Sunflowers with different UV bullseye patterns as we see them (top) and as a bee might see them (bottom). Credit: Marco Todesco, Author provided
Flowers are one of the most striking examples of diversity in nature, displaying myriad combinations of colors, patterns, shapes and scents. They range from colorful tulips and daisies, to fragrant frangipani and giant, putrid-smelling corpse flowers. The variety and diversity is astounding—consider the duck-shaped orchid.
But as much as we can appreciate the beauty and diversity of flowers, it is quite literally not meant for our eyes.
The purpose of flowers is to attract pollinators, and it is to their senses that flowers cater. A clear example of this are ultraviolet (UV) patterns. Many flowers accumulate UV pigments in their petals, forming patterns that are invisible to us, but that most pollinators can see.
The disconnect between what we see and what pollinators see is particularly striking in sunflowers. Despite their iconic status in popular culture (as testified by the arguably dubious honor of being one of the only five flower species with a dedicated emoji), they hardly seem the best example of flower diversity.
However, when looked at in the UV spectrum (that is, beyond the type of light that our eyes can see), things are quite different. Sunflowers accumulate UV-absorbing pigments at the base of the ligules. Across the whole inflorescence, this results in a UV bullseye pattern.
In a recent study, we compared almost 2,000 wild sunflowers. We found that the size of these UV bullseyes varies extensively, both between and within species.
The sunflower species with the most extreme diversity in the size of UV bullseyes is Helianthus annuus, the common sunflower. H. annuus is the closest wild relative to cultivated sunflower, and is the most broadly distributed of wild sunflowers, growing almost everywhere between southern Canada and northern Mexico. While some populations of H. annuus have very small UV bullseyes, in others, the ultraviolet-absorbing region covers the whole inflorescence.
When we compared sunflowers with different UV bullseyes, we found that pollinators were able to discriminate between them and preferred plants with intermediate-sized UV bullseyes.
Still, this doesn’t explain all the diversity in UV patterns that we observed in different populations of wild sunflowers: if intermediate UV bullseyes attract more pollinators (which is clearly anadvantage), why do plants with small or large UV bullseyes exist?
Other factors
While pollinator attraction is clearly the main function of floral traits, there is increasing evidence that non-pollinator factors like temperature or herbivores can affect the evolution of characteristics like flower color and shape.
We found a first clue that this could also be the case for UV patterns in sunflowers when we looked at how their variation is regulated at the genetic level. A single gene, HaMYB111, is responsible for most of the diversity in UV patterns that we see in H. annuus. This gene controls the production of a family of chemicals called flavonol glycosides, which we found in high concentrations in the UV-absorbing part of ligules. Flavonol glycosides are not only UV-absorbing pigments, but play also an important role in helping plants cope with different environmental stresses.
A second clue came from the discovery that the same gene is responsible for UV pigmentation in the petals of the thale cress, Arabidopsis thaliana. Thale cress is the most commonly used model system in plant genetics and molecular biology. These plants are able to pollinate themselves, and therefore generally do without pollinators.
Since they don’t need to attract pollinators, they have small, unassuming white flowers. Still, their petals are full of UV-absorbing flavonols. This suggests that there are reasons not related to pollination for these pigments to be present in the flowers of the thale cress.
Finally, we noticed that sunflower populations from drier climates had consistently larger UV bullseyes. One of the known functions of flavonol glycosides is to regulate transpiration. Indeed, we found that ligules with large UV patterns (which contain large amounts of flavonol glycosides) lost water at a much slower rate than ligules with small UV patterns.
This suggests that, at least in sunflowers, patterns of floral UV pigmentation have two functions: improving the attractiveness of flowers to pollinators, and helping sunflowers survive in drier environments by preserving water.
Thrifty evolution
So what does this teach us? For one, that evolution is thrifty, and if possible will use the same trait to achieve more than one adaptive goal. It also offers a potential approach for improving cultivated sunflower, by simultaneously boosting pollination rates and making plants more resilient to drought.
Finally, our work, and other studies looking at plant diversity, can help in predicting how and to which extent plants will be able to cope with climate change, which is already altering the environments they are adapted to.
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NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
