Debate still continues around the definition of generalism and specialism in nature. To some, generalism is equated solely with polyphagy, but this cannot be readily divorced from other essential biological factors, such as morphology, behaviour, genetics, biochemistry, chemistry and ecology, including chemical ecology. Viewed in this light, and accepting that when living organisms evolve to fill new ecological–evolutionary niches, this is the primal act of specialisation, then perhaps all living organisms are specialist in the broadest sense. To illustrate the levels of specialisation that may be found in a group of animals, we here provide an overview of those displayed by a subfamily of hemipteran insects, the Aphididae, which comprises some 1600 species/subspecies in Europe alone and whose members are specialised in a variety of lifestyle traits. These include life cycle, host adaptation, dispersal and migration, associations with bacterial symbionts (in turn related to host adaptation and resistance to hymenopterous wasp parasitoids), mutualisms with ants, and resistance to insecticides. As with polyphagy, these traits cannot easily be separated from one another, but rather, are interconnected, often highly so, which makes the Aphididae a fascinating animal group to study, providing an informative, perhaps unique, model to illustrate the complexities of defining generalism versus specialism.

中文翻译：

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蚜虫专业作为生态进化分歧的一个例子

关于自然界中通才和专业的定义的争论仍在继续。对某些人来说，通才仅仅等同于多食性，但这不能容易地与其他基本的生物因素分开，例如形态学、行为学、遗传学、生物化学、化学和生态学，包括化学生态学。从这个角度来看，并接受当生物体进化以填补新的生态-进化生态位时，这是专业化的原始行为，那么也许所有生物体都是最广泛意义上的专家。为了说明可能在一组动物中发现的专业化水平，我们在此概述了半翅目昆虫亚科蚜科、仅在欧洲就有大约 1600 个物种/亚种，其成员专门研究各种生活方式特征。这些包括生命周期、宿主适应、扩散和迁移、与细菌共生体的关联（反过来与宿主适应和对膜翅黄蜂寄生蜂的抗性有关）、与蚂蚁的共生关系以及对杀虫剂的抗性。与多食性一样，这些特征不能轻易彼此分开，而是相互关联，通常是高度相关的，这使得蚜科成为一个令人着迷的动物群体，提供了一个信息丰富的、也许是独特的模型来说明定义通才的复杂性对专业。与细菌共生体的关联（反过来与宿主适应和对膜翅黄蜂寄生蜂的抗性有关）、与蚂蚁的共生关系以及对杀虫剂的抗性。与多食性一样，这些特征不能轻易彼此分开，而是相互关联，通常是高度相关的，这使得蚜科成为一个令人着迷的动物群体，提供了一个信息丰富的、也许是独特的模型来说明定义通才的复杂性对专业。与细菌共生体的关联（反过来与宿主适应和对膜翅黄蜂寄生蜂的抗性有关）、与蚂蚁的共生关系以及对杀虫剂的抗性。与多食性一样，这些特征不能轻易地相互分离，而是相互关联，通常是高度相关的，这使得蚜科成为一个迷人的动物群体，提供了一个信息丰富的、也许是独特的模型来说明定义通才的复杂性对专业。