Some business to take care of

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Some business to take care of -- Go to your lab
this week. Read through Chapter 4, as well as
Chapter 12 BEFORE lab. -- There is a new lab on
Tuesday afternoon. If you wish to switch to this
lab, we can allow some movement this week.
However, it needs to be done unofficially, so
that it doesnt require drop-add. Check with me,
if you wish to switch to this early evening
lab. -- Lecture powerpoints can be downloaded
from website, along with lots of other really
good stuff. http//bio.fsu.edu/miller/BSC3402L/
-- There are always lots of seminars on campus.
If you have aspirations for graduate school or
are just curious, we encourage you to attend.
This week, there is -- January 15 Dr. George D.
Weiblen, University of Minnesota, St.
Paul Ecological specialization of tropical insect
herbivores insights from phylogeny and
population genetics -- January 16 Dr. George D.
Weiblen, University of Minnesota, St.
Paul Lessons in conservation politics from Papua
New Guinea Both are at 400 in this room.
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• Purpose of this Course
• The Scientific Method
• III. What are Foragers?
• A. Definition of foraging
• -- All behaviors related to obtaining resources
• -- Resources are things that increase fitness.
• Fitness is relative reproductive contribution
• to future generations

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• What are Foragers?
• A. Definition of foraging
• B. Types of Resources -- different types of
• foragers and foraging is associated with
• different resources. The Big 3 categories
• are (in no order)
• 1. Food
• 2. Sex
• 3. Shelter

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• What are Foragers?
• A. Definition of foraging
• B. Types of Resources
• 1. Food
• 2. Sex
• 3. Shelter

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There are at least six types of predators, based
on how they get their food. These
include a. true predators b. grazers c. paras
ites d. parasitoids e. detritivores f. plants!
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True predators kill prey immediately and
generally consume many prey during their lifetime
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Grazers only consume part of prey, generally
without killing, but also generally consume many
prey during their lifetime
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Parasites consume only part of prey, don't kill,
generally live in or on one to few hosts during
lifetime.
Human flea
Adult heartworms in dog heart
Human louse
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Parasitoids are usually insects with a free
living adult which forage for a living host on or
in which to lay eggs. Larvae usually kill host.
Often disgusting.
Pseudacteon curvatus, a South American species
that parasitizes fire ants in the saevissima
complex
Anaphes flavipes (cereal beetle parasitoid)
Parasitoid from film Aliens
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Scavengers consume dead or rotting flesh (note
distinction!).
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Plants dont fall into these categories well
because they have abiotic resources, but they
clearly forage for these resources.
Hydrocotyle bonariensis
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Carnivorous plants are active true predators
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• What are Foragers?
• A. Definition of foraging
• B. Types of Resources
• 1. Food (different types of foragers)
• 2. Sex
• 3. Shelter

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sex
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sex
Rock-Paper-Scissors In side-blotched lizards,
males can have either orange, blue, or yellow
throats. Orange males guard large sites with
many females and are dominant over blue males,
that guard smaller sites with fewer females.
Blues dominate over yellows, which actually
resemble females. Yellows, however are quite
good at sneaking into oranges large territories
and mating with oranges females.
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• What are Foragers?
• A. Definition of foraging
• B. Types of Resources
• 1. Food
• 2. Sex
• 3. Shelter

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shelter
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• What are Foragers?
• Decision making by foragers.
• A. Types of Decisions
• B. Balancing Decisions are based on
  costs/benefits
• C. Optimal Diet Model
• D. Spatial Distributions of Resources

