David James Hodgson

University of Exeter | UoE · College of Life and Environmental Sciences

Ecological theory predicts interactions between species to become more positive under abiotic stress, while competition should prevail in more benign environments. However, experimental tests of this stress gradient hypothesis in natural microbial communities are lacking. We test this hypothesis by measuring interactions between 10 different member...

Free‐roaming animal populations are hard to count, and professional experts are a limited resource. There is vast untapped potential in the data collected by nonprofessional scientists who volunteer their time to population monitoring, but citizen science (CS) raises concerns around data quality and biases. A particular concern in abundance modelin...

Aim The diversity of brood size across animal species exceeds the diversity of most other life‐history traits. In some environments, reproductive success increases with brood size, whereas in others it increases with smaller broods. The dominant hypothesis explaining such diversity predicts that selection on brood size varies along climatic gradien...

When selection is imposed by both social and ecological environments, the costs and benefits of social relationships can depend on life-history strategy. We argue that the formation and maintenance of differentiated social relationships will prevail in species and individuals with slow life histories. Social behaviours that benefit survival can pro...

Like all species, the demography of humans has been shaped under the framework of natural selection. Our understanding of human demography can thus be enhanced by viewing it through a comparative, cross-species, lens and exploring the position of humans among other animal species. Here we use demographic data in the form of matrix population models...

Sexual selection is thought to be responsible for the rapid divergent evolution of male genitalia with several studies detecting multivariate sexual selection on genital form. However, in most cases, selection is only estimated during a single episode of selection, which provides an incomplete view of net selection on genital traits. Here we estima...

Host life history and demography play important roles in host–pathogen dynamics, by influencing the ability of hosts and their pathogens to coexist. We introduce the concept of demographic competence to describe the ability of host populations to sustain endemic infectious disease. Hosts with high demographic competence are more likely to act as ke...

Aim Body size explains most of the variation in fitness within animal populations and is therefore under constant selection from ecological and reproductive pressures, which often promote its evolution in sex‐specific directions, leading to sexual size dimorphism (SSD). Several hypotheses have been proposed to explain the vast diversity of SSD acro...

Billions of vertebrates migrate to and from their breeding grounds annually, exhibiting astonishing feats of endurance. Many such movements are energetically costly yet there is little consensus on whether or how such costs might influence schedules of survival and reproduction in migratory animals. Here we provide a global analysis of associations...

Long‐term capture–mark–recapture data provide valuable information on the movements of individuals between locations, and the contemporary and/or co‐located captures of individuals can be used to approximate the social structure of populations. We introduce an r package (CMRnet) that generates social and movement networks from spatially explicit ca...

Biological systems, at all scales of organisation from nucleic acids to ecosystems, are inherently complex and variable. Biologists therefore use statistical analyses to detect signal among this systemic noise. Statistical models infer trends, find functional relationships and detect differences that exist among groups or are caused by experimental...

The scale at which variations in food availability affect the foraging habits of individual animals can determine how the distribution of food resources affects populations. For species of conservation concern, these factors can have important implications for the management of habitats, as spatial and temporal variations in resource availability i...

Social interactions present opportunities for both information and infection to spread through populations. Social learning is often proposed as a key benefit of sociality, while disease epidemics are proposed as a major cost. Multiple empirical and theoretical studies have demonstrated the importance of social structure for the transmission of eit...

As anthropogenic impacts on the natural world escalate, there is increasing interest in the role of humans in dispersing seeds. But the consequences of this Human‐Mediated Dispersal (HMD) on plant spatial dynamics are little studied. In this paper we ask how secondary dispersal by HMD affects the dynamics of a natural plant metapopulation. In addit...

Social interactions present opportunities for both information and infection to spread through populations. Social learning is often proposed as a key benefit of sociality, while disease epidemics are proposed as a major cost. Multiple empirical and theoretical studies have demonstrated the importance of social structure for either information or i...

Invasive plant species threaten native biodiversity, ecosystems, agriculture, industry and human health worldwide, lending urgency to the search for predictors of plant invasiveness outside native ranges. There is much conflicting evidence about which plant characteristics best predict invasiveness. Here we use a global demographic survey for over...

Wildlife hosts are important reservoirs of a wide range of human and livestock infections worldwide, and in some instances, wildlife populations are threatened by disease. Yet wildlife diseases are difficult to monitor, and we often lack an understanding of basic epidemiological parameters that might inform disease management and the design of targ...

The emergence and spread of infections can contribute to the decline and extinction of populations, particularly in conjunction with anthropogenic environmental change. The importance of heterogeneity in processes of transmission, resistance and tolerance is increasingly well understood in theory, but empirical studies that consider both the demogr...

Some microbial public goods benefit conspecifics, as well as other species. Here, we use evolution and competition experiments to determine how exploitation of public goods by the wider microbial community shapes the production of an interspecific public good: metal-detoxifying siderophores. By simultaneously studying whole microbial communities an...

