Construction of chimaeric gardens through fungal intercropping: a symbiont choice experiment in the leafcutter ant Atta texana (Attini, Formicidae)
Construction of chimaeric gardens through fungal intercropping: a symbiont choice experiment in the leafcutter ant Atta texana (Attini, Formicidae)
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通过真菌间作构建嵌合花园：切叶蚁 Atta texana（Attini，蚁科）的共生选择实验
DOI：
10.1007/s00265-010-0928-x
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发表时间：
2010
影响因子：
2.3
通讯作者：
U. Mueller
中科院分区：
文献类型：
--
作者：
R. Sen;Heather D. Ishak;Trevor R. Kniffin;U. Mueller
如果选择伙伴时偏向受益伙伴并歧视非受益伙伴，则种间或种内合作可以在进化上稳定下来。我们通过自助餐厅式偏好测定法对切叶蚁 Atta texana（Attini，蚁科）中的这种伙伴选择（共生体选择）进行了量化，其中使用了来自 A. texana 和 Acromyrmex versicolor 的基因型不同的真菌品种。共生体选择被测量为蚂蚁从几个纯（无菌）品种片段中选择一个或多个品种并将给定的真菌片段转化为花园的倾向。微卫星 DNA 指纹识别使我们能够识别蚂蚁为花园选择的品种。在 91% 的选择测试中，A. texana 工作人员将多个品种组合成一个间作的嵌合花园，并且这些品种在这种嵌合花园中共存了长达 4 个月的时间。嵌合花园中不同真菌基因型的共存似乎与最近的品种竞争模型相矛盾，该模型假设每个品种都会分泌损害其他品种的不相容化合物，这可能会排除我们实验中观察到的间作混养。尽管我们在实验嵌合花园中没有发现新的重组基因型的明确证据，但在自然条件下，品种基因型的间作可能偶尔会导致共存品种之间遗传物质的交换，从而将新的品种基因型引入切叶刀共生中。在我们的实验室测定中，蚂蚁的共生选择以及嵌合花园中共存品种菌株之间的任何竞争似乎运行得不够快，无法将嵌合花园转化为自然条件下观察到的德克萨斯州蚂蚁的单一栽培。
Interspecies or intraspecies cooperation can be stabilized evolutionarily if choosing partners favor beneficial partners and discriminate against non-beneficial partners. We quantified such partner choice (symbiont choice) in the leafcutter ant Atta texana (Attini, Formicidae) by presenting the ants in a cafeteria-style preference assay with genotypically distinct fungal cultivars from A. texana and Acromyrmex versicolor. Symbiont choice was measured as the ants' tendency to choose one or more cultivar(s) from several pure (axenic) cultivar fragments and convert a given fungal fragment into a garden. Microsatellite DNA fingerprinting enabled us to identify the cultivars chosen by the ants for their gardens. In 91% of the choice tests, A. texana workers combined multiple cultivars into a single intercropped, chimaeric garden, and the cultivars coexisted in such chimaeric gardens for as long as 4 months. Coexistence of distinct fungal genotypes in chimaeric gardens appears to contradict a recent model of cultivar competition postulating that each cultivar secretes incompatibility compounds harming other cultivars, which presumably would preclude the intercropped polyculture observed in our experiments. Although we found no clear evidence of novel, recombinant genotypes in the experimental chimaeric gardens, the intercropping of cultivar genotypes may occasionally lead under natural conditions to exchange of genetic material between coexisting cultivars, thus introducing novel cultivar genotypes into the leafcutter symbiosis. Symbiont choice by ants and any competition between coexisting cultivar strains in chimaeric gardens do not appear to operate fast enough in our laboratory assay to convert chimaeric gardens into the monocultures observed for A. texana under natural conditions.