Transcript BehaviorNotes06 - Redwood High School

Ecology
Available online @
www.redwood.org/stewart
I. WHY do organisms behave as they do?
– A. Evolution and Natural Selection
• 1.Behaviors have evolved (been selected and passed on to the
next generation) that help organisms be successful. Neither
individuals nor species "try" to evolve.
• 2. Natural selection, the process by which evolution occurs,
can be summarized in 3 steps:
– 1.variation (through mutation and sexual recombination
of genetic material)
– 2. selection (some variations survive, others do not)
– 3.reproduction (and passage of genetically inheritable
traits to the next generation).
I. WHY do organisms behave as they do?
– B. Genetics
• 1. Reproductive fitness, the number of surviving offspring
and relatives, is a biological measure of an organism's success.
• 2. Adaptations are the characteristics that evolve to help
organisms survive and maximize fitness.
– Physical adaptations: EXAMPLES: the meristem of grass is out
of reach of grazers, redwood trees build up chemical defenses
called tannins, roses have thorns.
– Behavioral adaptations: EXAMPLES will follow.
• 3. Though adaptations are genetically-based, behaviors can
also be learned.
it’s NURTURE AND NATURE!
II. HOW is a behavior motivated?
Energy Budgets
• Organisms only have only so much energy with
which to ensure survival and reproduction. Though
individual organisms do not necessarily "choose"
how to allocate energy, based on benefits and
tradeoffs, the following “abc’s” of life are where
the energy goes.
– a. Growth
– b. Defense
– c. Reproduction
II. HOW is a behavior motivated?
• EXAMPLES of different energy allocation strategies:
– r-strategists grow quickly, create fewer defenses, and allocate
more
energy
towards
producing
many
offspring.
– K-strategists grow more slowly, build up more defenses, and
allocate energy towards producing fewer offspring.
– In addition, individuals and groups exhibit a wide range of
behaviors when feeding, fighting, fleeing, and fraternizing.
III. WHAT are specific behaviors?
– A. Reproductive effort and Parental Care:
• Energy invested in reproduction and care of young.
Some organisms exhibit minimal parental care for
their precocial young. For other organisms, like
humans, parental care is essential and long-term for
their altricial young.
III. WHAT are specific behaviors?
• B. Social/Helping Behavior
altruism (helping
– True _________
another at the expense of
one’s own reproductive
fitness) is mal-adaptive by
definition.
Yet helping
behaviors and social groups
are commonly observed in
nature. The following are
explanations for helping
behaviors:
III. WHAT are specific behaviors?
• 1. Apparent altruism:
– EXAMPLES:
– Trickery: Ostriches will care for eggs of
another, but other eggs always on outside
where predators most likely to eat them
instead of the helper's eggs (predator
satiation).
– Reciprocity: Chimpanzees will give gifts
of food in exchange for future help.
III. WHAT are specific behaviors?
• 2. Relatedness/Kin Selection:
Increases inclusive (total or net) fitness.
Help of related organisms allow your
genes to be passed on through another.
– EXAMPLE: Ground squirrels live in
family groups. Individuals will
make loud alarm calls (which make
them obvious to predators) to warn
the rest of the (related) group when a
predators is spied.
III. WHAT are specific behaviors?
• 3. Eusociality: A special example of relatedness/kin
selection.
– EXAMPLE: Bees have a single queen who is the
mother of the entire hive. Worker bees are sterile and
work only for the benefit of the hive. The workers in
the hive are, on average, 75% related to each other.
Notes:
III. WHAT are specific behaviors?
• 4. Group Selection: It is theorized that groups with high levels of
altruism could do better (and be selected) as long as there is little
“cheating”.
Popula tion 1
All + + interactions! Likely to
continue as a group as long a s
no “cheating” o r non-altruistic
mutations.
Popula tion 2
Beards will help o thers (and
their group) but will not pass
on genes (+-) so this group
wil l eventually b ecome like
#3.
Popula tion 3
High - - interactions
(competition). Less likely to
continue as a group than #1.
III. WHAT are specific behaviors?
– C. Selecting Mates
• Sexual Selection: Special type of natural selection.
Sexual selection is not based on ability to survive. It
is based on the ability to attract (based on
possession of resources
_________ and/or a _______
genetic
characteristic) and be selected by mates of the same
species.
III. WHAT are specific behaviors?
– C. Selecting Mates
• Sexual Selection:
1. Intrasexual competition/ selection: male tortises fight for
the right to mate with a female.
2. Intersexual selection: one sex chosen by the other based on
display or territory. EXAMPLE 1: Leads to evolution of sexual
dimorphism (2 shapes) as is the case with peacocks and mallard
ducks. EXAMPLE 2: can be resource-based: the possession of a
quality territory, as with blackbirds.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Intrasexual:
Competition
Intersexual:
Genes only
Intersexual:
Resource-based
III. WHAT are specific behaviors?
D. Mating Strategies (Systems)
• Organisms/ species form pairs, groups, behaviors, and
physical adaptations to maximize fitness based on
ecological factors and needs.
•EXAMPLE: Albatross birds mate for life
(monogamy). Elephant females form long-term groups
to which single male bulls become attached for a
number of years ( polygamy ).
IV. Observing behavior:
• Observations gives a greater understanding of our
world and ourselves. Observing is an active
process. Ask questions. Don’t assume you know.
Use your journal. Be careful to observe what you
see, not what you think you see. Remember you
don’t know what the organism is “thinking.”
Consider:
–1. What?: What’s going on here? Observe, get basic
information. Thoroughly record what you see.
–2. How?: How is this behavior stimulated? Observe
immediate (proximal) causes of the behavior.
–3. Why?: Why has this behavior evolved (ultimate)?
Hypothesize, do further research, consider prior knowledge.
IV. Observing behavior:
• EXAMPLE behavioral observation and journal
entry:
–
–
–
–
Title:
Location:
Date and Time:
Observations: (Remember: What?, How?, Why?)
Dog Anxiety
Chimp Intelligence
Other