The Namaqualand region of South Africa is famous for its stunning landscapes and views.A semi-desert area of rolling hills and valleys, picture sunny skies, beautiful flowers, and grazing antelope. Hidden beneath this tranquil beauty, however, is an intense struggle for survival.
The area is especially known for its colorful flowers, and there’s more to these flowers than meets the eye. Colorful flower petals are a strategic, as they help attract pollinators. The most common type of flowers in this region are daisies, and daisies rely on insects like bees to pollinate them. The more pollinators a daisy can attract, the better.
Brightly colored petals help make the flower stand out against green foliage and make them easier to spot. While this is great for attracting pollinators, it’s also great for attracting the wrong type of attention.
Daises are the perfect snack for many herbivores in the region, like springbok and tortoises. The more visible the flowers are to the pollinators, the more visible they are to these predators, resulting in a trade-off. So how do daisies avoid predators while still attracting pollinators? A new study suggests that these Namaqualand daises might have a novel solution.
In a recent study, Jurene Kemp and Allan Ellis find that daisies may not be as defenseless as we’ve thought. They discovered a common trend of “cryptic petal coloration” among daisies, meaning that the coloration on the petals makes them less noticeable. This type of camouflage is called “visual crypsis”, and while it’s been noted in animals it hasn’t been well studied in plants.
For these daisies, the “cryptic petal coloration” was found on the lower flower petals. Having camouflaged lower petals is helpful because during the early morning and late evening, daisies close their flowers, leaving only the lower petals exposed. The flowers only stay open during the warmest part of the day. This means that for a lot of time when herbivores are active, the flowers only have their lower petals exposed.
The study explored how petal coloration impacted both attractiveness to pollinators and attractiveness to predators. They modeled bee, reptile, and ungulate vision to determine the visual appearance of flowers to both pollinators and predators. They found that the more apparent the flowers were to pollinators, the more apparent they were to herbivores as well. This supports their hypothesis that brightly colored petals attract pollinators, but also put the flowers at higher risk for getting eaten.
In their study, they gave tortoises a variety of different flowers, some open and some closed. Tortoises eat leaves and flowers but have a strong preference for flowers. During the experiment, the tortoises were more likely to eat the flowers when they were open than when they were closed. When the flowers were closed, the tortoises ate randomly, unable to tell the closed flowers apart from the leaves.
The same patch of daisies with the flowers open versus with the flowers closed. Tortoises can’t tell the flowers from the leaves when they are closed.
This indicates that the cryptic coloration on the lower petals acts as an anti-herbivory mechanism. This study opens the door to understanding complex biological trade-offs, and how different species deal with these.
While we may not think of flowers as particularly active, it turns out that petal colors may be an important part of survival strategy. The next time you see beautiful flowers, you’ll know that there’s more happening in those vibrant flower petals than meets the eye.