Mark Randall Forbes

Mark Randall Forbes
Carleton University · Department of Biology

PhD, University of Toronto ORCID 0000-0002-2288-3209

About

353
Publications
42,438
Reads
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7,571
Citations
Citations since 2017
32 Research Items
2382 Citations
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20172018201920202021202220230100200300400
20172018201920202021202220230100200300400
Additional affiliations
January 2010 - December 2014
Carleton University
Position
  • Assoc VP Research
January 1995 - December 2011
Carleton University
Education
January 1987 - January 1992
University of Toronto
Field of study
  • Zoology

Publications

Publications (353)
Article
Full-text available
Aggregation of macroparasites among hosts is a near-universal pattern, and has important consequences for the stability of host-parasite associations and the impacts of disease. Identifying which potential drivers are contributing to levels of aggregation observed in parasite-host associations is challenging, particularly for observational studies....
Article
Full-text available
Sexes often differ in foraging and diet, which is associated with sex differences in size, trophic morphology, use of habitats, and/or life history tactics. Herein, strikingly similar diets were found for adult sexes of a dragonfly ( Leucorrhinia intacta ), based on comparing 141 dietary taxa identified from the metabarcoding of mitochondrial DNA a...
Article
Glucocorticoid hormones (GCs) help vertebrates maintain homeostasis during and following challenging events. Short-term elevations in GC levels are necessary for survival, whereas longer-term changes can lead to reduced reproductive output and immunosuppression. Persistent environmental contaminants (ECs) are widespread globally. Experimental expos...
Article
Full-text available
Testing hypotheses in ecological and evolutionary parasitology can require testing whether host traits or coinfecting parasites explain variation in parasitism by focal species. However, when host traits and coinfecting parasites are considered separately, relations between either and parasitism by focal species can be spurious—a problem that is ad...
Article
Full-text available
Habitat loss, climate change, environmental contaminants, and parasites and pathogens are among the main factors thought to act singly or together in causing amphibian declines. We tested for combined effects of neonicotinoid pesticides and parasites (versus parasites-only) on mortality, growth, and white blood cell profiles of a model amphibian: t...
Article
Full-text available
Predators kill and consume prey, but also scare living prey. Fitness of prey can be reduced by direct killing and consumption, but also by non-consumptive effects (NCEs) if prey show costly risk-induced trait responses (RITRs) to predators, which are meant to reduce predation risk. Recently, similarities between predators and parasites as natural e...
Article
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Seabirds are thought to provide ecological services such as the movement of nutrients between marine and terrestrial ecosystems, which may be especially critical to productivity and diversity in nutrient-poor environments. Most Arctic ecosystems are unaffected by local human impacts and are naturally nutrient poor and especially sensitive to warmin...
Article
Amphibians are declining globally. Exposure to pesticides has been implicated in decreasing amphibian immune function, thus increasing their susceptibility to parasites and disease and thereby negatively affecting individuals and populations. Amphibians are likely exposed to neonicotinoids because these widely used insecticides are highly soluble i...
Article
Full-text available
Avian cholera, caused by the bacterium Pasteurella multocida , is a common and important infectious disease of wild birds in North America. Between 2005 and 2012, avian cholera caused annual mortality of widely varying magnitudes in Northern common eiders ( Somateria mollissima borealis ) breeding at the largest colony in the Canadian Arctic, Mitiv...
Article
Full-text available
Trematode-induced castration of snails is widespread and can lead to other life history changes of snails such as changes in trajectories of size and growth or survival. The changes produced likely depend on whether the parasite or host controls allocation of host resources remaining after partial or complete cessation of host current reproduction...
Article
Measures of parasitism often differ between hosts. This variation is thought due in part to age or sex differences in exposure to parasites and/or susceptibility to parasitism. We assessed how often age or sex biases in parasitism were found using a large, multi‐year (2006 – 2017) dataset of 12 parasite species of Icelandic Rock Ptarmigan (Lagopus...