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IV. Decision making by foragers. A. Types of
Decisions -- what to consume? -- when? --
how? -- where? -- ultimately must balance
out different needs such as food vs. sex or
eating vs. being eaten (remember Limas squirrel
exp.) -- The point is that foragers must make a
lot of decisions, often quickly and often
combining different needs and constraints.
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IV. Decision making by foragers. A. Types of
Decisions B. Balancing Decisions costs and
benefits 1. Benefits -- resources already
discussed, including food, shelter, and
matings. Must increase fitness. 2. Costs
are usually time, energy and survival. Time
is important because it could be spent
garnering more food, shelter, or
mates). 3. Which is more important, Benefits or
Costs? For some organisms, it is just benefits
(e.g. energy maximizers, such as hummingbirds).
For others, it may be costs (e.g., time
minimizers). But, usually, it is some
combination of both.
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IV. Decision making by foragers. A. Types of
Decisions B. Balancing Decisions costs and
benefits 1. Benefits 2. Costs 3. Which is
more important? If both are important --
could use overall benefit (B-C) -- B/C
ratio useful because units dont need to
match. Example, Energy/time
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• What are Foragers?
• Decision making by foragers.
• A. Types of Decisions
• B. Balancing Decisions are based on
  costs/benefits
• C. Optimal Diet Model
• D. Spatial Distributions of Resources

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IV. Decision making by foragers. C. Optimal Diet
Model 1. Logic -- foragers see a series
of potential prey -- which to eat and which to
ignore? -- depends on their rank in B/C. It
is thought that many predators are able to
estimate the B/C for each prey type. They can
then specialize on the prey types with higher B/C
and ignore the rest
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IV. Decision making by foragers. C. Optimal Diet
Model 1. Logic 2. Mathematical
Model Consider a predators options when it sees
a food item. If it eats that item (call it item
i), then it will get benefit Ei (the energy from
item i). The costs are just those associated
with catching and consuming the item hi (called
handling costs). So, the value of that item
for the predator is
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IV. Decision making by foragers. C. Optimal Diet
Model 1. Logic 2. Mathematical Model Now, if
the predator decides to skip that prey and search
for another, then the expected value of the next
prey would be the environmental average E, with
the average costs (h), PLUS the costs of
searching for the next item, called s. So the
next item has a different value First item
Second item
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IV. Decision making by foragers. C. Optimal Diet
Model 1. Logic 2. Mathematical Model So,
clearly the predator should take a prey when it
sees it if Otherwise, the predator should
keep searching. And, note that an experienced
predator should know all these values and, so ,
should be able to make good decisions, on average.
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• 3. Predictions based on Ei/hi gt E/(sh)
• If average search times are long and handling
  times are short, then forager should take most
  prey that it sees -- be a GENERALIST.
• If search times are short and handling times
  long, then predators should be SPECIALIST, taking
  only high E/h items.
• More productive habitats (short s) should lead to
  more specialized diets.
• The abundance of prey not taken should have no
  effect on selection of individual prey. That is,
  the right hand side of the equation has no s, so
  ignore low E prey. (Lousy prey are always lousy,
  even if common).

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IV. Decision making by foragers. C. Optimal Diet
Model 1. Logic 2. Mathematical
Model 3. Predictions 4. Evidence an
example with fish Werner, E. E., and D. J. Hall.
1974. Optimal foraging and the size selection
of prey by the bluegill sunfish (Lepomis
macrochirus). Ecology 551042-1052.
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Werner, E. E., and D. J. Hall. 1974. Optimal
foraging and the size selection of prey by the
bluegill sunfish (Lepomis macrochirus). Ecology
551042-1052. Earl Werner fed Daphnia to
bluegill sunfish. He gave the fish Daphnia of
three different sizes. He predicted that if he
gave the fish a low density of prey, they should
eat anything. But, if he gave them a higher
density, they should more and more become
specialists on just the better (larger) Daphnia.
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Optimal diet model would predict that as prey
become more abundant, predators should become
more picky (specialists).
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Example Study for the Week
Goss-Custard, J. D. 1977. Optimal foraging and
the size selection of worms by redshank, Tringa
totanus, in the field. Animal Behaviour 2510-29
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Their optimal prey was around 7 mm in length.
The most abundant prey is actually larger. The
redshanks are taking smaller, less numerous prey
because of the higher benefit/cost ratio
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Read the Bee Lab Chapter before lab! Chapters 4
(not 5) and 12
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Sutherland, W. J. and R. A. Stillman. 1988. The
foraging tactics of plants. Oikos 52239-244.
-- long nodes in bad patches, short in
good -- straight in bad patches, turn in
good -- dont branch in bad environments, do in
good
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