The study of flowers with two types of onions solves the mystery of Darwin.
Some flowers use a clever strategy to ensure effective pollination by bees by gradually removing pollen from two different ancestral collections.
Most flowering plants depend on honey pollinators, such as bees, to transfer pollen from the male stems of one flower to the female stigma of another flower, enabling fertilization to produce fruit and seeds. However, bee pollination implies a typical conflict of interest, as bees are only interested in pollen as a food source.
“The bee plant has different purposes, so plants have developed ways to optimize bee behavior to maximize the transfer of pollen between flowers,” said Kathleen Kay, an associate professor of evolutionary biology at UC Santa Cruz.
In a study published on December 23 Scientific Bulletin of the Royal Society B.Kay’s team described a pollination strategy involving flowers in two distinct collections that differ in color, size, and position. Darwin was ridiculed for such flowers, noting in a letter that he “put a lot of effort into them, he still can not understand the meaning of the parts.”
For years, the only explanation for this phenomenon, called post-piracy, was that a collection of homeless people specialized in attracting and feeding bees, while a less obvious collection of homeless people secretly pollinated them from pollen to move to another flower. This hypothesis of “division of labor” has been tested in various forms, although it seems to be used in several cases, but many studies have not been able to confirm it.
The new study offers another explanation և shows how it works in wildflower species ClarkiaThrough a variety of green field փորձ field experiments, Kay’s team demonstrated that consistency Clarkia is a way for the flowers to gradually introduce their pollen to the bees during multiple visits.
“What happens is the horns open at different times, so the plant gradually provides pollen to the bees,” Kay said.
This “pollen dosing” strategy is a way for bees to move to another flower without stopping to collect dust from their bodies, to pack it, and to bring it to their nest. Bees are very specialized in feeding pollen. They have hairs on their body that electrostatically capture pollen, for stiffening, stiff legs, կառույց structures that hold pollen on their legs or body.
“If a bee flower is the size of a ton of pollen, the bee is in the pollen sky, it will start to gather and then go to feed its offspring without visiting another flower,” Kay said. “So plants have different mechanisms for gradually removing pollen. In this case, the flower hides some cattle, gradually reveals them to pollinators, it limits what honey a bee can extract during each visit.
There are about 41 species Clarkia In California, about half of them have two types of homelessness. These tend to be pollinated by specialized species of native lone bees. Kay’s team focused on two types of bee pollination Clarkia, C. unguiculata: (elegant Clarkia) և: C. cylinders: (spotted clarkia).
In these other inappropriate Clarkias, in the center of the flower stands the homeless vortex, which is visually conspicuous, maturing quickly, first releasing its dust. The invisible murmur on the outside is against the petals until the inside is perfectly open. After that, the outsiders move to the center of the flower and gradually release their pollen. After a few days, the stigma becomes vertical and sticky, ready to receive pollen from another flower.
“In the field you can see flowers at different stages, միջոցով through photography we could see the whole sequence of individual flower events,” Kay said.
The division of labor requires that the two perfect groups produce pollen at the same time. Kay said he decided to investigate by looking at Clarkia flowers in the field, realizing that explanation was inappropriate. “I could see some flowers where one collection was active, some where the other collection was active, but no flowers where both were active at the same time,” he said.
Inside C. cylinders:, the two perfect collections produce different colored pollen, which allowed researchers to trace where it goes. Their experiments have shown that the powder of two onions is collected for food, “transferred to the flowers”, contradicting the hypothesis of division of labor.
“The color difference was convenient, because otherwise it is very difficult to get back the pollen,” said Kay. “We have shown that bees collect and transport pollen from two types of pollen, so they do not specialize in different functions.”
Kay said he did not realize how much time Darwin had spent in confusion before he began to study it. “He found out so much that it is difficult to find a case when he did not understand,” he said. Darwin was probably on the right track. Shortly before his death, he asked for a seed C. unguiculata: for use in experiments.
Reference. “Darwin’s disturbing cunning. A new version of why some flowers have two types of animals “Kathleen M. Kay, Tania ge inspiration, Diana Tataru Ա Sami Akiba, December 23, 2020. Scientific Bulletin of the Royal Society B.,
DOI: 10.1098 / rspb.2020.2593:
In addition to Kay, the paper is co-authored by postdoctoral fellow Tania Ge երկու, two UCSC students, Diana Tatarun, and Sami Akiba. Both students completed their senior theses and received support from the UCSC Norris Center for Natural History.