Body size shapes ecological interactions across and within species, ultimately influencing the evolution of large‐scale biodiversity patterns. Therefore, macroecological studies of body size provide a link between spatial variation in selection regimes and the evolution of animal assemblages through space. Multiple hypotheses have been formulated t...

Body size shapes ecological interactions across and within species, ultimately influencing the evolution of large‐scale biodiversity patterns. Therefore, macroecological studies of body size provide a link between spatial variation in selection regimes and the evolution of animal assemblages through space. Multiple hypotheses have been formulated t...

The borders of national parks in Kenya are hotspots for human–wildlife conflict. The deliberate killing of lions by Maasai pastoralists is illegal, but continues despite mitigation attempts. Currently, there is a somewhat pervasive opinion, within the human–wildlife conflict literature, that lions are killed by Maasai people either as cultural cere...

The current extinction and climate change crises pressure us to predict population dynamics with ever‐greater accuracy. Although predictions rest on the well‐advanced theory of age‐structured populations, two key issues remain poorly explored. Specifically, how the age‐dependency in demographic rates and the year‐to‐year interactions between surviv...

John Hodgson (1937–2018) is renowned worldwide as a passionate and principled researcher, dedicated to the study of interactions between grazing livestock and pasture sward, and to whole‐system management of grassland. He published over 250 scientific outputs during his 50‐year career, and inspired generations of grazing ecologists. Following his u...

Population structure is critical to infectious disease transmission. As a result, theoretical and empirical contact network models of infectious disease spread are increasingly providing valuable insights into wildlife epidemiology. Analyzing an exceptionally detailed dataset on contact structure within a high‐density population of European badgers...

Modern management of multifunctional woodlands must address many and various demands, including for recreation, timber production and the conservation of biodiversity. The responses of individuals and populations of protected species to woodland management and habitat change are often not well understood. Using radio-tracking and LiDAR, we investig...

Background Crops are often selected for traits that confer a selective disadvantage in the wild. A key trait that has been greatly altered by domestication is investment in herbivore defence. It remains unclear, however, whether variation in chemical defence affects a crop’s ability to colonize semi-natural habitats where it typically has to compet...

• Although strictly protected, populations of the hazel dormouse Muscardinus avellanarius in the UK declined by 72% from 1993 to 2014. Using National Dormouse Monitoring Programme data from 300 sites throughout England and Wales, we investigated variation in hazel dormouse population status (expressed as Indices of Abundance, Breeding, and populati...

There is widespread evidence that small-scale fisheries (SSF) bycatch threatens many populations of small cetaceans, yet conservation efforts are often limited by a lack of basic knowledge regarding their abundance, distribution, and habitat use. Here, we used passive acoustic monitoring from an SSF platform-of-opportunity to better characterize th...

1.The mutation accumulation theory of senescence predicts that age‐related deterioration of fitness can be exaggerated when inbreeding causes homozygosity for deleterious alleles. A vital component of fitness, in natural populations, is the incidence and progression of disease. 2.Evidence is growing for natural links between inbreeding and ageing;...

The use of linear mixed effects models (LMMs) is increasingly common in the analysis of biological data. Whilst LMMs offer a flexible approach to modelling a broad range of data types, ecological data are often complex and require complex model structures, and the fitting and interpretation of such models is not always straightforward. The ability...

In our increasingly unstable and unpredictable world, population dynamics rarely settle uniformly to long-term behaviour. However, projecting period-by-period through the preceding fluctuations is more data-intensive and analytically involved than evaluating at equilibrium. To efficiently model populations and best inform policy, we require pragmat...

Detecting opportunities for between-species transmission of pathogens can be challenging, particularly if rare behaviours or environmental transmission are involved. We present a multilayer network framework to quantify transmission potential in multi-host systems, incorporating environmental transmission, by using empirical data on direct and indi...

Estimates of disease prevalence in any host population are complicated by uncertainty in the outcome of diagnostic tests on individuals. In the absence of gold standard diagnostics (tests that give neither false positives nor false negatives), Bayesian latent class inference can be applied to batteries of diagnostic tests, providing posterior estim...

Supplementary Material 1. Theoretical model. Supplementary Material 2. Raw data.

Fig. S1. Copper reduced the growth rate (m) of both strains (T‐test, alt=1, producers (t5=6.8838, p<0.001, Fig S1), non‐producers (t5=10.987, p=0.0001, but had a greater inhibitory effect on non‐producers than producers when grown in isolation (t10 = 1.96, p < 0.05). Fig. S2. The impact of relatedness (r) on the relative fitness of cheats (W) is e...

Many organisms – notably microbes ‐ are embedded within complex communities where cooperative behaviours in the form of excreted public goods can benefit other species. Under such circumstances, intraspecific interactions are likely to be less important in driving the evolution of cooperation. We first illustrate this idea with a simple theoretical...

