Plants and Pollinators Need Each Other

Insects are attracted by floral traits

Ayesha Ali

Ayesha Ali

A rose by any other name would smell as sweet, but pollinators don’t care about names. They’re more interested in a flower’s appearance, particularly its colour and shape, says Prof. Ayesha Ali, Department of Mathematics and Statistics. As part of her research on pollination networks, she’s looking at the relationship between plants and insects in an ecosystem. She’s developing mathematical models to predict the probability of insects pollinating certain plant species based on their characteristics.

“What we’re trying to do is understand why do certain pollinators go to certain plants and how does that help to sustain the ecosystem at large,” says Ali. The decision to visit a particular plant depends on whether the insects are looking for pollen or nectar and whether they’re looking for food for themselves or their offspring.

Ali says that pollinators are like consumers looking for certain types of products. The insects are shopping for pollen, and the plants are trying to market themselves to attract the right pollinators. This econometrics approach looks at the probability of interaction between two groups. Just as with consumers, whose personal traits influence their brand preferences, pollinators within the same species have different attributes that influence their plant preferences.

“The behaviour within a species is different,” says Ali. “You can think of it as a mixture of these different linkage rules because their attributes may vary within the species.” This is a relatively new concept to researchers who study pollinator behaviour and believe that members of the same species behave the same way, she says. As a statistician, she often collaborates with biologists and ecologists, which enhances their collective knowledge.

“Based on certain floral traits or plant traits, the pollinators may be more attracted to come and visit them,” says Ali. Pollinators also have physical features that make them more inclined to visit certain types of plants. Insects with long proboscises, which are straw-like feeding appendages, are more likely to visit flowers that are long and tubular. Flowers that are flat and open, such as daisies, attract a wider variety of insects because their pollen is more accessible. Some pollinators are attracted by a particular colour of flower. A barrier trait, such as flowers that aren’t blooming, keeps pollinators away.

Plants and pollinators need each other to survive, and the absence of one or the other could harm the ecosystem. “You want to be able to understand the interactions between these plants and pollinators, and then you can start thinking about what would happen if a change happened in the ecosystem,” says Ali. “How does that affect the rest of the ecosystem, and at what point will the ecosystem break down?”

If one species of pollinators disappears, another species might take its place. Similarly, if a plant species becomes extinct, then its pollinators may be able to feed on other plants. If an ecosystem depends on a particular species, known as a foundation species, “that’s probably a very important one to keep,” and conservation efforts should be focused on saving it, says Ali.

Her interest in plant-pollinator networks came about through a “serendipitous meeting” with professor emeritus Peter Kevan, School of Environmental Sciences. He is part of the Canadian Pollination Initiative (CANPOLIN), a network of Canadian universities and government agencies looking at declining bee populations. Of all the researchers in the group, “I’m the only statistician,” says Ali. Kevan was looking for someone who could develop a statistical model to illustrate the relationships between plants and pollinators. Ali also works with CANPOLIN’s European counterpart called Status and Trends in European Pollinators.