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Biological Sciences
Marc Cadotte

Lecture 01 Tuesday January 8/2013 Ecology is the scientific study of the interactions between organisms and their envi- ronment(and one another). Ecology is a branch of Biology. Ecology is not conservation or protection it's about understanding. Species/natural systems do not necessarily return to their original state after a disturbance. Balance of nature idea where systems return to balance after a disturbance is wrong. Random disturbances/unbal- ance in nature play an important role. In addition each species does not necessarily have a distinct function/role to play within the ‘balance’. So ecology is more complex than a balance of species and nature. Some species are more 'important' than others. Events in nature are interconnected. Environmental science is more about solving the problems, not ecology. Ecological Maxims: • Interconnected All events in nature are interconnected and something that effect one organism/place will af- fect others as well. • Matter recycling Everything goes somewhere/is recycled into something. There is no ‘away’ place that waste materials disappear. • Growth Limits No population can increase in size forever. Limits to growth and resources. • Tradeoffs Resources including energy are finite. Increasing one thing will tradeoff for limiting another. • Evolving Organisms change and evolve over time, nothing is static. • Time Ecosystems change over time and past and present affects the future. • Space Environmental conditions change from one place to another. Organisms are influenced by processes at spatial scales from local to global(dont really get that) • Interactions Species depend on one another and life would be impossible without interactions. Scales are very important to ecologists, there are 2 types. 1)Spacial scales. Small spatial scale: Soil microorganisms; 1m2. Large spatial scale: Atmospheric pollutants; 100 km2. 2)Time- temporal scale. Period, era, epoch etc. Short temporal scale: Leaf response to sunlight; 10 seconds. Long temporal scale: How species change over geologic time; 100,000 years. Definitions: Population: group of individuals of a single species in a particular area that interact with one another. Community: an association of interacting populations of different species that live in the same area Ecosystem: community of organisms plus the physical environment in which they live. Landscape: Areas that vary substantially that typically include multiple ecosystems. Biosphere: consists of all living organisms on earth and the environment in which they live. Biotic: living components of a natural system Abiotic: Non-living, the physical environment. Adaptation: feature of an organism to improve its ability to survive or reproduce in its envi- ronment. Natural selection: evolutionary process where individuals that posses particular characteris- tics survive better than others without. Consumer: obtains energy by eating other organisms or their remains. Producer: organism that uses the energy from external source(i.e. sun) to produce its own food without having to eat others. Net Primary Production(NPP): Amount of energy/time that producers make through photo- synthesis or other means minus the amount they use for cellular respiration only. Nutrient Cycle: the pathway of nutrients between organisms and the physical environment. Evolution: The change in genetic characteristics of a population over time or descent with modification where organisms gradual accumulate differences form their ancestors. Between 5 and 20million species on earth...... A lot is still unknown. As well, a lot of species are going extinct that haven't even been discovered yet(mostly due to human exploitation). Most of our recordings of extinctions are large bodied animals because the are easier to know. Things are still going extinct today as well, 7 in the last 10 years. In the past it was exploitation but now it's because we are changing the earth too much and now there are no habitats for these species. Biodiversity defined as "the variability among living organisms from all sources, including: di- versity within species, between species and of ecosystems Human artifacts are important tools to enlighten us and help us to understand who we are. Biodiversity is the same...... Nature helps us to understand ourselves too. Energy moves between organisms. Energy is not recycled, it flows through the ecosystem and moves only in one direction. Nutrients are recycled. Lecture 02 Thursday January 10 Ecologists evaluate competing hypotheses with 1) Observational studies in the field 2) Experiments in the field 3) Controlled lab experiments 4) Quantitative models. Experimental design: replicate- Need to be able to perform each treatment more than once, assign tests at random and then to be able to perform statistical analysis on them to decide if the results are viable and mean something. Replicate Randomize(even opportunity for both test groups) Control(like the negative control... Placebo thing, used to account for anything that might in- fluence the results) Control group: lacks the factor being tested but used as a comparison. Experimental group: the factor being testes Experiments have three major attributes. 