Bill Kunin | University of Leeds (original) (raw)

Papers by Bill Kunin

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Frontiers in plant science, 2018

The domestication syndrome of many plants includes changes in their mating systems. The evolution... more The domestication syndrome of many plants includes changes in their mating systems. The evolution of the latter is shaped by ecological and genetic factors that are particular to an area. Thus, the reproductive biology of wild relatives must be studied in their natural distribution to understand the mating system of a crop species as a whole. (upland cotton) includes both domesticated varieties and wild populations of the same species. Most studies on mating systems describe cultivated cotton as self-pollinated, while studies on pollen dispersal report outcrossing; however, the mating system of upland cotton has not been described as mixed and little is known about its wild relatives. In this study we selected two wild metapopulations for comparison with domesticated plants and one metapopulation with evidence of recent gene flow between wild relatives and the crop to evaluate the mating system of cotton's wild-to-domesticated complex. Using classic reproductive biology methods,...

Ecology and evolution, 2017

The study of ecosystem processes over multiple scales of space and time is often best achieved us... more The study of ecosystem processes over multiple scales of space and time is often best achieved using comparable data from multiple sites. Yet, long-term ecological observatories have often developed their own data collection protocols. Here, we address this problem by proposing a set of ecological protocols suitable for widespread adoption by the ecological community. Scientists from the European ecological research community prioritized terrestrial ecosystem parameters that could benefit from a more consistent approach to data collection within the resources available at most long-term ecological observatories. Parameters for which standard methods are in widespread use, or for which methods are evolving rapidly, were not selected. Protocols were developed by domain experts, building on existing methods where possible, and refined through a process of field testing and training. They address above-ground plant biomass; decomposition; land use and management; leaf area index; soil m...

Journal of theoretical biology, Nov 24, 2016

Environmental stochasticity is known to be a destabilizing factor, increasing abundance fluctuati... more Environmental stochasticity is known to be a destabilizing factor, increasing abundance fluctuations and extinction rates of populations. However, the stability of a community may benefit from the differential response of species to environmental variations due to the storage effect. This paper provides a systematic and comprehensive discussion of these two contradicting tendencies, using the metacommunity version of the recently proposed time-average neutral model of biodiversity which incorporates environmental stochasticity and demographic noise and allows for extinction and speciation. We show that the incorporation of demographic noise into the model is essential to its applicability, yielding realistic behavior of the system when fitness variations are relatively weak. The dependence of species richness on the strength of environmental stochasticity changes sign when the correlation time of the environmental variations increases. This transition marks the point at which the st...

Nature, 2016

There is considerable concern over declines in insect pollinator communities and potential impact... more There is considerable concern over declines in insect pollinator communities and potential impacts on the pollination of crops and wildflowers 1-4. Among the multiple pressures facing pollinators 2-4 , decreasing floral resources due to habitat loss and degradation has been suggested as a key contributing factor 2-8. However, a lack of quantitative data has hampered testing for historical changes in floral resources. Here we show that overall floral rewards can be estimated at a national scale by combining vegetation surveys and direct nectar measurements. We find evidence for substantial losses in nectar resources in England and Wales between the 1930s and 1970s; however, total nectar provision in Great Britain as a whole had stabilized by 1978, and increased from 1998 to 2007. These findings concur with trends in pollinator diversity, which declined in the mid-twentieth century 9 but stabilized more recently 10. The diversity of nectar sources kept declining in most habitats, with four plant species accounting for over 50% of national nectar provision in 2007. Calcareous grassland, broadleaved woodland and neutral grassland are the habitats that produce the greatest amount of nectar per unit area from the most diverse sources, whereas arable land is the poorest with respect to amount of nectar per unit area and diversity of nectar sources. Although agri-environment schemes add resources to arable landscapes, their national contribution is low. Owing to their large area, improved grasslands could add substantially to national nectar provision if they were managed to increase floral resource provision. This national-scale assessment of floral resource provision affords new insights

