e. o = osmotic potential (dissolved solutes make  more neg) Osmosis water molecules move across a membrane from an area of high water concentration to an area of lower concentrationf. p = pressure potential (plant cell turgor = positive, xylem tension = negativei. atmosphere = very negative)ii. important for adhesion cohesion theory of transpirationg. soil = matric potential (water bound to surface of soil particles, fluid cohesion and surface tension) mi. Hydrostatic attractive forcesii. When water is in contact with solid particles (e.g., clay or sand particles within soil), adhesive intermolecular forces between the water and the solid can be large and important. The forces between the water molecules and the solid particles in combination with attraction among water molecules promote surface tension and the formation of menisci within the solid matrix.h. gravity mostly ignoredi. Total = o + p + m + gj. Organismal water relations: the acquisition of water and maintenance of water balance presents biological challengesk. Solute balance an isosmotic organism has concentrations of water and salt equal to its environmenti. Salts and water diffuse at approximately equalHyperosmotic organism has a higher concentration of salt than its environment. Water diffuses in at higher rateHypoosmotic organism has lower concentration of salt than its environment. Concern with water lossFish in brine solution before smoking makes them firmerInteractions between ecology and evolution ultimately generate tree of life and huge amount of biodiversity. Evolutions as change in population allele frequencies over time and descent with modification.Can happen quickly. Ex: soapberry bugs with long beak for feeding. Used to flat podded fruit. When balloon like fruit introduced, beak length changes in populations to adapt to size of fruit available.1. Organisms, populations and speciesGenotype: genetic makeup, represented by letters- one for each allele. A population is said to evolve when the proportional representation of alleles changes.Phenotype: traits, attributes, characteristicsHeritable vs. environmental variation in phenotypePhenotypes might not necessarily be heritable, but ability to change can beEx: industrial melanism, change in moth color frequency due to industrial air pollutionHigher recapture rate when tagged moths matched their environmentsChange in population, not individuals2. Natural selectionPhenotypic variation: acts as a sorting process+ Fitness differences+ Correlation between phenotypes and fitness+ Inheritance= Evolutionary change in mean phenotype4. Other processes that cause gene frequencies to changeGenetic drift: strength depends on population size. Can drive population to extinction or fixation. More effective on allele frequency than mutations are. Can rapidly remove genetic variation from a population. Large populations maintain heterozygosity while small populations are likely to lose heterozygosity. Loss of genetic variation reduces the ability of the population to respond to changing environmental condition. The increases of harmful alleles can reduce survival and reproduction. These effects are important for species that are near extinction.Ex: greater prairie chicken.Founder effect: population founded by few individualsPopulation bottleneck: population crash leads to reduced genetic variation.Applications: habitat fragmentationGene flowMutation: source of variationConsequences for populations: mutations occur at rates of 10-4 to 10-6 mutations per gene per generationIn each generation, one mutation would occur in every 10000 to 1000000 copies of a geneToo rare to cause allele frequency to change just as a cause of mutation rate. Genetic drift has a bigger effect.1. What limits a species' distribution?"Arrival (transplant) vs. survival (whether or not transplant kills them"Transplant experiments: transplant individual outside of range where they are found, if they survive then we need to understand why its distribution is limited. May be a problem with dispersal mechanism.4. ‘Survival’ (i.e. ability to maintain viable populations at a site)Niche axis - continuum or gradient of environmental conditions or resources. Depth of roots, distributions of elecational gradient, slope and aspect (north or south facing), temporal (axis of time), range of temperatures.N-dimension description of resources, habitat, and “lifestyle” of a species.Fundamental Niche: the set of conditions and resources required by a species to maintain positive population growthRealized niche: the subset of those conditions and resource levels occupied in the presence of competitors, predators, etc.Gradient -5. A physical transect with continuously changing conditions (elevation, tidal depth)An abstract continuum of a patchy abiotic environmental factor. Vernal pool: small scale environmental gradient (nutrient availability in soil)Fundamental niche: the set of conditions and resources required by a species to maintain positive population growth.Realized niche: the subset of those conditions and resource levels occupied in the presence of competitors, predators, etc.Biotic limits to range. Ex: Opuntia cactus in Australia. Moths ate most cacti, now distribution restricted to patches. Range limited by moths.Combined effect of biotic and abiotic on species ranges.In the northern hemisphere, abiotic tolerance often sets northern range limits, while competition and other biotic interactions often set southern range limits. Species are more diverse at lower latitudes. Transplant experiments to test if temperature or predators that are limiting distribution. Similar patters with elevation and depth of Cthalamus abiotic factors (desiccation stress, temperature) set upper limits. Biotic interactions (competition) set lower limit.1. Population size and densityUnitary vs. modular vs. clonal vs. eusocial organismsAbsolute vs. relative densityRelative population density can only be compared among sites, as the method for sampling individuals cannot capture all of them in a given area. Use technology to sample populations, even leeches.Ex: seaturtle population decline, conservation efforts have led to some positive change. Despite years of protecting eggs and nests had no effect on population size, because population growth was not limited by egg predation but by adult survival.2. Fertility scheduleFx = number of female offspring per surviving female in interval x to x+1