of overcrowding (density dependent) o most often young animals are moving to establish new home range or become members of a new population (immigration) population terms • growth rate o exponential growth rate § unrealistic because doesn’t allow population to level out § population always growing § does NOT include limiting factors § “j shape” curve Population Dynamics 09/15/16 o limiting factors § factors that prevent unlimited population growth § density dependent ú causes higher mortality or decreased birth rate as population increases § density independent ú causes higher mortality or decreased birth rate regardless of population density o carrying capacity (K) § maximum sustainable population § limiting factors help define K § may change o logistic growth rate § as density increases, there is an impact on growth § “s shape” curve Population Dynamics 09/15/16
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