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We’ve known for a long time that sexual selection—ultimately caused by differences in gamete size—can produce marked differences in the appearance and behavior of males versus females within a species. Often males are more ornamented than females, with bright colors and long feathers or ornaments on the head.  We also know that colors and ornamentation of males puts them at a disadvantage in certain respects, as they are more easily detected by predators than are the females, or have difficulty flying because of exaggerated feather displays. This disadvantage also applies to sexually-selected “weapons” like deer horns and moose antlers, which are shed and have to be regrown, at great metabolic expense, each year.

Perhaps the most famous of these features is the tail of the peacock, in which males have long, decorated, and spreadable tails that females lack.  We are pretty sure that this difference is due to sexual selection because experiments show that the “eyespots” on the male tails attract females: the more eyespots you have, the higher chance you have of reproducing. Thus the genes for exaggerated tails accumulate via sexual selection by females.

Of course female preference plays a key role here, as that preference has to exist to give more elaborate males a reproductive advantage.  We don’t fully understand, however, exactly why females prefer many exaggerated male traits. In some cases, like the orange-red color of the male house finch, we have an answer.  As I said, there are also costs of sexually-selected male traits like big bodies (elephant seals) or antlers (moose), who use them to directly fight for access to females. (Darwin called this the “law of combat”.)

But in most cases we don’t understand why females prefer certain bright colors or long tails, though we have theories that are largely untested. This difference in patterning and color was called “the law of beauty” by Darwin, who was the first person to suggest the idea of sexual selection (1871).

Both forms of sexual selection show that this type of selection—really a subset of natural selection—involves tradeoffs.  Males sacrifice flight ability, become more obvious to predators, and have to re-grow antlers and horns each year, which are considerable disadvantages. But those have to be more than compensated for by either the success in combat or the increased attractiveness to females of males with those traits—otherwise the exaggerated traits would not have evolved.

A new paper in Biology Letters (click title screenshot below) shows a novel form of tradeoff in pheasants, and the first such tradeoff known in any animal. In two species of pheasants, males have evolved “capes” around their neck that, when expanded, occlude the male’s visual field (but not the female’s), as well as head feathers that also appear to block the male’s vision.  These are sexually selected traits.  Noticing them, the five authors hypothesized the tradeoff: in the two species of pheasant with head and neck ornamentation (the Golden and Lady Amherst pheasant), they tested whether the male’s head feathers blocked part of his visual field compared to females in the same species.  As a control, they used two pheasant species (Silver pheasants and Green pheasants), in which males don’t have head ornamentation that would block the visual field.

The authors then measured the visual field of males and females of all four species, and, lo and behold, males of the Golden and Lady Amherst’s pheasants did have a considerable blockage of the vertical field of vision compared to conspecific females, while there was little or no difference between the sexes in the two control species.

Click the title below to read the original paper for free, or find the pdf here. There is also a brief précis piece in Science if you want the abridged version.  The quotes and figures below come from the original paper, while the six full-bodied photos of the pheasants come from Wikipedia (credits shown).

First, the birds.

A male Golden pheasant, Chrysolophus pictus:

Bjørn Christian Tørrissen, CC BY-SA 3.0, via Wikimedia Commons

. . . and a female Golden pheasant. The sexual dimorphism is bloody obvious.

Photo produced by David Castor (user:dcastor)

The heads of males (l) vs. females (r) of the Golden Pheasant, taken from the paper itself. You can see how the male’s head feathers could occlude its vision.

The one other “experimental” species with male vision-occluding feathers.

Male Lady Amherst’s pheasant, (Chrysolophus amherstiae):

Sylfred1977, CC BY-SA 3.0, via Wikimedia Commons

A female Lady Amherst’s pheasant:

Lencer, CC BY-SA 3.0, via Wikimedia Commons

And one of the two control species, the Green Pheasant, (Phasianus versicolor). First, a male, with vision not impeded by a crown. (The other control species, the Silver pheasant, Lophura nycthemera, isn’t shown.) Both of the control species show sexual dimorphism of color and plumage in the expected direction, but there are no feathers on the male’s head that could block his vision.

Alpsdake, CC BY-SA 3.0, via Wikimedia Commons

And a female:

Alpsdake, Alpsdake, CC BY-SA 3.0, via Wikimedia Commons, via Wikimedia Commons

How did they measure the visual field of males and females? They simply put the pheasants in a padded box and fixed their heads firmly so that they could not move. (No pheasants were harmed in this study, which is excellent.) Then, to measure whether an eye could see at a certain angle, they shined a light on the eye. If there was a reflection from the retina at the back of the eye, that meant the bird could see the light from that angle. By performing many tests at various angles around the head, the researchers were able to judge the field of vision of each bird. They could also do this in pheasants whose heads were tilted up or down (see below).

