Transcript Ecology - cloudfront.net

Ecology
“Biological Systems interact and
these systems and their
interactions possess complex
properties”
Introduction to Ecology
• Ecology can be studied at a variety of levels…
Inheritance Influences Behavior
• Behavior is any action
that can be observed
and described.
• The nature versus
nurture question asks to
what extent both our
genes (nature) and
environmental
influences (nurture)
affect behavior.
Study: Love bird nest-making
• How do love birds make nests?
• Experimental Observations:
▫ Fischer Lovebirds cut long strips leaves and carry
the strips with their beaks
▫ Peach-Faced lovebirds cut short strips of leaves
and carry strips in back feathers
▫ Hybrid lovebirds have difficulties because they cut
medium sized strips and try unsuccessfully to
carry strips in their back feathers
• Conclusions??
Study: Garter Snake food preference
• Coastal snakes typically eat slugs in the wild, eat
slugs in the lab
• Inland snakes typically eat frogs and fish, don’t
eat slugs in the lab
• Hybrid snakes have an intermediate incidence of
“slug acceptance”
• Tongue-flicking shows prey recognition
• When newborns are presented with cotton
swabs covered in slug juice, what happens?
• Conclusions?
Study: Garter Snake food preference
Study: Human Twins
• Twins separated at birth and throughout
childhood often have similar food preferences,
activity patterns, and select similar mates!
• Conclusions?
Conclusions:
• The studies on Love Birds, Garter Snakes, and
Humans SUGGEST behavior has a genetic basis
Study: Marine Snail and Egg laying behavior
• After copulation, snails extrude long strings with
more than a million eggs that are then put into
the snails’ mouth, covered with mucus, and
wound into an irregular mass that is attached to
a rock
• Researchers isolated gene for Egg Laying
Hormone (ELH) and noticed that it forms a
string of 271 amino acids while ELH only has 36
amino acids. The gene could be responsible for
more than just ELH!
• Conclusions?
Study: Maternal Behavior in Mice
• Maternal instinct hard-wired?
• Mice with gene fosB were found to actively
synthesize a particular protein after childbirth
• fosB mice were seen cuddling with their
newborns
• Mice without gene fosB did not have the protein
• Mice without fosB did not
show maternal
nurturing behaviors
• Conclusions?
Conclusions:
• Genetics do influence Behavior (“Nature”)
• But what about Environment (“Nurture”)?
Environmental Impact on Behavior:
Learning
• Fixed action patterns (FAPs) were believed to be
behaviors that were always performed the same way,
and they were elicited by a sign stimulus.
• Many behaviors formerly thought to be fixed action
patterns are found to have developed after practice.
• Learning is defined as a durable change in
behavior brought about by experience.
• Deer grazing on the side of a busy highway,
oblivious to traffic, is an example of habituation.
Instinct and Learning
• Laughing gull chicks beg food from parents by
pecking at the parents’ beaks
• Researchers tried to figure out if this behavior
was pure instinct or also learned
• The chicks first peck at any beak model; later
they only peck at models resembling the parents.
Pecking behavior in gulls, FAP?
Imprinting
• Imprinting, another form of
learning, involves a sensitive
period.
▫ Chicks, ducklings, and goslings
follow the first moving object
they see after hatching (usually
their mother).
▫ A sensitive period is the only
period during which a
particular behavior such as
imprinting, develops.
Associative Learning
• Classical Conditioning
▫ If paired stimuli presented consistently to produce
response, over time one stimulus alone will
produce the desired response
▫ This suggests that an organism can be trained
(conditioned) to associate any response with any
stimulus.
▫ Unconditioned responses are those that occur
naturally; conditioned responses are those that are
learned.
Associative Learning
• Operant Conditioning
▫ In operant conditioning, a stimulus-response
connection is strengthened.
▫ This resulted from reinforcing a particular
behavior.
• Skinner came up with Behaviorism based on his
experiments that used operant conditioning
Orientation
and
Migration
Ability to navigate
Cognitive learning
• Learning through observation, imitation, and
insight
• Insight learning: animal solves a problem it does
not have experience with
Animal Communication
• Communication is an action by a sender that
influences the behavior of a receiver.
• When the sender and receiver are members of
the same species, signals will benefit both the
sender and the receiver.
Animal Communication
• Chemical Communication
▫ These signals are chemicals (e.g., pheromones,
urine, and feces) and have the advantage of
working both night and day.
▫ A pheromone is a chemical released to cause a
predictable reaction of another member of the
same species.
Aphids responding to alarm pheromones
Auditory Communication
• Advantages
▫ Faster
▫ Effective night and day
▫ Modified by loudness, pattern, duration, and
repetition
Whale Song
Visual Communication
• Visually communicate intensions- no need for
chemical signal
• During the day
• Fighting/Defense and Courtship Displays
Courtship display
Tactile
Communication
• When one animal
touches another to
impart information
of some sort
Can Behavior Increase Fitness?
• Behavioral Ecology assumes behavior is
subject to natural selection i.e. really
dangerous/stupid behavior will lead to less
reproductive success
• Examine:
▫
▫
▫
▫
Territoriality
Reproductive Strategies
Social Behavior/Society
Altruism
Territoriality: Increased Fitness?
• Territory: animal’s home range
• Territoriality: defending the home range
• Defense could be dangerous if fighting occurs
and certainly uses a lot of energy
Different Reproductive Strategies
• Some animals, such as gibbons, are
monogamous; they pair bond, and both male
and female help with the rearing of the young.
• Most other primates are polygamous; males
monopolize multiple females.
• A limited number of primates are
polyandrous.
▫ Tamarins live together in groups of one or more
families in which one female mates with more
than one male.
Monogamous: African Antelope
Polygamous: Hyenas (although
matriarchal)
Polyandrous: Bees with their
queen
Sexual Selection  Increased Fitness?
• Sexual selection refers to adaptive changes in
males and females that lead to an increased
ability to secure a mate
• In males, this may result in an increased ability
to compete with other males for a mate.
• Females may select a mate with the best fitness
(ability to produce surviving offspring), thereby
increasing her own fitness.
Societies  Increase Fitness?
• Benefits: avoid predators, raise young, find food
• Costs: disagreements, individuals may be
disadvantaged because of their group affiliation,
parasites/disease spread more effectively
• Cost/Benefit analysis, is it worth it?
Altruism vs. Self Interest
• Altruism: behavior that potentially decreases
fitness of one individual while increasing another’s
fitness
• Inclusive fitness: fitness of individual and close
relatives
▫ Indirect vs. Direct selection
• Reciprocal Altruism: short term sacrifice to
potentially increase future reproductive success
▫ Ex. Birds who help parents raise future generations
Foraging and Fitness
• Foraging for food (gathering food) can obviously
increase fitness
• Benefits during foraging behavior must
outweigh risks
• Optimal foraging model: natural selection will
effect foraging behavior so it is as energetically
efficient as possible
Foraging Example
Territoriality Increased Fitness?
Group territoriality and the benefits of sociality in the
African lion, Panthera leo
• 38 years of data on 46 lion prides in the
Serengeti National Park, Tanzania
• Observed effects of territoriality on fitness of
both females and males
• Say-Mean-Matter activity