Research

I am interested in how organisms are affected by, and respond to, stressors in their environment, both natural and anthropogenic.  This research spans multiple layers of biological organization, from the behavioural and physiological responses of individuals to the evolutionary responses of populations and the ecological responses of communities.  I am especially interested in the role of individual variation in shaping these responses. Undergraduate and graduate students play an integral role in my research program, and I collaborate with scientists around the world.

While I have found that insects and amphibians often suit my research interests best, due to their complex life-cycles and particular sensitivity to environmental change, my students, collaborators, and I have worked on a variety of organisms best suited to the questions we are pursuing, from crayfish to lizards!  Read more about our research below, which has focused mainly on responses to Artificial Light at Night, Salinity and Temperature Stress, and Predation Risk:

Artificial Light at Night

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Trapping for insects under street lights in Melbourne suburbs

Most organisms have evolved over millions of years with a predictable day-night (circadian) cycle. This cycle, which is fundamental to the physiological health of both ourselves and wildlife, is now being disrupted however, due to anthropogenic light pollution.  Recent research has shown that 80% of the world’s human population, and more than 99% of Europeans and Americans in fact now live under light-polluted skies. While we are beginning to understand the health implications of this disruption to humans, our understanding of how wildlife and ecosystems may be impacted is still in its infancy. In collaboration with Drs. Therésa Jones and Mark Elgar at the University of Melbourne, Dr. Kevin Gaston at the University of Exeter, and Dr. Marcel Visser at the Netherlands Institute of Ecology, I am examining this question at multiple scales using insects. At the individual and population level, I am investigating how exposure to artificial light at night influences the mating behaviour and acoustic communication of Australian black field crickets (Teleogryllus commodus), and am comparing crickets from different habitats across Victoria, Australia, to investigate the potential for adaptation.  At the community level, my graduate student Martin Lockett and I are conducting work in both Melbourne and the Netherlands to examine how different street lighting technologies influences the community ecology of both terrestrial and aerial invertebrates, in the hopes of mitigating future negative effects on ecosystem and human health.

Representative Publications:

Hopkins, G.R., Gaston, K.J., Visser, M.E., Elgar, M.A., and T.M. Jones. 2018. Artificial light at night as a driver of evolution across urban-rural landscapes. Frontiers in Ecology and the Environment 16(8): 1-8 doi: 10.1002/fee.1828.
Botha, L.M. Jones, T.M., and G.R. Hopkins. 2017. Effects of life-time exposure to artificial light at night on cricket (Teleogryllus commodus) mating and courtship behaviour. Animal Behaviour 129: 181-188.

 

Salinity and Temperature Stress

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A female rough-skinned newt (Taricha granulosa) on a road polluted by deicing salts. These salts will run-off into aquatic habitats where the newt lays her eggs, and can negatively impact the survival and development of her offspring. However, it appears that the offspring of certain females do a lot better than those of others, invoking the potential for natural selection and adaptation.

Salinity and temperature are two of the most common abiotic stressors faced by aquaticorganisms.  While both stressors are naturally occurring in environments, they are also increasingly anthropogenically-applied, due to human activities such as the application of road deicing salts, land-use change, and climate change. In collaboration with Drs. Edmund Brodie, Jr., and Susannah French, at Utah State University, I have studied how how both temperature and salinity influence amphibian embryonic and larval development, and, importantly, found that the evolutionary history a species has with regulating a particular stressor can significantly influence its chances of survival.  I have continued to bring this evolutionary perspective to conservation problems by demonstrating that there is large variation in survival in saline environments among the offspring of different females from the same population, thus allowing natural selection to take place on salinity tolerance.  I have also discovered that populations of amphibians living in naturally saline environments are often more physiologically tolerant of these environments than those found in freshwater environments nearby, an adaptionist pattern that may be true across many different species of amphibians.  I am continuing to investigate the potential for amphibians to adapt to habitats influenced by salinity and temperature extremes (including in Australia, with Dr. Craig Williams and his undergraduate students at the University of South Australia), how these stressors might interact, and the ecological consequences of these effects.

