Facultative and obligate slavery in formicine ants: frequency of slavery, and proportion and size of slaves

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• 作者：SAVOLAINEN ; RIITTA ; DESLIPPE ; RICHARD J.
• 刊名：Biological Journal of the Linnean Society
• 出版年：1996
• 出版时间：January, 1996
• 年：1996
• 卷：57
• 期：1
• 页码：47-58
• 全文大小：101 K

文摘

Slave-making ants raid nests of other ant species, capture the developing offspring and rear them to slave workers. Here we compare slave-making of three formicine slave-making ants: the facultativeFormica subnuda, the obligatePolyergus breviceps, andF. subintegrawhich previously has been considered facultative but appears to be an obligate slave-making ant. IfF. subintegrais an obligate slavemaker, slave-making ofF. subintegrashould differ from that ofF. subnudabut closely resemble slave-making ofP. brevicepsin the following aspects: (1) Obligate slavemakers are rarer than facultative slavemakers. (2) Slaveless colonies of facultative slavemakers are found, but obligate slavemakers always have slaves. (3) Because obligate slavemakers depend on their slaves, they should have a higher proportion of slaves than facultative slavemakers. (4) Owing to special adaptations obligate slavemakers are able to raid bigger colonies, and hence have bigger slaves than facultative slavemakers. (5) Dufour's gland ofF. subintegrashould be larger than that ofF. subnuda. Per 100 freeF. podzolicacolonies, the number ofP. brevicepsandF. subintegracolonies withF. podzolicaslaves were 1·3 % and 3·9 % , respectively, and the number ofF. subnudacolonies withF. podzolica3·7 % , and withoutF. podzolica7·5 % . The proportion of slaves, when present, varied between 1–30 % in the colonies ofF. subnuda, and between 70–90 % in the colonies of the other species. The slaves ofF. subnudawere significantly smaller than those ofF. subintegraandP. breviceps. The length ofF. subnuda's Dufour's gland was one third of the length ofF. subintegra's gland. The results show that slave-making ofF. subintegraparallels that ofP. breviceps, and contrary to the earlier notion,F. subintegrais an obligate slave-making ant. We suggest thatF. subnudaandF. subintegrarepresent extreme modes of slave-making behaviour in theFormica sanguineagroup.