Spatial variation in the density of ectotherms

在物种内部，丰度（种群密度）在空间和时间上有明显的变化。因此，解释物种丰度的空间和时间模式是生态学的主要目标之一。丰富中心假说认为物种在其地理分布范围的中心附近最丰富，但经验数据并不支持这一假说，因此，很明显需要替代假说来更好地预测动物丰富度的空间格局，预测动物丰富度的空间格局具有重要的理论和应用意义。在理论方面，更好地预测丰度的空间格局可能有助于确定是什么驱动了生物多样性的广泛空间格局。在应用方面，更好地预测空间格局的能力将有助于确定濒危物种的关键栖息地。然而，在物种的地理范围内，栖息地选择可以强烈影响个体的分布和丰度。资源分布的空间异质性为生物体提供了一个机会，通过选择最高质量的栖息地来最大限度地提高其适应性。栖息地的适宜性取决于个体占据栖息地的平均成功率，并取决于诸如食物丰富度、住所可用性和竞争者密度等因素。大多数栖息地选择理论假设动物受到它们获取有限资源的能力的限制。但是如果动物处理资源的能力受到限制，会发生什么呢？大多数动物都是外温动物，在外温动物中，对资源同化的热约束可能比资源获取更强烈地影响可用的能量总量。我的工作假设是，在外温动物丰富的主要驱动力是他们的处理资源的能力，而不是他们获得资源的能力。我的研究计划的长期目标是确定是什么决定了丰富的外温动物的空间格局。为了实现这一目标，我的文件丰富的空间模式，我测试的机制，可以产生这些空间模式的假设。我在下一个资助周期的目标是确定是获取资源的能力还是处理资源的能力最能预测外温动物的丰度。我将在三个空间尺度上解决这一目标：在地理范围的规模（范围内的丰度变化），在景观的规模（在整个栖息地梯度的丰度变化），并在个人的家庭范围的规模（家庭范围之间的质量不同的健身变化）。

Within species, abundance (population density) varies markedly in space and in time. Accordingly, explaining spatial and temporal patterns in the abundance of species is one of the major goals of ecology. The abundant center hypothesis posits that species should be most abundant near the center of their geographic ranges, but the empirical data do not support it. Thus, there is a clear need for alternative hypotheses to predict better the spatial patterns in the abundance of animals.Predicting spatial patterns in the abundance of animals has important theoretical and applied implications. On the theoretical side, a better prediction of spatial patterns in abundance may help determine what drives broad spatial patterns in biodiversity. On the applied side, a better ability to predict spatial patterns will help define critical habitats for species at risk.Abundance at broad spatial scales is largely dictated by climate. Within the geographical range of species, however, habitat selection can strongly influence the distribution and abundance of individuals. The spatial heterogeneity of resource distribution provides an opportunity for organisms to maximize their fitness by choosing the highest quality habitat available. The suitability of a habitat is determined by the mean success rate of individuals that occupy the habitat, and depends on factors such as food abundance, shelter availability, and density of competitors.Much of the habitat selection theory assumes that animals are limited by their ability to harvest limited resources. But what happens if animals are limited by their ability to process resources? Most animals are ectotherms, and in ectotherms the total amount of energy available may be more strongly influenced by thermal constraints on resource assimilation than by resource acquisition. My working hypothesis is that the primary driver of abundance in ectotherms is their ability to process resources, not their ability to acquire resources.The long-term objective of my research program is to determine what dictates spatial patterns of abundance in ectotherms. To meet this objective, I document patterns of abundance in space and I test hypotheses about mechanisms that could generate these spatial patterns. My objective over the next grant cycle is to determine whether it is the ability to acquire, or the ability to process, resources that best predicts abundance of ectotherms. I will address this objective at three spatial scales: at the scale of the geographical range (variation in abundance across the range), at the scale of the landscape (variation in abundance across habitat gradients), and at the scale of the individual home ranges (variation in fitness between home ranges varying in quality).