Fire Ant Colony Fitness and Worker Polymorphism

火蚂蚁群体适合度和工蚁多态沃尔特·R·齐克尔项目概述达尔文认为，社会性昆虫中存在不育的工种是对他的自然选择进化论的挑战。毕竟，一个不能繁殖的个体的特征如何传递给下一代呢？达尔文和他的追随者们普遍接受的答案是，群体是自然选择所依据的生殖单位。因此，无论哪种工蚁的特征允许该种群在下一代中安置更多的新种群，自然选择都会对其有利。绝大多数蚂蚁物种只有两个物理种姓：生殖个体(女王)和或多或少不育的单一大小和形状的工蚁。在大约15%的蚂蚁物种中，工蚁的大小(体重差异高达1000倍)和形状不一。这种工人的多态，就像它所说的那样，总是与工人种姓内部的进一步分工有关。长期以来，人们一直认为，工蚁多态通过提高群体效率而使群体受益，因此节省的资金可以投资于额外的繁殖力，增强群体健康(有性生产)。对代用品进行几次健康测试(觅食、育苗等)。都产生了模棱两可的结果，但这些代孕药都与性生产没有密切联系。从未有过关于工蚁多态对群体适合度的影响的直接测试，也就是说，对性繁殖的影响。拟议中的实验将是第一次直接测试工蚁多态对群体适应能力的价值。在对火蚁Solenopsis invicta进行的为期两年的大型田间试验中，选定大小的工蚁蛹将在不同的蜂群之间转移，从而使一组蜂群在大型工蚁中得到增强，另一组在小工蚁中得到加强，第三组作为未改变的对照，第四组作为未受干扰的对照。这些实验蜂群的适合度将通过使用帐篷陷阱收集年性繁殖总量来衡量。改变工人多态的影响(如果有的话)可能是通过大型工人参与性生产的直接影响，也可能是通过改变领土防御或觅食的间接影响。因此，食物的数量和质量，以及领土的大小也将受到监测，并与控制措施进行比较。这些野外实验的结果将得到一系列实验室实验的补充，这些实验将测试工人的多态和群落性生产之间的每一种可能的联系(直接、食物、领土)。这些结果将解决进化生物学和社会昆虫生物学非常感兴趣的一个基本问题。

Fire ant colony fitness and worker polymorphismWalter R. TschinkelProject Summary Darwin considered the existence of a sterile worker caste in social insects to be a challenge to his theory of evolution by natural selection. After all, how could the traits of an individual that did not reproduce be passed on to the next generation? The answer that Darwin and his followers have generally accepted is that the colony is the reproductive unit on which natural selection acts. Thus, whatever worker traits allowed the colony to place more new colonies in the next generation would be favored by natural selection. The great majority of ant species have only two physical castes: reproductive individuals (queens), and more-or-less sterile workers of a single size and shape. In about 15% of ant species, the workers are present in a great range of sizes (up to 1000-fold difference in weight) and shapes. Such worker polymorphism, as it is called, is always associated with further division of labor within the worker caste. It has long been assumed that worker polymorphism benefits the colony by increasing colony efficiency, so that the savings can be invested in additional reproductives, enhancing colony fitness (sexual production). Several tests of surrogates for fitness (foraging, brood-rearing, etc.) have yielded equivocal results, but none of these surrogates are tightly linked to sexual production. There has never been a direct test of the effects of worker polymorphism on colony fitness, that is, on the production of sexuals. The proposed experiments will be the first direct test of the value of worker polymorphism to colony fitness. In a large, 2-yr field experiment on the fire ant, Solenopsis invicta, worker pupae of selected sizes will be transferred among colonies such that one set of colonies will be enhanced in large workers, another in small workers, a third will serve as unaltered control, and a fourth as undisturbed control. The colony fitness of these experimental colonies will be measured by collecting the total annual sexual production using tent-traps. Effects (if any) of altering the worker polymorphism might be either direct through involvement of large workers in sexual production, or indirect through altered territorial defense or foraging. Therefore, the food quantity and quality, as well as territory size will also be monitored and compared to controls. The results of these field experiments will be supplemented with a series of laboratory experiments that will test each possible link (direct, food, territory) between worker polymorphism and colony sexual production. The results will address a fundamental issue of great interest to evolutionary biology and social insect biology.