1) Generality(large scale studies) 2) Realism(field experiments) 3) Precision (lab experiments) However it's hard to get all three in an equal balance. Case study - High Incidence of Deformities in Amphibians -Declining amphibian populations and many becoming extinct/endangered(worldwide) -More with fatal or weird deformities. • Note that amphibians are viewed as good biological indicators of environmental condi- tions because of their permeable skin. • Originally thought to be pollutants but a controlled lab experiment was performed using a control group and an experimental group and proven theory is that Ribeiroia which is a parasite, causes cysts around developing limbs and therefore induces deformities in tad- poles. • In a field experiment, they had six ponds(all with Ribeiroia), 3 with pesticides and 3 without. In each pond half the frogs were subjected to parasites half were not. The studies found that the only deformities were the frogs with Ribeiroia, and the Ribeiroia frogs that were exposed to the pesticide were significantly worse than the Ribeiroia frogs without pesticides. So turns out parasites and the pesticides compounded make the deformities more frequent. This led to the hypothesis that pesticides may weaken the tadpole immune system making them more susceptible to parasites. • Revisited they decided that it is a compounded effect of many different things that is to blame. UV light and nitrates also makes it worse. Lecture 03 Tuesday Jan 15 *******need to know only what he says from chapter two but need to read and know every- thing from chapter 3 Climate: long term description of weather at a given location based on averages and variation measured over decades. Weather: the current temperature, humidity, precipitation, wind, cloud cover etc. Climate is the most fundamental component of the physical environment. Climate determines the geographic distribution of organisms. Species are not equally dis- persed. Effects of climate can be noticed acutely, There are latitudinal differences in solar radiation on the earths surface. At the equator, there is the most solar radiation, least at the poles. Because the equator is warm, the warm air rises as a low pressure system and cools and cre- ates clouds and rain. The tropics have the most rain since it is the hottest and there is the most uplift and cloud formation. This air rises and once it reaches the end of the troposphere it starts to move polewards and cools, about 30°N and S it cools enough and starts to sink, creating a cycle. Called Hadley cell. Deserts area at 30°N and S because thats where the high pressure air comes down to the ground and is very dry. There are three cells, Hadley, Ferrell, and Polar result in the three major climatic zones..... Tropical, temperate and polar. Polar cell has cold dry air dropping right at 90°N/S and so is very cold and dry, it then moves down and rises when it gets warm. Ferrell cell occurs kinda because of the other two. This also means there are bands of areas like lots of rain at equa- tor, desserts at 30° etc. Regional climate can be affected by topography and water bodies. Mountains are notorious for affecting weather as it cerastes a rain shadow, where the one side has lots of rainfall as the air cools and condenses and rains and then the other side is very dry. Another affect on climate is what the surface is covered with- Evapotranspiration: is the sum of water loss through transpiration by plants and evapora- tion from the soil. Evapotranspiration transfers energy as latent heat and water into the at- mosphere there by affecting air temperature and moisture. Therefore when the amount of vegetation is altered it can have effects on the climate. Defor- estation is such an issue because of 1. No foliage increases the albedo of the land which decreases the amount of radiation absorbed 2. Leaves land more open so also increases sensible heat loss by convection to wind. 3. HOWEVER reduced plants means less evapotranspiration so no latent heat loss by evapotranspiration. This heat retention makes up for the heat loss everywhere else and makes it hotter. Also less water returned to atmosphere and therefore less precipitation which makes it drier. If more heat is reflected back because of higher albedo and not high enough land tempera- ture because of convection then the regional climate of the land cools. But no evapotranspira- tion makes it hotter because no latent heat can be lost which adds up to more. Creates a feedback loop. Heat transfer: Albedo- reflected radiation from surface Sensible heat loss- Direct heat loss by direct So note that biomes vary with temperature and precipitation. 1. Tropical Rainforests(10°N and S) High constant year round temperature because at equator and high precipitation, more in summer/fall months. High biomass, high diversity(50% of earths species) Broad leaf evergreen and deciduous trees, key factor in plant survival is light because its so crowded. Emergent trees rise above the majority and make up the canopy. Lots of shrubs and forbs(broad leaf herbaceous plants) 2. Tropical Seasonal forests and Savannas(23.5°N and S) High temperature throughout the year but there is a pronounced wet and dry season(as op- posed to our hot and cold season) which is why its tropical seasonal. Lower tree densities, shorter trees, drought deciduousness(leaves drop in drought) and more grasses and shrubs. Fires increase the dry season and influence vegetation, sometimes re- current ones form savannas dominated by grasses and shrubs. 