Lecture outlines Part 2 Ecology Ecology lecture 1 Ecology and the ecological method A What is Science i Hypothetico deductive science The scientific method Making observations Forming hypotheses Making predictions Testing predictions ii Science as a cumulative process iii Scientific proof as an oxymoron B What is ecology i Definitions of Ecology Haeckel first definition the comprehensive science of the relationship of the organism to the environment Modern consensus e g Krebs 1972 the scientific study of the interactions that determine the distribution and abundance of organisms C Fundamental questions in ecology i Why are there so many species ii Why do the numbers of many species remain roughly constant iii What determines the distribution of a species D Introduction to Ecology i Individuals populations and communities ii Biotic pertaining to life or living organisms and abiotic non living factors iii Species distributions relevant to global warming invasions genetically engineered species habitat fragmentation Ecology lecture 2 Individuals adaptation and behavior Behavior and evolution behavioral ecology emphasizes evolutionary hypotheses for animal behavior based on the assumption that animals increase their fitness by optimal behavior A Group living i Advantages avoiding predation increased feeding rate energy gains ii Disadvantages increased predation increased competition increased disease increased cuckoldry increased cannibalism iii Weighing up costs and benefits an optimality approach using a common currency A method for the non mathematical bird A rule of thumb B Altruism i Kin selection the importance of inclusive fitness ii Reciprocal altruism you scratch my back I ll scratch yours The importance of discrimination against cheaters Apparent altruism may also turn out to be due to manipulation eg cow birds or actual individual benefit some alarm calls C Mating systems and parental care i Some terms to know Monogamy prolonged pair bond Polygamy one or both sexes has more than one mate Polygyny male mates with several females who each mate with one male Polyandry female mates with several males who each mate with only one female Promiscuity both male and female mate with several partners ii Birds generally limited by the rate of food delivery to the nest iii Mammals only females lactate often limiting the contribution by the male iv Fish little parental care but when it occurs either sex could carry it out eg fanning eggs v Environmental factors affecting mating systems The economics of defending resources in space and in time Resource defence polygyny Female defence polygyny Female synchrony as a means to enforce monogamy John Latto 7 10 07 Ecology lecture 3 Population biology I demography life history APopulation Structure i Density Difficulty of measuring directly Estimation e g mark release recapture assumes the proportion of marks in the second sample is equal to the proportion of marks in the population as a whole Knowing the number marked a and sampled b in the second sample and the number initially marked c we can calculate the population size d a b c d therefore d c x b a ii Distribution or dispersion Random rare in nature Regular or overdispersed frequently caused by competition Clumped or patchy many possible causes distribution of resources for example iii Age Structure organisms may change in many ways as they age eg food source predators and competitors may all change Comparison of human populations Graphical presentations B Population Analysis i Life tables death tables would be a better name Cohort follows a group of individuals born at the same time hard to do but accurate Static looks at all the individuals present during one time period easier but harder to interpret ii Survivorship curves Type I e g humans mortality is low until most individuals die late in their lifespan Type II e g some bird species a constant proportional mortality Type III e g many insect and fish species most individuals die young the few that survive may then live for much longer C Life histories i Life history components Semelparity vs iteroparity reproduce once or repeatedly Age at first reproduction precocity vs delay Clutch size Size as an adult and growth rates to reach that size ii Life history trade offs eg current reproduction may reduce future growth or survivorship Ecology lecture 4 Population biology II growth and regulation APopulation growth in an unlimited environment exponential growth i Derivation of equation staring with Nt 1 Nt B D I E Births Deaths Immigrants Emigrants ii Discrete time vs continuous time dN dt the population rate of change B Population growth in a limited environment i Four features of competition between individuals shared requirement for a resource resource is in limited supply leads to a reduction in vital rates ii Density dependence what it is a necessary condition for population regulation and what it is not not a sufficient condition iii Derivation of the logistic equation dN dt rN 1 N K K the carrying capacity r the intrinsic rate of increase of the population iv Population density determined by density dependent factors AND density independent factors v Limitation vs regulation vi Time delays generally lead to oscillations and instability vii Life histories K and r selected populations K selected long lifespan low mortality good competitors producing few high quality offspring r selected short lifespan high mortality good dispersers and colonizers producing many small offspring with little parental care C Human Population Growth i The population explosion is over ii The demographic transition describes the transition from high birth and death rates to low birth and death rates John Latto 7 10 07
View Full Document
Unlocking...