Biologists commonly compare variances among samples, to test whether underlying populations have equal spread. However, despite warnings from statisticians, incorrect testing is rife. Here we show that one of the most commonly employed of these tests, the F test, is extremely sensitive to deviations from normality. The F test suffers greatly elevat...

Aim Community assembly is traditionally assumed to result from speciation and colonization mediated by available niche space. This paradigm is expanded by the theory that niche space can also be saturated by intersexual adaptive divergence (ecological sexual dimorphism) when interspecific competition is relaxed. This theory (here termed ‘niche‐pack...

The use of linear mixed effects models (LMMs) is increasingly common in the analysis of biological data. Whilst LMMs offer a flexible approach to modelling a broad range of data types, ecological data are often complex and require complex model structures, and the fitting and interpretation of such models is not always straightforward. The ability...

The use of linear mixed effects models (LMMs) is increasingly common in the analysis of biological data. Whilst LMMs offer a flexible approach to modelling a broad range of data types, ecological data are often complex and require complex model structures, and the fitting and interpretation of such models is not always straightforward. The ability...

Contact networks are fundamental to the transmission of infection and host sex often affects the acquisition and progression of infection. However, the epidemiological impacts of sex-related variation in animal contact networks have rarely been investigated. We test the hypothesis that sex-biases in infection are related to variation in multilayer...

Following an increase in numbers from 1982 to 1998, the Greenland White-fronted Goose Anser albifrons flavirostris declined over the period 1999–2015, stimulating detailed analyses at the population and individual level to provide a better understanding of the dynamics of this subspecies. Here we synthesise the results of the analyses in order to d...

The evolution of key innovations promotes adaptive radiations by opening access to new ecological opportunity. The acquisition of viviparity (live-bearing reproduction) has emerged as one such innovation explaining reptile proliferations into extreme climates. By evolving viviparity, females provide embryos with internally stable environments to co...

Some microbial public goods can provide both individual and community-wide benefits, and are open to exploitation by non-producing species. One such example is the production of metal-detoxifying siderophores. Here, we investigate whether conflicting selection pressures on siderophore production by heavy metals – a detoxifying effect of siderophore...

Social interactions among hosts influence the persistence and spread of infectious pathogens. Daily and seasonal variation in the frequency and type of social interactions will play an important role in disease epidemiology and, alongside other factors, may have an influence on wider disease dynamics by causing seasonal forcing of infection, especi...

The use of linear mixed effects models (LMMs) is increasingly common in the analysis of biological data. Whilst LMMs offer a flexible approach to modelling a broad range of data types, ecological data are often complex and require complex model structures, and the fitting and interpretation of such models is not always straightforward. The ability...

Some microbial public goods can provide both individual and community-wide benefits, and are open to exploitation by non-producing species. One such example is the production of metal-detoxifying siderophores. Here, we investigate whether heavy metals select for increased siderophore production in natural microbial communities, or whether exploitat...

In order to conserve threatened species, knowledge of the status, trends and trajectories of populations is required. Co-ordinating collection of these data is challenging, especially for inconspicuous species such as the hazel dormouse Muscardinus avellanarius. The UK National Dormouse Monitoring Programme (NDMP) is comprised of nest box recording...

Host social structure is fundamental to how infections spread and persist and so the statistical modelling of static and dynamic social networks provides an invaluable tool to parameterise realistic epidemiological models. 2.We present a practical guide to the application of network modelling frameworks for hypothesis testing related to social inte...

Contact networks, behavioral interactions, and shared use of space can all have important implications for the spread of disease in animals. Social networks enable the quantification of complex patterns of interactions; therefore, network analysis is becoming increasingly widespread in the study of infectious disease in animals, including wildlife....

The European lobster Homarus gammarus is a marine crustacean prized for seafood, but populations across its range are threatened by fishery overexploitation. The species’ larval stages are planktonic, suggesting considerable dispersal among populations. The potential threats of overexploitation and erosion of population structure due to hatchery re...

One of the best-supported patterns in life history evolution is that organisms cope with environmental fluctuations by buffering their most important vital rates against them. This demographic buffering hypothesis is evidenced by a tendency for temporal variation in rates of survival and reproduction to correlate negatively with their contribution...

Woodlice (Isopoda: Oniscidae) are known to play important roles in soil profile development and nutrient cycling in agroecosystems. The aim of the present work was to understand the impact of different management regimes on woodlouse fauna in Mediterranean olive groves. The olive groves were located along the Kyrenia mountain range towards the nort...

The importance of social- and kin-structuring of populations for the transmission of wildlife disease is widely assumed but poorly described. Social structure can help dilute risks of transmission for group members, and is relatively easy to measure, but kin-association represents a further level of population sub-structure that is harder to measur...