Review Guide for Final Exam - Ecology | BIOL 2804, Study notes of Ecology and Environment

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Ecology 8/26 Tues Info: 60% 3 in class exams 20% 10 hw assignments 20% final  Ecology: quantitative (being able to measure) study of the interactions among organisms and the interactions of organism with the environment o Interactions:  Consumption/predation  Everybody eats somebody  Competition  Mating/genetic recombination  Food  With environment  Symbiosis (mutualism) o Units are # of organisms, matter and E rather than currency o Resources are scarce  Haeckel (1866) o German natural philosopher o Coined term ecology:  economy of nature  relationships among organisms and environment  natural selection 8/28 Thurs  The Economy of Nature o Ecology is a quantitative science o Units are # of organisms, matter (grams of carbon, mL of water, etc) and energy (calories in organisms in food chain) rather than currency o Resources are scarce  Food, water, etc resources o Ex: energy balance of a lizard  The cold-blooded animals utilize series of adaptations to maintain body temp (humans do this by eating, burning calories)  Inputs (food, solar radiation) and outputs (convection and conduction, excretion)  The balance of these inputs and outputs is what determines the metabolism, growth, and energy storage of an organism  Balance is governed by the 2nd law of thermodynamics o Ex: nitrogen balance of a forest watershed  Important to know the inputs coming in to know their effects  Inputs (nitrogen fixation, deposition, mineralization) and outputs (plant uptake, storage in soil organic matter, leaching, stream discharge) o Ecological balance sheet:  The Economy of Ecology: variability and the measure of nature o Variation: we’re all different; can b a pain in the butt for scientists; fundamental to ecology o Scientific method   If the results are inconsistent w predictions, then a new hypothesis must b constructed  If results are consistent w predictions, further hypotheses and predictions will b developed  Importance of understanding variability in the environment o Natural entities and phenomena are variable o Variability (diversity) causes stability in ecosystems o Genetic variability is the “raw material” of evolution  Partitioning variation o Collect data (measure, count, etc) o Calculate avg and “spread” or variation in data (and other statistical parameters) o Examine data for explanatory factors  Interpret graphs, charts, and tables in light of given info, and make inferences based upon what we kno bout ecological theory (often common sense) o Partitioning variation w Histograms o Evolutionary trade-off  Charles Darwin o Voyage of the Beagle, 1831-1836 o Marveled @ the variety of organisms inhabiting the natural world  Didn’t use the word genes  One is fit bc they have passed their traits to next generation o The Origin of Species  Fitness o The fitness of an individual is measured by her/his contribution to future generations  Case studies o Pepper moth (see below) o Sticklebacks o Darwin’s finches o Pocket mice  Different “morphs” (light and dark colored)  Variation is related to local geology and Cryptic coloration  Can still reproduce with each other  Convergent evolution  Different kinds of pressure in physical envir have influence in variation of pigmentation in organisms  Natural selection o Differential success (survival and reproduction) of individuals w in the pop that results fr their interaction w the envir o Requires:  Variation  Beak size in finch o Galapagos Islands  Diversity of habitats and niches  High and low elevation  Wet and dry  Islands range in age fr very young to very old (5MY)  1977 drought  Production of small seeds declined  Birds w larger bills fared better  Directional selection o Shift of distribution of traits  Stabilizing selection o Favors individuals w traits near the center of distribution  Disruptive selection o Favors those w traits near the tails of distribution  Heritable traits  Process of Heredity o Mendel o Pea flowers unlock secrets of heredity  Homo/heterozygous  Dominant/recessive o Concluded  There are alternate forms of until that control heritable traits (flower color)  For each inherited trait, offspring has 2 units (1 fr