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This spring, Postmedia’s Tom Spears looks at what makes our not-quite-warm, not-quite-cold season tick. It’s a series we call The Science of Spring, and today we catch up with an Ottawa biologist on a quest to figure out why one of our local wildflowers can’t decide which kind of pollen to produce.
Trout lilies bloom all through the forest in early May, soaking up sunshine as fast as they can before trees get their leaves and cast shade on the forest floor.
They’re funny little flowers, getting their name from the mottled leaves that look like a speckled trout. The flower is sunny yellow.
But there’s a quirk: The pollen ranges from yellow (the most common colour in flower species) through all shades of orange to deep red. This has been recorded for a very long time. But the “why” aspect of pollen colour remains a mystery.
Biologist Emily Austen, a postdoctoral fellow at the University of Ottawa, has been hunting for ways in which pollen colour might help a flower, publishing results recently in a journal of the Ottawa Field-Naturalists’ Club.
So far, the results are a bit frustrating:
• First she asked: Does one colour attract bees and pollinating flies better than another?
No. Austen spent 25 patient hours at six sites watching insects fly up to a flower. The 378 bees and flies didn’t have any preference at all.
• What about beetles that eat pollen?
Nope. She put 68 beetles into cages and let them choose a flower. A few more picked yellow than red, but the difference was not statistically significant. She writes that “the remaining 24 opted out of the experiment,” sitting stubbornly on the cage wall or floor.
• Maybe, she thought, the red pigment acts as a sunscreen to protect pollen against ultraviolet light?
No again. She messed around with UV-B light and petri dishes and filters, but found no difference in damage from the light.
“It may be that the answer lies in some function not yet considered,” she concludes. Then again, pollen colour may just be a genetic blip that is “blinking in and out of populations” but which neither helps nor hurts the plant.
But Austen isn’t giving up yet, and this spring she is chasing another recently-proposed theory, the idea that red pollen may work better than yellow. She has carefully applied pollen one colour at a time to some 80 flowers in Gatineau Park and more than 100 in her native New Brunswick, and tied tiny mesh bags around each plant to keep bees from pollinating them as well.
(Note to anyone walking along the Sugarbush Trail in Gatineau Park: Please leave the bags. These are science, not discarded wrappers.)
She will return in June and measure how well each flower has produced fruit.
But we had to ask her: Why? Why do all this work to find out what makes pollen red in one place and yellow in another?
The answer all comes down to understanding reproduction.
“I’m an evolutionary biologist,” she said.
“One of the fundamental questions we answer is: Why do we have so much variation in the world? If natural selection is a force that is pushing a population toward a fitness optimum, then how do we keep variation within a population?”
Variation is often key to survival. A species with varied individuals can adapt to changing conditions.
Trout lily flowers have a male phase for a couple of days, when they produce pollen. Then the anther (the part with the pollen) shrivels up and the same flower enters a female phase for a few days when it receives pollen and can be fertilized.
Trout lilies are also called dogtooth violets, but in fact they are in the lily family.
Austen also asks people to go online and report their local trout lilies and their pollen colour. She has a site set up: https://troutlilysurvey.wordpress.com.
Apart from science interest, she likes the cheerful little trout lily and other early flowers (including trilliums) known collectively as “spring ephemerals.”
“After a long winter in Canada it’s nice to get outside and see those guys. They were one of the first plants that I learned to identify. Everything in the spring forest is really distinct, so it’s a good entrance to botany.”
tspears@postmedia.com
twitter.com/TomSpears1
查看原文...
Trout lilies bloom all through the forest in early May, soaking up sunshine as fast as they can before trees get their leaves and cast shade on the forest floor.
They’re funny little flowers, getting their name from the mottled leaves that look like a speckled trout. The flower is sunny yellow.
But there’s a quirk: The pollen ranges from yellow (the most common colour in flower species) through all shades of orange to deep red. This has been recorded for a very long time. But the “why” aspect of pollen colour remains a mystery.
Biologist Emily Austen, a postdoctoral fellow at the University of Ottawa, has been hunting for ways in which pollen colour might help a flower, publishing results recently in a journal of the Ottawa Field-Naturalists’ Club.
So far, the results are a bit frustrating:
• First she asked: Does one colour attract bees and pollinating flies better than another?
No. Austen spent 25 patient hours at six sites watching insects fly up to a flower. The 378 bees and flies didn’t have any preference at all.
• What about beetles that eat pollen?
Nope. She put 68 beetles into cages and let them choose a flower. A few more picked yellow than red, but the difference was not statistically significant. She writes that “the remaining 24 opted out of the experiment,” sitting stubbornly on the cage wall or floor.
• Maybe, she thought, the red pigment acts as a sunscreen to protect pollen against ultraviolet light?
No again. She messed around with UV-B light and petri dishes and filters, but found no difference in damage from the light.
“It may be that the answer lies in some function not yet considered,” she concludes. Then again, pollen colour may just be a genetic blip that is “blinking in and out of populations” but which neither helps nor hurts the plant.
But Austen isn’t giving up yet, and this spring she is chasing another recently-proposed theory, the idea that red pollen may work better than yellow. She has carefully applied pollen one colour at a time to some 80 flowers in Gatineau Park and more than 100 in her native New Brunswick, and tied tiny mesh bags around each plant to keep bees from pollinating them as well.
(Note to anyone walking along the Sugarbush Trail in Gatineau Park: Please leave the bags. These are science, not discarded wrappers.)
She will return in June and measure how well each flower has produced fruit.
But we had to ask her: Why? Why do all this work to find out what makes pollen red in one place and yellow in another?
The answer all comes down to understanding reproduction.
“I’m an evolutionary biologist,” she said.
“One of the fundamental questions we answer is: Why do we have so much variation in the world? If natural selection is a force that is pushing a population toward a fitness optimum, then how do we keep variation within a population?”
Variation is often key to survival. A species with varied individuals can adapt to changing conditions.
Trout lily flowers have a male phase for a couple of days, when they produce pollen. Then the anther (the part with the pollen) shrivels up and the same flower enters a female phase for a few days when it receives pollen and can be fertilized.
Trout lilies are also called dogtooth violets, but in fact they are in the lily family.
Austen also asks people to go online and report their local trout lilies and their pollen colour. She has a site set up: https://troutlilysurvey.wordpress.com.
Apart from science interest, she likes the cheerful little trout lily and other early flowers (including trilliums) known collectively as “spring ephemerals.”
“After a long winter in Canada it’s nice to get outside and see those guys. They were one of the first plants that I learned to identify. Everything in the spring forest is really distinct, so it’s a good entrance to botany.”
tspears@postmedia.com
twitter.com/TomSpears1
查看原文...
