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Lecture 1.docx

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University of Toronto St. George
James Thomson

LECTURE 1 Diversity of Mice - biodiversity, differences Meadow Jumping Mouse vs. House Mouse (biomedical mouse) -long tail -short tail -long hind feet (field characteristics) -seed eater Experiment in Vietnam course  White sheet, shine a bright light at night  Moths are attracted – how many species? Biodiversity of collection?  Nobody could come up with a good guess because too much traffic  Possibly 100-200 species Diversity – evolution Columbines: two common flowers - genus Aquilegia - Similarities in structure, differences in structure - Radical diff in colours - All have long extensions: nectar spurs w/ sugar water that piles up at bottom of spur Blue one – Aquilegia caerulea  Adapted for long tongued hawk moths – come to flowers and push tongues all the way down Red one – Aquilegia elegantula  Adapted for hummingbirds Related – descended from ancestors that look more like the blue one What forces causes this adaptation? 1. Ubiquity of patchiness Ecology – Science of distribution, abundance of organism  Why animals are in certain places and not in other places Patchiness - organisms are not spread evenly, but also not randomly  World presents variation and organisms SORT OUT  Found in some places and not others for reasons not through random Patchiness at large scale  Arabian peninsula – desert  SE Asia – green  India – green and brown  Differences between that vegetated or bare – all driven by water Patchiness at a smaller scale Eastern Washington State  Short grass land & semi desert in lowlands  Mountains catch enough rain – green & forested  Even at regional scale patchiness Even closer patchiness - Habitat  Subalpine  Difference between plants and animals living Microhabitat variation  Coriso planes  Lots of moisture during the winter in the mountains = bloom of annual plants  Flowers are different colours  Yellow flower is dense of west  Orange/purple dense on east  Differences of soil, water levels, sun intensity Microhabitat variation – down to cm  Lichens growing  Black and yellow green  Even patchiness at millimetres So what is driving this patchiness? 2. Why organisms are found where they are? Abiotic factors – physical and chemical attributes of nature  Resources: actual substances needed for life processes o Exhaustible o Ex. Nitrogen, water  Conditions o Not exhaustible o Ex. Temperature o Not like one uses 30 degrees and one uses 10 In patchiness both factors are going to vary  gradient from high to low Biotic factors – living organisms that effect each other 3. Abiotic gradients and ranges of tolerance Species have range of tolerance along environmental gradients at certain levels Range of tolerance – what is the set of lvls of factor that determines life success?  R-R range: where organisms can reproduce & have evolutionary fitness -grow, have enough food, survive  Lethal G-G range: can grow, but cannot get enough resources to reproduce zones  S- S range: barely survive, but cannot grow  Lethal zones: dead Most important factors for plants 1. Temperature Large spatial 2. Soil moisture scale  Water 3. Nutrients  availability of certain chemicals that plants need  N (most important), P, K 4. Disturbance  Human farming  Fires (could be by humans too) 5. Herbivory  Diseases  Fungi – cryptic underground, tissues  Seed dispersers Smaller spatial  Pollinators scale For aquatic plant - Physiologically differences: Fresh vs. Salty - Salinity Most important factors for animals 1. Food & Water  Access = persistence 2. Temperature 3. Habitat  Cover from predators  Nesting 4. Predators, Diseases 4. Coarse global patterns of temperature and precipitation: latitudinal patterns Gradients at the global level: temperature, seasonality, rainfall 1) Temperature: - Temperature is important to life because of chemical life processes  Enzymes work best at a certain temperature - Latitude:  Warm @ equator  Cold @ poles 2) Seasonality: - Seasonal patterns: due to axis of Earth of rotation High latitudes – hot and cold season in annual cycle Ex. Hot summer in Toronto when leans more toward the Sun vs. Cold when leans away Low latitudes (tropical, sub-tropical) – alternating wet and dry seasons - Usually always warm enough for plant growth 3) Rainfall: - Supply of moisture - How air moves around in atmosphere = Atmospheric circ
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