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Genetics III: Examples Mutation Analyses- • Strengths: Implicate roles for specific genes in animal behaviors • Weakness: Lead to misconception that those genes alone cause the behavior… • Weakness: Confined to Lab model systems (e.g. mice, Drosophila)
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Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

Apr 01, 2015

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Page 1: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

Genetics III: Examples

• Mutation Analyses-• Strengths: Implicate roles for specific genes

in animal behaviors

• Weakness: Lead to misconception that those genes alone cause the behavior…

• Weakness: Confined to Lab model systems (e.g. mice, Drosophila)

Page 2: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

Genetics III: Examples

• Mutation Analyses-

• Concept: Knock-out expression of focal gene, and measure changes to behavior

Page 3: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

Genetics III: Examples

• Mutation Analyses-

• Concept: Knock-out expression of focal gene, and measure changes to behavior

• Classic Example: "Periodicity" gene in flies

(Bayles, Bargiello, Jackson & Young 1987)

Page 4: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

Standard Method to confirm functional role of gene:• Look at mutant, then insert a functional copy of that gene to

test whether normal phenotype is restored…

• E.g. "Met" gene and allometry: (Thomas Flatt, Douglas Emlen, Quenna Szafran & Olga Helmy)

Page 5: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

Standard Method to confirm functional role of gene:• E.g. Larval foraging behavior in Drosophila (Marla

Sokolowski)

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Page 8: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

• Hybridization Studies-

• 'Common Garden' Experiments: Rear animals from two populations (that differ) in a common (laboratory) environment. Do the differences persist? Are hybrids intermediate in phenotype?

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• Example:

• Migration in Blackcap Warblers:

• (Peter Berthold & colleagues)

Page 10: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

• Recent Twist (2005):• Female preferences for males

with different migration routes contributes to speciation…

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Page 11: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

• Heritability Studies-

• Strengths: Measure the heritability, which is directly relevant to the potential for that behavior to evolve…. (R = h2 * s)

• Weakness: A LOT of work

• Weakness: Tells us nothing about the actual genes or physiological/ developmental pathways involved

Page 12: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

• Example Methods:

• Parent/Offspring Regression and Sibling Analyses (1/2 Sib and Full Sib): Measure the resemblance among relatives to quantify heritability

Page 13: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

• Example:

• Heritability of cricket song (Anne Hedrick)

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Male song is heritable, and differs across populations & species…

Page 16: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

• Example Methods:

• Artificial Selection: Extremely powerful because the population actually does evolve

• But very labor-intensive!

R = h2 * s

Page 17: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

• Example Methods:

• Artificial Selection: Extremely powerful because the population actually does evolve

• But very labor-intensive!

R = h2 * sYou know the strength of selection (s) and you measure the response (R)

Page 18: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

• Example Methods:

• Artificial Selection: Extremely powerful because the population actually does evolve

• But very labor-intensive!

R = h2 * s

So you can calculate the heritability…

Page 19: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

Example: Nesting behavior of mice (Carol Lynch)

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Page 21: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

Example: Migratory behavior in milkweed bugs (Hugh Dingle & James Palmer)

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Page 22: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

Polyphenism: A special type of ‘reaction norm’

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Page 24: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.
Page 25: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

Household Thermostat

Page 26: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

The phenotype exhibits discrete variation,

and low heritability

Page 27: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

But the threshold varies continuously,

and heritably

Page 28: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.
Page 29: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.
Page 30: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.
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1. Artificial Selection can shiftthe threshold….

Page 32: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

1. Artificial Selection can shiftthe threshold….

2. Populations differ in theirThreshold...

Page 33: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

3. Species differ in their threshold

Page 34: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

• Many behaviors are 'threshold' traits: • Animals often do one thing at a time….

– Feed or run– Guard or sneak

• Individuals switch between alternative states,and they may differ heritably in their switchpoints….

• (e.g. boldness, aggressiveness)

Page 35: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

• Example: Diapause in green lacewings (Catherine & Maurice Tauber)

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Page 36: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

• Example: Sex ratio in snapping turtles (Frederick Jansen)

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Page 37: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

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Genomic Approaches:

-Measure levels of expression of thousands of genes simultaneously (i.e. genomes)

Can be used on non-model taxa!

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Page 39: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

Castes differ in the expression of many genes….

Page 40: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

Castes differ in the expression of many genes….

Queens

Page 41: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

Castes differ in the expression of many genes….

larvae

Page 42: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

Castes differ in the expression of many genes….

Workers

Page 43: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

Larval genes:

Worker genes:

Queen genes:

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Page 45: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

Different behaviors of bees are associated with the expression of different genes…

"age polyethism"

Young Nurse Bees

Old Forager Bees

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Page 47: Genetics III: Examples Mutation Analyses- Strengths: Implicate roles for specific genes in animal behaviors Weakness: Lead to misconception that those.

Genomics is transforming studies of the inheritance

of animal behavior

Compare gene expression in animals involved with all sorts of behaviors….

e.g. female sticklebacks choosing

and not choosing among male

mates (Molly Cummings, UT Austin)

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