The differences were most pronounced in the vertical line of sight. For example, as shown below, when the head is horizontal or looking down,  the male of the Golden pheasant sees 30° less above his head than does the female.  This would be a problem because, as the authors say, “Sexually selected traits such as feather ornamentation of male birds can act as an impediment to movement and predator detection.”  When you’re a male pheasant busily foraging on the ground, which is how they eat, you may not see an approaching predator. That is the cost of the sexual selection that produced head and neck feathers. (The figure says this is a Lady Amherst’s pheasant but it is apparently a Golden pheasant.)

From the paper (Fig 1). Panels (C) and (D) show vertical cross-sections through the binocular fields in the mid-sagittal plane of the head. The head drawings represent typical resting postures for each species, based on photographs of birds observed in aviaries.Panels (I) and (J) display vertical sections of binocular fields when the birds focus on prey items on the ground during foraging

Here are all four species.  The Lady Amherst’s pheasant has an even more severe impediment of vision in the male: he can see vertically a full 40° less than do conspecific females.  In contrast, the sex difference in the control species is much less: a mere 5° reduction in males in the Silver pheasant and no difference in the green pheasant.

(From Fig. 2 of paper): Figure 2. Vertical sections through the binocular fields in the median sagittal plane of the head of four pheasant species. The line drawings of the heads of the birds show them in the approximate orientations typically adopted by the species when at rest, as determined from photographs of birds held in the hand in their aviaries. The left panel shows males and right panel females of (A,B) golden (Chrysolophus pictus), (C,D) Lady Amherst’s (C. amherstiae), (E,F) silver pheasants (Lophura nycthemera) and (G, H) green pheasants (Phasianus versicolor)

The figure below in the paper gives a three-dimensional depiction of a bird’s view, with males on the left and females on the right. You can see that the males are effectively blind (black area) over a much larger space than are the females, and that space is mostly above the bird’s head. Since pheasants are ground foragers, blacking-out of “down” vision would be a very serious impediment, making males unable to locate food. Blocking “up” vision would surely have a smaller cost.

(From paper, Fig. 1): Panels (K) and (L) provide perspective projections of retinal field boundaries from the bird’s own viewpoint, with blind sectors highlighted in black.

The upshot is that the authors’ hypothesis is supported: males but not females in the pheasants having feathers around their eyes appear to have occluded vision, mostly above their heads.  Now we don’t know whether this occluded vision translates into a loss of fitness at all, much less a loss that is outweighed by the gain in fitness caused by the head and neck ornamentation.  Trying to answer questions about fitness is nearly impossible, as you’d have to measure survival and offspring production of males who have bigger and smaller feathers within a species (would you have to give the birds a haircut?). But there is a period of moulting in which males lose their head and neck feathers, and at least researchers could measure the field of vision, and perhaps foraging efficiency, during that period.  Nevertheless, I do suspect that occluded vision reduces fitness, and that the head ornamentation more than compensates for it.

Besides these results, the paper does show how natural selection and adaptation involves tradeoffs.  There are usually no mutations that are “universally” adaptive in that they convey a benefit without any cost. As I said, natural selection will favor the increase in frequency of mutations that produce net reproductive benefits to the individual that outweigh the costs.

We now have about four sets of photos, so I’m even more complacent. But please send in yours if you got ’em. Thanks.

Today we have regular Mark Sturtevant with a collection of insects and one vertebrate. Mark’s IDs and captions are indented, and you can enlarge his photos by clicking on them.

Readers may remember the recent post where I showed pictures of the dual emergence of 13- and 17-year cicadas during a trip to Illinois. I naturally did not take pictures of only cicadas, and so here are many examples of other insects I found in the parks that I visited. The rest will be in a later post.

First up is a banquet scene of ants feeding on a dead beetle. According to iNaturalist, the ants are a good match for Bearded Carpenter Ants (Camponotus subbarbatus). The picture took many hours to prepare since the ants were constantly moving around and the depth of focus would not capture all that I wanted. So I had to manually assemble some parts of most of the ants from different pictures to recover different focal points. Like focus stacking, only without the automated software that does that for you. I also moved some ants around to improve on the composition. For example, the one on the far left wasn’t where it is now. It’s worth clicking to embiggen this picture because jeez, it was a lot of work!!:

Next up are two pictures showing a bucket list item for me. This little beetle is from the Brentidae weevil family, and I was excited to find it since I don’t recall seeing a beetle from this family before. Weevils are divided into multiple families, but Brentid weevils are considered to be a primitive example of the group, identified by their straight snouts and lack of elbowed antennae. This particular species is the Oak Timberworm (Arrenodes minutus). Do you see the little mites? They were probably phoretic hitch-hikers, using the weevil for dispersal:

