Textbook Notes (280,000)
CA (170,000)
McMaster (10,000)
BIOLOGY (700)
Chapter 51

BIOLOGY 1M03 Chapter Notes - Chapter 51: Waggle Dance, Corn Oil, Sensory Cue


Department
Biology
Course Code
BIOLOGY 1M03
Professor
Jon Stone
Chapter
51

This preview shows pages 1-3. to view the full 20 pages of the document.
Chapter 51: Behaviour
Proximate causation explains how actions occur in terms of neurological,
hormonal and skeletal-muscular mechanisms involved
Ultimate causation explains why actions occur, based on their evolutionary
consequences and history
Types of Behaviour: An Overview
Learning is defined as a change in behaviour that results from a specific
experience in the life on an individual
Innate Behaviour
oHighly inflexible behaviour patterns are called fixed action patterns
(FAPs)
oFAPs are stereotyped, meaning that they are performed in the same way
every time and are usually triggered by a simple stimuli called releasers
or sign stimuli
oEx. When a person hears a scream
A simple sign stimulus releases a FAP, a rapid, jumping movement
backward, away from the direction of the stimulus
oFAPs may result in survival
oFAPs are examples of innate behaviour, behaviour that is inherited and
shows little variation based on learning or the individual’s condition
oIt is common to observe innate behaviour in response to
Situations that have a high impact on fitness and demand a reflex-
like, unlearned response
Situations where learning is not possible
Conditional Strategies and Decision Making
oAlthough all species studied to date show some degree of innate
behaviour, it is much more common for an individual’s behaviour to
change in response to learning and to show flexibility in response to
changing environmental conditions
oAnimals take in information from the environment and based on that
information, make decisions about what to do

Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

oAnimals appear to take in information about their environments and weigh
the costs and benefits of responding
oCosts and benefits are measured in terms of their impact on fitness, the
ability to produce offspring
oWhat Decisions do White-Fronted Bee-Eaters Make when Foraging
Given a choice, what should an animal eat
Biologists answer this question by assuming that individuals should
forage in a way that maximizes the amount of usable energy they
take in, given the costs of finding and ingesting their food and the
risk of being eaten while they’re at it
This claim, that animals should maximize their feeding efficiency, is
called optimal foraging
Researchers began studying feeding behaviours in a bird called the
white-fronted bee-eater
Mated pairs of this species dig tunnels in riverbanks and raise their
young inside
Appropriate riverbanks are rare, so many pairs build tunnels in the
same location, forming a colony
To feed their young, pairs have to fly away from the colony, capture
insects and bring the prey back to the nest
Each pair defend a specific area where only they find food
The key observation is that some individuals forage a few metres
from the colony, while others have to look for food hundreds of
metres away
It takes only a few seconds to make a round trip to the closest
feeding territories, versus several minutes to the farthest territories
Thus, the fitness cost of each feeding trip varies widely among
individuals
If optimal foraging occurs, how do individuals maximize their
benefits, given the cost that they have to pay in time and energy
Individuals that have to find food far from the colony stay away
longer on each trip
Individuals foraging far from the colony bring back a much larger
mass of insects on each trip, on average, than do individuals that
fly a short distance each time

Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

White-fronted bee-eaters appear to make decisions that maximize
the energy they deliver to their offspring, given their costs of finding
food
This behaviour is highly flexible and condition dependent
oWhy do some Bluehead Wrasses Undergo a Sex Change
Male defend territories that contain nesting sites and feeding areas
A group of females lives inside the boundaries of the territory
When these females lay eggs, the male fertilizes the eggs
Thus, a single male monopolizes all the matings in that territory
This male is the largest individual in the group because the male
guards the territory and because fights are usually won by the
biggest contestant
When the territory-holding male dies, the largest female in the
group changes sex
Her reproductive organs change from egg production to sperm
production and her colouration changes
She becomes the dominant male and begins fertilizing all of the
eggs laid in the territory
An idea called the size-advantage hypothesis states that if a group
of fish is living in a territory dominated by a single male and if that
male dies, then the largest female should switch from female to
male
The hypothesis is based on the observation that fish have
indeterminate growth, meaning they continue to grow throughout
their lives
The logic behind the hypothesis is that suppose a small fish can lay
10 eggs a year, but a large female of the same species can lay 20
eggs a year
If six small females and two large females live in a harem, the male
that owns the territory fertilizes 100 eggs a year
If the male dies, the largest female can increase the number of
offspring she produces each year from 20 to 80 by changing sex
and taking over the role of the dominant male
The switch is costly in terms of time and energy, but the benefit is
large
You're Reading a Preview

Unlock to view full version