BIOL180 Exam 4 Review PDF

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BIOL180 Exam 4 Review Topics: – Species interactions – Ecosystems: human impacts, nutrients and energy cycling, restoration strategies – Biodiversity Carbon Cycle: Carbon sinks – On land, where were major sinks? Plants! Trees, or long lived plants. – On water? Dissolved organic matter, petroleum products under the ocean and in rocks. Dead Zones – Gulf of Mexico, Hood Canal – The thing that triggers these are an increase in nutrients (often due to humans. Sources are possibly sewage, fertilizer). – Increase in nutrients leads to increase in NPP, and increase in primary producers. After some period of time, algae dies off, then decomposers. Large decrease in O2. Leading to dead zones. Positive and Negative Feedbacks – Positive feedback: when result of initial change causes additional change in the same direction – Example: Forest fires and climate change – Warmer climate due to increased CO2—> increased forest fires (more unstable conditions, drier vegetation, etc) —> Forest fires burn forests and releases CO2 into atmosphere —> Which leads to warmer climates —> Which leads to more forest fires, and so on and so on. – Negative feedback: when the result of the initial change causes additional change in the opposite direction. – Example: More CO2 in air due to human activity. This means that there is additional plant growth because photosynthesis requires it. These plants take CO2 out of the atmosphere, so there is a reduction of CO2 by the plants that are growing, so

negative feedback. The Nitrogen Cycle: – Just think about how humans impact it – Understand dead zones and how nitrogen plays a role – Also, NITROGEN-FIXING PLANTS, AND MUTUALISM. Biodiversity Hotspots: – It is simply an area with high levels of diversity – Area of concern to protect them better. “Worth protecting,” versus a desert or something barren. – What are key terms associated with biodiversity? – Competitive Exclusion: Two species canʼt occupy the exact same niche. If there were two species in the same niche… if they need exactly the same resources… if there is COMPLETE overlap, then one species will go extinct (since there is nowhere for it to go) – Niche: Range of resources that can be used by an organism – Resource (niche) partitioning: A change in resource use to avoid competition – Character Displacement: An evolutionary change in traits that allows resource partitioning. “Some change in (selection for) traits that allows for resource partitioning.” – Interspecific Competition: Competition between individuals of different species – Infraspecific Competition: Competition between individuals of same species Species Interactions: – Mutualism: only if needed. E.g. plant wonʼt make structures for nitrogen-fixing bacteria if nitrogen is not needed Standing and Inducible Defenses: – Hard to tell which is which sometimes, so not going to be the focus in this class – Important thing: knowing the costs and benefits of each – Inducible: only present in response to a predator – Standing: always present

Edge Habitats: habitat fragmentation – Changes in conditions, causes problems – Problem with edges: – Conditions are drier and lose moisture fast. Harder for plants adapted to interior, moister environments and sudden change will be bad for them. – More exposed to predators, humans, and adverse weather conditions, etc. – Edge habitats vs. Vicariance: – Vicariance/smaller patches: Decreased gene flow and increased inbreeding. Increased vulnerability to drift Food Webs and Trophic Levels – Phytoplankton are primary producers, so then copepods are primary consumers – Salmon, are eating herring, and herring eat copepods, and copepods eat phytoplankton, so herring are secondary consumers, and salmon are tertiary consumers – Orcas eat salmon, and seals which make them quaternary OR pentanary (5th predator) – Seals could be tertiary or quaternary Facilitation –...