Sociality and reproductive tactics in ground-dwelling squirrels: cooperation, tolerance and reproductive skew

生活史理论假设动物有有限的能量投资于生长，维持和繁殖，并预测投资于一个特征将以另一个特征为代价（权衡）。繁殖和生存之间的权衡是研究的一个主要焦点，特别是在具有缓慢（大型，长寿）和快速（小型，短命）生活史的物种之间。在不遵循通常模式的物种中检查这些权衡，以及恶劣环境放大限制的地方，将拓宽我们对生命史策略进化的理解。 我的研究计划侧重于了解影响社会性和生殖策略进化的选择性力量。我们将使用行为、分子和内分泌技术，在适应干旱的非洲地松鼠中测试关于生活史、替代生殖策略和合作育种的基本假设。我对这个物种的长期研究是一个富有成效的系统，可以用来研究社会的复杂性，因为雌性是合作的繁殖者，生活在有多个繁殖者的家庭群体中，雄性生活在全雄性的群体中。雄性和雌性群体都是非领土性的，缺乏统治等级，很少表现出攻击性（在哺乳动物中很少见）。它们寿命长，尽管体型小，而且很少有后代，类似于大型哺乳动物。雄性有两种选择策略--它们要么推迟分散并与家人呆在一起，要么分散并加入全是雄性的乐队。战术没有不同的繁殖成功，但不到30%的男性，无论是战术父系后代。检查这种倾斜的繁殖成功，延迟传播和长寿的男性是我的计划的重点之一。在复杂的动物社会中，雌性通常与近亲生活在一起，但这些近亲也是它们最亲密的竞争对手。因此，社会性可以被看作是群体成员之间合作与竞争的拔河比赛。在雌性开普地松鼠中，大多数繁殖尝试都未能使后代断奶，但这种生殖偏差的原因尚不清楚。家庭群体内部的生殖冲突并不明显，因此这种倾斜是意料之外的。测试与生活史和家庭群体中的社会复杂性相关的假设似乎是平等主义的，这是我计划的第二个重点。 合作繁殖，即个体照顾不是自己的后代，通常被解释为帮助亲属，但在开普地松鼠的雄性照顾者提供照顾作为一种租金。问题是，男性照顾者是否会增加繁殖成功率或繁殖者的生存率？或者饲养者是否要支付来自梳理男性护理人员的感染费用？这项工作的另一个重点是了解男性护理对女性的好处和成本。这项研究的结果将对进化生物学、人类医学和兽医学产生理论和应用影响，并将培养HQP在这些领域的关键实验室和实地工作技能。

Life-history theory assumes animals have finite energy to invest in growth, maintenance and reproduction and predicts that investment in one trait will come at a cost to another (trade-offs). The trade-off between reproduction and survival is a major focus of research, especially between species with slow (large-bodied, long-lived) and fast (small-bodied, short-lived) life histories. Examining these trade-offs in species that do not follow the usual patterns, and where harsh environments magnify constraints, will broaden our understanding of the evolution of life history strategies. My research program focuses on understanding the selective forces influencing the evolution of sociality and reproductive strategies. We will test fundamental hypotheses on life-history, alternative reproductive tactics and cooperative breeding in an arid-adapted African ground squirrel, using behavioural, molecular and endocrine techniques. My long-term study of this species has been a productive system for examining social complexity because females are cooperative breeders living in family groups with multiple breeders, and males live in all-male bands. Both male and female groups are non-territorial, lack dominance hierarchies and display little aggression (rare in mammals). They are long-lived, despite a small body size, and have few offspring, similar to a large mammal. Males have two alternative tactics - they either delay dispersal and stay with their family, or disperse and join all-male bands. Tactics do not differ in reproductive success but less than 30% of males of either tactic sire offspring. Examining this skewed reproductive success, delayed dispersal and longevity in males is one focus of my program. In complex animal societies, females usually live with their close kin but these close kin are also their closest competitors. Thus sociality can be seen as a tug-of-war between cooperation and competition among groupmates. In female Cape ground squirrels, most breeding attempts fail to wean offspring, but the reasons for this reproductive skew are unclear. Reproductive conflict within the family group is not apparent, so such skew is unexpected. Testing hypotheses related to life-history and social complexity in family groups that appear to be egalitarian is the second focus of my program. Cooperative breeding, where individuals care for offspring that are not their own, is usually explained as helping kin, but male carers in Cape ground squirrels provide care as a form of rent. The question is, do male carers increase the reproductive success or survival of breeders? Or do breeders pay the cost in terms of infections from grooming male carers? Understanding the benefits and costs of male care to females is another focus of this work. Results of this research will have theoretical and applied implications to evolutionary biology, and human and veterinary medicine, and will train HQP in crucial laboratory and fieldwork skills for these fields.