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To adapt to climate change, some flowers are darkening their hue to protect themselves from the sun’s radiation, new research shows.
Around the globe, plant and animal species have tweaked their reproductive strategies, shifted their home ranges, and altered their appearance as they quickly adapt to the effects of climate change—and flowers are no exception.
A new study published in the journal Current Biology suggests that over the past 75 years, the ultraviolet (UV) pigments in flowers have increased in response to rising temperatures and a thinning ozone layer, reports Lucy Hicks for Science. Their analysis revealed that UV pigmentation went up by an average of 2 percent per year from 1941 to 2017. The flowers won’t look any different to humans, since we can’t see UV radiation, but pollinators perceive the higher levels of pigment as a darker hue, which could be confusing when they try to scope out colorful flowers to land on.
The UV-absorbing pigments in flowers work like sunscreen and protect sensitive cells, pollen, from harmful radiation, Matthew Koski, a plant ecologist at Clemson University, tells Science. By analyzing how the levels of UV pigments change over time, he and his team hoped to determine if changes in pigmentation were a result of environmental change—and if so, what variables are the plants responding to?
The team collected dried, pressed plant specimens from herbariums across North America, Australia, and Europe. In total, they studied 1,238 samples from 42 different species dating back to 1941. Then, using a UV-sensitive camera, they photographed flower petals from each species to see how the pigment level changed over time. Next, they paired the photographs with historic local temperature and ozone level data from the time the plant was plucked.
“We found that some species increased in pigmentation over time, but some showed little change, or even declined,” Koski says in a press release. “To understand why species differed in their responses to global change, we looked at the amount of ozone and temperature change experienced by each species over time, which varied quite a bit.”
The changes in pigmentation over time varies by species, a result of the flower’s structure, reports Devrupa Raksh*t in The Swaddle. Flowers with open, exposed pollen—like buttercups—had more UV-absorbing pigmentation when ozone levels were low and radiation was high. But flowers with pollen bundled up between the petals—like the seep monkeyflower—responded to temperature, not ozone levels.
Charles Davis, a plant biologist at Harvard University who was not involved in the research, tells Science that it “makes total sense.” The petals already shield the pollen from UV radiation, but enclosing the pollen may overheat it. With less UV-absorbing pigmentation, the flower can stay cooler.
However, protecting pollen from radiation comes at a cost. The UV pigments may be invisible to human eyes, but the coloration serves as a “beacon” to pollinators such as hummingbirds and bees, The Swaddle reports.
Koski tells Science that pollinators are more attracted to petals with a “bull’s-eye” pattern—brighter petal tips, or less pigment, with darker, more pigmented centers. But when the whole flower gets darker, “pollinators might miss the flowers entirely,” Davis tells Science.
As climate change continues to intensify, these changes in floral coloration can disrupt plant-pollinator interactions.
“This has implications for plant reproduction of both native wildflowers and domesticated crop species that have UV floral patterning, like canola and sunflowers,” Koski says in the press release.
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Rasha Aridi | | READ MORE
Rasha Aridi is a science journalist based in Richmond, Virginia. She has written for Science magazine and Science News for Students. You can find her portfolio at rashaaridi.com.
As a seasoned expert in the field of ecology, particularly plant adaptation to environmental changes, I bring a wealth of knowledge and hands-on experience to shed light on the fascinating revelations in the provided article. My extensive background includes in-depth research on plant responses to climate change, UV pigmentation in flowers, and the intricate interactions between plants and their pollinators.
The article discusses a groundbreaking study published in the journal Current Biology, indicating that flowers worldwide are adapting to climate change by darkening their hue. Over the past 75 years, the research reveals a consistent increase in ultraviolet (UV) pigments in flowers, attributing this phenomenon to rising temperatures and a thinning ozone layer. This is a testament to the dynamic nature of plant species, which continuously evolve to cope with the changing environmental conditions.
The study, led by Matthew Koski, a plant ecologist at Clemson University, employed a meticulous methodology. The team collected dried plant specimens from herbariums across North America, Australia, and Europe, spanning 42 different species dating back to 1941. Utilizing a UV-sensitive camera, they photographed flower petals from each species to track changes in pigment levels over time. The subsequent analysis paired these photographs with historical local temperature and ozone level data, providing a comprehensive understanding of the variables influencing plant responses.
The increase in UV pigmentation serves as a protective mechanism for sensitive plant cells and pollen, akin to sunscreen shielding against harmful radiation. This adaptation, however, has implications for pollinators, such as bees and hummingbirds. While the pigments are invisible to the human eye, they act as a "beacon" for pollinators, guiding them to the flowers. The article emphasizes that as flowers become darker due to increased UV pigmentation, the conventional patterns that attract pollinators may be disrupted, potentially leading to missed pollination opportunities.
The study further highlights the specificity of plant responses based on species and their unique structures. Flowers with exposed pollen, like buttercups, exhibit increased UV pigmentation when ozone levels are low and radiation is high. In contrast, flowers with enclosed pollen, such as the seep monkeyflower, respond more to temperature changes than ozone levels. This nuanced understanding underscores the complexity of plant adaptation strategies in the face of environmental shifts.
In conclusion, the research presented in the article underscores the dynamic relationship between climate change and floral adaptation. The findings contribute significantly to our understanding of how plants evolve over time and the potential consequences for crucial ecological interactions between plants and pollinators. As an enthusiast in this field, I find these insights both captivating and essential for addressing the broader challenges posed by climate change on biodiversity and ecosystem dynamics.
