Posts Tagged: Science
Reporter Lizzie Wade, Science's Latin America correspondent based in Mexico City, led with: "It started with the best of intentions. When evidence emerged that monarch butterflies were losing the milkweed they depend on due to the spread of herbicide-resistant crops in the United States, people across the country took action, planting milkweed in their own gardens. But a new paper shows that well-meaning gardeners might actually be endangering the butterflies' iconic migration to Mexico. That's because people have been planting the wrong species of milkweed, thereby increasing the odds of monarchs becoming infected with a crippling parasite."
Wade pointed out that "tropical milkweed—at least when planted in warm environments like southern Texas and the U.S. Gulf Coast—doesn't die back in the winter like native milkweed does. When presented with a place to lay their eggs year-round, many monarchs don't bother making the trip to Mexico at all." Some think the year-round tropical milkweed is "an even more direct threat to the butterflies. Milkweed hosts a protozoan parasite called Ophryocystis elektroscirrha (OE). As caterpillars, monarchs ingest the parasite along with their normal milkweed meals, and when they hatch from their chrysalises they are covered in spores."
She quoted a butterfly scientist as saying that infected monarchs are much weaker than their healthy counterparts and don't live nearly as long. And if an OE-infected monarch tries to migrate, it will probably die long before it arrives in central Mexico, she wrote.
Shapiro has been monitoring and studying populations of butterflies in central California for more than four decades and posts the information on his website. In an email response to inquiries from a UC Master Gardener and Farm Advisor (initially sent my way), wrote: “The story is basically correct, but there has to be more to it. Monarchs are normally in 'reproductive diapause' in winter, which means their sex organs and sex drive are inactive; this condition (as in migratory birds) is believed to be induced by seasonal day-length changes. We never used to get attempted winter breeding. Tropical milkweed has been in gardens in California for decades, but only very recently are we seeing attempted winter breeding, first in Southern California and now in the Bay Area. Many of us would like to understand why these animals are NOT in diapause! There have been unexplained changes in the seasonal geography of monarch breeding: for example, here in the Sacramento Valley, there is now virtually no spring breeding (as before) but tons of fall breeding (which didn't use to happen; the animals migrating coastwise were generally in reproductive diapause)."
The reference to OE is correct, Shapiro said. "However, there is an easy 'fix' that nobody talks about for some reason: just cut the plants to the ground a few times a year. This will encourage new growth, which will be cleaner, prettier, more nutritious, and uncontaminated with OE. There is nothing inherently 'bad' about winter breeding if it's clean. Infected winter breeding is a population sink. The animals are often too feeble to fly, and may be unable to expand their wings. But perfectly healthy ones are being produced right now in the East Bay on clean plants."
Many of the public comments that people posted about the research, Shapiro said, show a large amount of ignorance. “Observation: the commonest eastern (Asclepias syriaca complex) and Californian (A. fascicularis) milkweeds are usually almost if not quite non-toxic, which means the monarchs that feed on them will be edible to birds. If you want to breed monarchs as bird food, by all means plant those! But if you want to breed nasty monarchs that will make birds vomit and never try one again, plant one of the more toxic species! There is no good evidence that the females discriminate between high-and low-cardenolide milkweeds, or that larvae do better on one than on the other. There is no garden equivalent of "one size fits all." You want to use species that make sense where you are located! That's what gardening 'zones' are there for...The genus Asclepias extends south to Argentina (the s-most species, A. mellodora, is the major host of the South American Monarch, Danaus erippus) so yes, there are milkweeds in Mexico…. There are so many resources readily available, but people are lazy, don't know how to search properly, or prefer to create their own 'facts' a la Fox News...it gets discouraging. God bless Master Gardeners and Farm Advisers!”
A male monarch nectaring Mexican sunflower (Tithonia). (Photo by Kathy Keatley Garvey)
The times, they change. Standard textbook knowledge, that can change, too.
It did today.
For several decades, few people challenged "the hump-shaped model" developed in the early 1970s by British ecologist Philip Grime who proposed that the number of species rises, then declines with increasing productivity.
Today an international team of 58 ecologists announced that habitat productivity does not predict the diversity of plant species, as previously assumed for several decades.
