Cooperative Breeding and Chimerism in Marmosets Callithrix kuhlii

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Cooperative Breeding and Chimerism in Marmosets
(Callithrix kuhlii)

• Cory Ross

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Marmoset Reproduction

• Obligate fraternal twinning

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Marmoset Reproduction

• Cooperative breeding (Alloparenting)

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Marmoset Reproduction

• High levels of
• paternal investment
• (ie carrying, and
• food sharing)

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Social Systems

• Monogamous???
• Typically one breeding female and male in large
  family group

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Social Systems

• Polyandrous
• In wild, social groups also found with two adult
  males and one breeding female
• Researchers suggest that monogamous pairs are
  unsuccessful in rearing first set of infants

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Social Systems

• Although helpers at the nest are not rare.
• the amount of time spent is unusual.
• Multiple male care is unheard of (unless
  paternity is shared).
• Are there unusual factors contributing to
  cooperative care in this family of primates?

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Chimerism

• Twins are fraternal
• During development the placentas fuse
• Allows stem cell exchange between twins
• Documented in 1930s
• XY chromosomes found in female liver in 1960s

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Chimerism
Twin 2
Twin 1
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Chimerism
Twin 2
Umbilicus 2
Umbilicus 1
Twin 1
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Goals for Study

• To develop microsatellite markers specific for
  Callithrix kuhlii
• To document the extent and distribution of
  chimerism
• by screening 40 sets of twins with ten
  microsatellite markers for multiple tissues

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Predictions

• Tissues derived from bone marrow stem cells will
  be chimeric, whereas other tissues will have
  genotypes unique to the individual

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Callithrix kuhlii (Wieds Black Tufted-Ear
Marmosets)

• The only North American captive breeding colony
  was established in 1990 at the University of
  Nebraska at Omaha

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Callithrix kuhlii

• There were 12 founding breeding animals from
  Brazil
• Today the colony has over 80 living animals, as
  many as 6 generations from the founders

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Callithrix kuhlii

• Animals available
• Of the 304 animals in the database
• Over 90 of the animals are represented by tissue
  or organ samples.

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Study Group

• Tissues collected for study
• blood, hair, sperm, fecal, saliva, brain, kidney,
  liver, spleen, lung, heart, muscle, skin, gonad,
  etc...

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Microsatellite development

• Currently have 7 primers with high variation
  (more than 6 alleles)
• 6 other primers have been tested - set aside with
  low variation
• Need to develop at least three more with high
  variation

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Genotyping IDEAL
Male
150
120
124
136
132
Infant 1
120
115
136
150
155
Infant 2
155
115
136
130
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Genescan Analysis
126 132 138
Liver
126 132 138

• This individual exhibits
• 3 alleles for one locus
• in several tissues while
• other tissues exhibit
• 2 alleles

Spleen
132 138
Lung
132 138
Muscle
132 138
Gonad
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Genescan Analysis
155 163 165
Liver
163
Lung
Another example of liver tissue exhibiting
extra peaks
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Genescan Analysis
155 161 167
128 132 138
Gonad
Heart
However, this phenomenon does not appear to be
limited to the liver tissue. These samples from
additional individuals also exhibit 3 peaks.
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Summary

• Microsatellite development
• Continuing....
• Twin Study
• Tissue collection 90 completed
• 100 samples genotyped for 5 loci
• Three distinct peaks found for 20 samples
• Shadow peaks found for 25 additional samples
• Liver, spleen, gonad, heart, and muscle tissue
  all found to be chimeric

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Implications

• Presence of genetic mosaic across tissues could
  affect
• Determination of individuality
• Paternity testing
• Population census
• Which tissue do you use?

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Implications

• Evolutionary thoughts and predictions for
• Transfer of genetic information

?
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Implications

• Evolutionary thoughts and predictions for
• Transfer of genetic information
• Paternal Care and Investment
• Hamiltons rule states
• rb - c gt 0
• where r relatedness coefficient (probability
  that two individuals share a particular allele
  identically by descent)
• b benefit of altruism
• c cost

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• Paternal care is typically thought to be
  beneficial because of the high relatedness
  between parent and offspring

r 0.5
r 0.5
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• In a chimera it is possible that the relatedness
  values have increased

r
r
p1
r 0.5 p1
Hence, a higher drive towards altruism??
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Implications

• Evolutionary thoughts and predictions for
• Transfer of genetic information
• Paternal Care and Investment
• Cooperative breeding, calculation of kinship

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• If brothers raise infants together

r 0.5
r 0.5
r 0.25
In a normal organism
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• If brothers raise infants together

r gt 0.5
p1
r gt 0.25
p2
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• If brothers raise infants together

AA
Aa
AA
Aa

r 0.5
a
r gt0.25
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• Between sibs

In typical organisms all siblings have an r 0.5
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• Between sibs

Chimeric individuals would have higher rs with
their twins but the r between siblings should
also be increased to a lesser extent??
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• There is also the possibility in poylandrous
  groups for

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• Conclusions
• If gametes carry chimeric cells than the r values
  are increased in Callithrichid families,
  enhancing the drive for altruism

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• Conclusions
• If gametes carry chimeric cells than the r values
  are increased in Callithrichid families,
  enhancing the drive for altruism
• If somatic cells are chimeric and gonad cells are
  not, r does not technically change. However,
  intergenomic conflict is at work.

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• Conclusions
• If gametes carry chimeric cells than the r values
  are increased in Callithrichid families,
  enhancing the drive for altruism
• If somatic cells are chimeric and gonad cells are
  not, r does not technically change. However,
  intergenomic conflict is at work.
• Even if somatic cells are the only cells involved
  these are the cells often mediating kin
  recognition and therefore perhaps kin altruism.

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Acknowledgments

• For lab assistance and psychological support
• Alicia Startzer, Justin Meeker, Sara Brant, Jeff
  Fite, Erin Kinally, Mike Bessert, and Annie
  Paradis
• Funding
• UNL Special Funds Grants -awarded to CR
• UNL Initiative for Ecological and Evolutionary
  Analysis -awarded to CR
• UNL Laymans Grant- awarded to GO and CR
• Sigma Xi Grant- awarded to CR
• American Society of Primatology Research Grant -
  awarded to CR