14 research outputs found

    Quantifying range-wide variation in population trends from local abundance surveys and widespread opportunistic occurrence records

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    1. Species’ abundances vary in space and time. Describing these patterns is a cornerstone of macroecology. Moreover, trends in population size are an important criterion for the assessment of a species’ conservation status. Because abundance trends are not homogeneous in space, we need to quantify variation in abundance trends across the geographical range of a species. A basic difficulty exists in that data sets that cover large geographic areas rarely include population abundance data at high temporal resolution. Whilst both broad-scale geographic distribution data and site-specific population trend data are becoming more widely available, approaches are required which integrate these different types of data. 2. We present a hierarchical model that integrates observations from multiple sources to estimate spatio-temporal abundance trends. The model links annual population densities on a spatial grid to both long-term count data and to opportunistic occurrence records from a citizen science programme. Specific observation models for both data types explicitly account for differences in data structure and quality. 3. We test this novel method in a virtual study with simulated data and apply it to the estimation of abundance dynamics across the range of a butterfly species (Pyronia tithonus) in Great Britain between 1985 and 2004. The application to simulated and real data demonstrates how the hierarchical model structure accommodates various sources of uncertainty which occur at different stages of the link between observational data and the modelled abundance, thereby it accounts for these uncertainties in the inference of abundance variations. 4. We show that by using hierarchical observation models that integrate different types of commonly available data sources, we can improve the estimates of variation in species abundances across space and time. This will improve our ability to detect regional trends and can also enhance the empirical basis for understanding range dynamics

    Data integration for large-scale models of species distributions

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    With the expansion in the quantity and types of biodiversity data being collected, there is a need to find ways to combine these different sources to provide cohesive summaries of species’ potential and realized distributions in space and time. Recently, model-based data integration has emerged as a means to achieve this by combining datasets in ways that retain the strengths of each. We describe a flexible approach to data integration using point process models, which provide a convenient way to translate across ecological currencies. We highlight recent examples of large-scale ecological models based on data integration and outline the conceptual and technical challenges and opportunities that arise

    Re-designing adaptive selling strategies: the role of different types of shopping companions

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    This paper explores the influence of shopping companions in retail sales conversa-tions and the necessity of designing more comprehensive sales training programs. In particular, the characteristics and behaviors of shopping companions and their sub-sequent effects on accompanied shoppers, the salesperson and the sales conversa-tion are examined. Shopping companions have not played a role in adaptive selling research and most practical trainings for salespeople so far, although they can signif-icantly affect shopper behavior and decision-making, and require distinct approaches by salespeople. Systematizing in-depth interviews with salespeople and qualitative content analysis reveal a variety of different character traits and behaviors of shop-ping companions that can lead to positive and negative outcomes from a salesper-son’s perspective. The interactions that take place between customers and salespeo-ple are the core element of customer-oriented service in retailing. When a holistic customer-oriented service is part of their value proposition, retailers should consider re-designing training programs for salespeople and include the influence of shop-ping companions. In doing so, salespeople’s customer orientation can be increased by augmenting their capabilities and enabling them to make use of adaptive selling techniques specifically designed for co-shopping situations

    Environmental drivers of demographic variation across the global geographical range of 26 plant species

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    International audience1 Understanding how rates of reproduction and survival respond to environmental variation across species’ geographical ranges is a key task for both basic and applied ecology. So far, however, environmental drivers of range‐wide demographic variation have only been studied in a few plant species without considering the potentially confounding effects of population density on demographic rates.2We present a large‐scale demographic study of 26 shrub species (Proteaceae) from the Cape Floristic Region. All study species have a fire‐dependent life cycle and are serotinous: they exclusively form a canopy seed bank which contains the seeds produced since the last fire. Fire triggers seed release from the canopy so that recruitment is largely limited to a short period after fire.3 Across the global geographical ranges of the study species, we collected 3454 population‐level records of total fecundity since the last fire (size of individual canopy seed banks), per‐capita recruitment (ratio between post‐fire recruits and pre‐fire adults) and adult fire survival. We used linear regressions to quantify how climate, population density, fire interval and soil nutrients affect demographic variation.4 A trade‐off between survival and reproduction is evident throughout the geographical ranges of our study species: resprouting species with fire‐protected buds had much higher fire survival than nonsprouters without fire‐protected buds (97% vs. 2%) but they also had substantially lower fecundity and recruitment rates. We found little intraspecific variation in fire survival rates but considerable intraspecific variation in fecundity and recruitment.5 Range‐wide variation in fecundity was dominated by fire interval whereas recruitment was mostly climate‐driven. Population density and soil nutrients generally had smaller effects but were important for the fecundity and recruitment of several species. Effects of fire interval on fecundity were consistent across species, but other demography–environment relationships showed substantial interspecific differentiation.6 Synthesis. This study extends demographic research beyond the population to cover the geographical ranges of multiple species. Such large‐scale studies are a necessary first step of a research agenda that aims to understand how range dynamics emerge from first principles of demography, how they are shaped by functional traits and macroevolution and how they will be impacted by global change
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