each parent) which may b the same of different  When 2 units are diff, one is fully expressed, and the other has no discernable effect on the organism’s outward appearance (phenotype)  The unit that’s expressed is the DOMINANT (purple) and the other is called RECESSIVE (white)  DNA: Unit of Heredity o Watson and Crick o Genes are the units of inheritance  Aa, heterozygous  BB, homozygous dominant  cc, homozygous recessive  Evolution in action: peppered moths o Alleles for dark-bodied moth is dominant o Light-bodied moth is recessive o Variety of birds feed on these moths o As tree/bark colors changed, went fr lighter-colored to dark color (industrial melanism)  Evolution is a change in gene frequency o Gene freq remain constant (Hardy-Weinberg Equilibrium)  Mating is random  Mutations don’t occur  Population is lrg  Natural selection doesn’t occur  Migrations don’t occur o We must break these rules in order for evolution to occur  Variability and natural selection o Variability in traits among individuals in a population contributes to differential survival and reproduction  Evolution via natural selection o Variability in traits among individuals in a pop contributes to differential survival and reproduction o Heritability of variation is an essential feature of natural selection and evolution HW 1  Adaptations: characteristics that give an organism an advantage in a given envir  Natural Selection: mechanism of evolution on which Darwin focused in The Origin of Species  Alleles: alternative forms of genes  Mutation: primary original source of genetic variation in a population  Evolution is a change in gene frequencies  Hardy-Weinberg principle: mating is random, mutations don’t occur  Sympatric: 2 species that occupy the same area  Reproductive isolation: necessary for the process of speciation 9/4 Thurs  Genetic variation drives evolution o Sexual selection (non-random mating) o Migration  New individuals coming in, bringing in new things o Mutations o Existing genetic variation w in a pop  Natural selection requires o Heritable variation o Variation results in differential survival and reproduction among individuals  Mechanisms of Selection o Geographic separation  Allopatric speciation   Populations separate and reproductive isolating mechanisms evolve bc of a geographic barrier  Salamander separation bc of river blockage o Sympatric mechanism  Disruptive selection  Mutations  New species habitat the same reason but there’s a new factor that separates them  Mutations  Ex: polyploidy in plants o Larger seeds and fruits  Genetic variation drives evolution o Like fern, lots of bitty leaves  Surface/volume ratios o Exchange surface  Water conservation  Heat dissipation  Light interception  Water o Carbon allocation o Mineral nutrition of plants  Definitions o Autotrophs  plants o Heterotrophs  animals 9/9 Tuesday  Adaptations to envir represent trade-offs bt conflicting costs o Different “architecture” in leaves  Help to maintain heat balance  Greater surface area= greater water loss bc exposure to full light o Plant adaptations to E balance and water availability  For the CO2 the plant gains, it loses more water molecules  Water goes thru roots, stem, xylem tissue, leaves, then into the atmosphere  Fr high water pressure to low water pressure o Water potential (Ψ))  A measure of E needed to move water molecules across a semi- permeable membrane  water tends to move fr areas of high (less negative) potential to areas of low (more negative potential)  Water potential of pure water is 1 Mpa (mega-pascals)  Water movement is passive (water moves fr soils, thru roots, stem, leaves, and eventually to atmosphere in response to a pressure gradient measured in water potential  Osmotic potential  Maintain water balance bt soil and roots  Matric potential  The more surface area available, the greater affinity of water potential o Plant adaptations to water availability  0=highest water potential; 3= lowest water potential o Water use efficiency  Ratio of net primary productivity to transpiration by a plant o Plant adaptation to temp and moisture  Photosynthetic pathways  C3 “cool season” o Biomass starts around April and then comes back down by July o Lots of leaves in the spring  C4 “warm season” o Start out low then increase