Article
To understand the diversity and strength of predation in natural communities, researchers must quantify the total amount of prey species in the diet of predators. Metabarcoding approaches have allowed widespread characterization of predator diets with high taxonomic resolution. To determine the wider impacts of predators, researchers should combine...
Article
In recent decades, mercury concentrations have increased in fish of Great Slave Lake (GSL), a subarctic great lake in northern Canada with important recreational, subsistence, and commercial fisheries. This study characterized habitat use and trophic position of common fish species in GSL near the City of Yellowknife (Northwest Territories, Canada)...
Article
Carrier solvents are used frequently in toxicity testing to assist hydrophobic chemicals into solution, but such solvents may have toxic effects on test subjects. Amphibians are model organisms in toxicity studies; however, little is known about the direct effects of solvents on native amphibians. Following modifications to standardized guidelines...
Article
Parasites and pathogens (hereafter parasites) commonly challenge organisms, but the extent to which their infections are physiologically stressful to hosts remains unclear. Importantly, vertebrate hormones, glucocorticoids (GCs), have been reported to increase, decrease, or show no alterations stemming from infections, challenging the generality of...
Article
Field experiments where parasites are removed through treatment and contaminant levels in host tissues are recorded can provide insight into the combined effects of parasitism and contaminants in wild populations. In 2013 and 2014, we treated northern common eider ducks (Somateria mollissima) arriving at a breeding colony with either a broad-spectr...
Article
Full-text available
Little information is available on the effects of neonicotinoid insecticides on vertebrates. Previous work using amphibians found chronic exposure to some neonicotinoids had no detrimental effects on fitness-relevant traits. However, there is some evidence of more subtle effects of neonicotinoids on immune traits and evidence that other pesticides...
Article
Full-text available
In birds, parasites cause detrimental effects to the individual host, including reduced survival and reproductive output. The level of parasitic infection can vary with a range of factors, including migratory status, body size, sex, and age of hosts, or season. Understanding this baseline variation is important in order to identify the effects of e...
Article
Full-text available
Significance The paucity of monitoring data for seabird populations at suitable temporal and spatial scales challenges the development of realistic and effective conservation policies. We employ newly developed paleoenvironmental techniques at 10 key subarctic seaduck colonies to reconstruct broadscale population changes at decadal timescales throu...
Article
Neonicotinoids are widely used insecticides that are detectable in agricultural waterways. These insecticides are of concern due to their potential impacts on non‐target organisms. Pesticides can affect development of amphibians and suppress the immune system, which could impact disease susceptibility and tolerance. No previous studies on amphibian...
Article
Full-text available
Documenting how climate change will affect Arctic ecosystems and food web dynamics requires an understanding of current sources of variation in species distributions, frequency, and abundance. Host–parasite interactions are expected to be altered in the coming decades under warming conditions. However, in many Polar Regions, there is little informa...
Chapter
Full-text available
Parasites are ubiquitous in the environment, and can cause negative effects in their host species. Importantly, seabirds can be long-lived and cross multiple continents within a single annual cycle, thus their exposure to parasites may be greater than other taxa. With changing climatic conditions expected to influence parasite distribution and abun...
Article
Full-text available
Studies on parasite-mediated selection often focus on single parasite taxa infecting single species of hosts. However, host populations experience infections by multiple parasite taxa simultaneously; coinfection is expected to influence how host- and/or parasite-related factors affect host exposure and susceptibility to various parasites, and the r...
Article
Full-text available
Background Accumulating evidence suggests that the gut microbiota shapes developmental processes within the immune system. Early life antibiotic use is one factor which may contribute to immune dysfunction and the recent surge in allergies by virtue of its effects on gut microbiota. Objective and methods As a first step towards determining whether...
