非传粉小蜂对榕树-传粉蜂共生系统的选择及其强度研究

Explaining the evolution and maintenance of cooperation is a fundamental scientific problem that has yet to be fully resolved. Most studies have focused on resource utility mode and cooperative behavior of partners in maintenance of cooperative systems. However, I and my colleagues made a recent breakthrough by showing that wasps that parasitize the pollinators (inquilines or parasitoids) in three Australasian Ficus (including F. racemosa) help promote mutualism stability by increasing the costs to those foundresses who lay eggs in outer ovules, which might be a new mechanism to explain the maintenance of mutualistic systems. To measure the effects of non-pollinating fig wasps (NPFWs) on fig-pollinator mutualisms thus requires the identification of the trophic statuses of wasps associated with divergent Ficus species, and also to quantify temporal and spatial variation in these wasp communities. The nature of the Ficus syconium as a discrete ecological microcosm provides a unique opportunity to do this by laboratory and field experimentation, and the novel use in this system of stable isotope analysis (SIA). The results of this research will enable for the first time the direct formal quantification of the strength and nature of selection inflicted by third-parties (NPFWs) on both partners in a globally important mutualism. Most importantly, we will make a novel breakthrough in producing formal, standardized measures of the natural selection exerted by associated species on both parties of a well-known model mutualism to make considerable progress towards explaining how stability is achieved.

合作行为如何演化而来，以及合作系统如何维持其稳定性是进化生态学领域的重要问题。以往的研究主要集中在互利合作双方的资源利用模式及合作行为对共生系统稳定性的影响上。然而，申请人最近的对榕树-榕小蜂系统的研究表明，该系统中的第三方（非传粉小蜂）能改变共生者的资源利用模式，维持互利共生系统的稳定。这可能是一种新的共生系统稳定性维持机制。为了进一步阐明非传粉小蜂对该系统稳定性的影响，首先要明确非传粉蜂群落在时间和空间上的变化以及非传粉小蜂的营养级状态（trophic statuses）。榕果是一个相对独立的微环境，是研究物种群落时空变化的理想实验对象。结合使用稳定同位素分析（Stable Isotope Analysis，SIA）技术，我们可以确定每种小蜂的营养级状态。本研究的结果将定量的揭示第三方（非传粉小蜂）对互利共生系统双方（榕树、传粉小蜂）的自然选择特性及其强度。

合作行为如何演化而来，以及合作系统如何维持其稳定性是进化生态学领域的重要问题。以往的研究主要集中在互利合作双方的资源利用模式及合作行为对共生系统稳定性的影响上。通过对榕树-榕小蜂系统的研究，我们发现该系统中的第三方寄生性小蜂能改变共生者的资源利用模式，维持互利共生系统的稳定。这可能是一种新的共生系统稳定性维持机制。我们发现宿主榕树对寄生性小蜂存在差异性惩罚，而奖励诚实传粉小蜂。并明确非传粉蜂群落在时间和空间上的变化以及非传粉小蜂的营养级状态（trophic statuses）。结合使用稳定同位素分析（Stable Isotope Analysis，SIA）技术，我们确定了每种小蜂的营养级状态。本研究的结果定量的揭示第三方（非传粉小蜂）对互利共生系统双方（榕树、传粉小蜂）的自然选择特性及其强度。