The groundbreaking research, to be published Sept. 23 in the journal Science (the embargo lifted today at 2 p.m., Eastern Standard Time) shows “no clear relationship between productivity and the number of plant species in small study plots,” said Utah State University plant ecologist Peter Adler, lead author of the paper.
The ecologists sampled 48 diverse grassland sites on five continents in an innovative, unprecedented project partially supported by the National Science Foundation (NSF).
For more than 30 years, the relationship between net primary productivity and species richness has generated intense debate in ecology about the processes regulating local diversity. The original view, which is still widely accepted, holds that the relationship is hump-shaped, with richness first rising and then declining with increasing productivity. Although recent meta-analyses questioned the generality of hump-shaped patterns, these syntheses have been criticized for failing to account for methodological differences among studies. We addressed such concerns by conducting standardized sampling in 48 herbaceous-dominated plant communities on five continents. We found no clear relationship between productivity and fine-scale richness within sites, within regions, or across the globe. Ecologists should focus on fresh, mechanistic approaches to understanding the multivariate links between productivity and richness.
The paper in Science is one of the first to emerge from the research, launched five years ago when the ecologists formed the Nutrient Network or “NutNet,” a cooperative research initiative dedicated to investigating biodiversity and ecosystem processes in global grasslands.
University of Minnesota researchers Elizabeth Borer and Eric Seabloom received funding from NSF to coordinate the network research. NSF also funds an annual meeting workshop in Minneapolis, where the researchers gather to analyze data.
Among the 58 ecologists participating: Louie Yang, assistant professor of entomology at UC Davis.
When asked about the research, Yang commented: “It’s a really innovative approach to ecology. We conducted a coordinated study in diverse grasslands at the 48 sites and we pooled our data together to address some persistent issues in the field. In this paper, we show that plant diversity is not predicted by productivity in any general or simple way; instead, it looks like patterns of plant diversity result from more complex processes which are variable at local, regional and global scales.”
Yang’s research contributions to the network came from a field site at the Sagehen Creek Field Station, located near Truckee in Nevada County. He and Dan Gruner of the University of Maryland have managed a montane or highland meadows site (elevation 6500 feet) since 2007 for their research.
And how did the ecologists measure productivity? Yang talks about this on the UC Davis Department of Entomology website. You'll also want to read what Michael Willig of the University of Connecticut has to say about the paper: Perspective on Biodiversity and Productivity.
Willig begins with: "Researchers predict that human activities—especially landscape modification and climate change—will have a considerable impact on the distribution and abundance of species at local, regional, and global scales in the 21st century."
Meanwhile, we're anxiously awaiting more published research from the Nutrient Network.
This is the research site at the Sagehen Creek Field Station managed by ecologists Louie Yang of UC Davis and Dan Gruner of the University of Maryland. (Photo Courtesy of Louie Yang)
Biodiversity creates biodiversity.
That point comes through loud and clear when you read the scientific paper on the apple maggot/parasitic wasp research led by UC Davis evolutionary ecologist Andrew Forbes.
The news embargo lifted at 11 a.m. today and the research will be published Friday, Feb. 6 in the journal Science.
When the apple maggot shifted hosts from the hawthorn to the apple, that triggered a cascading effect on the ecosystem.
A parasitic wasp (Diachasma alloeum) that attacks the apple maggot (Rhagoletis pomonella) has “formed new incipient species as a result of specializing on diversifying fly hosts, including the recently derived apple-infesting race of R. pomonella,” Forbes said.
The apple maggot, native to
A host race is a group of organisms in the process of becoming a new species due to its close association with a particular host (plant or animal).
In this new study, Forbes and his co-authors showed that the wasp D. alloeum is undergoing the same evolutionary changes.
“The research shows the process of speciation in action and might tell us more about why certain groups of organisms are more diverse than others.” said Forbes, who received his doctorate from the University of Notre Dame and is now a postdoctoral researcher in professor
The research, titled “Sequential Sympatric Speciation Across Trophic Levels,” provides insight into what Forbes calls “the tangled bank of life.”
“As new species form, they create new opportunities for others to exploit which, in turn, begets ever more new species,” he said.
“And all this is happening right before our eyes in our own backyards.”
Forbes captured excellent images of the apple maggot fly and wasp. His image of a wasp emerging from an apple maggot pupa is particularly amazing./st1:personname>/st1:place>
Apple Maggot Fly