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BIOL 1070 (204)

Bio Lecture Second Part

7 Pages

Course Code
BIOL 1070
Wright& Newmaster

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th October 5 2011 Hypothesis: A proposed explanation for a fairly narrow set of phenomena usually based on prior experience, scientific background knowledge, preliminary observations and logic. To measure ecosystem diversity: - To measure, we must define what organisms are sampled, the spatial area sampled, and when/how long we sampled (time). Species Richness: The number of species per specified collection/sample area OR specified number of individuals. th October 17 2011 What are the unique properties of a community? - Number of species (diversity) - Trophic structure (plants, herbivores, carnivores) - Composition (abundance, evenness, dominance) - (Richness, trophic level and abundance) – d What are the unique properties of a population? - Size = number of individuals (abundance) - Geographic distribution = area in which the individuals occur. - Growth (increase or decrease in size) - (Number of individuals (within species), area and growth) What ecological factors place limits on a species’ geographic range? - Abiotic factors - Dispersal - Biological interactions - Habitat selection What are abiotic factors? - Climate (temperature, moisture) - Soils (minerals, texture, acidity) - Geology (rock type, land formations) - Light (sun, shade) - Nutrients (nitrogen, phosphorus, potassium) - Habitat - Pollutants How do abiotic factors influence the distribution of plants and animals? - Restrict access to resources o Food/nutrients o Habitat - Limit physical tolerances o Hot/cold o Chemistry (toxins) - Physical barriers o River, mountain, lake and ocean How would you determine which abiotic factor is limiting the distribution of a species? - Field observation of actual range of distribution. - Determine ecological tolerances. - Correlation between environmental gradients and a species optimum range. - Experiments (field transplant, controlled environment) Light Water Survival A Low High 90% B High High 44% C High Low 19% Which factor is most important? Light or water? - Light is a critical factor in determining tree line. th October 19 2011 The concepts of a niche - A species has a range of tolerance to the environment - Tolerance range defines suitable habitat (potential range) A Niche consists of all the factors necessary for a species’ existence in terms of time, space, and required resources. Fundamental Niche: All the possible dimensions in which a species can survive in principle. Realized Niche: The dimensions in which a species actually survives after the effects of biotic interactions. Niche differentiation (realized niche) – Natural selection for bigger and smaller beak sizes due to competition for food. Community Assemblage – Development of ecological niche in a forest along a gradient of time. An ecosystem engineer is any organism that creates or significantly modifies habitats. A functional trait of alder shrubs is nitrogen fixation via a symbiotic relationship with nitrogen fixing bacterium. - Increased nitrogen allows colonization of spruce. Are old growth forests important for maintaining biodiversity? - Yes and No - th October 12 2011 What is a woodlot? - A forest in a city. (urban forest) What is a forest? - Ecosystem: A system formed by the interaction of a community of organisms with their physical environment. Temperate Deciduous Forest Biome - Seasonal variation in temperature (5-20 degree Celsius) - Precipitation is even among the seasons (80-120 cm/year) - Deciduous trees dominate. Why? - Deciduous trees outcompete conifers in summer because large leaves = greater photosynthetic capacity. Why do deciduous trees lose their leaves in the fall? - Winter = drought, (water frozen in the ground),
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