1. Unit 3 in ECOLOGY
BEHAVIORAL ECOLOGY
The study of evolutionary basis for animal behavior due to ecological pressures.
Behavioral ecology is a scientific field of study that looks at how behavior is controlled and how it
contributes to survival and reproductive success.
Behavior
An action carried out by muscles or glands under the control of the nervous system in response to an
environmental cue.
ETHOLOGY
The study of animal behavior.
Genetic Variation and the Evolution of Behavior
Behavioral ecologists distinguish between proximate and ultimate causes of behavior. Behavioral
differences between closely related species, such as meadow and prairie voles, are common. Significant
differences in behavior can be also found within a species but are often less obvious. When behavioral
variation between populations of a species corresponds to variation in environmental conditions, it may
be evidence of past evolution.
BEHAVIORAL ECOLOGY
Behavior is eveything an animal does and how it does it.
To study behavior, two basic questions are asked.
1. PROXIMATE QUESTIONS are often considered “How” questions.
• “environmental stimuli, trigger event, genetic, physiological, and anatomical mechanisms”
2. ULTIMATE QUESTIONS are often considered “Why” questions “asks the evolutionary significance of a
behavior and how it interferredfitness”
Causes of Behavior
1. Proximate Cause- The trigger for the behavior
2. Ultimate Cause- The evolutionary reason behind the behavior
Proximate causes of behavior focus on:
- Environmental stimuli that trigger a behavior (nurture).
- Genetic and sensory motor mechanisms underlying a behavior (nature).
2. Ultimate causes of behavior focus on:
- The evolutionary significance of a behavior
ALTRAUISM
Altruism - behavior that decreases the individual fitness of the practitioner and increases the fitness of
the recipient.
ALTRAUISTIC BEHAVIOR occurs in honeybee societies, in which the workers are sterile. The workers
themselves never reproduce, but they labor on behalf of a single fertile queen. Furthermore, the
workers sting intruders, a behavior that helps defend the hive but results in the death of those workers.
Animal Communication
Communication It comes from Latin word communicare “to share”.
Animal Communication is the transfer of information from one or a group of animals (sender or senders)
to one or more other animals (receiver or receivers) which affects either the current or future behavior.
Forms of Animal Communication
Visual (seeing)
Visual communication
Information transmitted by visual mean is called visual communication.
Chemical communication (smelling)
Olfactory (chemical signals)
Communication through smell and taste.
Auditory communication (hearing)
- In the third stage of courtship, the male extends and vibrate his wing, producing a specific courtship
song.
- This singing, an example of auditory communication, informs the female that the male is of the same
species.
- Only if all of these forms of communications are successful will a female allow the male to attempt
copulation.
- The male’s sense of smell or olfactory system, detects chemical system released into the air by the
female.
Electro-communication
3. Electrocommunication is the communication method used by weakly electric fishes.
- Weakly electric fishes are a group of animals that utilize a communicating channel that is “invisible” to
most other animals: electric signaling.
- Electric fish generate electric organ discharges (EODs) from an electric organ and sense these
discharges via sensory cells termed eletroreceptors.
- Amazingly, electrocommunication evolved independently in two groups of fishes. EODs are used in the
same ways as signals in other modalities and are similarly influenced by natural and sexual selection.
Tactile communication(touch)
- Having recognized the female, the male approaches and taps the female with foreleg.
- This touching or tactile communication alerts the female to the male’s presence.
- In the process, chemicals are on her abdomen are transferred to the male, providing further chemical
confirmation of her species identity.
Seismic communication, sometimes called vibrational communication, describes the conveying of
information through seismic vibrations of the substrate.
Functions of animal communication
- Communication during contests
- Mating rituals
- Ownership/Territorial
- Food-related signals
- Alarm Calls
- Meta-communication
Foraging behavior
Foraging behavior is a complex and important subject that has received considerable attention.
Food-obtaining behavior, or foraging, includes not only eating but also any activities an animal uses to
search for, recognize and capture food items.
Types of foraging behavior
Solitary Foraging is when animals find. Capture and consume their prey alone.
Group Foraging is when animals find capture and consume prey in the presence of other individuals.
4. Classification of Foraging Behavior
Herbivores- are animals that consume living plants tissue.
Carnivores- consume the tissue of living animals
Omnivores- eat a mixture of plants and animals
Detritovores- consumed dead organic matter
Mating behavior and mate choice
- Just as foraging is crucial for individual survival, mating behavior and mate choice play a major role in
determining reproductive success.
- These behaviors include seeking or attracting mates, choosing among potential mates, competition for
mates, and caring for offspring.
- Although we tend to think of mating simply as the union of male and female, the mating relationship
between males and females varies greatly from species to species, defining number of distinct mating
systems.
Sexual selection
- The degree of sexual dimorphism within a species results from sexual selection, a form of natural
selection in which differences in reproductive success among individuals are a consequence of
differences in mating success.
- The sexual selection can take the form of intersexual selection, in which numbers of one sex choose
mates on the basis of characteristics of the other sex, such as courtship songs, or intrasexual selection,
which involves competition between members of one sex for mates.
Mating Systems and Sexual Dimorphism
- Mating systems vary with regard to both the lengths and number of relationships.
- In many animal species, mating is promiscuous, with no strong pair-bonds.
- In species in which the mates remain together for a longer period, the relationship may be
monogamous (one male mating with one female) or polygamous (an individual of one sex mating with
several of the other).
- Polygamous relationships most often involve a single male and many females, a system called polygyny,
through some species exhibit polyandry, in which a single female mate with several males
- The extent to which males and females differ in appearance, a characteristic known as sexual
dimorphism, typically varies the type of mating system.
5. - Among monogamous species, males and females are often so much alike morphologically that they
may be difficult or impossible to distinguish based on external characteristics.
- In contrast, polygynous species are generally dimorphic, with males being showier and often larger
than females.
- Polyandrous species are also dimorphic, but the females are generally more ornamented and larger
than the males.
In polygamous species, such as elk, the male is often highly ornamented.
In polyandrous species, such as these Wilson’s phalaropes, females are generally more ornamented
than males
