Chap.02 The Evolution of Behavior

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Chap.02 The Evolution of Behavior

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The Evolution of Behavior

• Artificial selection
• Natural selection
• Behavioral genetics
• The modern theoretical framework for animal
  behavior
• Sociobiology and selfish genes
• Antipredator behavior in guppies
• Adaptation
• Genetic techniques
• phylogeny

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Both natural and artificial selection have
produced many morphological varieties of the
pigeon.
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Pigeon breeders have selected for behavioral
varieties of pigeons, including (A) tumbler (???)
pigeons, and (B) homing pigeons.
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If hunting in larger groups (up to some maximum
group size) provides more food per dog than
hunting in smaller groups (or alone), natural
selection can favor group hunting.
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When population size equals 100, the number of
wild dogs that hunt in groups will increase in
frequency, and they will eventually make up 100
percent of the population. No mutation and no
migration.
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Heritability (???)

• Selection differential, S
• Generation 1 ???,?????????(X1) ?? ???????? (X0)?
• ??, X0 60? X190? S90-6030
• Response, R
• Generation 2???? (X2) ?? Generation 1???? (X0)?
• ??,X270? R70-6010
• Heritability, h2
• h2 R/S 10/30 0.33
• ?????
• h2 Low 0.0-0.1, moderate 0.1-0.4

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Behavioral genetics

1. Using Mendels laws of genetics to predict the
   distribution of behavioral phenotypes
2. Mapping genes for behavioral traits
3. Using other measures of heritability to determine
   what percentage of the variation in a behavioral
   trait is genetic and what percentage is
   environmental.

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Some of differences in the mating behavior of (A)
satellite males and (B) independent males are
controlled by a single gene with two alleles
labeled S and s. The S allele is dominant and
codes for satellite male behavior, while the s
allele is recessive. The ss is for independent
males.
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Polygenic traits

• Quantitative trait loci (QTLs)
• Fear/fearlessness in mice (Flint, et al., 1995)
• ?? mice ? open-field behavior (fear)
• ??the more fearfull mice, ???DNA
• ??fear??????,six different chromosomes
  (1,4,12,15,17?18)?
• ???????fear,???? chromosomes (1,12,?15)?

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Dissecting behavioral variation

• Parent-offspring regression
• Breeding colony size in parents and offspring
  (Fig.2.11)
• Cross-fostering experiment

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The modern theoretical framework for animal
behavior

• Antipredator behavior in guppies
• (A) an upstream, low-predation stream, and
• (B) a downstream, high-predation stream.

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Male
Female
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1. A pike cichlid, Crenicichia alta. These predators
   are common in downstream sites native to guppies.
2. A killifish, Rivulus hartii. These small,
   fairly innocuous predators can eat only tiny
   guppies and are found in upstream sites.

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1. Group size where there is low-predation pressure
   leads to a preference for small groups.
2. Group size where there is medium to high
   predation pressure.

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(C) Groups size where there is very-high
predation pressure leads to a preference for
larger group sizes.
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Here, some guppies from high-predation sites are
transplanted to low-predation sites, and vice
versa.
Over the courses of several years, transplanted
populations converge on the characteristics of
the fish in the populations into which they were
transplanted.
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Adaptation

• In more than 100 different species of birds,
  females engage in brood parasitism.
• While waterfowl make up only about 2 percent of
  bird species, they account for more than 25
  percent of the cases of parasitic egg dumping.
• Semel and Sherman found that a remarkable 95 of
  active nests were parasitized, despite many empty
  nest boxes that could be used to raise young.
• Wood ducks that nest in man-made boxes in
  Missouri
• Many heavily parasitized nests were simply
  abandoned by the wood ducks, and no eggs in such
  nests hatched.

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1. A male and female wood duck at a man-made nesting
   box.
2. many different wood ducks lay their eggs in the
   same nest.

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Five hypotheses

1. Dump eggs to reduce the risk of predation on all
   their eggs at once, thereby engaging in what is
   called bet hedging.
2. Be forced to parasitize the nests of others for
   lack of suitable, hidden nests.
3. Parasitze when their own nest is destroyed
4. Gain some benefit by placing eggs in the nests of
   genetic relatives.
5. Enhance their reproductive success in general by
   simply laying eggs in any available nest they
   come across.

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Maladaptations

• When nest boxes were not present and good
  territories were dispersed throughout the
  environment, there was likely a very high premium
  placed on finding good cavities in which to nest.
• Thus, females may have egg dumped in such
  cavities, and they may have benefited from such
  parasitism.
• But when nest boxes were present and clumped,
  such egg dumping was no longer adaptive. (Fig.
  2.21)

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Kinship and naked mole rat behavior Genetic
techniques to test hypotheses in animal behavior
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(??)
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Phylogeny and the study of animal behavior
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Phylogenetic trees

• Phylogenetic trees
• Homology(??) vs. homoplasy (??)
• Convergent evolution(????)
• Polarity (??)
• Parsimony analysis(????)

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Phylogeny and parental care

• Ray-finned fish (????)
• There are of families, mad up of over 20,000
  species.
• High variety of parental care
• To build a phylogenetic tree of 224 families of
  ray-finned fish and examined the evidence for
  parental care. (Mank et al, 2005)

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Phylogeny and parental care

1. Fish paternal care evolved on 21 independent
   occasions.
2. Maternal care and biparental care also evolved
   independently numerous times.
3. Maternal care tended to evolve after species had
   moved from external to internal fertilization.
4. Paternal care was often found alongside intense
   male coloration and nest construction (external
   fertilization)
5. Male coloration was also associated with systems
   in which females fertilized eggs internally.

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Phylogeny, mating systems, and male aggression

• Male fighting one another for access to females,
  since the payoff for such aggression.
• If sexually receptive females are not present,
  the costs of males fighting one another may
  outweigh the benefits.
• Wasps of the genus Nosonia lay their eggs inside
  a host species, and their larvae feed on the host
  as they develop.
• Three species of Nasonia, N. vitripennis., N.
  giraulti and N. libgucirnus.

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