Bio_Sci 1010 1st Edition Lecture 21Outline of Last Lecture I. Fundamental Process of an EcosystemII. Interactions between Organisms Outline of Current Lecture I. EcosystemII. ClimateIII. Nitrogen Current Lecture• Keystone species: plays a central role in holding a community together• The removal of a keystone species has a dramatic impact on the community-bees are a keystone species: many of the crops that we rely on for food, fuel, and fiber are pollinated by bees• Competitive exclusion principle: two species can’t share the resources in an identical niche, one is inevitably driven to extinction• Fundamental niche: what is could occupy• Realized niche: what it does occupy due to competition Ecosystem• An ecosystem is a community of organisms and the physical environment with which these organisms interact • Cycling in ecosystems-cycling transfers elements from one place to another-water and 30 elements cycle through the ecosystem-this cycling occurs through a relatively closed system ClimateThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.• Climate change is a natural part of the environment • Scientists are finding evidence that humans are accelerating the pace of change • The Earth’s climate naturally fluctuates • Climate change causes species distributions to change • Changes in climate can have economic impacts• Climate change can shorten or lengthen the growing season of crops • Rising temperatures affect plant behavior• Temperature cues seasonally appropriate tasks such as mating or producing flowers• Rising temperatures interfere with these natural rhythms • Climate change alters suitable habitats• Climate change is having a dramatic impact on entire ecosystems Nitrogen• The Nitrogen Cycle-N entered the living world through bacterial conversion of atmospheric nitrogen (N2)-two forms that can be taken up and used by living things • Nitrogen as fertilizer-nitrogen was primary limiting factor in crop production (nitrogenous fertilizers)-this comes with consequences… nitrogen as a pollutant can harm aquatic ecosystems • Gulf of Mexico “dead
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