A Test of the Role of Haplodiploidyin the Evolution of Hymenopetran Eusociality

Gadagkar, Raghavendra (1990) A Test of the Role of Haplodiploidyin the Evolution of Hymenopetran Eusociality. In: 11th International Congress IUSSI, August, Bangalore,India, pp. 539-540.

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Abstract

The haplodiploid genetic system found in all Hymenoptera creates an asymmetry in genetic relatedness so that full-sisters are more closely related to each other (coefficient of genetic relatedness, r = 0.75) than a female would be to her daughters (r = 0.5). The multiple origins of eusocia1ity in the Hymenoptera have therefore been ascribed to haplodiploidy . But a Hymenopteran female is related to her brothers by 0.25. A worker who rears equal numbers of brothers and sisters therefore has no advantage over a solitary nest foundress because her average relatedness to brood will be reduced to 0.5. But workers can potentially gain more inclusive fitness than solitary foundresses if they invest more in their sisters than in their brothers. When queens mate multiply and simultaneously use sperm from different males, they produce different patrilines of daughters who would only be related to each other by 0.25. This again reduces the inclusive fitness that workers can potentially gain. Whether or not the genetic asymmetry created by haplodiploidy can by itself be sufficient to allow workers to have more inclusive fitness than solitary foundresses thus depends on their relatedness to their sisters and on their ability to skew investment in favour of sisters. A number of estimates of genetic relatedness between sisters in Hymenopteran colonies have now been published. To test the haplodiploidy hypothesis I assume that workers are capable of investing in their brothers and sisters in the ratio that is optimal for them and compute the threshold relatedness to sisters required for them to obtain a weighted mean relatedness to siblings of 0.5 and thus break even with solitary foundresses.

Item Type:	Conference Paper
Publisher:	Oxford and IBH
Additional Information:	Copyright of this article belongs to Oxford and IBH.
Department/Centre:	Division of Physical & Mathematical Sciences > Centre for Theoretical Studies (Ceased to exist at the end of 2003) Division of Biological Sciences > Centre for Ecological Sciences
Date Deposited:	27 Dec 2006
Last Modified:	19 Sep 2010 04:33
URI:	http://eprints.iisc.ac.in/id/eprint/9203

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