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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
QuickTime™ and a TI FF (Uncompressed) decompressor are needed to see this pict ure.
Interactions
between factors
Mediterranean
Fruit Fly and Tel
Aviv climates in
Two years
QuickTime™ and a TI FF (Uncompressed) decompressor are needed to see this pict ure.
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 ck Ti me ™a nd a TIFF (Unc om pres se d) de co mp re ss or are n ee de d to s ee th is pi ctu re .
Quic kTime™ and a TIFF (Uncompr es sed) dec ompres sor are needed to see this picture.
Quic kTime™ and a TIFF (Uncompr es sed) dec ompres sor are needed to see this picture.
Pupae of tachinid fly, just left
their moth larva host
Ichneumonid wasps and caterpillar host
Parasitoids
QuickTime™ and a TIFF (Uncom press ed) d eco mpres sor a re n eede d to see thi s pi ctu re.
Quic kTime™ and a TIFF (Uncompr es sed) dec ompres sor are needed to see this picture.
Quick Time™a nd a TIFF ( Uncomp res sed) deco mpre ssor are n eede d to s ee this picture .
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