in the summer  CAM “catcti and euphorbs” o Photosynthesis  C3 photosynthesis  Most common (older pathway)  CO2 binds to RuBisCO (5-C compound) o Ribulose bisphosphate carboxylase-oxygenase o World’s most abundant enzyme  CO2 + RuBisCO -> 2 PGA (phosphoglyceric acid)  PGA is a 3-C compound (hence C3 photosynthesis)  C4  Modification of the C3 pathway, mainly by tropical grasses (corn, sugarcane, amaranth)  Step 1: CO2 is fixed by phosphoenolpyruvate (“PEP”) carboxylase in the mesophyll to produce: o Oxaloacetic acid (OAA) which is then…  Rapidly transformed into 4-C sugars (malic and/or aspartic acid)  Step 2: the 4-C compound is transported to adjacent specialized cells called bundle sheath cells where “normal” caboxylation is facilitated by RUBISCO. CO2 is release in such high concentrations that the O2 reaction is blocked  Requires more energy  Typically: o Hot/dry adaptation o Most common in tropical and subtropical grasses and desert shrubs o PEP carboxylase doesn’t react w O2-no photorespiration o Better water use efficiency than C3 pathway o High root to shoot ratio o High soil organic carbon o Crassulacean Acid Metabolism (CAM)  Specialized photosynthetic pathway where the light and dark reactions are decoupled  Plants fix carbon @ night and stores it as malic acid and release it in the mesophyll cells during the day to complete photosynthesis  Advantage= the plant has a stomata that can remain closed during the day to minimize water loss  @ night  Absorbs CO2 and out puts water  During day  Stomata closed  Malate converted to CO2 which combines w RuBP RUBISCO to make sugars o C4 plants spatially decouple  CO2 uptake and carboxylation  Carbon allocation o A matter of balance of mass above and below ground mass o Switch grass  Native C4 grass  High root to shoot ratio  Can grow on a land that may not support commercial crops  Drought resistant  Grows on marginal land  Major nutrient elements o Hydrogen o Carbon o Nitrogen o Oxygen o Phosphorous o Sulfur  Nitrogeochemical elements o Na o Mg o K o Ca o Cl o I o B o Fe  Depends upon metabolic costs and thermal regulation strategies.  Examples  Animal Thermoregulation Strategies o Metabolic o Behavioral  Term and ‘therms o Mechanisms of Heat Balance  Endothermy - Metabolic energy production, “heat from within”.  Ectothermy - Environmental/behavioral energy regulation, “heat from without” o Body Temperature Regulation Strategies  Homeotherms - Organisms that maintain relatively constant body temperatures through endothermic mechanisms.  Poikilotherms - Organisms that have variable body temperatures regulated by ectothermic mechanisms.  Heterotherms - Organisms that regulate body temperatures through both endothermic and ectothermic mechanisms.  Body temperatures of homeotherms exhibit less variation than poikilotherms over a range of ambient temperatures  Homeotherms Use Metabolic Energy to Maintain Homoeothermic Body Temperature Regulation o Requires high investment of food energy  Homeostatic Temperature Regulation  Homeothermic Temperature Regulation  Poikilotherms Use Ectothermic mechanisms to Regulate Body Temperature  Behavioral Temperature Regulation Diurnal Temperature Variation In Typical Poikilotherm Seasonal Temperature Variation In Typical Poikilotherm Body Temperature and Metabolic Rate For Poikilotherms Limits how small a homeotherm can get and how large a heleotherm can get o Consequences of body volume-area relations are different for homeotherms and poikilotherms: o Homeotherms increase biomass with decreasing temperature to minimize heat loss o Homeotherms must have a minimum biomass to offset metabolism-body mass relationships o Large poikilotherms are confined to warm environments o Poikilotherms have much smaller minimum biomass o Scaling Laws and Metabolism  Size Doesn’t Matter? o Metabolic-Biomass Relationships are Scale Invariant  Y≈M3/4 o All biomass from cells, to organs and microbes to whales depend upon distribution of materials and energy through biological networks. Universal quarter scaling results from the following 3 conditions: o “Networks” fill volumes according to fractal geometry. o Terminal “branches” of network are size invariant. o Energy required to distribute resources is minimized.  