The grasshopper shown next is called the Green-legged Spur-Throat Grasshopper, Melanoplus viridipes. This small forest grasshopper has vestigial wings, although I don’t know why. Flightlessness in grasshoppers is more typical in large species where flying is not practical. In any case, they were pretty common in the screaming forest (screaming because of the millions of cicadas above), and it was fun stalking them because they are quite wily, moving to the opposite sides of leaves as I approached. But I snuck up on this one from a distance and this is a heavily cropped picture:

A few Lepidopterans are next. This is the caterpillar of the Hackberry Emperor Butterfly (Asterocampa celtis). Emperor butterflies are exceedingly common along forest margins, but the caterpillars are seldom seen (at least to me). Perhaps they are a species that stays hidden during most of the day. I believe this one was parasitized since it was not looking nor behaving normally. Notice the elaborate head ornamentation:

The butterfly in the next picture is the Question Mark (with the great binomial Polygonia interrogationis). They are close relatives of the similar Comma butterflies. Commas have a single white squiggle (a , ) on their hind wings, but here you can see a squiggle and a dot – so it’s a ?.:

This small moth is aptly named the Pale Beauty (Campaea perlata). One can easily recognize moths from its large family, Geometridae. Geometrids rest with their wings held out flat, and they usually have angular wing margins. The larvae of Geometrids are the familiar inchworms, and they have a distinctive way of crawling that probably everybody has seen:

Next is an odd little insect known as a Hangingfly (Bittacus sp.). Hangingflies look like craneflies, but they have four wings rather than two, and they belong to a completely different insect order. They hang vertically like this, but usually with their hind legs dangling free in order to snag small flying insects out of the air:

What is going on in the next picture? This insect is a plant bug in the family Miridae, and this particular species is Hyaliodes vitripennis. Plant bugs are Hemipterans that feed on sap, but the puzzle here are the eggs. They are Hemipteran eggs by the looks of them, but they seem way too big for this insect to have laid. Still, it showed no interest in moving away from the clutch:

Next up is a Hemipteran that is NOT a sap feeder. This was one of about a dozen hatchling Wheel Bugs (Arilus cristatus) that were milling around on some plants, slowly dispersing after emerging from eggs. Wheel bugs are predators, and are our largest species of assassin bug. You can see something of their eventual size and why they are called Wheel Bugs in the linked picture:

Finally, here is a dozy tree frog, quietly waiting out the day deep in the woods. It should be either Dryophytes chrysoscelis, or D. versicolor, but it is fairly impossible to visually tell them apart and their ranges broadly overlap. If the former species, then it is diploid with conventional pairs of chromosomes. But if it is the latter species, then it will be a tetraploid with four of each chromosome:

Jerry can most definitely correct me here, but this is one way in which a new species can emerge quite rapidly because once a fertile tetraploid population is established, any hybridization between tetraploid individuals and their diploid ancestors will produce triploid offspring, and these are generally sterile.

JAC:  Yes, Mark is right. An increase in ploidy can cause instantaneous reproductive isolation, and is in fact fairly common in plants.  One issue is how a tetraploid species (which could arise from the union of a diploid sperm and egg, or chromosome doubling after fertilization) can actually establish a population.  That usually requires that the new tetraploid species can occupy a different habitat from the progenitor diploid species, for if it’s outcompeted by the progenitor, then there is no ecological isolation and the tetraploid could be “hybridized to death”.

What can an ancient supernova teach scientists about Earth and celestial objects? This is what a recently submitted study to Astronomy & Astrophysics hopes to address as a team of scientists investigated the interaction of the remnants of supernova that occurred 10-million years ago with Earth. This study has the potential to help scientists better understand how Earth is influenced by celestial objects and what this could mean for the future of life on Earth, along with potentially habitable worlds beyond Earth.

What can equatorial jet streams on gas giant planets teach scientists about gas giant planetary formation and evolution? This is what a recent study published in Science Advances hopes to address as a team of scientists investigated the mechanisms of jet streams on gas giants (Jupiter and Saturn) and ice giants (Uranus and Neptune). This study has the potential to help scientists better understand not only the formation and evolution of giant planets in our solar system, but exoplanets, too.

A crew of tiny worms will be heading on a mission to the International Space Station in 2026 that will help scientists understand how humans can travel through space safely, using a Leicester-built space pod.

It's obviously not good that people have lost trust in the FDA, NIH, and CDC. However, since those once vulnerable institutions are now lead by naked emperors, it's good that the American public, at least those that read the news, has uniformly recognized they have no clothes.

The post Read the Comments: “Just Do the Opposite of Whatever This Administration Recommends!” first appeared on Science-Based Medicine.

