Ecology Notes Lecture 1 What is Ecology Trophic cascades Big picture impacts smog etc zone fish kills etc antibiotics Ecological successes o Energy production the type of energy we use creates acute health o Food production Intensive agriculture results in eutrophication dead o Health and medicine Patterns of lyme disease intensity resistance to o Bare bones research feeding and reproductive patterns o DDT causes developmental handicaps thin shells etc that result in reproductive failure o Ban on DDT was followed by bird of prey recovery bald eagles ospreys Fundamentals o Relationship between organisms and their environment o Distribution and abundance o Levels individuals populations communities ecosystems Example o Why are trees not on the island o Develop hypothesis and design experiment o Maybe no seeds Supply problem Transplant seeds if successful yes seed supply if not its something else Set of tools o Observations to identify trends o Translate observations into questions should be falsifiable question that can be tested o Design test analyze data communicate results Observations o Biomes o Examples deserts tropical forests tundra savannah chapparal temperate grasslands temperate deciduous forests taiga freshwater biomes o Marine biomes open ocean pelagic benthic deep sea mud hydrothermal vents rocky shores intertidal kelp forests coral reefs sandy shores seagrass eelgrass beds marshes mangroves Communicating Results Written and oral presentations Logistics o Sarah and Chris TAs No lab this week o Pay attn to Blackboard online text SimUText o First chapter Population Growth WEDS SECTION 1 syllabus read schedule Lecture 2 Population Growth Four levels of ecology individuals populations communities and ecosystems Populations all the members of a single species in an area Understand ecological dynamics of populations over time The whole party of life depends on distribution and abundance of producers History All flesh is grass o Egyptian censuses in 3050 B C for military and tax purposes o Romans 5 29 B C o Bills of Mortality used birth and death rates to predict onset of plague John Graunt 1662 discovered geometric growth o T R Malthus 1798 Essay on the Principle of Population suggested limits to exponential population growth Open and Closed Populations o Closed populations isolated dependent on birth and death rates o Open populations same factors as closed populations including two new immigration and emigration o Long term growth potential positive birth feedback loop both parents that remain viable as well as viable offspring can contribute further to population Geometric Growth o Unbounded growth with non overlapping generations annual reproduction events within a timestep net finite growth rate ratio of pop size b n two gens N t 1 Nt o If If 1 population growth 1 population decline o Across 1 timestep N t 1 N t o Across multiple timesteps Nt t N0 o Can have different values depending on timesteps used for o Ecologists use logarithm plots because if log N vs time is linear then reference is constant o ln ab ln a ln b slope of line r ln ex In ppt o Can have constant rates of increase and decrease Exponential Growth o Unbounded growth with overlapping generations o Large chunks of total change in variables o o dN dt r N where r slope dN dt instantaneous change in population size how fast is the population changing right now N t N o Integrate between specific timesteps simplify formula to N T N 0 erT change over continuous time o Review of ln and exponents o Relating to r geometric to exponential growth r instantaneous rate of increase whereas change between timesteps Same rank order relationship as is proportional with 1 but r relates to 0 r 0 growth r 0 decline r 0 constant ln r then Nt N0 ert the continuous equation for exponential growth e r o Geometric growth implies that o In exponential growth environment is constant improving is constant birth rate death rate environment means growing populations deteriorating environment implies decline o Implies density independent change doesn t depend on number of individuals already present o Ideal conditions and density independence usually aren t met in real world populations can cause a lot of variance in o Doubling time dt 0 693 r r ln o LOOK OVER SLIDES 39 and 40 Lecture 3 Population Growth 2 0 Accuracy Precision Use of and r are number based and very black and white Ex People in different age groups make different contributions to the population we need to account for that Bills of Mortality o Originally causes and places later came life tables that looked at B and D Horizontal Approach conditions survivorship Vertical Approach o Looks at cohorts a group born at the same time experiencing similar o Horizontal Life Table follows a cohort from birth until death o Impractical for species with a long generation time ex Elephants o Can plot number of individuals number dying mortality o Vertical table time specific snapshot of multiple cohorts simultaneously majority of studies are this way o Can plot number of individuals over time as well as calculate the number dying per timestep survivorship proportion and mortality inverse of survivorship o Take the log to make the slope of the line increasingly linear Three types of survivorship curves o Type 1 High survivorship until end of life span low fecundity low infant mortality advanced parental care abundant resources o Type 2 Linear w a slope of 1 diagonal w moderate fecundity and or early mortality and moderate parental care o Type 3 Sharp drop in survivorship directly following birth shorter life span high fecundity and high early mortality virtually no parental care Survivorship inverse of death and births are correlated Age distribution Derived from vertical life tables Birth Terms o Birthrate number of young born per female in a timestep o Birth refers to any process that produces new individuals collectively o Fecundity schedule average birth rate for females in a particular age class Age distribution fecundity schedule estimate net reproductive rate R0 o Only really valid when age structure is stable o Multiply proportional survivorship lx by age specific fecundity bx then sum the age groups o Population is increasing because R0 1 Generation Time T o Definition average age from when an individual is born to when its o Discrete generations annual organisms plants some insects o Overlapping generations T Age of first reproduction Age of last offspring are born