Metabolic Theory of Ecology o Geoffrey West and James Brown  Size Doesn’t Matter? o Metabolic(process)-Biomass Relationships are Scale Invariant Y≈M3/4 o “Networks” fill volumes according to fractal geometry. o Terminal “branches” of network are size invariant. o Energy required to distribute resources is minimized. o Examples:  Mammalian circulatory system  Mammalian bronchial networks  Insect Tracheal tubes  Plant vascular systems  Metabolic rate scales as the 3/4 Power of biomass over 27 orders of magnitude.  Life in the Fast Lane  Mass and Metabolism Are Linked to Life History Traits o Age at first reproduction o Parental Investment o Fecundity (No. of offspring) o Semelparity vs. Iteroparity o r vs. K strategies 9/16 Tues  Ecological population o A grp of individuals of the same species living in a given area at a given time o Populations have structure  Distribution of organism in space  Density- #s of orgs (usually per unit area)  Demography- #s of juveniles and adults  Pops exhibit diff kinds of growth  Why study populations o Manage natural populations  Control pests  Manage rare and endangered species  Help in managing ecosystems o Help understanding diseases and pandemics o Understanding human population dynamics  Ecological Population o Grp of individuals of the same species living in a given area @ a given time  Spatial distribution: o geographic range  The area that encompasses the entire spatial distribution of a species  Populations may have discontinuous distribution across a geographic range o Discontinuous or “nested scales”  Comparison of Exponential and Logistic Growth  What conditions favor exponential vs. logistic growth?  Life Tables o First developed by insurance industry o Used to predict life expectancy and calculate insurance cost o Age-specific account of mortality & survival o Examine population dynamics o Can be used to calculate r  Life Tables and Insurance o Annual Cost Per $1,000 of Coverage  Gray Squirrel Population Dynamics o Bob Smith ~ University of West Virginia  Important herbivore species  Easy to catch  Short life expectancy Three Basic Types of Survivorship Curves Type 1: Exampie, mammals Type 2: Examples. rodents, reptiles, perennial plents Type 3: Examples, invertebrates, fish ect. (r-selected species) Life Table: Population (n,) and Mortality (d,) x Ty dy sag ayteO OT = 530 = 159 ; nO oo My, — Np = 159 — 80 3 48 af 4 21 “6 5 5 5 x=time step n, = total population d, = age specific mortality where dy = nyt Life Table: Life Expectancy a RD aa ee = Mo # 1) 2 = (530 + 159) /2= 344.5 i 2 1186 _~ = (ns #n.)/2= (80 + 48)/2=64 3 48 34.5 ? 4) 130 = (Ng +14) 2 = (5+0)/2=25 5 5 5 x =time step otal population obability at birth of surviving to a given age(x) yerage # individuals alive during age interval x to x+4 where L, = (Mtes1)/2 Lambda= Nx/n(x-1)  Geometric Population Growth o Geometric Rate of Increase, Lambda (λ): Factor by): Factor by which the size of a population increases over a period of time.  Geometric vs. Exponential Population Growth  Stochasticity and Population Dynamics o Demographic stochasticity  Variation in sex, death and fecundity o Environmental stochasticity  Severe weather, fires, flood, draughts 9/23 Tuesday  The Limits to Growth  Logistic Population Growth o dN = change in number of individuals o dt= change in time o r = constant representing birth rate-death rate o N = initial population size o K = carrying capacity  Logistic Population Growth  Carrying Capacity o Number (K) of individual organisms the resources of a given area can support, usually through the most unfavorable period of the year o The Environment functions to Limit Population Growth  Properties of r and K selected Species o r strategist :  short lived  high reproductive rate (semelparous)  small body size  rapid growth rate  large number of offspring  low parental investment  Example: “weedy” annual plants, bacteria, protists o K strategist:  Competitive species  Stable population  Slow growth rate  Long-lived individuals  Low # of offspring  Large parental investment  Example: vertebrates (esp. mammals), some trees  Life in the Fast Lane  Limits to Growth o Density Dependent: Limitations to growth regulated by biotic factors such as competition, predation and disease which are compounded by high population densities.