Nonevolutionary Responses to Environmental Change

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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

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Time scales, mechanisms, flexibility Regulatory
Physiological/behavioral ltlt1 generation Reversible
Acclimatory Physiological/behavioral lt1
generation Reversible Developmental Developmental/
behavioral 1 generation Irreversible Evolutionary
Genetic/ecological gt1 generation Reversible
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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.
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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)
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Developmental Responses (Phenotypic
Plasticity) Differences in body form or behavior
depending on environmental conditions
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Induced defenses and cyclomorphosis
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Nonevolutionary responsesare 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
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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
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Ranges
Geographic-- set of places actually occupied
Ecological-- set of places with suitable
conditions
C
B
A
Ecological gt Geographic Reasons why involve most
topics of interest to ecologists
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Explaining an Absence

• Species does not occur because
• It cant reach it
• It doesnt choose to (habitat selection)
• Physical or chemical conditions not favorable
• Other organisms in the area prevent establishment
  (competition, predation, parasitism) or a key
  species (food, mutualist) is missing
• Chance

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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
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Solutions Compare occupied and unoccupied
environments What major factors differ? --gt
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
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Lessons from Invasions and Introductions
Chestnut Blight
Starling
Dutch Elm Disease
Gypsy moth
Hessian Fly
Aedes albopictus
Norway maple
Rabbits to Australia
Failed introductions Fish stocking Seeds in
wool
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Dispersal Barriers
Become clearest when they are overcome and
followed by successful invasions
European Starling
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Chestnut Blight
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Gypsy Moth
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Gypsy Moth, recent
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Gypsy Moth
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Antarctic Beech, Nothofagus
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Antarctic Beech, Nothofagus
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Dispersal Strategies
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Water Striders
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Desert Locusts
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Niche
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Tsetse Fly
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Temperature and Aedes aegypti
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Barnacle life cycle
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Temperature and Barnacle dist.
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Moisture
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Composition of Calif. Forests
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Other factors
Fire
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Currents
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Oxygen
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Light, or tolerance to shade
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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.
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Interactions between factors
Mediterranean Fruit Fly and Tel Aviv climates in
Two years
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Interactions between factors
Mediterranean Fruit Fly and Tel Aviv climates in
Two years
Georgia climates (A coastal plain B northern
mountains)
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Interactions between factors
Climographs
Mediterranean Fruit Fly and Tel Aviv climates in
Two years
Georgia climates (A coastal plain B northern
mountains)
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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.)

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Parasitoids
Pupae of tachinid fly, just left their moth larva
host
Ichneumonid wasps and caterpillar host
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Parasitoids
Braconid wasp pupal cocoons on Tobacco Hornworm
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Predation
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Food Supply
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Competition
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Parasites, Mutualists
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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
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Niche and Distribution
Places
Conditions
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Niche and Distribution
Places
Conditions
Fundamental Niche
Ecological Range
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Niche and Distribution
Places
Conditions
Fundamental Niche
Ecological Range
Species Interactions
Realized Niche
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Niche and Distribution
Places
Conditions
Fundamental Niche
Ecological Range
Species Interactions
Realized Niche
Geographic Range
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Niche and Distribution
Places
Conditions
Fundamental Niche
Ecological Range
Species Interactions
Dispersal limits Habitat selection
Realized Niche
Geographic Range