3. Hot Deserts(30°N and S) Incredible heat during a few seasonal months and little rainfall at anytime of the year. Sparse vegetation and animal populations but may have high diversity.... often many succu- lents which can store water in their tissues and desert plants include drought-deciduous shrubs, grasses and short lived annuals that are only active after rain. High levels of evapo- transipiration so limited water. 4. Temperate Grasslands(30°-50°N and S) Both temperature and incredible rainfall peak at certain months(May-Sept) with other times precipitation and temperature are below freezing. Dominant plant is grasses, soils are pretty good so good for agriculture and therefore most human-used biome on earth. 5. Temperate Shrublands and Woodlands(30-40°N and S) Hot and dry summers(May-Oct), cool and wet winters. -Plants include evergreens or tough/leathery leaves for hot and dry in summer. Evergreen leaves allow plants to be active even during the cooler wetter periods. Sclerophyllous leaves are tough and leathery and deter herbivores and prevent wilting. -Fires are common and important to promote high species diversity otherwise lands may be replaced by forests -FIRE important 6. Temperate Deciduous Forests(30-50°N/S) Seasonal peaking rainfall and temperature, lesser of both in winters(Oct-April) -deciduous trees... need enough rainfall and soil nutrients to support plant growth. Oak, maple, beech trees are common ones. Canopy trees and shorter shrubs common. -Fertile soils and climate are good for agriculture so clearing and wood hauling is unfortunate- ly quite present in this biome. 7. Temperate Evergreen Forests(30-50°N/S) -commonly found in nutrient poor soils(due to acidic nature of evergreen tree leaves) -some subject to fires at regular intervals of every 30-60years however some in Northern america are suppressed so the forest is allowed to fill in more which is bad because when there is a fire then it is a lot worse. -low diversity. Conifers, junipers, fir etc. - subject to extensive clearing for paper products. 8. Boreal Forests(50-60°N only) Very cold and dry in winters and warm in summers with a bit of precipitation. Very cold in win- ters so vegetation must withstand permafrost and freezing ground. Little precipitation but per- mafrost does not allow for drainage so solid are moist to saturation. -coniferous species, spruce, pines(resist freezing better than deciduous). Cold and wetness does not allow for decomposition so a lot of underbrush builds up and makes for forest fires in summer drought months. Will burn trees and the soil too! Which can stay burning for months/years. -Peat bogs formed sometimes, some logging/oiling etc but not a lot. 9. Tundra(beyond 65°N and S) Primarily in arctic but a little in antarctic regions. Cold temperature with peak in summer and little rainfall with same peak in summer Cold temperatures and lack of rain is due to zones of high pressure generated by the polar cell of air coming down from poles. - trees cease to be the dominant vegetation, and forbes, low grasses, low growing shrubs and lichens and mosses grow. - Maintain life by growing dormant. - widespread permafrost(keeping soil wet despite low precipitation) - simlar to boreal forest - probably most untouched region from humans but has greatly shown effects of climate change - Pingo’s- small hills formed in arctic because of freezing of permafrost thrusting the soil - Polygons- around pingo’s resulting from the freezing and thawing of soils which push- es nutrients and coarse materials to the edges of the hills. Elevation- there are also large scale biomes replicated through elevational ranges(ex tem- perate forests to grasslands to tundra ex.) Freshwater Systems Biological zones in freshwater systems are associated with velocity, depth, temperature, clarity and chemistry of the water.. Not driven by climate/environment in the same way as ter- restrial. - affected by slope of landscape and placement of rocks and such. - Dont talk about biomes but zones. Streams(Lotic), First order stream: Highest elevations, usually trickling brooks. Second order: Is two first order streams coming together Third order: when two second order streams come together. etc etc Massive rivers(Nile)- like 6 order streams m Note that the aquatic life in first order streams is much different than 10 order streams. Main channel has the swimming organisms that live in the flowing water Benthic Zone: Stream bed. home to invertebrates that consume dead stuff in Hyporheic zone: Sediment area. water movement still occurs, sometimes front the ground below but rotifers and copepods and insects live in this substratum zone. In Lakes(Lentic), Lakes are where depressions in the landscape occur and fill with water. Can be formed by glacial processes, from rivers, from craters, tectonic basins, and animal activities including beavers and humans.
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