According to research by the State University of New York, Binghamton, climate change has caused warming in the Pacific Northwest. This has resulted in some insect species invading northern oak forests. Dylan Jones displayed two photos of oak leaves side-by-side. The one with green leaves was healthy and was dotted with occasional galls, which were structures made by an oak gall wasp, a herbivorous species. The other leaf was yellowed and tattered, resulting in an insect population that didn’t have predatory checks and balances. The Pacific Northwest has seen warming temperatures, which has caused species like Neuropterans salutatories and others to expand their range to more northern oak savannas.
“In the native range, you might only find a few galls per leaf. Kirsten Prior, Assistant Professor of Biological Sciences, said that you might find thousands on a single tree in the expanded range. This is quite common on Vancouver Island. Jones is a doctoral student in biological sciences from Binghamton University, and Clifford D. Clark Diversity is a Fellow and the lead author of the Journal of Animal Ecology paper. Julia Kobelt, a former field technician, Jenna Ross, and Thomas Powell are co-authors of “Latitudinal gradients in species diversity provide high niche opportunities to a range expanding phytophagous insect.”
Oak savannas can be described as areas with oaks that are dominated by one tree species. Quercus Garryana, the oak species of concern, requires a dry environment. Kirsten Prior explained that oak savannas could be found in the rain shadows of West Coast mountain ranges. Oaks are a diverse collection of environmentally significant trees all over North America. They host numerous insect species, including oak gall wasps. These wasp classes create galls, which look striking in all their forms. Some may resemble large apples, while others have colorful spikes that remind one of the sea urchins.
Prior stated that this species has long fascinated amateur biologists because of its charismatic nature. “You can see all the structures on an oak if you go to it.” These galls are not only herbivorous but also host other species of insects. This includes a stunning variety of parasitoid wasps. Oak gall wasps can be found in North America. They are diverse, but their evolutionary relationships and identifying certain species are not well-documented. Jones and Prior are part of a consortium of scientists from across the continent working to change this.
“It is essential to continue documenting biodiversity. During that summer, researchers visited their study locations three times. Others were located on the Bureau of Land Management land or preserves related to native communities. Others were suburbia, just a short drive from major cities.”
Urbanization has caused the disappearance of many oak savannas on Vancouver Island. Those that remain are well documented and maintained by landowners. Prior stated that they have had long-standing relationships with many landowners in the area, allowing them to work on their properties.
“Some of them are so thrilled to have researchers there,” Jones said that biodiversity is a function of latitudinal gradients. The closer you get to the equator, the more species there are. The same holds true for higher altitudes. Warmer temperatures allow one species to expand its range, moving into areas that lack predators or competitors and eventually overwhelming the ecosystem.
Researchers point out that the case of the oak gall wasps demonstrates the importance of biodiversity and the possible enduring significance of climate change. Jones stated that biodiversity could be a great way to protect areas from invading animals. “Areas less vulnerable to invading species if they have strong predators and competitors,” Jones said.