Mesocosm experiment at SNARL near Yosemite testing how predation modifies the establishment of range shifting species

Mesocosm experiment at SNARL near Yosemite testing how predation modifies the establishment of range shifting species

Lake in Yosemite National Park

Lake in Yosemite National Park

Climate change and novel community assembly

Climate change is altering the latitudinal and elevational range limits of species, often driving poleward and upward range shifts. Good dispersers will track favorable climatic conditions causing species that normally do not interact to co-occur, reshuffling species composition, potentially altering the abundance, diversity and functioning of local communities. Despite the growing number of climate change studies, forecasting the coexistence outcomes of these novel communities is challenging because we lack quantitative experiments that isolate how physiological tolerances and novel species interactions combine to structure communities across environmental gradients (Jones and Gilbert 2016 invited review for special issue in Plant Ecology). To date, the impact of novel competitors on resident communities appear idiosyncratic, with studies coming to conflicting conclusions on the importance of species interactions in modulating the direct responses of organisms to climate change. I am currently conducting experiments to isolate how trophic interactions mediate the invasion success of range shifting species, with the ultimate goal of clarifying how biotic and abiotic conditions influence the dynamics of reshuffled communities.

 

Summer nights of field work

Summer nights of field work

Lake sampling in Beautiful British Columbia

Lake sampling in Beautiful British Columbia

Changes to community composition in space & time

Lakes at higher latitudes are expected to show higher rates of species turnover over time, both because of larger temperature changes in these regions and because these lakes support lower species diversity. This species turnover can result from two distinct processes – colonization by new species and local extinction events. Zooplankton form an interesting group to test the roles of local extinction and colonization on species turnover because there are conflicting views on colonization rates and because many species form egg banks that may slow rates of local extinction. Moreover, it is likely that there is spatial directionality to community change over time, but this is underappreciated. In this project, we resample zooplankton in lakes across an 1800 km latitudinal gradient in western Canada and provide evidence that changes to community composition depend on geographic location and are associated with differences in colonization-extinction dynamics and species traits. 

 

Collecting sediment in the Yukon

Collecting sediment in the Yukon

An adult daphnia

An adult daphnia

CLIMATE CHANGE AND TIME TRAVELING THROUGH DORMANCY

Plastic life-history strategies have the potential to mitigate the direct effects of climate change on populations, communities and ecosystems. Dormancy is a particularly important persistence strategy, as it allows individuals to remain inactive for decades to hundreds of years before emerging during favourable conditions. Dormant propagules are essential to the persistence of many species in seasonal climates and, because temperature is the primary cue responsible for the termination of dormancy, species that have dormant stages may be strongly impacted by climate change. By exposing dormant eggs to hatching cues, I showed that responses of zooplankton resting eggs to hatching cues change with latitude, and that the pattern of this change differs among taxa (Jones and Gilbert 2015, Journal of Animal Ecology). I am currently conducting a meta-analysis to determine how biotic and abiotic cues impact dormancy and will use this information to continue to ask questions related to how life history strategies can safeguard populations against extinction.

 

Natural metacommunity of aspen stands

Natural metacommunity of aspen stands

An aspen specialist, Aquilegia formosa

An aspen specialist, Aquilegia formosa

Dispersal and metacommunity dynamics

Many communities are not contiguous and instead rely on dispersal to connect local habitat patches. In a recent study (Jones et al. 2015 Journal of Ecology), my collaborators and I showed that the diversity patterns of plants depend on whether they are associated with animal dispersal vectors, where the degree of isolation did not impact the biodiversity of plant communities in patches that had adaptations for animals to disperse them long distances. In addition, my collaborators and I used an alternative system of insects that specialize on milkweed (Grainger, Germain, Jones and Gilbert accepted Ecology) to test how trophic interactions impact species persistence in metacommunities. These studies revealed interesting insights into metacommunity theory and suggested that considering life-history characteristics associated with dispersal can clarify broad scale diversity patterns in nature. In the future, I will continue to investigate how species level differences in traits can alter coexistence in patchy landscapes.

 

Our focal species, Viola praemorsa

Our focal species, Viola praemorsa

The effects of temperature on the mixed mating system of plants

The long-term impacts of climate change on plant populations remain unclear.  Many significant responses to climate change have been described, including earlier flowering time and seed maturation, changes in distribution along latitudinal or elevational gradients, and increased vegetative growth. Other studies, however, have shown modest or inconsistent responses to shifts in temperature and precipitation, under both experimentally imposed conditions and longer-term field observation. We experimentally imposed a warming/drought treatment on a hermaphroditic self-compatible violet and provide some of the first field evidence that elevated temperatures can substantially increase the frequency of self-fertilization (Jones et al. 2013 ProcB). Although setting seed by selfing can allow populations to persist in the absence of pollinators, this short-term resiliency could mask future demographic difficulties.