当前位置:文档之家 > Behav Ecol Sociobiol (2004) 55494–501 DOI 10.1007s00265-003-0706-0 ORIGINAL ARTICLE

Behav Ecol Sociobiol (2004) 55494–501 DOI 10.1007s00265-003-0706-0 ORIGINAL ARTICLE

Behav Ecol Sociobiol(2004)55:494–501

DOI10.1007/s00265-003-0706-0

O R I G I N A L A R T I C L E

F.B.Kraus·P.Neumann·J.van Praagh·

R.F.A.Moritz

Sperm limitation and the evolution of extreme polyandry

in honeybees(Apis mellifera L.)

Received:16December2002/Revised:7October2003/Accepted:7October2003/Published online:29November2003 Springer-Verlag2003

Abstract Honeybee queens(Apis mellifera)show ex-treme levels of polyandry,but the evolutionary mecha-nisms underlying this behaviour are still unclear.The “sperm-limitation hypothesis”,which assumes that high levels of polyandry are essential to get a lifetime sperm supply for large and long-lived colonies,has been widely disregarded for honeybees because the semen of a single male is,in principle,sufficient to fill the spermatheca of a queen.However,the inefficient post-mating sperm trans-fer from the queen’s lateral oviducts into the spermatheca requires multiple matings to ensure an adequate sper-matheca filling.Males of the African honeybee subspe-cies A.m.capensis have fewer sperm than males of the European subspecies A.m.carnica.Thus,given that sperm limitation is a cause for the evolution of multiple mating in A.mellifera,we would expect A.m.capensis queens to have higher mating frequencies than A.m. carnica.Here we show that A.m.capensis queens indeed exhibit significantly higher mating frequencies than queens of A.m.carnica,both in their native ranges and in an experiment on a North Sea island under the same environmental conditions.We conclude that honeybee queens try to achieve a minimum number of matings on their mating flights to ensure a sufficient lifetime sperm supply.It thus seems premature to reject the sperm-limitation hypothesis as a concept explaining the evolu-tion of extreme polyandry in honeybees.

Keywords Apis mellifera·Honeybee·Evolution·Polyandry·Sperm-limitation hypothesis

Introduction

Despite intensive research in the last decades(e.g.Cole 1983;Crozier and Page1985;Boomsma and Ratnieks 1996;Palmer and Oldroyd2000;Crozier and Fjerdingstad 2001,among others),the phenomenon of multiple mating by queens(=polyandry)is still one of the unsolved riddles in the evolution of insect societies.If a queen is only single mated,the haplo/diploid sex determination system in the Hymenoptera should favour kin selection and the evolution of sociality(Hamilton1964).Polyandry de-creases the average relatedness of colony members and should therefore weaken selection that maintains euso-ciality(Wilson1971;Crozier and Pamilo1996).More-over,multiple matings are also costly at the level of the individual queen.Indeed,multiple matings can increase the predation risk(Ruttner1980;Koeniger et al.1994) and the risk of acquiring sexually transmitted diseases (Oldroyd et al.1997).Nevertheless,there are several phylogenetically isolated genera in the eusocial Hymen-optera that have evolved high levels of polyandry(>2);

e.g.Atta(Fjerdingstad and Boomsma1998)and Pogonomrymex(Gadau et al.2003)in ants,Vespula in wasps(Goodisman et al.2002),and Apis in bees(Estoup et al.1994;Boomsma and Ratnieks1996).

The highest mating frequencies detected so far in the social insects are found in the genus Apis,with queens of the giant honeybee Apis dorsata mating with more than 100males(Wattanachaiyinhcharoen et al.2003).Also,in the western honeybee,A.mellifera,high mating frequen-cies with up to45matings per queen have been reported for the Cape honeybee,A.m.capensis(Moritz et al. 1996).A.mellifera is the best studied of all Apis species, showing a complex mating system(Ruttner1988)with

Communicated by R.E.Page

F.B.Kraus())·P.Neumann·
R.F.A.Moritz Institut für Zoologie,

F.B.Kraus())·P.Neumann·R.F.A.Moritz Institut für Zoologie,

Martin-Luther-Universität Halle-Wittenberg, 06099Halle/Saale,Germany

e-mail:kraus@zoologie.uni-halle.de

Tel.:+49-345-5526235

Fax:+49-345-5527264

P.Neumann

Department of Zoology and Entomology, Rhodes University,

6140Grahamstown,South Africa

J.van Praagh

Niedersächsisches Landesinstitut für Bienenkunde, Wehlstr.4a,29221Celle,Germany