Journal of Applied Ecology, 2015

1. The magnitude of the benefits derived from organic farming within contrasting managed landscap... more 1. The magnitude of the benefits derived from organic farming within contrasting managed landscapes remains unclear and, in particular, the potential scale-dependent response of insect parasitoids is relatively unexplored. Identifying the scale at which parasitoids are affected by organic farming will be an important step to enhance their conservation. 2. We sampled tachinid parasitoids at the centre and margin of arable and grassland fields on paired organic and conventional farms located in landscapes with different proportions of organic land. A total of 192 fields were sampled in two biogeographical regions of the UK. 3. We found that the positive effect of organic farming on tachinid parasitoid diversity can be observed at multiple spatial scales. At the local scale, we found higher abundance and species richness of tachinid parasitoids on organic than on conventional farms and on field margins than on field centres. At the landscape scale, the diversity of tachinids was higher in landscapes with higher proportions of organic land. At both scales, the positive effect of organic farming was clear for arable fields, while it was almost neutral for grasslands. 4. Synthesis and applications. Any attempt to enhance parasitoid diversity in agricultural landscapes needs to consider the local management in relation to the habitat type, location within the field and agricultural management in the surrounding landscape. To restore parasitoid diversity, the promotion of organic agriculture should aim to increase both the total extent of organic farming and the connectivity of individual farms. As the benefits of organic farming to biodiversity clearly spread beyond individual farm boundaries, any assessment of organic farming should consider these positive externalities.

Apidologie, 2014

Competition between managed honeybees and wild pollinators is thought to be a key factor in struc... more Competition between managed honeybees and wild pollinators is thought to be a key factor in structuring foraging communities on flowers. The majority of studies have focused on impacts such as floral visitation rates and resource overlap. However, direct measurement of fitness is required to fully assess the impacts of competition. We compared in 2 years the weight and reproductive success of bumblebee colonies located at two sites that were either close to or far from a large honeybee apiary, and which were located in the same landscape and with access to similar floral resources. We found that bumblebee colonies located at the site near the honeybee apiary gained less weight, and produced fewer and smaller queens, in both years than colonies at the site far from the apiary. The ratio of queen weight/size was lower in the colonies near honeybees in 1 year, while males were smaller and offspring sex ratio more male biased in colonies close to honeybees than in those far from honeybees. Proximity to managed honeybee hives was therefore associated with significantly reduced fitness of bumblebee colonies, but studies from many more sites are needed to confirm the effect.

The Journal of animal ecology, Jan 2, 2015

In 2003, 24 presence-absence β-diversity metrics were reviewed and a number of trade-offs and red... more In 2003, 24 presence-absence β-diversity metrics were reviewed and a number of trade-offs and redundancies identified. We present a parallel investigation into the performance of abundance-based metrics of β-diversity. β-diversity is a multi-faceted concept, central to spatial ecology. There are multiple metrics available to quantify it: the choice of metric is an important decision. We test 16 conceptual properties and two sampling properties of a β-diversity metric: metrics should be 1) independent of α-diversity and 2) cumulative along a gradient of species turnover. Similarity should be 3) probabilistic when assemblages are independently and identically distributed. Metrics should have 4) a minimum of zero and increase monotonically with the degree of 5) species turnover, 6) decoupling of species ranks and 7) evenness differences. However, complete species turnover should always generate greater values of β than extreme 8) rank shifts or 9) evenness differences. Metrics should 1...

Nature, Jan 17, 2013

To protect the biodiversity of flatlands against the effects of climate change (M. Tingley et al.... more To protect the biodiversity of flatlands against the effects of climate change (M. Tingley et al. Nature 500, 271-272; 2013), we need strategies to buy time for species to adapt to warmer environments or to move to cooler ones. This will mean adding more protected areas in cool regions and improving connectivity between protected sites. One way to increase resilience among resident communities would be to reduce the intensity of summer grazing on flatlands. Shade from tall, dense swards helps to cool the soil by up to 5 °C (J. A. Thomas et al. Science 325, 80-83; 2009), an effect that is enhanced as the land becomes more uneven (J. Settele and E. Kühn Science 325, 41-42; 2009). Conservation measures in existing protected sites, as in Europe's Natura 2000 programme (see go.nature.com/ ykf7vt), remain important but may prove inadequate on their own and will need to be adapted and revivified as the climate warms.

