Plants that lie to bees and plants that tell the truth.
Much of evolution seems to be a “versus” game. Predators vs prey. Parasites vs hosts. An arms race of run faster, fight harder, resist here, infiltrate there. But there are different kinds of arms races—think of them as nature’s equivalents of putting a daisy in the barrel of a gun—where the race is to cooperate more fully.
One such instance is the game played out between plants and pollinators. Until human gardeners started selected for blooms of certain colors and making crosses to get the features they liked, the brightest, largest, must elaborate, ruffled, frilled, and perfumed flowers on the planet were produced purely out of this ‘soft war’ for the precious services of some creature that would carry pollen.
The signals that plants send in terms of size of flowers and colorful patterns, many of which contain much more explicit patterning in the ultraviolet bands that are visible to some insect eyes, often correlate with a solid payment for service. ‘Over here!’ says the visual or odor-based signal. ‘Come and get it!’ Bees, wasps, ants, beetles, bats, birds, small mammals, or whatever else shows up in response to that signal, are likely to find a sweet reward.
Except some times they don’t. Some plants have all the attractive patterns, the same enticing smells. But pollinators that land on them don’t get less for their efforts than one of Donald Trump’s contractors. There’s a good reason for this on the plant side—making all those sugars to give away is costly. If you can get one of those dumb bees to carry your pollen for no payment at all … so much the better. But of course there’s also a risk with this strategy: What happens when the pollinators learn to ignore your signal? Can they perhaps mimic the signal of a plant that does provide a reward? And what if everyone is lying? And … the race is on.
Plants can send floral signals to advertise their reward for pollinators. Based on the presence or absents of such signals, pollinators can determine whether to visit plants. Plants can send dishonest signals but foraging behaviours of pollinators can limit the cheating strategies of plants. … Pollinators can learn from the interactions with plants and can update their willingness to visit plants’ flowers to maximize their foraging efficiency. We find three general conditions that are required for the evolutionary stability of honest signaling. Those conditions are satisfied if there is (a) a high frequency of high-yield signalling plants in the population, (b) the balance between cost and benefit of signalling, and (c) high cost of dishonest signalling.
Ecosystems that contain too many “dishonest” plants are unstable, because pollinators spend too much of their energy visiting plants that don’t provide a calorie-rich reward. So an area can only support a population of cheats, if most plants are honest. Not only that, but liars have to stay on their (metaphorical) toes, because the pollinators will learn to ignore them.
Let’s just say … 99 percent have to be honest, hard-working plants so the 1 percent of dishonest liars can take advantage of their efforts. The study doesn’t come up with those numbers, but somehow they seem right.
Okay, come on in. Let’s read science!
Biology
Where do little mitochondria come from?
Within (almost) ever cell in your body there are mitochondria. These little organelles are the powerhouses of the cells, converting sugars into energy, and for a long time there has been a prevailing theory about how they got there. Once upon a very, very long time ago, when there was nothing on Earthy but a bunch of very simple organisms like bacteria and prokaryotic algae, a few of these simple organisms formed a partnership. From this grew the first complex, eukaryotic cells.
Mitochondria do seem very like some bacteria. So they’ve been the star attraction of this theory almost from the begining. Other internal cell bits may be baffling, but the mitochondria, hey lookee, those sure are bacteria. But just which bacteria can we call brothers?
Many researchers have pointed at a group called alphaproteobacterial, which contains bacteria that cause such wonderful diseases as typhus and Rocky Mountain spotted fever. These bacteria are mostly intracellular parasites. They already live inside the cells of plants and animals. So it makes sense that some ancient member of this group might have started playing percussion in the early-complex-cell band. Except ...
Here we re-evaluate the phylogenetic placement of mitochondria. We used genome-resolved binning of oceanic metagenome datasets and increased the genomic sampling of Alphaproteobacteria with twelve divergent clades, and one clade representing a sister group to all Alphaproteobacteria. Subsequent phylogenomic analyses that specifically address long branch attraction and compositional bias artefacts suggest that mitochondria did not evolve from Rickettsiales or any other currently recognized alphaproteobacterial lineage. Rather, our analyses indicate that mitochondria evolved from a proteobacterial lineage that branched off before the divergence of all sampled alphaproteobacteria. In light of this new result, previous hypotheses on the nature of the mitochondrial ancestor should be re-evaluated.
