BSC 2011 UNIT IV STUDY GUIDE Ecology 1 a Define ecology b How does a population differ from a community c How does a community differ from an ecosystem d Please provide a specific example that exists in nature of a population a community and an ecosystem Ecology study of the interactions between organisms and their environment Population vs community populations are a group of organisms of the same species occurring in time and space Communities are all the organisms in a particular area all different species Community vs ecosystem communities are all of the different kinds of species in one particular area Ecosystems are the communities AND the biotic living components abiotic nonliving components of a particular environment Example of population size density and dispersion of animals that are the SAME SPECIES Example of community species richness total number of different species and the relative abundance the proportion each species represents total community 2 Define demography and list several types of vital statistics used in demography b Be able to interpret age structure diagrams for populations 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 Demography the study of population vital statistics and the factors that influence these Vital stats population size density and dispersion Age structure diagrams a function of birth rate and death rate and vary with age Rapid growth looks like a triangle Broad base Most population is young age Slow growth looks pretty even Population is pretty steady No growth zero population growth Narrow bases 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 b Be able to interpret survivorship curves c Explain the concept of trade offs with respect to life history 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 Cohort group of individuals born at the same time Life table an age specific summary of survival for a population Interpreting survivorship curves they change varying with age Type 1 humans large mammals low death rate when young Have few young most survive Type 2 birds small mammals lizard constant death rate regardless of age The cause of death is not because of age Type 3 trees marine inverts high death rate when young but then declines Few offspring survive Trade offs any E expended to one of these needs takes E away from other functions Survival vs reproduction Tradeoffs between E needed for survival and for reproduction shape species life history over evolutionary time Life history it refers to a species specific pattern of births reproduction and death Semelparity reproduce once and then die Have many offspring with low chance of survival Big bang reproduction adaptive to variable environment Iteroparity repeated reproduction throughout life They have less offspring but they survive more Mammals They adapt to stable environments 4 a Explain what carrying capacity is b How does carrying capacity affect population growth Carrying capacity K the maximum population size a particular environment can support Carrying capacity affects population growth resources are limited in the real world Population growth rates will decline when resources are used up and when population grows Resources in environment get used up as population increases in size 5 a Explain the difference between populations that grows exponentially as opposed to one that grows logistically b Describe the shapes of the two different growth curves c What does the logistic equation take into account that the exponential equation does not d Define the meaning of each term in the logistic growth equation e What is the difference between r and rmax Exponential growth growth rate is constantly growing Logistic growth growth rate changes depending on density Growth rate will slow as the population increases Exponential growth shape J shape Logistic growth shape s shape sigmoid The logistic equation takes into account that there is only a certain amount of resources that people can survive on and that there is a carrying capacity in the environment Logistic growth equation dN dT rmaxN K N K The part that is added to the logistic growth equation that is not apart of the exponential growth equation is K N K This term modifies growth rate R as N increases resources diminish Rmax vs r Rmax species specific intrinsic rate of increase and reflects the maximum per capita rate of increase under ideal conditions R overall rate of population increase as a function of birth rate death rate 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 small population of mice in the large meadow will proceed to grow exponentially at first when it is introduced because there is so much land and resources However resources are limited in the real world Soon the population growth rates will decline because there will not be enough resources to sustain the population When there are no more resources growth rates decline And maybe death rates increase if they cannot adapt to the limited resources 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 of birth rate or death rate changes in response to change in population density Limited resources Extrinsic DD regulating factors environment Predation Accumulation of waste Intrinsic DD regulating factors biological Crowding effect Density independent if birth and death rates change but it does not have to do with population density Hard to predict changes in population Weather Sudden catastrophes 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 b Name two types of organisms exhibiting Type I survivorship and two others that exhibit Type III survivorship Survivorship curves show survival as a function of
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