Chapter
Full-text available
In this chapter, we discuss insect behavioural responses to parasites. Dividing behaviours conceptually into those that occur before and after infection, we start by reviewing the evidence that insects identify and avoid potentially infectious environments to minimize negative consequences of infection. We then consider behavioural responses follow...
Article
We examined hepatic concentrations of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), manganese (Mn), mercury (Hg), rubidium (Rb), selenium (Se) and zinc (Zn) in 10 breeding female common eiders (Somateria mollissima) from each of three colonies across 20° of latitude. Levels of many elements were elevated in eiders, although generally below le...
Article
Full-text available
Parasite species often show differential fitness on different host species. We developed an equation-based model to explore conditions favouring host species exploitation and discrimination. In our model, diploid infective stages randomly encountered hosts of two species; the parasite’s relative fitness in exploiting each host species, and its abil...
Article
Full-text available
The patterns and mechanisms by which biological diversity is associated with parasite infection risk are important to study because of their potential implications for wildlife population’s conservation and management. Almost all research in this area has focused on host species diversity and has neglected parasite diversity, despite evidence that...
Article
Studies generally have neglected parasite-centric views in explorations of whether the oft-seen patterns of parasite aggregation are adaptive. Using simulation models, we explored the effects of aggregation on coinfection with hetero- or conspecific parasite species characterized by different mean abundances. Increasing aggregation increased the pr...
Article
Arctic wildlife can be exposed to high mercury (Hg) levels, and are also naturally exposed to gastrointestinal parasites that can reduce condition and negatively affect reproductive output and/or survival in similar ways. Importantly, both Hg and parasites are increasing in wildlife in some Arctic regions. We studied the northern common eider duck...
Article
Full-text available
Emerging infectious diseases are a growing concern in wildlife conservation. Documenting outbreak patterns and determining the ecological drivers of transmission risk are fundamental to predicting disease spread and assessing potential impacts on population viability. However, evaluating disease in wildlife populations requires expansive surveillan...
Article
Although physiological traits and phenology are thought to be evolved traits, they often show marked variation within populations, which may be related to extrinsic factors. For example, trace elements such as mercury (Hg) and lead (Pb) alter biochemical processes within wildlife that may affect migration and breeding. While there is a growing unde...
Article
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This article reviews research on the evolutionary mechanisms leading to different transmission modes. Such modes are often under genetic control of the host or the pathogen, and often in conflict with each other via trade-offs. Transmission modes may vary among pathogen strains and among host populations. Evolutionary changes in transmission mode h...
Article
Full-text available
Infectious diseases have the potential to spread rapidly and cause high mortality within populations of immunologically naïve hosts. The recent appearance of avian cholera, a highly virulent disease of birds caused by the bacterium Pasteurella multocida, at remote Arctic seabird colonies is an emerging conservation concern. 2.Determining disease ri...
Article
The causes and consequences of aggregation among conspecifics have received much attention. For infecting macroparasites, causes include variation among hosts in susceptibility and whether infective stages are aggregated in the environment. Here, we link these two phenomena and explore whether aggregation of infective stages in the environment is a...
Article
Full-text available
Parasites are detrimental to host fitness and therefore should strongly select for host defence mechanisms. Yet, hosts vary considerably in their observed parasite loads. One notable source of inter-individual variation in parasitism is host sex. Such variation could be caused by the immunomodulatory effects of gonadal steroids. Here we assess the...
Article
Full-text available
Certain parasite species have free-living stages, so habitat range may influence host-species range. We tested whether regional occurrence and habitat use of parasitic water mites were related to their host-species range. We collected 7445 Arrenurus Dugès, 1834 mites from 7107 coenagrionid damselflies, representing 11 host species from 13 sites in...
Article
Full-text available
Related host species often demonstrate differences in prevalence and/or intensity of infection by particular parasite species, as well as different levels of resistance to those parasites. The mechanisms underlying this interspecific variation in parasitism and resistance expression are not well understood. Surprisingly, few researchers have assess...