Methods in Ecology and Evolution, 2014

Land-use changes can alter the spatial population structure of plant species, which may in turn a... more Land-use changes can alter the spatial population structure of plant species, which may in turn affect the attractiveness of flower aggregations to different groups of pollinators at different spatial scales. To assess how pollinators respond to spatial heterogeneity of plant distributions and whether honeybees affect visitation by other pollinators we used an extensive data set comprising ten plant species and their flower visitors from five European countries. In particular we tested the hypothesis that the composition of the flower visitor community in terms of visitation frequencies by different pollinator groups were affected by the spatial plant population structure, viz. area and density measures, at a within-population ('patch') and amongpopulation ('population') scale. We found that patch area and population density were the spatial variables that best explained the variation in visitation frequencies within the pollinator community. Honeybees had higher visitation frequencies in larger patches, while bumblebees and hoverflies had higher visitation frequencies in sparser populations. Solitary bees had higher visitation frequencies in sparser populations and smaller patches. We also tested the hypothesis that honeybees affect the composition of the pollinator community by altering the visitation frequencies of other groups of pollinators. There was a positive relationship between visitation frequencies of honeybees and bumblebees, while the relationship with hoverflies and solitary bees varied (positive, negative and no relationship) depending on the plant species under study. The overall conclusion is

Trends in Ecology & Evolution, 1993

Trends in Ecology & Evolution, 2010

Pollinators are a key component of global biodiversity, providing vital ecosystem services to cro... more Pollinators are a key component of global biodiversity, providing vital ecosystem services to crops and wild plants. There is clear evidence of recent declines in both wild and domesticated pollinators, and parallel declines in the plants that rely upon them. Here we describe the nature and extent of reported declines, and review the potential drivers of pollinator loss, including habitat loss and fragmentation, agrochemicals, pathogens, alien species, climate change and the interactions between them. Pollinator declines can result in loss of pollination services which have important negative ecological and economic impacts that could significantly affect the maintenance of wild plant diversity, wider ecosystem stability, crop production, food security and human welfare.

The American Naturalist, 2011

The species-area relationship (SAR) is considered to be one of a few generalities in ecology, yet... more The species-area relationship (SAR) is considered to be one of a few generalities in ecology, yet a universal model of its shape and slope has remained elusive. Recently, Harte et al. argued that the slope of the SAR for a given area is driven by a single parameter, the ratio between total number of individuals and number of species (i.e., the mean population size across species at a given scale). We provide a geometric interpretation of this dependence. At the same time, however, we show that this dependence cannot be universal across taxa: if it holds for a taxon composed from two subsets of species and also for one of its subsets, it cannot simultaneously hold for the other subset. Using three data sets, we show that the slope of the SAR considerably varies around the prediction. We estimate the limits of this variation by using geometric considerations, providing a theory based on species spatial turnover at different scales. We argue that the SAR cannot be strictly universal, but its slope at each particular scale varies within the constraints given by species' spatial turnover at finer spatial scales, and this variation is biologically informative.

Proceedings of the National Academy of Sciences, 1998

The coexistence of many plant species competing for a few resources is one of the central puzzles... more The coexistence of many plant species competing for a few resources is one of the central puzzles of community ecology. One explanation is that different species may be competitively superior in different microhabitats. Many species could then coexist within each piece of a mosaic landscape by what has been termed “mass effects,” because subpopulations in areas with negative growth rates would be supplemented by propagules from areas with reproductive surpluses. If mass effects are important, plant species diversity should increase near habitat boundaries, especially where habitat differences are moderate. In the first experimental test of this prediction, plants were censused on 54 transects within the long-established Rothamsted Park Grass plots. Very few showed significant declines in species richness with distance from subplot boundaries. Nonetheless, the regression coefficients were negative much more often than expected by chance, suggesting that weak mass effects operated. Th...

