UC Riverside

Due to habitat fragmentation, many of the populations in nature have been broken into smaller subpopulations that are connected by migration (i.e., metapopulation). Subpopulation synchrony within a metapopulation is of practical importance because it has consequences for the conservation of species. Moran effect and dispersal are the main causes of metapopulation synchrony, but spatial distribution of subpopulations has also been shows to influence synchrony and persistence in metapopulations. In population ecology, synchrony has been shown to negatively influence persistence in metapopulations. In chapter 1 of this dissertation, I review how synchrony is studied in ecology with the aim of identifying a unifying role of synchrony across ecological processes. In this chapter, I showed a novel framework for classifying synchrony across ecological processes. I referred to synchrony that is within a single trophic level as horizontal synchrony and synchrony that takes place between species at different trophic levels as vertical synchrony. This framework classified vertical synchrony into antagonistic synchrony (predator-prey and parasite-host) and synergetic synchrony (mutualism and commensalism). The horizontal synchrony was categorized as intraspecific synchrony (i.e., synchrony within a population), and interspecific synchrony (i.e., among species synchrony). In chapter 2, I ran theoretical simulations to investigate how spatial distribution of subpopulations (i.e., homogeneous vs heterogeneous metapopulation networks) influences persistence in metapopulations. I showed that there appears to be an intermediate optimal amount of heterogeneity but in my study intermediate and high heterogeneity were fairly similar and both were better for persistence than homogeneous metapopulation networks. I also showed that more dispersal appears to be more beneficial than less dispersal. In chapter 3, I ran theoretical simulations to investigate the role of positive (red noise) and negative (blue noise) autocorrelations of environmental variation in large heterogeneous metapopulation networks. I showed that the when the autocorrelation of environmental noise shifts from positive (red noise) to negative (blue noise), this may benefit the persistence of a species in large heterogeneous metapopulation networks. Higher dispersal between patches increased occupancy and persistence. Overall, this dissertation summarizes the role of synchrony in ecological interactions and could this be a useful resource for educational purposes. It also contributes to conservation science by allowing the conservationists involved in decision making to optimally design reserves under varying natural conditions.