Disturbance and dispersal are two fundamental ecological processes that shape diversity patterns, yet their interaction and the underlying mechanisms are still poorly understood, and evidence from natural systems is particularly lacking. Using an invertebrate rock pool metacommunity in South Africa as a natural model system, we studied potential interactive effects of disturbance regime and patch isolation on diversity patterns of species with contrasting dispersal modes (passive vs. active dispersal). Isolation and disturbance regime had negative synergistic effects on alpha diversity: both directly, by excluding late-successional species from isolated patches; and indirectly, by modulating establishment success of generalist predators in well-connected patches. Unimodal relationships between isolation and alpha diversity, as predicted by mass effects, were only detected for passive dispersers in frequently disturbed patches and not in active dispersers. For passive dispersers, indications for a positive effect of isolation and a negative effect of disturbance on beta diversity were found, presumably due to differences in deterministic succession and stochastic colonization-extinction dynamics among different patch types. Our findings illustrate that interactions between dispersal rates and disturbance regime are important when explaining species diversity patterns in metacommunities and support the idea that diversity in frequently disturbed habitats is more sensitive to effects of dispersal-based processes.

BackgroundHigher temperatures and increased environmental variability under climate change could jeopardize the persistence of species. Organisms that rely on short windows of rainfall to complete their life-cycles, like desert annual plants or temporary pool animals, may be particularly at risk. Although some could tolerate environmental changes by building-up banks of propagules (seeds or eggs) that buffer against catastrophes, climate change will threaten this resilience mechanism if higher temperatures reduce propagule survival. Using a crustacean model species from temporary waters, we quantified experimentally the survival and dormancy of propagules under anticipated climate change and used these demographic parameters to simulate long term population dynamics.ResultsBy exposing propagules to present-day and projected daily temperature cycles in an 8 month laboratory experiment, we showed how increased temperatures reduce survival rates in the propagule bank. Integrating these reduced survival rates into population models demonstrated the inability of the bank to maintain populations; thereby exacerbating extinction risk caused by shortened growing seasons.ConclusionsOverall, our study demonstrates that climate change could threaten the persistence of populations by both reducing habitat suitability and eroding life-history strategies that support demographic resilience.Electronic supplementary materialThe online version of this article (10.1186/s12898-018-0158-z) contains supplementary material, which is available to authorized users.

Temporary pool inhabitants face altered inundation regimes under climate change. While their exposure to these changes has received considerable attention, few studies have investigated their sensitivity or adaptability. Here, we use zooplankton as a model to explore how decreasing hydroperiods affect extinction risks and assess whether changes in life history traits could promote persistence. For this, we construct a three-stage matrix population model parameterised with realistic life-history values for the fairy shrimp Branchipodopsis wolfi from pools with varying hydroperiods. Our results suggest that extinction risks increase drastically once the median hydroperiod drops below a critical threshold. Although changes in life-history parameters could potentially compensate for this risk, the relative importance of each trait for population growth depends on the median hydroperiod. For example, survival of dormant eggs seemed to be most important when hydroperiods were short while the survival of freshly laid eggs and adult individuals were more important in longer-lived pools. Overall, this study demonstrates that zooplankton species are sensitive to climate change and that the adaptive capacity of organisms from temporary pools with dissimilar hydrology hinges on selection of different life history traits.

The Living Planet Index (LPI) is a standardised indicator for tracking population trends through time. Due to its ability to aggregate many timeseries in a single metric, the LPI has been proposed as an indicator for the Convention on Biological Diversity's post-2020 Global Biodiversity Strategy. However, here we show that random population fluctuations introduce biases when calculating the LPI. By combining simulated and empirical data, we show how random fluctuations lead to a declining LPI even when overall population trends are stable, and imprecise estimates of the LPI when populations increase or decrease non-linearly. We applied randomisation null models that demonstrate how random fluctuations exaggerate declines in the global LPI by 9.6%. Our results confirm substantial declines in the LPI, but highlight sources of uncertainty in quantitative estimates. Randomisation null models are useful for presenting uncertainty around indicators of progress towards international biodiversity targets. Nations of the world are in the process of negotiating the post-2020 Global Biodiversity Framework under the Convention on Biological Diversity. One of the ambitions of the post-2020 framework is "bending the curve of biodiversity loss" by first slowing down declines by 2030 and then improving the state of biodiversity by mid-century 1-3 . Reliable biodiversity indicators are essential for tracking progress towards global biodiversity targets 4 . A prominent indicator of species abundance over time is the Living Planet Index (LPI) 5-7 . The LPI aggregates population time-series for vertebrates from terrestrial, freshwater and marine systems into a relative index (where the baseline is

The view that conservation is a linear exchange of knowledge between scientists and practitioners has led to the conceptualization of a "research-implementation gap". However, conservation is not only about translating science into action but also includes the interplay of values, cultural norms, social interactions, and political consequences. In response, an alternative conceptualization is one where research and implementation exist in a "space", where conservation partners interact. Here, we argue that post-normal science (PNS) can fill this space. PNS is used when information is incomplete, values are pluralistic, stakes are high, and decisions are urgent. It relies on an extended community of practice that aims to produce knowledge fit for end-users, without the constraints of settled scientific paradigms. We advocate for the wider use of PNS in conservation by showing how aspects of PNS have been useful in mainstreaming conservation planning in South Africa. By following an approach typical of PNS, South Africa has made considerable progress in creating an implementation space for conserving biodiversity despite its limited resources, cultural heterogeneity, and controversial history. We outline the interventions used in South Africa to facilitate PNS and, based on this, propose an operating model that can be applied elsewhere. K E Y W O R D Sconservation planning, extended peer community, post-normal science, research-implementation gap, scientific paradigms, South Africa, transdisciplinary