UNIT IV STUDY GUIDE Ecology 1 a Define ecology The study of the interactions between organisms and their environment b How does a population differ from a community A population is a group of organisms of the same species co occurring in time and space and a community is all of the organisms inhabiting a particular area c How does a community differ from an ecosystem A community is all of the organisms inhabiting a particular area and an ecosystem is the biotic and abiotic components of a particular environment d Please provide a specific example that exists in nature of a population a community an ecosystem Population species of fish in a pond Community all the species of plants and animals in the pond Ecosystem all the species of plants and animals in the pond and the other factors such as the water and rocks or soil 2 a Define demography and list several types of vital statistics used in demography The study of population vital statistics and the factors that influence these Population size absolute of individuals Population density individuals area or volume Population dispersion how individuals are distributed in a population b be able to interpret age structure diagrams for populations A function of birth rate and death rate 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 Rapid population growth Triangle shaped Slow growth Rectangle shaped but more narrow at top ZPG narrow base but rectangle shaped Age Structure Diagrams RAPID growth ZPG ZERO growth SLOW growth 1 3 a What is a cohort What can a person learn from a life table and a reproductive table that has been constructed for a particular population of some species Cohort a group of individuals born at the same time Shows birth rate and death rate variance Can be used to predict the future population structure b be able to interpret survivorship curves I low death rate when young higher later in age large investment of E caring for relatively few young most survive to max lifespan II intermediate type curve and intermediate E investments relatively constant death rate regardless of age III high death rate when young but declines for the few survivors little or no investment of E caring for large s of offspring and few survive to max lifespan The Survivorship Curves I II III c Explain the concept of trade offs with respect to life history All organisms have a limited amount of E to allocate to enhance their fitness survival and reproduction Normally there is a trade off between the two Any E expended to one of these needs takes away E from the other 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 Life history is a species specific pattern of birth reproduction and death Age of 1st reproduction Frequency of reproduction Length of reproductive activity Number of offspring per brood Sparrow vs Albatross Sparrow less E invested in survival and more E into reproduction Reproduce earlier die earlier Albatross More E into survival than annual reproduction By living longer they are still able to produce enough offspring to maintain species 2 4 a Explain what carrying capacity is K the maximum population size a particular environment can support b How does carrying capacity affect population growth N K dN dt is positive and the population grows N K dN dt is zero and the population doesn t grow ZPG or zero pop n growth N K dN dt is negative and the population shrinks 5 a Explain the difference between a population that grows exponentially as opposed to one that grows logistically An exponential function is under ideal conditions which has unlimited resources and population growth rate is maximized A logistic function is realistic since resources are limiting and population growth rates will decline as resources are used up as the population grows b Describe the shapes of the two different growth curves Exponential growth is J SHAPED and logistic growth is S SHAPED c What does the logistic equation take into account that the exponential equation does not Logistic takes into account that resources are not unlimited and assume growth rate changes with density and acknowledges the carrying capacity d Define the meaning of each term in the logistic growth equation r overall RATE of of pop n increase birth rate death rate or b m e What is the difference between r and rmax rmax reflects the max rate of increase under ideal conditions 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 With logistic population growth the population growth will slow as the population reaches K the carrying capacity here it will level out and should keep a constant population size 7 What is the difference between density dependent and density independent factors that regulate population growth Please give an example of each Density dependent if a factor birth rate death rate changes in response to changes in the population density Ex Of seeds decrease as density increases Nestlings decreases as density increases Survival decreases as density decrease Density independent birth rate death rate does not change with population density Ex Weather Sudden catastrophes disturbances fire flood 3 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 1 curve low death rate when young higher later in age large investment of E caring for relatively few young most survive to max lifespan Type 3 curve high death rate when young but then declines for the relatively few survivors little or no investment of E caring for large s of offspring few survive to max lifespan b Name two types of organisms exhibiting Type I survivorship and two others that exhibit Type III survivorship Type 1 humans and other large mammals Type 2 birds small mammals some lizards Type 3 trees marine inverts fish 9 What is the concept of maximum sustainable yield and how might you best manage a population for maximum sustainable yield To maximize population growth rate by
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