Browsing by Subject "Persistence"

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  • Van Teeffelen, Astrid; Cabeza, Mar; Moilanen, Atte (Springer, 2006)
    Biodiversity and Conservation
    Reserve selection methods are often based on information on species’ occurrence. This can be presence–absence data, or probabilities of occurrence estimated with species distribution models. However, the effect of the choice of distribution model on the outcome of a reserve selection method has been ignored. Here we test a range of species distribution models with three different reserve selection methods. The distribution models had different combinations of variables related to habitat quality and connectivity (which incorporates the effect of spatial habitat configuration on species occurrence). The reserve selection methods included (i) a minimum set approach without spatial considerations; (ii) a clustering reserve selection method; and (iii) a dynamic approach where probabilities of occurrence are re-evaluated according to the spatial pattern of selected sites. The sets of selected reserves were assessed by re-computing species probability of occurrence in reserves using the best probability model and assuming loss of non-selected habitat. The results show that particular choices of distribution model and selection method may lead to reserves that overestimate the achieved target; in other words, species may seem to be represented but the reserve network may actually not be able to support them in the long-term. Instead, the use of models that incorporated connectivity as a variable resulted in the selection of aggregated reserves with higher potential for species long-term persistence. As reserve design aims at the longterm protection of species, it is important to be aware of the uncertainties related to model and method choice and their implications.
  • Dallas, Tad A.; Saastamoinen, Marjo; Ovaskainen, Otso (2021)
    The spatial arrangement of habitat patches in a metapopulation and the dispersal connections among them influence metapopulation persistence. Metapopulation persistence emerges from a dynamic process, namely the serial extinctions and recolonizations of local habitat patches, while measures of persistence are typically based solely on structural properties of the spatial network (e.g., spatial distance between sites). Persistence estimators based on static properties may be unable to capture the dynamic nature of persistence. Understanding the shape of the distribution of extinction times is a central goal in population ecology. Here, we examine the goodness of fit of the power law to patch persistence time distributions using data on a foundational metapopulation system-the Glanville fritillary butterfly in the angstrom land islands. Further, we address the relationship between structural measures of metapopulation persistence (i.e., metapopulation capacity) and our temporal distributional fits to patch persistence times based on a power law. Patch persistence time distributions were well fit by a power law for the majority of semi-independent networks. Power law fits to persistence time distributions were related to metapopulation capacity, linking structural and temporal measures of metapopulation persistence. Several environmental variables and measures of network topology were correlated with both measures of metapopulation persistence, though correlations tended to be stronger for the structural measure of metapopulation persistence (i.e., metapopulation capacity). Together, our findings suggest that persistence time distributions are useful dynamic properties of metapopulations, and provide evidence of a relationship between metapopulation structure and metapopulation dynamics.
  • Draper, L. A.; Ryan, F. J.; Smith, M. K.; Jalanka, J.; Mattila, E.; Arkkila, P.; Ross, R. P.; Satokari, R.; Hill, C. (2018)
    BackgroundFaecal microbiota transplantation (FMT) is used in the treatment of recurrent Clostridium difficile infection. Its success is typically attributed to the restoration of a diverse microbiota. Viruses (including bacteriophages) are the most numerically dominant and potentially the most diverse members of the microbiota, but their fate following FMT has not been well studied.ResultsWe studied viral transfer following FMT from 3 donors to 14 patients. Recipient viromes resembled those of their donors for up to 12months. Tracking individual bacteriophage colonisation revealed that engraftment of individual bacteriophages was dependent on specific donor-recipient pairings. Specifically, multiple recipients from a single donor displayed highly individualised virus colonisation patterns.ConclusionsThe impact of viruses on long-term microbial dynamics is a factor that should be reviewed when considering FMT as a therapeutic option.
  • Draper, L. A; Ryan, F. J; Smith, M. K; Jalanka, J.; Mattila, E.; Arkkila, P. A; Ross, R. P; Satokari, R.; Hill, C. (BioMed Central, 2018)
    Abstract Background Faecal microbiota transplantation (FMT) is used in the treatment of recurrent Clostridium difficile infection. Its success is typically attributed to the restoration of a diverse microbiota. Viruses (including bacteriophages) are the most numerically dominant and potentially the most diverse members of the microbiota, but their fate following FMT has not been well studied. Results We studied viral transfer following FMT from 3 donors to 14 patients. Recipient viromes resembled those of their donors for up to 12 months. Tracking individual bacteriophage colonisation revealed that engraftment of individual bacteriophages was dependent on specific donor-recipient pairings. Specifically, multiple recipients from a single donor displayed highly individualised virus colonisation patterns. Conclusions The impact of viruses on long-term microbial dynamics is a factor that should be reviewed when considering FMT as a therapeutic option.