Article
Full-text available
For birds, unpredictable environments during the energetically stressful times of moulting and breeding are expected to have negative fitness effects. Detecting those effects however, might be difficult if individuals modulate their physiology and/or behaviours in ways to minimize short-term fitness costs. Corticosterone in feathers (CORTf) is thou...
Article
Full-text available
Commonly used proxies for measuring immune responses in invertebrates include the amount of melanin deposited on nylon inserts and assays of activity of the enzyme phenoloxidase (PO) in the haemolymph. We used these proxies to estimate immunity in unpar-asitized individuals from four Lestid damselfly species from popula-tions with different levels...
Article
In this study, we tested which host species’ characteristics explain the nature and level of parasitism for host damselfly (Coenagrionidae)–water mite (Arrenuridae) parasite associations. Prevalence and intensity of mite parasites, and mite species richness were examined in relation to geographic range size, regional occurrence, relative local abun...
Article
Mercury (Hg) is a naturally occurring trace element that is also a by-product of anthropogenic activities and, in its methylated form, it is a neurotoxin that can have adverse effects on wildlife. The toxicity of Hg for humans, wildlife, and ecosystem health merits monitoring of its concentrations by various sampling means. Marine birds are widely...
Data
Table S1. Model selection based on information-theoretic approach to assess the effect of immune parameters on mortality. Figure S1. Probability of mortality in relation to the first two components of a Principal Component Analysis. Figure S2. Relationship between immune parameters and clutch size in incubating common eider females. Appendix S1. Bo...
Article
Full-text available
A review of recent studies published over a 23-year timespan (1990–2012) showed rapidly increasing interest in exploring how environmental contaminants and parasitism might influence each other and (or) interact to affect host health. Those experimental and observational studies fall into three broad categories (comparative studies of the possible...
Article
Full-text available
In natural populations, epidemics provide opportunities to look for intense natural selection on genes coding for life history and immune or other physiological traits. If the populations being considered are of management or conservation concern, then identifying the traits under selection (or ‘markers’) might provide insights into possible interv...
Article
Full-text available
Here, we offer a novel hypothesis to explain why some host species evolve resistance, whereas other related species remain susceptible to a shared parasite species. We first describe instances of single water mite species that are ectoparasitic on different species of host dragonflies, where the mites are killed by resistance mechanisms and have li...
Article
Full-text available
Closely related host species are known to show variation in the level of resistance towards the same or similar parasite species, but this phenomenon is understudied. Such studies are important for understanding the ecological factors that might promote susceptibility or resistance to parasites: in particular, whether one host species is a larger t...
Article
Full-text available
Populations of invasive species tend to have fewer parasites in their introduced ranges than in their native ranges and are also thought to have fewer parasites than native prey. This 'release' from parasites has unstudied implications for native predators feeding on exotic prey. In particular, shifts from native to exotic prey should reduce levels...
Article
Full-text available
Northern polar regions have warmed more than other parts of the globe potentially amplifying the effects of climate change on biological communities. Ice-free seasons are becoming longer in many areas, which has reduced the time available to polar bears (Ursus maritimus) to hunt for seals and hampered bears' ability to meet their energetic demands....
Article
The common eider (Somateria mollissima) is an abundant sea duck breeding around the circumpolar Arctic, and is an important component of subsistence and sport harvest in some regions. We determined hepatic cadmium (Cd) and zinc (Zn) concentrations in the livers of breeding females sampled during three time periods including 1992/3, 2001/2 and 2008...
Article
Full-text available
The abundance of Canada geese (Branta canadensis) nesting in temperate regions of North America has increased dramatically during the past half century. Numbers have reached nuisance levels in many areas and supplementary hunting seasons, which are timed to occur before and after traditional waterfowl hunting periods, are widely employed to limit p...
