title: Selective resource allocation may promote a sex ratio in pollinator fig wasps more beneficial for the host tree.
abstract: Mutualisms play a key role in most ecosystems, yet the mechanisms that prevent overexploitation of the mutualistic relationship are still poorly understood. In the mutualism between fig trees and their pollinating wasps both partners depend on each other. Fig trees benefit from female wasps that disperse their pollen, whereas wasps frequently benefit from a higher ratio of male offspring. Here we use manipulative field experiments to address whether host trees (Ficus racemosa) can influence the offspring sex ratio of the pollinator wasp. We controlled wasp matings; virgin wasps can lay only male eggs. We found that virgin foundress wasps had fewer offspring than mated foundresses. This was not caused by virgin wasps having a shorter lifespan, or laying fewer eggs. Instead, male wasp larvae were more likely to die during development. Additionally, male eggs were deposited in flowers of equal style length to those of female eggs, yet emerged from galls with shorter pedicels than those of female wasps. We suggest that male larvae are either allocated less resources by the tree, or are less able to attract resources, during development. If the tree orchestrates this difference it would promote a more female-biased wasp brood, thus increasing the tree's fitness.
authors.affiliation: State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, Yunnan, China.|Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming 650204, Yunnan, China.
authors.forename: Zhao-Tian
authors.initials: ZT
authors.lastname: Li
authors.affiliation: Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun 666303, Yunnan, China.
authors.forename: Yan-Qiong
authors.initials: YQ
authors.lastname: Peng
authors.affiliation: State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, Yunnan, China.|Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming 650204, Yunnan, China.
authors.forename: Xiao-Lan
authors.initials: XL
authors.lastname: Wen
authors.affiliation: Department of Organismic and Evolutionary Biology, 26 Oxford Street, Harvard University, Cambridge MA 02138, USA.
authors.forename: K Charlotte
authors.initials: KC
authors.lastname: Jandér
mesh_terms: D000818:Animals; D017753:Ecosystem; D005260:Female; D030681:Ficus / Q000254:growth & development / Q000502:physiology*; D008136:Longevity; D008297:Male; D008954:Models, Biological; D010941:Plant Tumors; D054817:Pollination / Q000235:genetics / Q000502:physiology*; D012744:Sex Ratio; D012726:Sexual Behavior, Animal; D013559:Symbiosis / Q000235:genetics / Q000502:physiology*; D014863:Wasps / Q000235:genetics / Q000254:growth & development / Q000502:physiology*