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Midterm notes 1 Ecology the study of interactions among organisms and between organisms and their environment. Ecology's fundamental goal To assess the biological and physical factors that determine the distribution and abundance of species. Evolution A change in the properties of populations of organisms that transcend the lifetime of a single individual. Species Richness the number of species in a given area Species Evenness The degree to which species are equally abundant Species Diversity A measure that combines both richness and evenness Two types of species Morphological and Biological Morphological Individuals are grouped into species based on their similar appearance. Pro: Practical and simple to apply, often reflects evolutionary relationships. Con: Genetic variation within populations, changing morphology in response to environment (plasticity), some species may look similar because they evolved those traits independently. Plasticity Changing morphology in response to environment. Biological Species Groups of actually or potentially interbreeding individuals that are reproductively isolated from other such groups. Pro: Clear biological and evolutionary meaning Con: Difficult to apply in practice. Asexual don't interbreed, reproductive barriers hard to recognize, potential inbreeding doesn't mean actual interbreeding. Climate average and annual variation in ______ and _______ in a given region over the long-term. Temperature and Precipitation What determines Climate? Incident solar radiation (season and latitude) Air circulation driven by solar radiation and Earth's rotation. Hadley Cells

When the sun is directly overhead, the atmosphere is heated causing air to rise, then the air cools. Cool air holds less moisture than warm air, so water precipitates out and falls as rain. Rain at equator, deserts at 30 N and S b/c of dry air. Surface winds influenced by Earth's rotation Incident radiation also changes with season ITCZ Intertropical Convergence Zone the area of intense rainfall in Hadley Cell circulation Local variation in climate independent of latitude. The rainshadow: Warm moist air goes up the mountain on the windward side, rising air cools and condenses and rains, the dry air cools and sinks on the lee ward side. Vegetation Changes Valley Grassland - foothil woodlands - yellow pine - lodgepole - subalpine forest - red fir forest (highest) - woodland - scrub Populations evolve in response to local climate Local adaption Wallace's Line Biotic interchange and its limits (when the sea levels rise and fall to let animals pass) Methods of estimation Floras and Faunas Extrapolation from sampling number of species in a defined area. The species - area relationship S = cA^z Works for estimating diversity in a single habitat type, but different taxonomic groups and habitats have different 'c' and 'z' parameters. s=species, c= constant depends on goup, A = area, z= constant determines the shape and slope of the curve (ranges from 0.15 to 0.35) Threats to Biodiversity Habitat alteration and destruction Haresting/Fishing Climate Change Introduced Species Fraction of species remaining = fraction of area remaining ^z Sr/Si = (Ar/Ai)^z

Reasons why Biodiversity Matters 1.) Humans depend on species for food, clothing and medicine. 2.) Aesthetic pleasure and the dependence of tourism revenues of biodiversity. Trade-Off The relationship between the benefits of a trait in one context and its costs in another context. Principle of allocation All life functions cannot be simultaneously maximized. Bulk of an organism's biomass Carbon, Oxygen, Hydrogen Bulk of organisms metabolic machinery (proteins, enzymes, cofactors) Nitrogen, Phosphorus, macro and micro nutrients required to run the machinery and build infrastructure (calories) Energy Medium in which biological reactions occur Water Autotrophs can live exclusively on inorganic sources of carbon, nitrogen and other essentiial resources. Photoautotrophs Use energy from sunlight to power metabolism, growth, and resource-gathering. Heterotrophs Use pre-formed organic molecules such as food (source of carbon, nitrogen, energy and other essentials.) Visible light is ranges 400-700 Visible light is available for autotrophs to use for photosynthesis Chlorophyll is a light harvesting pigment of green plants because It only reflects green and absorbs all other colors. In addition to carbon, plants need N (Stunted growth), P, Fe (wilting), k, mg, etc Heterotrophs: Classified by WHAT they eat. Herbivores, Carnivores, Omnivores, Detritivores Heterotrophs: classified by HOW they gather food Suspension feeder (filter feeder)- remove suspended particles from the water Deposit feeders - consume dead organic matter Predator - active hunter of live organisms using and/ or stealth. Symbiont - Live in with or in another organism and obtain nutrition from that organism. Symbiont - Parasitic Benifit comes at the expense of the host

Symbiont - Mutualistic Host benifits as well Why specialize (eat few types of prey)? Evolution of increased efficiency of predation on preferred prey Why generalize? Eat more types of prey? Balanced diet, dilute toxins, reduced search costs. How do generalists choose among different prey? 1.) Effort required to capture and consume prey -relative size of pretator and prey -prey defenses 2.) Value of the prey -energy content -presence of rare/critical nutrients -defenses that reduce digestibility -toxic chemicals Food choices by animals often _____ net energy intake MAXIMIZE Forager Goals 1. Avoid predators 2. find mates 3. Obtain specific micronutrients or vitamins Without adaptions stress leads to a _______ performance decreased Adaption Evolutionary change in genotype that maximizes performance. Acclimation change in phenotype within an individual's lifetime to maximize performance (usually reversible.) Ectotherms body temp is determined primarily by external conditions. Lizards. Endotherms body temp is determined primarily by metabolic energy. Humans. Transpiration Evaporation of water through the stomata keeps leaves from over-heating. Adaptions that reduce water and/or heat stress in plants Traits that decrease water loss or heat load: -waxy covering to leaves -small vertical leaves -Low SA/V Wilting -Shedding Reduced stomatal density or opening.

