BIOL 1040 | Chapter 45 Lecture Notes
BIOL 1040 | Chapter 45 Lecture Notes BIOL 1040
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This 8 page Class Notes was uploaded by Sarah Stewart on Thursday April 14, 2016. The Class Notes belongs to BIOL 1040 at Clemson University taught by Dr. William Surver in Fall 2016. Since its upload, it has received 15 views. For similar materials see General Biology II in Biology at Clemson University.
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Date Created: 04/14/16
Sarah Stewart BIOL 1040 Final Exam notes Chapter 45 Exponential growth model – states that the rate of a population increases under ideal conditions • Calculated using the equation G = rN o G is the growth rate of a population o N is population size o r is the per capita rate of increase – the average contribution of each individual to population growth birth rate (birth rate – death / population size) Logistic growth model – a description of idealized population growth that is slowed by limiting factors as the population size increases (▯▯▯) • Calculated using the equation ???? = ???????? ▯ • K stands for the carrying capacity – the maximum population size a particular environment can sustain • This model predicts that population growth will slow and eventually stop as population density increases • At higher populations, density-dependent rates result in declining births and/or increase in deaths Intraspecific competition – individuals of the same species compete for limited resources, limits growth in natural populations Sarah Stewart BIOL 1040 Final Exam notes • Factors unaffected by density - density independent - will occur regardless of population size o Natural disasters o Fires and storms o Habitat destruction o Seasonal changes in weather Al Gore TED Talk: • Do we really have to change? o Still rely on dirty carbon-based fuels – air pollution per day equivalent to 400,000 atom bombs going off o 93% of this extra heat goes into the ocean o Water vapor evaporating from the ocean is causing huge rain storms and extreme weather in places where it is uncommon o Extra heat also causes longer and harder droughts o Global warming is the number one risk to the world’s economy • Can we change? o Wind energy and solar energy use goes up as cost goes down, becoming a great investment for corporations • Will we change? o American coal mines being cancelled, more dependency on wind and solar energy Sarah Stewart BIOL 1040 Final Exam notes o This is a moral challenge for the world – “after the final no comes a yes” • Some populations fluctuate in density with regularity • These boom and bust cycles may be due to food shortages or predator-prey interactions o Ex) One of first studies: snowshoe hare and lynx populations based on number of pelts sold by Hudson Bay company over 100 years. What causes their boom and bust cycles? Used radio collars to track hares, found 90% of hares had died due to predation, none from starvation. Supports predation hypothesis, but food availability still plays an important role. o As prey population increases, predator population increases Life history – the traits that affect an organism’s reproduction and death make up its life histories • Key life history traits include 1. Age of first reproduction 2. Frequency of reproduction 3. Number of offspring 4. Amount of parental care • Populations with R-selected life history o Found in disturbed or transitory environments o Have short life spans Sarah Stewart BIOL 1040 Final Exam notes o Breed early in life o Opportunistic and adaptable o Short generation times o Produce large numbers of offspring o Little parental care, infant mortality is high o Have efficient means of dispersal o Type III survivorship curve o Never reach K (carrying capacity) • Populations with K-selected life history o Found in stable environments o Long life span o Breed later in life o Long generation times o Produce small numbers of offspring and have parental care of their young o Have type I or II survivorship curve o Efficient in exploiting an ever-narrowing slice of their environment o Tend to reach K • Sustainable resource management involves harvesting crops but eliminating damage to that resource i.e. not overfishing fish populations Human Population th • Grew rapidly during the 20 century, now stands at 7 billion • Imbalance between births and deaths causes changes; increase vs. decrease • Expected to continue increasing for the next several decades • Demographic transition of a shift from zero pop. growth where the birth and death rate are low and equal – Mexico on it’s way to zero pop. growth • In developing nations o Death rates have dropped o Birth rates are high Sarah Stewart BIOL 1040 Final Exam notes o Populations growing rapidly Age structure – the proportion of individuals in different age groups; affects the future growth of the population and used to make predictions about it Ecological footprint – an estimate of the amount of land required to provide the raw materials an individual/nation consumes; includes food, fuel, water, housing, and waste disposal • The US has a huge ecological footprint – greater than the land which causes a large ecological deficit • If everyone on earth had the same standard of living as people in the US, would need the resources of 4.5 planets Community ecology – concerned with factors that influence species composition/distribution of communities and factors that affect community stability • Community ecologists seek to understand how abiotic factors and interactions among populations affect the composition and distribution of communities Biological community – an assemblage of all the populations of organisms living close enough together for potential interaction; described by its species composition • The boundaries of a community vary with research question investigated Habitat – the place where an organism lives; characterized by physical and chemical features and the array of other species living in it • Populations of all species in a habitat associate with one another - directly or indirectly Sarah Stewart BIOL 1040 Final Exam notes • What are some factors that shape community structure? o Climate and topography o Available food/resources o Adaptions of species in a community o Species interactions o Arrival/disappearances of species o Physical disturbances Niche concept – the sum of activities and relationships in which a species engages to secure and use resources necessary for survival and adaption • Distinguish between a habitat and a niche; habitat is your address, niche is your occupation • 2 kinds of niches: 1. Fundamental niche – theoretical niche occupied in the absence of any competing species 2. Realized niche – the niche a species actually occupies, some fraction of the fundamental niche Community Interactions Commensalism – one benefits, the other is not affected; very difficult to determine • Ex) Remoras and sharks Competition – can be intraspecific and interspecific between species • Intraspecific usually fiercer and has more consequences Sarah Stewart BIOL 1040 Final Exam notes • Gause proposed the Principle of Competitive Exclusion where multiple niches overlap • The greater the overlap, the greater the competition • Suggested that exclusion occurs when niches completely overlap – is this true? o Know Gause’s Paramecia experiment o No concrete example of this kind of exclusion in nature • Resource partitioning - locating new resources within your niche to avoid competition Predation – where the predator is the feeder and the prey is the feed • Predators get food from their prey but do not take up residence on/in the prey • Adaptions of predators and victims arose through coevolution • Prey have defenses which protect them from predators o Camouflage o Warning coloration o Mimicry o Moment of truth defenses – where predator and prey much interact Ecological Succession • Communities come into being by ecological succession; change in the composition of species over time • Classical model describes a predictable sequence with a stable climax community • 2 kinds of succession: Sarah Stewart BIOL 1040 Final Exam notes 1. Primary succession – new environments; bare rock succession 2. Secondary succession – communities were destroyed or displaces Climax community – stable array of species that persists unchanged over time; does not always move predictably towards a specific climax community
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