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Nonevolutionary Responses to Environmental Change Organisms can change to perform better in different conditions, without a change in population genetic makeup Time scales, mechanisms, flexibility Regulatory Acclimatory Developmental Evolutionary Physiological/behavioral Physiological/behavioral Developmental/behavioral Genetic/ecological <<1 generation <1 generation ~1 generation >1 generation Reversible Reversible Irreversible Reversible Regulatory Responses No morphological change required, involves physiology or behavior Modified activity to maintain favorable body conditions Examples: Sweating, panting, shivering, altered kidney filtration, altered heart rate, drinking, basking Objective: homeostasis-- buffer the internal environment of an individual, or to modify the immediate external environment. Acclimatory Responses Change in physiology, behavior, or morphology, in response to environmental changes, especially seasonal changes Examples: Fur growth Color change Foliage loss Flowering Mating coloration Antler growth Mating rituals Feeding patterns Responses to environmental cues (e.g. change in day length) Developmental Responses (Phenotypic Plasticity) Differences in body form or behavior depending on environmental conditions Induced defenses and cyclomorphosis Nonevolutionary responses are not adaptations, but they are adaptive Response itself is done without genetic change, but the ABILITY to make the response has very likely evolved through adaptation (i.e. natural selection) Success of response Survival and Reproduction Establishment and Maintenance of population Distributions Summarize the locations where a species has been successful Do not tell us about locations where they could be successful Do not tell us about places where a species has failed Understanding distributions relies on knowing what factors prevent species from occupying a particular location or region Ranges Geographic-- set of places actually occupied A B Ecological-- set of places with suitable conditions C Ecological > Geographic Reasons why involve most topics of interest to ecologists Explaining an Absence Species does not occur because: 1) It can’t reach it 2) It doesn’t choose to (habitat selection) 3) Physical or chemical conditions not favorable 4) Other organisms in the area prevent establishment (competition, predation, parasitism) or a key species (food, mutualist) is missing 5) Chance Transplant experiments Remove suspected dispersal barrier Success: transplanted populations grow Reject: physical/chemical factors Reject: species interactions Support: dispersal barrier Failure: transplanted populations dwindle Reject: dispersal barrier Consistent with species interactions or physical/ chemical factors Problem: ethical considerations of transplantation Solutions: Compare occupied and unoccupied environments What major factors differ? --> hypotheses Duplicate differences in laboratory setting “Transplant” occurs in lab; hypotheses tested limitation: lab setting Conduct transplants in field under highly controlled conditions Catch species in the act of invasion Lessons from Invasions and Introductions Starling Chestnut Blight Gypsy moth Dutch Elm Disease Aedes albopictus Hessian Fly Rabbits to Australia Norway maple Failed introductions: Fish stocking Seeds in wool Dispersal Barriers Become clearest when they are overcome and followed by successful invasions European Starling: Chestnut Blight Gypsy Moth Gypsy Moth, recent Gypsy Moth Antarctic Beech, Nothofagus Antarctic Beech, Nothofagus Dispersal Strategies Water Striders Desert Locusts Niche Tsetse Fly Temperature and Aedes aegypti Barnacle life cycle Temperature and Barnacle dist. Moisture Composition of Calif. Forests Other factors Fire Currents Oxygen Light, or tolerance to shade Interactions between factors Climographs Hungarian Partridge: Climograph for home range and for two places where introductions were attempted. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Interactions between factors QuickT ime™ and a TI FF (Uncompressed) decompressor are needed to see this picture. Interactions between factors Mediterranean Fruit Fly and Tel Aviv climates in Two years QuickT ime™ and a TI FF (Uncompressed) decompressor are needed to see this picture. Mediterranean Fruit Fly and Tel Aviv climates in Two years Interactions between factors Georgia climates (A: coastal plain; B: northern mountains) Climographs Mediterranean Fruit Fly and Tel Aviv climates in Two years Interactions between factors Georgia climates (A: coastal plain; B: northern mountains) Interspecific Interactions and distribution Restriction of a species’ distribution Some areas may be unfavorable because of: •Predation in unoccupied areas •Food supply is inadequate in unoccupied sites •Competition with another species in unoccupied sites •Parasitism and disease in unoccupied areas •Commensalism (absence or shortage of host sp.) •Mutualism (absence or shortage of partner sp.) Parasitoids Qu i c k Ti m e ™ a n d a TI FF (U n c o m p re s s e d ) d e c o m p re s s o r a re n e e d e d to s e e th i s p i c tu re . Quic kT ime™ and a T IFF (Unc ompres sed) dec ompres sor are needed to s ee this picture. Quic kT ime™ and a T IFF (Unc ompres sed) dec ompres sor are needed to s ee this picture. Pupae of tachinid fly, just left their moth larva host Ichneumonid wasps and caterpillar host Parasitoids Qui ckTime™ and a TIFF ( Uncompr essed) decompressor ar e needed to see this pi cture. Quic kT ime™ and a T IFF (Unc ompres sed) dec ompres sor are needed to s ee this picture. Qu ickT ime™ an d a T IFF ( Unco mpr esse d) de com press or a re ne eded to s ee th is pi cture . Braconid wasp pupal cocoons on Tobacco Hornworm Predation Food Supply Competition Parasites, Mutualists Niches Fundamental Niche: set of physical, chemical and resource conditions necessary for population maintenance Realized Niche: set of physical, chemical and resource conditions necessary after taking species interactions into account-- a smaller set and a subset of Fundamental Niche Niche and Distribution Conditions Places Niche and Distribution Conditions Fundamental Niche Places Ecological Range Niche and Distribution Conditions Fundamental Niche Species Interactions Realized Niche Places Ecological Range Niche and Distribution Conditions Places Fundamental Niche Species Interactions Ecological Range Realized Niche Geographic Range Niche and Distribution Conditions Places Fundamental Niche Species Interactions Ecological Range Dispersal limits Habitat selection Realized Niche Geographic Range