Representative Publications:

Hopkins, G.R., French, S.S. and E.D. Brodie, Jr. 2017. Interacting stressors and the potential for adaptation in a changing world: Responses of populations and individuals. Royal Society Open Science 4: 161057
Hopkins, G.R., French, S.S. and E.D. Brodie, Jr. 2013. Potential for local adaptation in response to an anthropogenic agent of selection: effects of road deicing salts on amphibian embryonic survival and development. Evolutionary Applications 6: 384-392.
Hopkins, G.R., French, S.S., and E.D. Brodie, Jr. 2013. Increased frequency and severity of developmental deformities in rough-skinned newt (Taricha granulosa) embryos exposed to road deicing salts (NaCl & MgCl2). Environmental Pollution 173: 264-269.
HopkinsG.R., Brodie, Jr., E.D., and S.S. French. 2014. Developmental and evolutionary history affect survival in stressful environments. PLoS ONE 9: e95174. doi:10.1371/journal.pone.0095174.
Hopkins, G.R. and E.D. Brodie, Jr. 2015. Occurrence of amphibians in saline habitats: A review and evolutionary perspective. Herpetological Monographs 29: 1-27.
Hopkins, G.R., Brodie, Jr., E.D., Neuman-Lee, L.A., Mohammadi, S., Brusch IV, G.A., Hopkins, Z.M., and S.S. French. 2016. Physiological responses to salinity vary with proximity to the ocean in a coastal amphibian. Physiological and Biochemical Zoology 89 (4): 322-330.
Smith,  G.D., Hopkins, G.R., Mohammadi, S., Skinner, H.M., Hansen, T., Brodie, Jr., E.D., and S.S. French. 2015. Effects of temperature on embryonic and early larval growth and development in the rough-skinned newt (Taricha granulosa). Journal of Thermal Biology 51: 89-95.

Predation Risk

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Traditionally thought of as a top aquatic predator, this Anax junius dragonfly nymph prepares to strike its spines at, and bite, a simulated predator (forceps) in a sequence of stereotyped antipredator behaviours. Such behaviours allow older (but not younger) nymphs to be active around predators and still escape predation by large salamander larvae 100% of the time (even after being inside the mouth of the predator for several minutes!). Younger nymphs prefer to sit still and avoid detection. See Hopkins et al. 2011. Ethology.

Predation risk is one of the most common natural stressors organisms face on a daily basis, and one with obvious fitness consequences. I have long been interested in the behavioural, chemical, and physical adaptations animals may employ to avoid being detected (predator avoidance) and preyed upon (antipredator) by predators.  My collaborators and I have examined the chemical and behavioural defences of amphibians (including the physiological control of behaviour), the physical defences and related behaviours of aquatic insects, and how the interactions between, and roles of, predators and prey in ecosystems may change with ontogeny.  Finally, I am also interested in understanding how exposure to other stressors, including anthropogenic pollution, might influence predation risk in a variety of species.

Representative Publications:

Hopkins, G.R., Gall, B.G. and E.D. Brodie, Jr. 2011. Ontogenetic shift in efficacy of antipredator mechanisms in a top aquatic predator, Anax junius (Odonata: Aeshnidae). Ethology 117: 1093-1100.
Hopkins, G.R. and P.N. Lahanas. 2011. Aggregation behaviour in a neotropical dendrobatid frog (Allobates talamancae) in western   Panama. Behaviour 148: 359-372.
Ferry, E.E., Hopkins, G.R., Stokes, A.N., Mohammadi, S., Brodie Jr, E.D. and B.G. Gall. 2013. Do all portable cases constructed by caddisfly larvae function in defense? Journal of Insect Science 13: 1-9
Neuman-Lee, L.A., Stokes, A.N., Greenfield, S., Hopkins, G.R., Brodie, Jr., E.D. and S.S French. 2015. The role of corticosterone and toxicity in the antipredator behavior of the rough-skinned newt (Taricha granulosa). General and Comparative Endocrinology 213: 59-64.
Neuman-Lee, L.A., Hopkins, G.R., Brodie, Jr., E.D., and S.S. French. 2013. Sublethal contaminant exposure alters behavior in a common insect: Important implications for trophic transfer. Journal of Environmental Science and Health Part B 48: 442-448.
Hopkins, G.R. and S.W. Migabo. 2010. Antipredator skin secretions of the Long-toed Salamander (Ambystoma macrodactylum) in its northern range. Journal of Herpetology44: 627-633.