Testing models of
comparative reproductive biology in the eusocial hymenopteraTesting models of
comparative reproductive biology in the eusocial hymenoptera
This project aims to determine the number of mating in all species of Apis.
This is an interesting question, because it should shed light on why multiple
mating has evolved. Our progress (and that of others) is summarised by the following
table.
Mean levels of polyandry and intra-colonial genetic relationships
in the genus Apis as determined by microsatellite analysis
|
Species |
Number of matings ± var |
Average relatedness |
Effective number of matings |
Author |
|
A. mellifera |
13.8 ± 30.7 |
0.30 ± 0.0001 |
12.4 ± 24.8 |
Estoup et al. 1994 |
|
A. andreniformis |
13.5 ± 20.3 |
0.30 ± 0.0001 |
9.08 ± 2.75 |
Oldroyd et al. 1997 |
|
A. florea |
8.0 ± 5.5 |
0.35 ± 0.017 |
5.6 ± 1.06 |
Oldroyd et al. 1995 |
|
A. dorsata* |
26.7 ± 117.6 |
0.29 ± 0.0001 |
20.0 ± 175.7 |
Oldroyd et al. 1996 |
|
A. cerana |
18.0 ± 3.0 |
0.29 ± 0.005 |
12.0 ± 1.6 |
Oldroyd In prep |
Key findings are:
Much higher levels of polyandry than expected on the basis of earlier work.
Extreme polyandry in Apis dorsata.
Very high variance in levels of polyandry within species (see table).
The results suggest that all species of Apis mate more than 6 times. The number 6 is interesting, because matings beyond 6 do not further reduce average relatedness or the risk of homozygosity at the sex locus. Therefore our tentative conclusion is that polyandry evolved to increase the possibility of within-colony behavioural polymorphism or to increase resistance to diseases and pathogens, not to reduce queen-worker conflict over sex allocation
This project has fostered a strong relationship between the our lab and Prof. Wongsiri at Chulalongkorn University in Bangkok. So far, one Sydney student has worked in Thailand, and two Thais have worked in Sydney. Further exchanges would be great!
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