Yeah. That was a mouthful. Basically it says that mitochondria didn’t come from any existing group of alphaproteobacterial, but do seem to share a common ancestor with the group. So, tick born diseases are not your long lost sibling — they’re just some third-cousin twice-removed that you can rightfully scorn.
Science Ethics
Playing with cells that someone could be thinking with.
The ethics of experimenting directly with human brains seem pretty cut and dried—though since people have regularly subjected human brains to everything from drugs, electricity, high intensity magnetic fields, and everybody’s favorite, the prefrontal lobotomy, it might seem otherwise. But what are the ethics involved in dealing with brain cells? Cells that aren’t inside a living person, but sitting in a bit of laboratory glassware?
If researchers could create brain tissue in the laboratory that might appear to have conscious experiences or subjective phenomenal states, would that tissue deserve any of the protections routinely given to human or animal research subjects?
This question might seem outlandish. Certainly, today’s experimental models are far from having such capabilities. But various models are now being developed to better understand the human brain, including miniaturized, simplified versions of brain tissue grown in a dish from stem cells — brain organoids. And advances keep being made.
This question actually has a high degree of squidge factor. As in thinking about it makes me say “geeuuu.” Considering that we have such a poor understanding of what constitutes conscious thought, where that thought arises, or what generates a sense of self, it seems reasonable to be concerned about generating a brain mass that’s caught up in one endless, existential scream that boils down to “Oh my creator, I’m a brain in a jar!” On the other hand, the ease with which fully-there human beings give up the conscious thing with a sharp rap to the skull or a couple of Tylenol PMs, it seems that consciousness is a state that requires a pretty good balance of elements. One that’s unlikely to be achieved by a disconnected mass with few sensory inputs.
Still … squidge. It’s a question that has to be asked.
Neurology
Pain vs Hunger … fight!
If plants and pollinators represents a kind of soft war for resources, there are other balances in nature that are a bit less fun to contemplate. In this case: Which wins out? Pain or hunger?
Pain is a pretty loud signal. Though, speaking as someone who once ran a nail completely through his foot and felt zero pain until he looked down and saw that he had run a nail completely through his foot, it’s also more complicated than just touch-nerve, generate scream. Hunger is also a big dog. It’s hard to think about anything else when your stomach seems prepared to start in on other organs if you don’t do something to address that empty feeling.
But what happens when you’re feeling pain and hunger? Who gets top-billing?
Warning: Mice lovers, prepare to be upset.
Alhadeff and colleagues deprived mice of food for 24 hours, and analysed how the hungry animals responded to pain. The researchers found that responses to long-term inflammatory pain — of the type associated with chronic disease and recovery from injury — were reduced in the food-deprived animals compared with controls. By contrast, short-term responses to acute pain that was induced by chemicals, heat or force remained intact in hungry mice.
It’s not immediately obvious that there’s a lot we can do with this knowledge. If you’re starving, you may temporarily forget those achy knees, but will still notice that red hot poker to the (wherever). Great. However, the researchers tracked down the pain-suppressing effect of hunger to neurotransmitters produced by AgRP neurons. So it may be possible to produce pain-mediating medications based on these transmitters, without having to starve to find the benefits.
Thank you for your service, poor hungry, tortured mice.
Flickering lights make imaginary colors.
The idea that stark areas of black and white can make the brain appear to see spots of color can be demonstrated with any number of static “optical illusions.” And simply turning a light on and off very rapidly can also have some interesting effects. The speed and pattern of flashes can change the perceived color. Even when there is no color.
By varying the temporal waveforms of complex flickering stimuli, we can produce alterations in their mean color that can be predicted by a physiologically based model of visual processing. The model highlights the perceptual effects of a well-known feature of most visual pathways, namely the early separation of visual signals into increments and decrements.
The study really focuses on what this says about how humans see, but it’s enough to make it seem possible that there could be some kind of display that actually had only black and white, and simulated all the other colors by varying the flicker rates. Except looking at it might not be all that pleasant.