Traits that enhance water supply: -deep tap roots -storage of water during times of plenty Through the stoma H20 vapor diffuses out of the leaf and CO2 diffuses into the leaf. Steeper the gradient the faster the diffusion. Alternative photosynthetic systems -Alter the CO2 gradient -Change the timing of the stomatal opening. C3 Photosynthesis The most ancient and common system: Photosynthesis takes place in the mesophyll cells. W/ rubisco. -Perform better at lower temp Rubisco enzyme has a weak affinity for CO2 so stomata stay open longer and much water is lost per C gained. C4 Photosynthesis Evolved later and is more water-efficient. -spatially seperate uptake of CO2 and its fixation. -PEP carboxykase enzyme is more efficient at grabbing CO2, so C4 plants keep stomata open for less time. -Inefficient at low light The niche the set of environmental conditions (temp, moisture, salinity) under which individuals of a species can grow and reproduce. Probability of being eaten P(detection) x P(capture) x P(consumption) Avoiding detection -Burrow -Camouflage Two costs of being cryptic: 1.) tied to particular habitats 2.) Limited mobility Greenhouse Effect Atmospheric "blanket"containing greenhouse gases Problems with the positive CO2 view: -Increading CO2 leads to warmer temps. -this leads to increased transpiration

-changes in temp may change precipitation -other things limit photosynthesis besides carbon Population Collection of organisms of the same species living in the same place at the same time Exponential population growth The per-capita growth rate is constant or density independent Logistic population growth rate (asymptotic) the per-capita growth rate varies with population density or is density dependent. Open population # change due to I and E and B and D Closed Population # change due to only B and E A population ______ in size when its birth rate exceeds its death rate Increases B>D or when r is positive Density independent limitations agent of mortality is not triggered by population density (extreme weather) Density dependent regulation: per individual birth and death rates DEPEND on density -Decreased per individual birth rates (fecundity) -Decreased individual growth (fewer offspring) -Increased death rate (resource depletion, predators, disease, dispersal) Carrying capacity (K) the maximum population size that can be supported by available resources or physical space. Population growth equals the amount expected under exponential growth multiplied by what percent of the carrying capacity is left. If N is very close to k then population growth will be slow. If N is very small relative to K then growth will be nearly exponential. If N is very large compared to K then growth will be logistic and go back down to the K r-selected species High intrinsic rate of population growth traits that are successful when densities are far from K and popn growth is driven by r. (early reproduction, large # of offspring w little parental care, etc.) K-selected species

traits that are favored when population sizes are near K (large investment in few offspring, continuous reproduction...etc. The principle of allocation: there is a tradeoff between the number of offspring and investment per offspring. Attributes of r - selected Many, small highly dispersed offspring, small body size, short life, early reproduction, allocate rapid growth and high reproduction, little parental care, semelparity (reproduce one time before death) Attributes of K-Selected Fewer, higher quality offspring, large body size, long life expectancy, delayed reproduction, allocate to defense, persistence, high parental care and investment, Iteroparity (reproduce many times before death) Environmental conditions favor for r - selected Keep populations are low density, habitat is unpredictable, variable, harsh, disturbed, mortality IS independent of other organisms and often catastrophic. Environmental Conditions favor for K-selected Populations can reach high density, habitat is predictable, favorable for growth and survival, mortality is often caused by interactions with other organisms. How to get r estimate Direct method: -Follow a cohort (group of individuals born at about the same time) through time Indirect Method: -Determine the age of death from remains Fecundity (mx) avg # of offspring produced by individual of age x. Net reproductive rate (R0) avg # of offspring produced by an individual during its entire lifetime. R0 = Ixmx R0>1 increasing R0 Challard Geographic Isolation (Allopatry) -species with low dispersal isolated by small distances -little opportunity for gene flow/ mating -pre-zygotic reproductive isolation Ecological Isolation -two sympatric species in different habitats rarely cross each other (even if reproductively compatible, they do not actually mate i.e. incipient species) Ex. hawthorns to apples Rhagoletis pomonella -pre-zygotic reproductive isolation Temporal Isolation -species that breed at different times of day/ seasons/ years cannot mate -initial - final => different times equation thing -pre-zygotic reproductive isolation Behavioral Isolation -species has highly specific courtship behaviors/ songs/ chemical signals/ visual cues -pre-zygotic reproductive isolation Mechanical Isolation -mismatched anatomically and can't have sex -pre-zygotic reproductive isolation Gametic Incompibility -gametes incompatible and cannot fuse to form zygote (important for water/wind spawning) -pre-zygotic reproductive isolation Evolutionary radiation rapid proliferation of many species from single ancestor and occurs because: -key innovations -ecological speciation -sexual selection -vacant ecological niches Adaptive radiation species adapt to different ecological niches key innovation adaptation that enhances the diversification rate of a lineage Primary Succession substrate that living organisms or legacy of former living organisms

Ex. Mount St. Helens Secondary Succession substrate that has been disturbed but contains a legacy of organisms that lived there before Ex. Florida Cyclical Succession pattern of change in community composition (succession) due to reoccurring events or changing interacts between plants/ animals Ex. mussels and barnacles cycling Pioneer species/ like r-selected -rapid growth -highly dispersive -tolerant/ hardy in harsh conditions -low competitive ability -not defended against herbivores -produce lots of offspring Late-successional species/ like K-selected -slow growth -low dispersion -not tolerant in harsh conditions -high competitive ability -defended against herbivores -produce fewer offspring Feeding Links Required to Connect two Species Together -2 -6 degrees of separation per human individual (getting smaller to 3.5-3.6 range) Trophic cascades predators in food web suppress abundance or alter behavior of their prey, releasing next lower trophic level from predation/ herbivory Ex. orca/ otters/ urchins Partitioning resources -allows species to coexist -leaves to increasing diversity when habitat (or resource) diversity is high...