Outline for ECOL 482 at UA
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This 15 page Class Notes was uploaded by an elite notetaker on Friday February 6, 2015. The Class Notes belongs to a course at University of Arizona taught by a professor in Fall. Since its upload, it has received 18 views.
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Date Created: 02/06/15
Fish as Prey AntiPredation Cycle Predatorprey arms racequot results in prey evolving strategies to deter each stage in the predation cycle In prey selection strongly favors strategies that disrupt the predation cycle as early as possible ie don t be seen and you can t be eaten Predation Cycle5 parts Searching Pursuing Attacking Capturing Handling The AntiPredation Cycle Avoid detection Evade pursuit Prevent and deflect attacks Discourage capture Discourage handling Avoid detection Evade pursuit Prevent and deflect attacks Discourage capture Discourage handling Avoid Detection Camouflage Protective resemblance Make yourself look like your background Body growths Background matching coloration Reduced movement eg leafy seadragons mimic seaweed eg at sh change color and pattern Avoid Detection As an alternative to camouflage prey may be conspicuous but use mimicry to resemble something inedible Eg look like plant material or mimic a toxic sh Below a tasty prey fangblenny w color pattern that mimics b a juvenile bluestreak cleaner wrasse that is left alone by most predators Shown in c and d are fangblennies that lack mimetic coloration Avoid Detection Camouflage Disruptive coloration Body covered regions contrasting colors or vertical bars or spots Breaks up outline of fish less recognizable as potential food item eg angelfish left jacknife fish right Av0id Detection Invisibility Countershading Unique to aquatic systems raptors Pattern on fish opposite to patterns of light in water Dark on top light on bottom View from top fish blends into dark water background View from bottom blends into light background of sky Works for all viewing angles Reverse countershading used by males during breeding season Cu unfershadi ng in Fish Avoid Detection Invisibility silvery sides Open water species Covered in small mirrors Laterally compressed to be as vertical as possible deviations from vertical make the fish visible hence silvery flashes Avoid Detection Invisibility Transparency Surface dwelling species eg glass fish Larvae and juvenile sh Clear muscles and bones Brain eye gonads can t be clear Covered by silver film function unknown Avoid Detection Detect your predator before it detects you Swim in a shoal or school more eyes on the lookout Spend time under objects that cast a shadow Being in shadow allows a fish to see predators in the open well before the predator sees them think about driving through a forest But predators use the same strategyl Avoid Detection Swim with others Lower probability of detection for an individual in a school than an individual on its own Different species form monospeoi o groups Predators target different individuals Prey can act as a group aggressively towards predator mobbing behavior also seen in birds Predator inspection Single sh go out and evaluate predator ie somebody drew the short straw Avoid Detectio Beyond visual detection In general little known Sound is more important to conceal in terrestrial habitats easier to hear in water but harder to locate source of sound Electric insulation to avoid detection by electrolocation Mucous cocoons of resting parrotfishes excreted from gills may prevent the release of body chemicals that could reveal their presence to predators 7 The AntiPredation Cycle Avoid detection Evade pursuit Prevent and deflect attacks Discourage capture Discourage handling Evade Pursuit Strategies to discourage predator Spines Toxic skininternal organs Make use of aposematic warning coloration or behavior 0 Bright conspicuous coloration andor slow escape response 0 Signal to predator that they are dangerous 0 eg surgeonfish lionfish Move to shelter Complex habitats Bottom sediments Macrophytes Corals Evade Pursuit Move to shelter Complex habitats Eg garden eels zooplanktivores razorfish Evade Pursuit Open water escape Outrun outmaneuver or fly Most prey can t outrun predators are smaller Prey may be able to outmaneuver Flyingfish fly ie jump and glide out of the water Can double their speed up to 70 kmh amp 8m out of water Many prey species jump out of water do not glide like flyingfish The AntiPredation Cycle Avoid detection Evade pursuit Prevent and deflect attacks Discourage capture Discourage handling Prevent with last Deflect with structural Prevent and Deflect Attack second evasive move defenses ie spines etc 10 Prevent and Deflect Attack Foraging in groups helps prevent attack Dilution effect the probability of an individual being eaten decreases with larger group size Prevent and Deflect Attack Prevention of attack by group foragers Confusion effect Predators become confused by so many prey some speci c prey behaviors encourage this Predators switch targets too often to catch many prey Prey fish choose to enter larger schools when given the choice 11 The AntiPredation Cycle Avoid detection Evade pursuit Prevent and de ect attacks Discourage capture Discourage handling Discourage Capture Take advantage of gape limitation Static or dynamic adaptations associated with body sizeshape Prey may be difficult to handle or hard to eat Elongate spines orfins or very deep body l A Blow up eg pufferfish or erect spines eg bluegill 12 Discourage Capture Alarm chemicals Ostariophysi Produced when the skin is broken other fish may respond by schooling more densely leaving area etc response varies by species Alarm chemicals may also attract larger predatory fishes that scare off the target predator Visual alarm signals fin movements head bobbing again used to communicate with others Auditory signals Evolution of signals requires a benefit to individual Kin selection Attraction of larger predator The AntiPredation Cycle Avoid detection Evade pursuit Prevent and deflect attacks Discourage capture Discourae handlin 13 Discourage Handling Rabbitfishes forward I a directed spines so they can t go in backward or forward Mucus excretion Distasteful eg O toadfish or may make mechanical handling difficult eg hagfish Tough dermis Releasable scales Smixhsoninn Envimnmcmnl Restard i Ccnler Foraging vs Threat of Predation Tradeoff the more a fish forages the more food it will acquire but also more likely to be eaten Many fish species change foraging behavior or switch habitats when predators are present Fish constantly conducting costbenefit analyses VWling take more risks if rewards are greater Anotherway to think of optimal foraging theory ie increase benefit and minimize cost Trophic Cascades more later Density mediated Picsivores effect zooplankton by eating zooplanktlvores zoap ankm herblvcraus crustaceans Indirect interaction Topdown Behaviorally mediated Picsivores effect zooplankton by causing zooplanktivores to change their foraging behavior phytoplankton gt Bottomup
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