Genetics and evolution
Spiders in the news.
The combination of genetics and paleontology has kicked off a constant reevaluation and refinement of the “tree of life” for various groups of plants and animals. A new study of spiders even ‘netted’ a mention in the New York Times.
Before evolutionary biologists were using DNA sequencing regularly, the consensus was that the two groups that make different versions of the orb web had a common orb-weaving ancestor.
DNA has complicated that picture, however. In the last few years, Dr. Hormiga’s lab and others have built detailed family trees by sequencing small sections of spiders’ DNA. In these trees, spiders that have similar genetic markers are deemed more closely related to one another than to spiders whose markers are different. In order to have more points of comparison, the team behind the new paper used a more recently developed approach to compare approximately 2,500 genes.
Especially for small creatures that don’t come with handy hard parts that are easily preserved, leaving their fossil records somewhere below “spotty,” genetic patterns are pretty much the only lens we have for how they evolved.
A genetic-evolution ‘moonshot’.
But forget spiders. Or rather, treat spiders as one very small part of a very much larger whole.
A large international group of researchers wants to do a genetic map of everything to find out not just how life evolved within groups, but across groups and kingdoms.
Herein, we present a perspective on the Earth BioGenome Project (EBP), a moonshot for biology that aims to sequence, catalog, and characterize the genomes of all of Earth’s eukaryotic biodiversity over a period of 10 years. The outcomes of the EBP will inform a broad range of major issues facing humanity, such as the impact of climate change on biodiversity, the conservation of endangered species and ecosystems, and the preservation and enhancement of ecosystem services. We describe hurdles that the project faces, including data-sharing policies that ensure a permanent, freely available resource for future scientific discovery while respecting access and benefit sharing guidelines of the Nagoya Protocol. We also describe scientific and organizational challenges in executing such an ambitious project, and the structure proposed to achieve the project’s goals. The far-reaching potential benefits of creating an open digital repository of genomic information for life on Earth can be realized only by a coordinated international effort.
This is one of those things that is Very Cool. I’m looking to get in touch with some of the researchers involved to see what can be done to keep track of the project, interview some of those involved, and also look to see if there are areas in this project where backyard scientists can lend a hand (just mail that interesting polliwog you caught to Earth BioGenome, Dept. “Hey, this looks weird.”)
Drunk biology
Alcohol tolerant beetles.
There really should be a field of “drunk biology.” And there probably is. Only it’s probably Ethanolintoxi… something, something. Drunk biology. Whether it’s deer who get eaten by lions because they were partaking in too many overripe apples, or monkeys who run around the forest seeking out that fruit-buzz, there always seems to be something about animals and alcohol.
Ambrosia beetles are among the true fungus-farming insects and cultivate fungal gardens on which the larvae and adults feed. … Here we demonstrate that ambrosia beetles rely on ethanol for host tree colonization because it promotes the growth of their fungal gardens while inhibiting the growth of “weedy” fungal competitors. We propose that ambrosia beetles use ethanol to optimize their food production.
Rather disappointingly, the beetles do not get drunk. But what they do instead is pretty interesting. They seem to use alcohol to screen out low-quality fungi, preferentially growing their fungal gardens around trees that generate alcohol — even though the trees produce the alcohol to reduce fungi.
So they’re not drunk beetles, they are farmer beetles. And alcohol is the herbicide they use to keep their gardens free of ‘weeds.’ Which is … pretty sober behavior for a beetle.
Exogeology
Looking inside Mars via Mars-quakes.
Pretty much everything we know about what’s happening inside the earth below the depth we can drill a hole, comes from looking at how waves propagate through the planet when an earthquake sends vibrations not just along the crust, but through the mantle and core.
And now we’re about to get the chance to do the same with Mars.
On 5 May, NASA plans to launch its US$994-million InSight spacecraft from Vandenberg Air Force Base in California. The mission’s main job will be to place a seismometer on the Martian surface and listen to seismic waves pinging around the planet’s interior.
Image
This week’s image comes from Andy Brunning at Compound Interest. Visit his site for more informative infographics, and for a larger, easier to read version of today’s image.