Ecology

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 AntelopePolygamous: 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