In light of the recent COP26 climate change conference and increasing worry over the impact of anthropogenic global warming on our planet, researchers are working tirelessly to examine the various effects of this worldwide phenomenon on organisms of all biomes. This includes the work being done by undergraduate ecology researchers at UofT in collaboration with researchers at Ohio Wesleyan University on how the movements of lizards could potentially be an adaptive behaviour in the face of climate change.
The research involves investigating lizard movements along a modelled thermal gradient, which is established using heat lamps. Lizards are then observed in a metre-long sand-filled area with differences in temperature between the two ends. By collecting movement data from footage of the lizards’ behaviour, the team hopes to extract a set of data that they can statistically analyse to find trends connecting the lizards’ movement patterns to differences in temperature. They also hope to find evidence regarding how lizards may be able to adapt behaviourally to ongoing climate change.
Lizards are of particular interest in this investigation because they are ectothermic. This means that they regulate their body temperature externally, using the temperature of their environment. Therefore, unlike endothermic animals, lizards do not maintain a constant body temperature. Body temperature is important for various metabolic processes, including biomass synthesis in growth and development. The temperature of the surrounding environment is correlated with the growth rate of ectotherms, where colder climates cause slowed growth and development, and vice versa. However, high temperatures beyond the maximum range of tolerance for ectotherms can lead to enzyme denaturation and inactivation. Since enzymes regulate many metabolic processes such as biomass synthesis, this can result in reduced growth and development at extremely high temperatures.
Furthermore, in many ectotherms, temperature can regulate the sex determination of offspring. For example, at warmer temperatures, crocodiles generally produce more male offspring, while turtles produce mainly female offspring. Given the impact that temperature has on the lives of ectotherms, as well as the role that ectotherms play in maintaining the biodiversity of global ecosystems, research on how ectotherms are adapting to climate change and how our mitigation of climate change can positively impact such organisms is paramount.
Previous studies done on ectotherms and their ability to adapt to various temperatures—as well as subsequent impacts on ecosystems—have produced some intriguing results. A 2018 study at the University of Connecticut by Garcia-Robledo et al. concluded that nocturnal ants in four Mexican ecosystems had lower heat tolerance than diurnal counterparts in the same ecosystems. A separate study by O’Donnell et al. in 2020 showed that the temporal partitioning of army ant species into diurnal (active in the daytime) and nocturnal (active in the nighttime) species allowed them to co-exist and reduced competition between species for common prey items, thus increasing ant biodiversity in tropical ecosystems where season-based specialisations may not be as prominent.
As ant species temporally separate, this also increases their network specialisations with plants. While we still have limited knowledge of the pollination behaviours of ants, other nocturnal species such as moths are highly important pollinators that have co-evolved and developed specialised pollination relationships with species of flowering plants in the genus Orchidaceae (orchids). Even in the presence of diurnal pollinators such as butterflies, generalist flowering plants that are pollinated by many different species still benefit greatly from the additional nocturnal pollination services provided by moths. Protecting nocturnal ectotherms that may be more adversely impacted by warming temperatures is therefore important to preserve ecological integrity in addition to their interactions with other organisms.
It is known that fossil fuels are the major source of global carbon dioxide emissions. As a greenhouse gas, carbon dioxide traps infrared radiation in the atmosphere, resulting in the warming of the planet and increasing Earth’s average temperature. Divestment from fossil fuels could be a powerful solution to the woes faced by ectotherms that are particularly sensitive to climate change. While ectotherms may show adaptive behaviour along relatively shallow temperature gradients, the escalating rate of global warming may outpace their adaptive abilities.
Divestment is the opposite of investment: it is halting any further investment and parting with stocks, bonds, or investment funds in causes that are unethical or morally unjust. Given the harm done by anthropogenic climate change on people, ecosystems, and biodiversity, fossil fuel divestment campaigns are demanding that institutions halt further investment in fossil fuel companies. They are also asking for institutions to end their sponsorship of fossil fuel corporations and divest from direct ownership, public equities, and corporate bonds tied to fossil fuel companies.
To this end, the University of Toronto announced its commitment to fossil fuel divestment in late October of this year, and promises to divest from all direct investments in fossil fuel companies within the next twelve months. The University is also committing to achieve net-zero carbon emissions associated with its endowment fund by 2050. The action was accelerated in large part due to mounting calls to action from student groups.
Climate change policymakers are attempting to limit the global average temperature increase to 1.5˚C, but this is becoming an increasingly difficult task without unified mitigation efforts. Climate models that predict higher average temperature change conclude that organisms will not be able to adapt sufficiently to avoid adverse impacts. By divesting from fossil fuels, we are taking steps to reduce global average temperature increase and protecting biodiversity and the fate of ectotherms in the process.
