BSC 2011 UNIT IV STUDY GUIDE Ecology 1 a Define ecology Ecology is the study of organisms their interactions with their environment b How does a population differ from a community A population is a group of organism of the same species A community is different organisms living in one area c How does a community differ from an ecosystem the biotic abiotic components of a particular environment d Please provide a specific example that exists in nature of a population a community an ecosystem A population would be all the banner tailed kangaroo rats in a desert A community would be all the living organisms biotic factors occupying the same area in this case the desert as the banner tailed kangaroo rat The ecosystem would include all the living organisms and the abiotic factors such as soil sun temperature and weather 2 Define demography and list several types of vital statistics used in demography Demography is the study of a population s vital statistics and the factors that influence these Vital statistics are size density and dispersion b be able to interpret age structure diagrams for populations Age structure the distribution of different age classes in a pop n birth rate and growth rate influence age structure c discuss the appearance of an age structure diagram for a population that is growing rapidly as opposed to one that is actually decreasing in size or experiencing ZPG zero population growth Pyramid shaped indicates rapid growth inverted pyramid indicates decreasing population and a narrow base with some width in population in 40 60s but not huge differene throughout is Zero growth 3 b be able to interpret survivorship curves c Explain the concept of trade offs with respect to life history Energy Allocation an organism only has a limited amount of energy to allocate to increase their fitness which includes survival and reproduction A trade off occurs between E spent on survival vs reproduction There is a cost of parental care on parental survival This means if more energy is being spent taking care of offspring the organism is morel likely to have fewer offspring in order for the parent to survive If little energy is spent taking care of offspring then there might be less offspring since there is less cost on parental survival d Explain what a species life history refers to and provide an example of two species that have different or contrasting life history strategies describing how they differ Semelparity big bang reproduction reproduce once but many offspring low survival rate Examples of semelparity organisms are centrials salmon many annuals such as dandelions Iteroparity reproduce multiple times throughout life fewer offspring higher survival rate Examples of Iteroparity organisms are most mammals 4 a Explain what carrying capacity is Carrying capacity is the number of individuals of a species an environment can support based on limited resources b How does carrying capacity affect population growth Carrying capacity limits the population of a species but also as a population approaches its carrying capacity it will experience the fastest population growth rate at about half the carrying capacity then it will slow as it approaches the carrying capacity If the population exceeds the carrying capacity the population can experience a dramatic crash in the size of the population 5 a Explain the difference between a population that grows exponentially as opposed to one that grows logistically A population that grows exponentially is at ideal conditions with unlimited resources without a carrying capacity and continues to grow rapidly A population that grows logistically has a carrying capacity and its growth slows as it approaches its carrying capacity for a specific population realistic b Describe the shapes of the two different growth curves An exponential grow will look like a J while logistic growth will looks more similar to an S shaped curve c What does the logistic equation take into account that the exponential equation does not The logistic equation takes into account the carrying capacity of the environment d Define the meaning of each term in the logistic growth equation r is the per capita rate of population increase rmax is the maximum growth rate N is the number of individuals in the population K is the carrying capacity which is the maximum in size an environment can support e What is the difference between r and rmax r is the current per capita rate of population increase while rmax is the maximum per capita rate of population increase 6 Imagine a natural population say a newly established small population of mice in large meadow that is initially small in size and that will proceed to grow logistically Describe how the rate at which this population grows changes over time as it continues to grow in a natural environment in which there are limited resources The population will experience growth similar to exponential growth initially when the population reaches about half of the carrying capacity it will be at rmax after this point the growth rate will decrease and eventually become zero growth as it continually decreases as it approaches the carrying capacity 8 a How does a Type I survivorship curve differ from a Type III curve with respect to both age specific mortality and survivorship lifespan Type I differs from type III in respect to Type I have relatively few young that they expend a lot of energy on taking care of and therefore their young have a low mortality high survival rate young but a higher mortality rate later in life most offspring live a max lifespan compared to type III where there is a high mortality low survival rate in young but then decreases for the few survivors low no energy is put into caring for offspring few survive to max lifespan b Name two types of organisms exhibiting Type I survivorship and two others that exhibit Type III survivorship Two examples of type I include humans and elephants Two examples of Type III are mollusks and trees 9 What is the concept of maximum sustainable yield and how might you best manage a population for maximum sustainable yield The maximum sustainable yield of a population is the concept of maximizing the number of an organism that can be cultivated harvested and return to the carrying capacity the fastest This occurs at exactly half of the carrying capacity of a population This is often used in fisheries to determine how much fish they can harvest right now that will allow the population to
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