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

地栖松鼠的社会性和繁殖策略：合作、宽容和繁殖偏差

• 批准号: RGPIN-2021-03355
• 负责人: Waterman, Jane
• 金额: $ 2.4万
• 依托单位: University of Manitoba
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=742510
• 关键词: Sociality; reproductive; tactics; ground; dwelling

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.

生命史理论假设动物投资于生长、维持和繁殖的能量有限，并预测对一种性状的投资将以牺牲另一种性状为代价（权衡）。繁殖与生存之间的权衡是研究的一个主要焦点，特别是在生命史缓慢（体型大、寿命长）和生命史快（体小、寿命短）的物种之间。检查不遵循通常模式的物种的这些权衡，以及恶劣环境放大限制的情况，将拓宽我们对生命史策略进化的理解。 我的研究项目侧重于了解影响社会性和生殖策略进化的选择力。我们将使用行为、分子和内分泌技术，测试关于适应干旱的非洲地松鼠的生活史、替代繁殖策略和合作繁殖的基本假设。我对这个物种的长期研究已经成为研究社会复杂性的一个富有成效的系统，因为雌性是合作繁殖者，生活在有多个繁殖者的家庭群体中，而雄性则生活在全雄性群体中。雄性和雌性群体都没有领地意识，缺乏统治等级，并且很少表现出攻击性（在哺乳动物中很少见）。尽管体型较小，但它们的寿命却很长，并且后代很少，与大型哺乳动物类似。雄性有两种替代策略——要么推迟分散并与家人呆在一起，要么分散并加入全男性群体。策略在繁殖成功率方面没有差异，但任一策略的雄性后代的雄性后代的成功率均低于 30%。检查雄性的繁殖成功率、传播延迟和寿命的偏差是我项目的重点之一。在复杂的动物社会中，雌性通常与它们的近亲生活在一起，但这些近亲也是它们最亲密的竞争对手。因此，社交可以被视为群体成员之间合作与竞争之间的拉锯战。在雌性开普地松鼠中，大多数繁殖尝试都未能使后代断奶，但这种繁殖偏差的原因尚不清楚。家庭群体内的生殖冲突并不明显，因此这种偏差是意料之外的。在看似平等的家庭群体中检验与生活史和社会复杂性相关的假设是我项目的第二个重点。 合作繁殖，即个体照顾不属于自己的后代，通常被解释为帮助亲属，但开普地松鼠的雄性照顾者以租金的形式提供照顾。问题是，男性照顾者是否会提高繁殖成功率或繁殖者的生存率？或者繁育者是否要为美容男性护理人员的感染付出代价？了解男性护理对女性的好处和成本是这项工作的另一个重点。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，并将培训 HQP 在这些领域的关键实验室和实地工作技能。