Plant Ecology, 2005

is a self-incompatible shrub which forms a major component of many Mediterranean habitats. It typ... more is a self-incompatible shrub which forms a major component of many Mediterranean habitats. It typically occurs in large, dense mono-species stands, though in some areas individuals may be more sparsely distributed. The plant produces prominent flowers which attract a wide diversity of pollinators. A proportion of these flowers subsequently develop into fruits which are subject to parasitism and seed predation. 2. C. landanifer populations were surveyed at three sites. Information relating to plant pollination success, reproductive effort and fruit parasitism was recorded. This data was plotted against plant density in order to determine density-dependant patterns of reproductive success. 3. Overall, pollination success declined significantly as the distance to the nearest cospecific increased. Reproductive effort and fruit parasitism showed the opposite pattern. Pollination success and reproductive effort per fruit increased with fruit height, but only in dispersed plants. 4. Measures of reproductive success were the product of a significant interaction between pollination success and reproductive effort. This means that dispersed plants were able to compensate for reduced pollination success by increasing reproductive effort. 5. These results indicate that overall reproductive success is the accumulated result of several different processes which may each respond to plant density in different ways. In order to effectively manage plant populations it is necessary to understand in greater detail the dynamic interactions between these processes.

Methods in Ecology and Evolution, 2010

Journal of Biogeography, 2012

Aim We test the prediction that beta diversity (species turnover) and the decay of community simi... more Aim We test the prediction that beta diversity (species turnover) and the decay of community similarity with distance depend on spatial resolution (grain). We also study whether patterns of beta diversity are related to variability in climate, land cover or geographic distance and how the independent effects of these variables depend on the spatial grain of the data. Location Europe, Great Britain, Finland and Catalonia. Methods We used data on European birds, plants, butterflies, amphibians and reptiles, and data on British plants, Catalonian birds and Finnish butterflies. We fitted two or three nested grids of varying resolutions to each of these datasets. For each grid we calculated differences in climate, differences in land-cover composition (CORINE) and beta diversity (b sim , b Jaccard) between all pairs of grid cells. In a separate analysis we looked specifically at pairs of adjacent grid cells (the first distance class). We then used variation partitioning to identify the magnitude of independent statistical associations (i.e. independent effects in the statistical sense) of climate, land cover and geographic distance with spatial patterns of beta diversity. Results Beta diversity between grid cells at any given distance decreased with increasing grain. Geographic distance was always the most important predictor of beta diversity for all pairwise comparisons at the extent of Europe. Climate and land cover had weaker but distinct and grain-dependent effects. Climate was more important at relatively coarse grains, whereas land-cover effects were stronger at finer grains. In the country-wide analyses, climate and land cover were more important than geographic distance. Climatic and land-cover models performed poorly and showed no systematic grain dependence for beta diversity between adjacent grid cells. Main conclusions We found that relationships between geographic distance and beta diversity, as well as the environmental correlates of beta diversity, are systematically grain dependent. The strong independent effect of distance indicates that, contrary to the current belief, a substantial fraction of species are missing from areas with a suitable environment. Moreover, the effects of geographic distance (at continental extents) and land cover (at fine grains) indicate that any species distribution modelling should take both environment and dispersal limitation into account.

Journal of Applied Ecology, 2006

1. Spatial autocorrelation is an important source of bias in most spatial analyses. We explored t... more 1. Spatial autocorrelation is an important source of bias in most spatial analyses. We explored the bias introduced by spatial autocorrelation on the explanatory and predictive power of species' distribution models, and make recommendations for dealing with the problem. 2. Analyses were based on the distribution of two species of freshwater turtle and two virtual species with simulated spatial structures within two equally sized areas located on the Iberian Peninsula. Sequential permutations of environmental variables were used to generate predictor variables that retained the spatial structure of the original variables. Univariate models of species' distributions using generalized linear models (GLM), generalized additive models (GAM) and classification tree analysis (CTA) were fitted for each variable permutation. Variation of accuracy measures with spatial autocorrelation of the original predictor variables, as measured by Moran's I, was analysed and compared between models. The effects of systematic subsampling of the data set and the inclusion of a contagion term to deal with spatial autocorrelation in models were assessed with projections made with GLM, as it was with this method that estimates of significance based on randomizations were obtained. 3. Spatial autocorrelation was shown to represent a serious problem for niche-based species' distribution models. Significance values were found to be inflated up to 90-fold. 4. In general, GAM and CTA performed better than GLM, although all three methods were vulnerable to the effects of spatial autocorrelation. 5. The procedures utilized to reduce the effects of spatial autocorrelation had varying degrees of success. Subsampling was partially effective in avoiding the inflation effect, whereas the inclusion of a contagion term fully eliminated or even overcompensated for this effect. Direct estimation of probability using variable simulations was effective, yet seemed to show some residual spatial autocorrelation effects. 6. Synthesis and applications. Given the expected inflation in the estimates of significance when analysing spatially autocorrelated variables, these need to be adjusted. The reliability and value of niche-based distribution models for management and other applied ecology purposes can be improved if certain techniques and procedures, such as the null model approach recommended in this study, are implemented during the model-building process.

