Summary of Lecture 1 Chapter 50

1
Summary of Lecture 1Chapter 50

• Definitions of ecology and levels of organization
• Abiotic factors that determine distribution
  patterns of organisms (solar radiation,
  latitudinal variation in temperature and
  rainfall, effects of water and topography)
• Aquatic and terrestrial biomes understand the
  key features of those biomes that are reviewed
• Basic organismal ecology the principle of
  allocation of resources (costs of regulating or
  conforming)

2
Organismal Ecology

• Investigations of physiological, morphological or
  behavioral responses answering proximate
  questions. By what mechanism does this response
  occur?
• Investigations that seek to explain how responses
  arose in evolutionary terms answering ultimate
  questions. Does the response maximize fitness
  (survival and reproductive success)?

3
Responses to environment in ecological time

• Physiological e.g. tolerance curves identify
  optimum conditions and capacity to operate beyond
  these (Goldfish example L1)
• Morphological e.g. acclimation (reversible
  changes e.g. winter fur) irreversible changes
  (e.g. leaf structural variation correlated with
  environmental gradients)
• Behavioral e.g. rapid reactions, migratory
  behavior, social behavior (this lecture)

4
Behavioral Ecology

• See Chapter 51, pp 1053-1060
• Find notes at www.ent.orst.edu/jepsonp
• Lecture 2!

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Behavioral Ecology

• A blend of both proximate and ultimate questions
• Proximate e.g. environmental triggers
  underlying genetics and physiology
• Ultimate e.g. effect on fitness
• Integration of behavior and evolutionary ecology
  led to the field of behavioral ecology 25 years
  ago

6
Behavior resulting from genes and environment

• Both genes and environment influence behavior
• Behaviors exhibit phenotypic variation, like
  other traits
• e.g. nest building in lovebirds strong genetic
  influence, but capacity to modify with experience
  (following slide)
• Most behaviors have very broad norms of reaction

7
Fischers lovebird cuts long strips of vegetation
for nest building
Peach-faced lovebirds cut short strips and tuck
them into tail feathers
Experimental hybrids exhibit intermediate
behavior. Strips are mid length, and birds fail
to let go when tucking strips into tail. Birds
learn to use beaks for transport
After years, birds still turn back, revealing a
genetic component to behavior but behavior is
modified by experience
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Do innate behaviors exist?

• E.g. newly hatched birds begging for food
• Behavior does not appear to alter across a range
  of environmental conditions
• Ultimate cause for apparent innate behavior may
  be that automatic behavior maximizes fitness to
  such a degree that variants have been lost

9
Classical Ethology

• Von Frisch, Lorenz, Tindbergen
• Investigation of Fixed Action Patterns (FAPs),
  elicited by sign stimuli
• e.g. red bellies, even on unrealistic models,
  elicit aggressive responses by male sticklebacks
  (next slide)
• Stereotypic behaviors occur throughout the animal
  kingdom

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Classical demonstration of innate behavior
Red bellies on fish models elicit aggressive
territorial responses in male sticklebacks Male
fish will not attack invading males that lack the
red belly
11
Classical ethologyTindbergen
Careful experimentation demonstrated that Digger
wasp females locate nest using visual cues
(arrangement of landmarks, not the objects
themselves)
12
Behavioral ecology

• Exploits evolutionary hypotheses do animals
  behave in a way that maximizes fitness?
• Research based upon the expectation that animals
  will increase Darwinian fitness by optimizing
  behavior

13
Songbird repertoires

• Individual male birds exhibit repertoires of song
• Does this confer a benefit in terms of fitness?
• Hypothesis Do females prefer to mate with males
  that have a large song repertoir?

14
Sonograms of the partial repertoire of one male
brown-headed cowbird
Some species can generate hundreds of song
variants
Does this confer a fitness advantage?
15
Female warblers prefer males with large song
repertoires
16
Optimal foraging behavior

• Food is not taken randomly
• Search images may guide to prey, with switching
  when prey become rare
• Does behavior maximize the profitability of
  foraging?
• Profitability energetic return per unit of
  effort
• Easy to develop testable hypotheses

17
Optimal foraging

• E.g. Bluegill sunfish feeding on Daphnia
• Optimal foraging theory predicts that fish will
  be more selective when prey become abundant
  enough to justify this energetically

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Apparent size used to select prey
Small prey
Low prey density
High prey density
Medium prey
available
Large prey
Predicted diet
Large prey favored at high density, but not to
extent predicted
Observed diet