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SC BIOL 301 - Predator/ Prey

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Biol 301 1nd Edition Lecture 14 Outline of Last Lecture I. Species InteractionsII. ResourcesIII. Population CyclesIV. ResponsesOutline of Current Lecture II. Species InteractionsIII. ResourcesIV. Population CyclesV. ResponsesCurrent LecturePredation- Predators that exhibit active hunting strategies spend most of their time moving around looking for prey (e.g., birds foraging on lawns for worms).- Predators that exhibit ambush (sit-and-wait) hunting strategies lie in wait for a prey to pass by (e.g., chameleons waiting for insect prey).- Hunting can be thought of as a series of events, including detecting, pursuing, catching, handling, and consuming prey.- Prey have evolved numerous defenses to thwart predators at different points in this process.Defenses- Alarm calling warns relatives that predators are approaching.- Spatial avoidance occurs when a prey moves away from a predator.- Some prey reduce activity to avoid being detected by a predator.- Crypsis: camouflage that either allows an individual to match its environment or breaks up the outline of an individual to blend in better with the background (e.g., katydids, horned lizards). Structural defenses reduce a predator’s ability to capture, attack, or handle prey.- Chemical defenses are often more effective at deterring predators if the prey can convey thedefense before an attack occurs.These 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.- Warning coloration (aposematism): a strategy where distastefulness evolves in association with very conspicuous colors and patterns. Predators have innate aversions to aposematic colors; others learn to avoid certain colors and markings through experience.- Batesian mimicry: when palatable species evolve warning coloration that resembles unpalatable species (e.g., hover flies and hornet clearwings resemble the common wasp).- Müllerian mimicry: when several unpalatable species evolve a similar pattern of warning coloration (e.g., several species of poison dart frogs have evolved similar warning coloration).- Mullerian—unpalatable prey organisms adopt a single pattern of warning coloration- Batesian– palatable prey organisms resemble noxious ones- Selective pressure from herbivores has caused the evolution of plant defenses; some have phenotypically plastic defenses induced by attack, whereas others have fixed defenses.- Structural defenses (e.g., sharp spines, hair) deter herbivores from consuming leaves, stems,flowers, and fruits.- Chemical defenses include sticky resins and latex compounds that are hard to consume, and alkaloids (e.g., caffeine, nicotine, morphine) that have a wide range of toxic effects.- Many species of insects have evolved tolerance to chemical defenses.- Some plants employ the strategy of tolerating herbivory and can rapidly replace tissues that are consumed, or grow more tissue in areas that are not being consumed.Costs of defenses- Behavioral defenses are often costly because they result in reduced feeding activity or crowding in locations away from predators. Mechanical defenses are often energetically expensive to produce. Defense costs can reduce growth, development, and reproduction.Coevolution- Coevolution: when two or more species affect each other’s evolution; selection for prey defenses should favor the selection for counter-adaptation in predators.- Reciprocal process in which adaptations in one population promote the evolution of adaptations in another population- Mediated by biological agents- Unlike evolutionary responses to physical factors because:o Biological factors stimulate mutual responses; not so with environmento Biological agents foster diversity of adaptations, rather than similarity Organisms responding to similar physical stresses tend to evolve similar adaptations—ConvergenceParasites- Ectoparasites live on the outside of an organism.o Mostly arthropods (e.g., ticks, mites, lice, fleas)o Includes some leeches, lamprey, Nematodes- Endoparasites live inside organisms.o Intracellular: live inside the cells of a hosto Intercellular: live in spaces between cells of a hosto They begin as beneficial brain proteins. o A protein folds into an incorrect shape and becomes pathogenic.o It replicates by coming into contact with other proteins.o Transmission occurs through consumption of infected dead animals or their feces.- Emerging infectious disease: a newly discovered or rare disease that increases in abundance.- Often occurs when a mutation allows a pathogen to jump to a new host species- Populations of hosts and parasites fluctuate over time.- Dynamics are similar to predator-prey, but parasites often have a higher reproductive rate than their hosts and do not often kill their hosts.- Horizontal transmission: When a parasite moves between individuals other than parents and offspring.- Vertical transmission: When a parasite is transmitted from a parent to its offspring.- Vector: an organism that disperses a parasite between hosts.- Some parasites require multiple hosts to complete their life


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