Since its conception over 100 years ago, the idea of the ecological niche remains a topic of enduring interest (Pocheville, 2015). The continued coexistence of multiple species and the myriad ways in which species adapt to, and survive, the environments in which they make their home continues to fascinate not only fully time ecologists, but those simply interested in the natural world. Among scientists, understanding a species or population's nice brings together those interested in behaviour, ecology and physiology and in particular those who seek to link these disciplines together and understand the life‐history consequences of physiological adaptation (Ricklefs & Wikelski, 2002). Such questions are particularly important in the context of environmental change and there is a critical lack of mechanistic understanding of the capacity that animals have to alter their behaviour, within the limits of their physiology and hence buffer against change (Urban et al., 2016). Indeed physiological ‘markers’ have recently been proposed as sensitive indicators of biodiversity challenges, in their role as links from environment to demography (Bergman et al., 2019).

In understanding an animal species’ niche, there is a temptation to generalise and understand patterns in behaviour and physiology based on simple traits such as body size (Brown et al., 2004) or broad‐scale patterns in the environment (Boyles et al., 2013). However, if there were single and simple answers to how species exist in their local environment and in particular how species appear to coexist in the same environment, then as functional ecologists we would soon be out of a job. Instead, it is clear that the strategies by which animals are able to survive and reproduce and the niches they occupy are as diverse as the animal kingdom itself. This diversity is elegantly characterised in a recent study by Menzies et al. (2020) which defines the contrasting functional niches of two sympatric herbivorous mammal species (the snowshoe hare and the red squirrel) that allow them to survive and coexist in the extreme conditions of winter in the Canadian Yukon.

Winter temperatures at the study site ranged from 10 to −30°C, superimposed with short‐term variation within and between days. Both study species are described appropriately by the authors as ‘too big to be small, and too small to be big’ (Lovegrove, 2000), thus must remain active above the snow throughout winter while remaining homeothermic, yet without the thermoregulatory advantages of large size. Menzies et al. (2020) used biologging tags to record physiological characteristics (body temperature, heart rate) and behaviour (activity levels) of both species in the same place at the same time. This allowed them to reveal differential responses to the same environmental challenge. While small in scale in comparison to differences between generalists and specialists or autotrophs and heterotrophs, the differences between the species were stark and sufficient to easily define two very different niches. The hares are nocturnal and worked hard to defend and maintain a constant body temperature at all times, via variation in heart rate, reflective of thermogenesis. They maintained constant, relatively high, levels of activity as they foraged continually during the night and crepuscular periods. They responded to supplemental food by reducing activity and to colder temperatures by increasing heart rate, again reflecting the role of thermogenesis. In contrast the squirrels remained primarily inactive in their insulated nests, particularly during cold periods and at night. Their body temperature was far more labile and varied in proportion to activity and heart rate. In warmer temperatures, the squirrels were more active and had higher body temperatures. They responded to food supplementation by reducing activity but increasing heart rate and temperature.

The differing niches that are described and the strategies that define them are both ultimately successful and highlight how studies that might be dismissed as descriptive, actually provide critical insights into evolution by clearly demonstrating divergent adaptation to common problems. Next steps would be to ascertain precisely which of these strategies might provide better protection to these species in the face of environmental change. This goes beyond the biology of these two species, however, and it would be interesting to determine whether the species which favoured metabolic regulation of body temperature (the hare) fared more successfully than the one favouring behavioural regulation (the squirrel) and whether these findings are generalisable to other studies and systems. Indeed looking across seasons there is some evidence that both metabolic and behavioural approaches may be balanced in some species (Dunn et al., 2020), again illustrating the diversity of solutions to nature's challenges. This is particularly important for species facing limits to their metabolic rates and/or activity levels on either a seasonal or annual basis (Halsey et al., 2019).

Biologging approaches such as those used in this study are now an established mechanism by which to understand the behaviour and ecology of animals in their natural environments (Cooke et al., 2004). As such they are increasingly proposed as key tools for conservation management (Hays et al., 2019; McGowan et al., 2017), with the potential to define a species or population's niche and hence provide the link from environment to demography (Bergman et al., 2019). Indeed researchers across taxa with extensive biologging datasets might continue to examine or re‐examine how, when and why homeotherms defend body temperature or allow it to vary (Butler & Woakes, 2001). The work of Menzies et al. (2020) promotes the use of such physiological, alongside behavioural, data streams in defining the functional niche, in order to better understand adaptation and coexistence. This further supports the idea that the drivers of species distributions and coexistence are unique, complex and multi‐dimensional. As ecologists and policy‐makers know, further exploration of this niche diversity will continue to reap rewards.