Article
Full-text available
One of the main challenges in evolutionary parasitology is to determine the factors that explain variation among host species in parasitism. In this study, we addressed whether host phylogeny or ecology was important in determining host species use by water mites. Parasitism (prevalence and intensity) by Arrenurus water mites was examined in relati...
Article
Full-text available
Abstract Fluctuating abiotic conditions within intertidal zones have been shown to affect the emergence of free-swimming trematode infectious stages (cercariae) from their gastropod first intermediate hosts, likely reflecting adaptations to maximize transmission in this marine environment. We investigated the influences of temperature (17 and 22 C)...
Article
Full-text available
Methylmercury is a toxic form of mercury which persists in food webs for long periods of time and biomagnifies up successive trophic levels. Shorebirds breeding in the Arctic are exposed to methylmercury, derived from both natural and anthropogenic sources, when they ingest their invertebrate prey. Populations of many shorebird species are believed...
Article
Full-text available
Host individuals and populations are commonly infected by more than one type of parasite, yet studies examining parasite effects on host fitness often limit observations or experiments to only a single parasite taxon or to a narrow subset of potential parasite taxa. Addressing covariation between parasite taxa is important for determining the poten...
Article
Full-text available
Dispersal, the movement of an individual away from its natal or breeding ground, has been studied extensively in birds and mammals to understand the costs and benefits of movement behavior. Whether or not invertebrates disperse in response to such attributes as habitat quality or density of conspecifics remains uncertain, due in part to the difficu...
Data
Linear and exponential (increasing at an accelerating rate and increasing at a decelerating rate) relationships in a) untransformed space and b) in log10 transformed space. The slopes for log-transformed lines are indicated. If the x-axis represents population density, the density dependent relationships can be thought of in a similar way to functi...
Data
ANOVA results for densities (ind. m-3, log10[datum+1]-transformed) of swimming Corophium volutator in the upper Bay of Fundy, summer 2010. All sources of variation are random. The degrees of freedom are the same as in Table 2. (DOCX)
Data
Results for correlation analyses between standardized swimming activity and mud resident variables of Corophium volutator. Significant results are bolded. Patchiness was calculated as variance/mean for the given variable. Body lengths are in mm. (DOCX)
Article
Full-text available
Mites (Arachnida: Acari) are one of the most diverse groups of organisms associated with bark beetles (Curculionidae: Scolytinae), but their taxonomy and ecology are poorly understood, including in Canada. Here we address this by describing the diversity, species composition, and host associations of mesostigmatic and oribatid mites collected from...
Article
During the breeding season, seabird colonies are attended by active breeders, failed breeders, and non-breeding birds. Determining breeding status of some seabirds can be challenging, but tracking non-breeder attendance can provide important information on the health of the colony or the local marine environment. We used behavioural and energetic d...
Article
The diets of 99 pumpkinseed sunfish Lepomis gibbosus from a pair of small, adjacent lakes in Ontario, Canada, were estimated from their stomach contents, trophically transmitted parasites and stable isotopes of carbon and nitrogen in fish tissue. The three methods provided virtually unrelated information. There was no significant correlation in the...
Article
Climate change has the potential to influence host–parasite interactions. In this study, we tested how an increase in temperature outside of the common range (12–17 °C) in the Upper Bay of Fundy affected the infection success and impact of a marine parasite (the trematode Gynaecotyla adunca) to its second intermediate host, the intertidal amphipod...
Article
Full-text available
Ecosystems are valuable as well as aesthetic. The natural functions of ecosystems can have profound effects on the economy, and human and wildlife health. The aggregate value of these “ecosystem services” may far exceed the economic value derived from resource extraction or industrial development, especially when considering the costs of restoring...
Article
Climate change has the potential to influence host–parasite interactions. In this study, we tested how an increase in temperature outside of the common range (12–17 °C) in the Upper Bay of Fundy affected the infection success and impact of a marine parasite (the trematode Gynaecotyla adunca) to its second intermediate host, the intertidal amphipod...