Journal of Applied Ecology, 2013

1. A substantial proportion of the global land surface is used for agricultural production. Agric... more 1. A substantial proportion of the global land surface is used for agricultural production. Agricultural land serves multiple societal purposes; it provides food, fuel and fibre and also acts as habitat for organisms and supports the services they provide. Biodiversity conservation and food production need to be balanced: production needs to be sustainable, while conservation cannot be totally at the expense of crop yield. 2. To identify the benefits (in terms of biodiversity conservation) and costs (in terms of reduction in yields) of agricultural management, we examined the relationship between crop yield and abundance and species density of important taxa in winter cereal fields on both organic and conventional farms in lowland England. 3. Of eight species groups examined, five (farmland plants, bumblebees, butterflies, solitary bees and epigeal arthropods) were negatively associated with crop yield, but the shape of this relationship varied between taxa. It was linear for the abundance of bumblebees and species density of butterflies, concave up for the abundance of epigeal arthropods and butterflies and concave down for species density of plants and bumblebees. 4. Grain production per unit area was 54% lower in organic compared with conventional fields. When controlling for yield, diversity of bumblebees, butterflies, hoverflies and epigeal arthropods did not differ between farming systems, indicating that observed differences in biodiversity between organic and conventional fields are explained by lower yields in organic fields and not by different management practices per se. Only percentage cover and species density of plants were increased by organic field management after controlling for yield. The abundance of solitary wild bees and hoverflies was increased in landscapes with high amount of organic land. 5. Synthesis and applications. Our results indicate that considerable gains in biodiversity require roughly proportionate reductions in yield in highly productive agricultural systems. They suggest that conservation efforts may be more cost effective in low-productivity agricultural systems or on non-agricultural land. In less productive agricultural landscapes, biodiversity benefit can be gained by concentrating organic farms into hotspots without a commensurate reduction in yield.

Insect Conservation and Diversity, 2013

1. Alien species are often reported to perform better than functionally-similar species native to... more 1. Alien species are often reported to perform better than functionally-similar species native to the invaded range, resulting in high population densities, and a tendency to become invasive. The Enemy Release Hypothesis (ERH), explains the success of invasive alien species (IAS) as a consequence of reduced mortality from natural enemies (predators, parasites and pathogens) compared to native species. The harlequin ladybird, Harmonia axyridis, a species alien to Britain, provides a model system for testing the ERH. 2. Pupae of H. axyridis and the native ladybird Coccinella septempunctata were monitored for parasitism between 2008 and 2011, from populations across southern England in areas first invaded by H. axyridis between 2004 and 2009. Additionally, a semi-field experiment was established to investigate the incidence of parasitism of adult H. axyridis and C. septempunctata by Dinocampus coccinellae. 3. Harmonia axyridis pupae were parasitised at a much lower rate than conspecifics in the native range, and both pupae and adults were parasitised at a considerably lower rate than C. septempunctata populations from the same place and time (H. axyridis: 1.67%; C. septempunctata: 18.02%) or in previous studies on Asian H. axyridis (2-67%). We found no evidence that the presence of H. axyridis affected the parasitism rate of C. septempunctata by D. coccinellae. 4. Our results are consistent with the general prediction that the prevalence of natural enemies is lower for introduced species than for native species at early stages of invasion. This may partly explain why H. axyridis is such a successful IAS.