自从100年前提出这一概念以来，生态位概念一直是人们持续关注的话题（Pocheville，  2015年）。多种物种的持续共存以及物种适应和生存的多种方式不仅使全职生态学家着迷，而且对自然界仅感兴趣的人也着迷。在科学家中，了解物种或种群的友善将对行为，生态和生理学感兴趣的人聚集在一起，尤其是那些寻求将这些学科联系在一起并了解生理适应的生命历史后果的人（Ricklefs和Wikelski，  2002年））。这些问题在环境变化的背景下尤其重要，并且对动物必须在其生理范围内改变其行为的能力缺乏机械理解，因此对变化的缓冲（Urban et al。，  2016） 。实际上，最近已经提出生理学``标记''作为生物多样性挑战的敏感指标，因为它们是从环境到人口统计学的链接（Bergman et al。，  2019）。

在了解动物物种的生态位时，人们倾向于基于简单的特征，例如体型（Brown等，2004）或环境中的广泛模式（Boyles等，2004）来概括和理解行为和生理 模式。 ，  2013年）。但是，如果对物种如何在其本地环境中生存，特别是物种在同一环境中如何共存存在简单而简单的答案，那么作为功能生态学家，我们很快就会失业。相反，很明显，动物能够生存和繁殖的策略以及它们占据的生态位与动物界本身一样多样。Menzies等人最近的一项研究优雅地描述了这种多样性。（2020年）定义了两种同属草食性哺乳动物物种（雪兔和红松鼠）的相对功能性生态位，使它们能够在加拿大育空地区的冬季极端条件下生存并共存。

研究地点的冬季温度介于10至-30°C之间，且几天之内和几天之间的短期变化叠加在一起。作者对这两个研究物种都恰当地描述为“太大而又小又太大而又不大”（Lovegrove，  2000年），因此必须在整个冬季保持活跃在雪上，同时保持恒温，但又没有大的体温调节优势。尺寸。孟席斯等。（2020年）使用生物记录标签同时记录两个物种在同一地点的生理特征（体温，心率）和行为（活动水平）。这使他们能够揭示对相同环境挑战的不同反应。尽管与通才和专家或自养和异养之间的差异相比规模很小，但物种之间的差异却十分明显，足以轻松定义两个非常不同的生态位。这些野兔是夜行性动物，并且通过心率变化反映出生热作用，始终努力捍卫和维持恒定的体温。他们在夜间和夜间不断觅食，保持了相对较高的活动水平。他们通过减少活动来响应补充食品，并通过增加心率来应对低温，这再次反映了生热作用。相比之下，松鼠在绝热的巢中仍然保持不活动状态，尤其是在寒冷的夜晚。他们的体温更加不稳定，并且与活动和心率成比例地变化。在温暖的温度下，松鼠更活跃，体温也更高。他们通过减少活动但增加心率和体温来应对食物补充。他们的体温更加不稳定，并且与活动和心率成比例地变化。在温暖的温度下，松鼠更活跃，体温也更高。他们通过减少活动但增加心率和体温来应对食物补充。他们的体温更加不稳定，并且与活动和心率成比例地变化。在温暖的温度下，松鼠更活跃，体温也更高。他们通过减少活动但增加心率和体温来应对食物补充。

所描述的不同壁ni和定义它们的策略都最终成功，并突显了可能被视为描述性的研究如何通过清楚地表明对常见问题的不同适应性，为进化提供了重要的见解。下一步将是准确确定在面对环境变化时，哪些策略可以为这些物种提供更好的保护。但是，这超出了这两个物种的生物学范围，因此确定一个有利于体温代谢调节（野兔）的物种是否比一个有利于行为调节（松鼠）的物种表现得更有趣，以及这些发现是否有趣。可推广到其他研究和系统。 2020年），再次说明了应对自然挑战的解决方案的多样性。这对于面临季节性或年度代谢速率和/或活性水平受限的物种尤其重要（Halsey等人，  2019）。

现在，诸如本研究中使用的生物记录方法已成为一种建立的机制，通过该方法可以了解动物在其自然环境中的行为和生态（Cooke等，  2004）。因此，越来越多的人将其作为保护管理的关键工具（Hays等人，  2019年; McGowan等人，  2017年），具有定义物种或种群生态位的潜力，并因此提供了从环境到人口统计学的联系（Bergman等人）。等，  2019）。确实，跨类群且具有大量生物记录数据集的研究人员可能会继续检查或重新检查恒温疗法如何，何时以及为何捍卫体温或使其发生变化（Butler＆Woakes，  2001）。孟席斯等人的工作。（2020年）促进在定义功能性利基市场时使用此类生理数据和行为数据流，以更好地理解适应性和共存性。这进一步支持了物种分布和共存的驱动因素是独特，复杂和多维的观点。正如生态学家和政策制定者所知，对这种利基多样性的进一步探索将继续获得回报。