Evolutionary genetics of meerkats (Suricata suricatta)
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Date
29/06/2013Author
Nielsen, Johanna Fonss
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Abstract
Cooperative species have long been the focus of much research due to the ‘special
difficulty’ cooperation poses to the theory of evolution via natural selection. Despite
this long history of scientific interest we actually know relatively little about the
evolutionary genetics of cooperative mammalian species, especially in the wild. In
this study I use long-term data from the Kalahari Meerkat Project to investigate some
aspects of the evolutionary genetics of meerkats (Suricata suricatta).
First, I reconstructed a genetically-validated pedigree of the Kalahari meerkat
population. 1,494 meerkats (83% of the total known population) were genotyped at
a panel of 18 highly variable microsatellite markers. This genetic data, in
combination with phenotypic information and two different programs, COLONY2 and
MASTERBAYES, was used to infer familial relationships. The resulting pedigree
spanned seven generations and included 1,614 individuals of which 1,076 had both
parents known. I conclude by discussing the particular merits of using COLONY2 to
infer familial relationships for social animals such as meerkats.
Second, I investigated the extent of inbreeding and inbreeding depression in early
life traits in the Kalahari meerkat population. In the pedigree, 44% of individuals
have non-zero (F>0) inbreeding coefficients. Although I found more inbreeding in
meerkats than initially expected, there were few cases of inbreeding between very
close relatives. Nonetheless, even low to moderate inbreeding appeared to result in
inbreeding depression for pup mass at emergence, hind-foot length, growth until
independence, and juvenile survival. I also found some tentative evidence for a
positive effect of the social environment in ameliorating the effects of inbreeding
depression.
Third, I conducted a quantitative genetic analysis on mass, skull length, skull width,
forearm length, and hind-foot length in up to five key meerkat life stage periods,
while accounting for a number of fixed effects, including inbreeding coefficient. By
attempting to apportion variance in these traits to a variety of sources I found that
birth litter identity often explained much of the variance in morphological traits,
although the magnitude of this effect appeared to decline with age. Furthermore,
when birth litter was removed from models, the amount of variance explained by
additive genetic effects tended to increase.
Finally, I conducted a quantitative genetic analysis on two measures of cooperative
care and on adult mass. Fixed effects, including inbreeding and relatedness
coefficients, were also examined, which revealed that inbred individuals contribute
more to pup-feeding, and that helper-recipient relatedness was negatively associated
with baby-sitting. I found low heritable variation for baby-sitting (h2 = 0.10) and
pup-feeding (h2 = 0.08), and higher heritable variation for adult body mass (h2 =
0.19). I also estimated the magnitude of non-genetic sources of variation in these
traits and provide evidence for positive genetic correlations between baby-sitting and
pup-feeding, and baby-sitting and adult mass.
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