I am interested in how organisms are affected by, and respond to, environmental change. 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 increasingly interested in understanding not just how animals respond to individual stressors, but also how they respond to restoration of their natural habitat. Undergraduate students play an integral role in my research program, and I collaborate with scientists around the world.
While I have found that invertebrates (especially insects and spiders), amphibians, and reptiles often suit my research interests best, due to their 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. Read more about our research below:
Responses of Invertebrate and Vertebrate Communities to restoration of Gary Oak Habitats
Undergraduate students sampling for invertebrates in the savannah at our Garry Oak long-term ecological monitoring site
Gary Oak (Quercus garyanna) woodlands and savannahs are a unique and endangered ecosystem in the Pacific Northwest, which provide valuable habitat for wildlife. This ecosystem type has been reduced to less than 10% of their native range, however, through habitat destruction and degradation. I have been working with undergraduate students and my collaborator, plant ecophysiologist Dr. Ava Howard, since 2019 to document the effects of this degradation and experimental habitat restoration on terrestrial invertebrate and vertebrate communities. With the co-operation of local land-owners, we have developed a long-term ecological monitoring site in the mid-Willamette valley where we have experimentally worked to restore part of an oak woodland habitat by logging competing Douglas Fir trees that encroach and overtop oaks, while leaving the other part of the habitat as a mixed conifer-deciduous forest “control”. Before and after this restoration, my students have been collecting, processing, and identifying invertebrates (insects, spiders, collembola, isopods, etc.) at numerous replicate sites within each habitat type (savannah, restored woodland, woodland in the process of restoration, and mixed-conifer-deciduous control forest) to understand the individual, population, and community-level responses of invertebrates in these habitats. I have also had students undertake a detailed study of herbivorous invertebrate infestation of oak acorns (mostly Filbert worms and weevils), to determine the effects of these insects on acorn germination success and restoration efforts. Finally, I am conducting bioacoustic monitoring of the ecosystem using automated recorders to gain insights of stridulating insect, frog, and bird diversity, and conducting ground-level surveys for amphibians and reptiles in these habitats. Linking the responses of all these different groups back to each other and to tree health and ecology (through my plant biologist colleagues) provides an important holistic ecological view, and critical new insights for conservation and restoration activities.
Responses of Reptiles to Habitat Restoration and Outdoor Recreation in Urban Parks
An endangered Northwestern Pond Turtle at Minto Brown Island Park, Salem, OR, in one of our nesting restoration areas.
In a collaboration with the Oregon Department of Fish & Wildlife (State agency), the City of Salem, and Oregon State University recreation ecologist, Dr. Ashley D’Antonio, my students and I are investigating the effects of habitat restoration and outdoor recreation activities on local reptiles inhabiting urban parks in the mid-Willamette valley. This has included the effects of bike-path recreation on abundance and diversity of snakes and lizards in a park in Corvallis, Oregon (revealing that different types of recreation might have different effects on these animals), as well as a long-term examination of endangered native freshwater turtles (Northwestern Pond Turtle, Actinemys marmorata, and Western Painted Turtle, Chrysemys picta) at Minto Brown Island Park in Salem, Oregon. At Minto Brown, we have been restoring nesting and basking habitat for turtles since 2019 and monitoring the impacts of these efforts on native and non-native turtle species through student-led in-person and camera-trap surveys. We are also studying the possible impacts of outdoor recreation on turtles at this busy urban park. With my computer science collaborator, Dr. Lucas Cordova, we have also launched a community-science website (oregonturtles.org) and mobile phone app to engage members of the public in reporting turtle sightings. This has enabled us to also track invasive turtles, and spurred a recent student project analysing the spatial distribution of invasive common snapping turtles (Chelydra serpentina) in the state. Our work on turtles is funded through a grant from the Oregon Conservation and Recreation Fund.
Invertebrate Responses to Artificial Light at Night
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 and other terrestrial invertebrates. At the individual and population level, in collaboration with several undergraduate students, 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 conducted work in both Melbourne and the Netherlands to examine how different street lighting technologies influence the community ecology of both terrestrial and aerial invertebrates, in the hopes of mitigating future negative effects on ecosystem and human health. Martin’s dissertation research also continued to examine the community-level responses to light pollution in the tightly-knit psyllid – eucalyptus – bell miner food web (see recent publications).
Representative Publications:
*mentored undergraduate student ; **mentored graduate student
Lockett, M.T.**, Jones, T.M., Elgar, M.A., Gaston, K.J., Visser, M.E., and G.R. Hopkins. 2021. Urban street lighting differentially affects community attributes of airborne and ground-dwelling invertebrate assemblages. Journal of Applied Ecology 58: 2329-2339.
Lockett, M.T.**, Rasmussen, R*., Arndt, S.K., Hopkins, G.R., and T.M. Jones. 2022. Artificial light at night promotes bottom-up changes in a woodland food chain. Environmental Pollution 310: 119803
Thompson, E.K.*, Cullinan, N.L.*, Jones, T.M., and G.R. Hopkins. 2019. Effects of artificial light at night and male calling on movement patterns and mate location in field crickets. Animal Behaviour 158: 183-191.
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.
Responses of Amphibians to Salinity and Temperature Stress
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., Maftei-Muirson, J.*, Doherty, S.*, Micham, G., and C.R. Williams. 2020. Salinity tolerance and brackish habitat utilization in the common Australian frog Crinia signifera. Journal of Herpetology 54: 161-167.
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.
Hopkins, G.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.
Responses of Animals to Predation Risk
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. Studies of antipredator and predator avoidance behavior make for great undergraduate research projects (especially in classes such as BI 360: Animal Behaviour), and I recently supervised WOU undergraduate student Nick Carter on investigations of predator avoidance behaviour in tidepool sculpins on the Oregon coast (manuscript currently being prepared for publication). I also continue my collaborations with researchers examining the ecology of rough-skinned newt toxicity and antipredator behaviours.
Representative Publications:
Gareth R. Hopkins, PhD 