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 Physiological/behavioral <<1 generation ReversibleAcclimatory Physiological/behavioral <1 generation ReversibleDevelopmental Developmental/behavioral ~1 generation IrreversibleEvolutionary Genetic/ecological >1 generation 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 growthColor changeFoliage lossFloweringMating colorationAntler growthMating ritualsFeeding patterns

Responses to environmental cues (e.g. change in day length)

Developmental Responses (Phenotypic Plasticity)

Differences in body form or behavior depending on environmentalconditions

Induced defenses and cyclomorphosis

Nonevolutionary responsesare not adaptations, but they are

adaptive

Response itself is done without genetic change, butthe ABILITY to make the response has very likely evolvedthrough adaptation (i.e. natural selection)

Success of response

Survival andReproduction

Establishment andMaintenance of population

DistributionsSummarize 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

Ecological-- set of placeswith suitable conditions

Ecological > GeographicReasons why involve most topicsof interest to ecologists

A B C

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 growReject: physical/chemical factorsReject: species interactionsSupport: dispersal barrier

Failure: transplanted populations dwindleReject: dispersal barrierConsistent with species interactions or physical/chemical factors

Problem: ethical considerations of transplantation

Solutions:

Compare occupied and unoccupied environmentsWhat major factors differ? --> hypotheses

Duplicate differences in laboratory setting“Transplant” occurs in lab; hypotheses testedlimitation: lab setting

Conduct transplants in field under highly controlled conditions

Catch species in the act of invasion

Lessons from Invasions and Introductions

Starling

Gypsy moth

Aedes albopictus

Rabbits to Australia

Failed introductions:Fish stockingSeeds in wool

Norway maple

Hessian Fly

Dutch Elm Disease

Chestnut Blight

Dispersal BarriersBecome 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

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Interactions between factors

Hungarian Partridge:Climograph for home range and for two places where introductions were attempted.

Mediterranean Fruit Fly and TelAviv climates in Two years

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Interactions between factors

Interactions between factors

Mediterranean Fruit Fly and TelAviv climates in Two years

Georgia climates (A: coastal plain; B: northern mountains)

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Interactions between factors

Climographs

Mediterranean Fruit Fly and TelAviv climates in Two years

Georgia climates (A: coastal plain; B: northern mountains)

Interspecific Interactionsand 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

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Pupae of tachinid fly, just lefttheir moth larva host

Ichneumonid wasps and caterpillar host

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Parasitoids

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Braconid wasp pupal cocoons on Tobacco Hornworm

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Predation

Food Supply

Competition

Parasites, Mutualists

Niches

Fundamental Niche: set of physical, chemical and resourceconditions 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 DistributionPlacesConditions

Niche and Distribution

Fundamental Niche Ecological Range

PlacesConditions

Niche and Distribution

Fundamental Niche

Realized Niche

Species InteractionsEcological Range

PlacesConditions

Niche and Distribution

Fundamental Niche

Realized Niche

Species InteractionsEcological Range

PlacesConditions

Geographic Range

Niche and Distribution

Fundamental Niche

Realized Niche

Species InteractionsEcological Range

PlacesConditions

Dispersal limitsHabitat selection

Geographic Range