Evolutionary stability of mutualism: interspecific population regulation as an evolutionarily stable strategy
Evolutionary stability of mutualism: interspecific population regulation as an evolutionarily stable strategy
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DOI：
10.1098/rspb.2004.2789
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发表时间：
2004-09-07
影响因子：
4.7
通讯作者：
Schultz, ST
中科院分区：
文献类型：
--
作者：
Holland, JN;DeAngelis, DL;Schultz, ST
种间互利共生往往容易受到不稳定性的影响，因为低效益：成本比可以迅速导致灭绝或将互利共生转化为寄生虫-宿主或捕食者-猎物的相互作用。我们假设，互利共生的进化稳定性可以取决于一个互利主义者的收益和成本如何随其合作伙伴的人口密度而变化，如果互利主义者可以影响人口统计率并调节其合作伙伴的人口密度，则可以保持稳定性。我们测试这一假设在一个模型中的互利共生的关键功能的仙人掌（Pachycereus schottii）-老蛾（Upiga virescens）的相互作用，授粉的好处和成本的幼虫种子消费植物健身取决于传粉密度。我们表明，植物可以最大限度地提高自己的健身资源分配生产过剩的花在牺牲水果。果实败育导致过量的花生产减少授粉种子消费者的成年前生存，并保持其密度低于阈值，这将破坏互利共生。这种过度的花生产和果实败育的策略是收敛的，并且在进化上是稳定的，以防止产生很少的花和很少甚至没有果实败育的作弊植物的入侵。这种新的机制，实现进化稳定的互惠互利，即种间种群调节，是从其他机制调用合作伙伴的选择或选择性奖励的性质不同，并可能是一个一般的过程，有助于保持互惠互利的相互作用的性质。
Interspecific mutualisms are often vulnerable to instability because low benefit: cost ratios can rapidly lead to extinction or to the conversion of mutualism to parasite-host or predator-prey interactions. We hypothesize that the evolutionary stability of mutualism can depend on how benefits and costs to one mutualist vary with the population density of its partner, and that stability can be maintained if a mutualist can influence demographic rates and regulate the population density of its partner. We test this hypothesis in a model of mutualism with key features of senita cactus (Pachycereus schottii) - senita moth (Upiga virescens) interactions, in which benefits of pollination and costs of larval seed consumption to plant fitness depend on pollinator density. We show that plants can maximize their fitness by allocating resources to the production of excess flowers at the expense of fruit. Fruit abortion resulting from excess flower production reduces pre-adult survival of the pollinating seed-consumer, and maintains its density beneath a threshold that would destabilize the mutualism. Such a strategy of excess flower production and fruit abortion is convergent and evolutionarily stable against invasion by cheater plants that produce few flowers and abort few to no fruit. This novel mechanism of achieving evolutionarily stable mutualism, namely interspecific population regulation, is qualitatively different from other mechanisms invoking partner choice or selective rewards, and may be a general process that helps to preserve mutualistic interactions in nature.