FOR 232 1st Edition Lecture 11 Outline of Last Lecture I Population II Density III Genets and Ramets IV Metapopulations V Spatial Dispersion VI Temporal Dispersion VII Dispersal Movement VIII Age structure and Sex ratios IX Population growth and Carrying Capacity X Density Dependence XI Density Independence XII Natality and mortality XIII Survivorship Curves Outline of Current Lecture I Stable Population II Unstable Population III Geometric Function vs Exponential Function IV Carrying Capacity V Elements that influence populations density VI Extinction VII Dispersal Current Lecture I Stable Population a Available data tend to reflect a balance among births immigration losses to predation other mortality emigration and dispersal at least for animals plants do not immigrate or emigrate i Consider the Law of Tolerance the chart that has a big bump in the center and the center of the curve represents the safe tolerable zones for a certain organism b In a stable population i Mortality Emigration Reproduction Immigration ii A fit populations remains in a steady state These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute II III IV c Ration of males to females and the age structure of a population affect the balance between births and deaths d Example red deer middle aged does have highest birth rate populations with primarily old or young deer have reduced birth rates Unstable Population a Mortality Emigration Reproduction Immigration i When gains exceed losses b Example Red deer populations with middle aged deer and a high birth rate population will increase given no abnormal losses and good habitat quality Geometric Function vs Exponential Function a Geometric function fits response data to discrete points at fixed intervals and the dependent variable changes at a constant rate b Exponential function fits response data to a long span of time even for time intervals lacking an observation of the response variable i But uses the number associated with those years having an observations to predict change over time c Regression solution sorts out the variability and reveals a general relationship among the variables i Can t except a population to increase forever limitations of key habitat elements will constrain growth to the carrying capacity ii The maximum will equal the number that available resources can sustain d But increased rates of reproduction and good rates of survival the population may increase exponentially until it taxes the capacity of its habitat carrying capacity or K e Make sure to actually look at the different kinds of charts in the textbook or the teachers notes Carrying Capacity a The population density of an organism that resources of an area can sustain i Based on key factors animals 1 Space 2 Food 3 Cover 4 Water 5 General environment b HQ Habitat Quality i HQ f Food cover Water Space ii Determines the number that remain fit and live iii Population growth or stability with optimal HQ c Based on two kinds of structural factors i Biological structure the density size and height of plants and other food resources Dead materials like snags fallen trees forest floor organic layer V VI ii Physical structure soil precipitation temperature seasons etc Objects like rocks holes crevices surface water Elements that influence populations density a How do the combination of critical habitat elements influence population s density i By limiting how many can survive and remain fit given the availability of key habitat elements and constrained by the element present in limiting amounts b When numbers become too many for more to remain alive and fit then i Fitness declines ii Reproduction decreases iii New and weak ones die iv Some fit ones disperse or emigrate v Many fit ones and others say in place c The population will then again stabilize to a level in balance with available resources d When life essentials generally favorable over long periods populations remain in general steady state e Trigger periodic decreases followed by later increases i Naturally recurring events lead to such cyclic responses and affect the amplitude of change ii Example competitors capturing the habitat iii Particularly in small mammals and birds populations cycle around an average long term average density f More factors that have effects on population density i Fecundity ii Sex and age structure f the population iii Habitat quality iv Immigration v Environmental variations vi Predation vii Competition viii Emigration Extinctions a Not likely to occur across populations of several species at any point in time b More likely in species that occur overall in limited numbers c More likely in species that occur in a restricted geographic distribution or having a narrow environment niche d Think more about competition i between different species as for a common habitat condition deer and cow interspecific VII ii Between individuals of the same species of the same population intraspecific e Competition happens when a desired or necessary resource in short supply food water shelter other i Active competition occurs in animals based on a decision to act ii Mobile creatures animals can move about become aggressive submit to others and find new habitat iii Passive competition among plants and immobile creatures due to chance placement and differences in growth rate iv Also consider interference due to another organism already occupying the space or developing more rapidly f Scramble or exploitative competition i resource in limited supply ii all get some iii none get sufficient iv General population fitness decreases g Contest or interference competition i Resource in limited supply ii aggressive individuals take what they need iii Others weaken and do not reproduce iv Or individuals lacking minimally necessary resource die Dispersal a Vigorous individuals leave the stressful situation for a vacant space with adequate resources and that reduce demand within the original space b Dispersal short distance movement does not change the total numbers of a population c Crowded animal may explore adjacent territory searching for a vacant area to establish its home range d Through time other siblings do the same thing family members disperse into open areas within the population i Commonly at least fit females of a population tend to disperse short distances Often overlapping the mother s home range e What happens in