1、N1 社 群、合作和利他行为要 点合 作 许多动物，个体间有互利合作。这种合作可以是暂时性的（如共同猎食、关怀后代），或者是长久性的，在一生中都保持着（如蚂蚁的群体，或一对缄默的天鹅）。集群 好处 许多动物有集群，如椋鸟群、鲱鱼群、狮子群。集群给动物带来好处：逃避捕食动物、找食物和捕捉受围困的或大个的猎物。加里福尼亚鸟群In many animal species, individuals cooperate for their mutual benefit. This cooperation can be temporary e.g. (for hunting or offspring ca
2、re), or permanent, lasting the individual (e.g. an ant colony, or a pair of mute swans).Key NotesCooperationMany species of animals form groups, such as flocks of starlings, shoals of herring or prides of lionsbeing in a group gives an animal some advantages: avoidance of predation, location of food
3、 and catching elusive or large prey.Grouping - benefitsN1 SOCIAL GROUPS,COOPERATION AND ALTRUISM集群 代价 作为集群的一员也有弊处：增加竞争食物的强度、更易引起捕食者的注目、提高感染疾病的风险。利他 行为 利他行为出现在：当一个个体行为导致另一个适合度增加，同时以其牺牲自身存活或产后代为代价。例如真社会性的蚂蚁群体中不育的工蚁，它们牺牲自身生殖的机会，代之以对其母后生殖的支持。这意味着，利他主义者积极地减少其适合度。利他行为看起来似乎是矛盾的，然而，如果利他行为者与受惠者具有亲缘关系，这种对策可以使
4、利他行为者有更多的基因遗传给下一代。There are also costs of belonging to a group: increased competition for food, increased conspicuousness to predators, increased risk of disease.Grouping costs Altruism occurs when an individual causes an increase in the fitness of another individual of the same species at a cost to
5、 its own survival or offspring production. An example is the sterile worker in a eusocial ant society, which sacrifices its opportunity of reproducing and instead supports its mothers reproduction. This appears paradoxical, as it implies that the altruist is actively reducing its fitness, However, i
6、f the altruist is related to the beneficiary, this strategy may result in more of the altruists genes passing to the next generation.Altruism真 社会性的群体有一类动物种具有生殖分工，表现出极端的社会生活类型：一些个体放弃生殖（常常称为工蚁或工蜂），另一些则是能生殖的（有性的，如蚁后和蜂王）。此类社会群仅仅出现在具长刺的膜翅目昆虫，如蚂蚁、蜜蜂和胡蜂。相关主题 种内 竞争（见 I2） 生态学中的性（见 N2）蜂王Related topics Intrasp
7、ecific competition (I2) Sex in ecology (N2)Eusocial society A select group of animal species display an extreme form of sociality, in which there is a reproductive division of labor: some individuals (usually called workers) forego reproduction, whilst others are fertile (sexuals such as queens). This type of society is only common among a group of insects in the order Hymenoptera equipped with a sting ants, bees and wasps.N2 生态学中的性要 点性 性是 植物和动物中广泛分布的现象，性有一系列生态后果。性在进化上的重要性是由于它产生遗传变异，它在生态学上的重要性则是因为不同性别的生物其行为不同。两性之间的区别是由于它们对后代发育的能量投资不对称性而产生的。