Quantum communication is edging closer to reality thanks to a breakthrough in teleporting information between photons from different quantum dots—one of the biggest challenges in building a quantum internet. By creating nearly identical semiconductor-based photon sources and using frequency converters to sync them, researchers successfully transferred quantum states across a fiber link, proving a key step toward long-distance, tamper-proof communication.

Quantum communication is edging closer to reality thanks to a breakthrough in teleporting information between photons from different quantum dots—one of the biggest challenges in building a quantum internet. By creating nearly identical semiconductor-based photon sources and using frequency converters to sync them, researchers successfully transferred quantum states across a fiber link, proving a key step toward long-distance, tamper-proof communication.

The discovery of strange, ultra-red objects—especially the extreme case known as The Cliff—has pushed astronomers to propose an entirely new type of cosmic structure: black hole stars. These exotic hybrids could explain rapid black hole growth in the early universe, but their existence remains unproven.

The discovery of strange, ultra-red objects—especially the extreme case known as The Cliff—has pushed astronomers to propose an entirely new type of cosmic structure: black hole stars. These exotic hybrids could explain rapid black hole growth in the early universe, but their existence remains unproven.

Nearly a century after astronomers first proposed dark matter to explain the strange motions of galaxies, scientists may finally be catching a glimpse of it. A University of Tokyo researcher analyzing new data from NASA’s Fermi Gamma-ray Space Telescope has detected a halo of high-energy gamma rays that closely matches what theories predict should be released when dark matter particles collide and annihilate. The energy levels, intensity patterns, and shape of this glow align strikingly well with long-standing models of weakly interacting massive particles, making it one of the most compelling leads yet in the hunt for the universe’s invisible mass.

Nearly a century after astronomers first proposed dark matter to explain the strange motions of galaxies, scientists may finally be catching a glimpse of it. A University of Tokyo researcher analyzing new data from NASA’s Fermi Gamma-ray Space Telescope has detected a halo of high-energy gamma rays that closely matches what theories predict should be released when dark matter particles collide and annihilate. The energy levels, intensity patterns, and shape of this glow align strikingly well with long-standing models of weakly interacting massive particles, making it one of the most compelling leads yet in the hunt for the universe’s invisible mass.

We now have two more batches of photos in reserve, so I’m feeling complacent (but not happy, which is a rare event!).  If you have good wildlife photos, please send them in.

Today’s photos of fungi come from Rik Gern of Austin, Texas. Rik’s captions are indented, and you can enlarge his photos by clicking on them.

 Here is the first of several batches of pictures of mushrooms taken in northern Wisconsin last September.

The first seven photos are of Mica cap mushrooms (Caprinellus macaceus), so called because the caps appear to be covered with what look like small grains of salt. Like a lot of mushrooms, they grow in clusters on rotting wood. Their soft colors gave the collection a very autumn-like feel.

One of your contributors recently experimented with black and white, and that inspired me to do the same with the last two in the series (photos 6 and 7).

The remaining three pictures are of oddly-shaped fungi. They’re not nearly as common as the mushrooms, but they’re hard not to notice.

The first one is a peeling puffball (Lycoperdon marginatum), and the one that follows is a White coral fungus (Clavulina coralliodes). The puffball must be very young, because the surface turns darker with age and eventually crumbles off, exposing a brown surface.  The Peeling puffball and the White coral fungus were both covered with bits of the soil from which they had recently emerged, but I used Photoshop to remove the schmutz and create idealized images of both fungi:

Unfortunately, I could not identify the final image below, but since there are a lot of deer in the area I’m calling it “Antler fungus” until a better name comes along:

 

Quickie with Bob: Helion Fusion Update; News Items: CRISPR Wheat Sources Nitrogen, LLMs and Collective Intelligence, Origins of Theia, Holiday Scams, Hypervelocity White Dwarves; Who's That Noisy; Your Questions and E-mails: Cellulose Correction; Science or Fiction

How can star populations help astronomers re-evaluate the search for intelligent extraterrestrial life, also called technosignatures? This is what a recently submitted study hopes to address as a team of scientists investigated the parameters of identifying locations of technosignatures, also called extraterrestrial transmitters. This study has the potential to help astronomers constrain the criteria for finding intelligent life in both our galaxy and throughout the universe.

ETH Zurich scientists have found the holy grail of brewing: the long-sought formula behind stable beer foam. Their research explains why different beers rely on different physical mechanisms to keep bubbles intact and why some foams last far longer than others.

What can star variability—changes in a star’s brightness over time—teach astronomers about exoplanet habitability? This is what a recent study accepted to The Astronomical Journal hopes to address as a team of scientists investigated the interaction between a star’s activity and exoplanetary atmospheres. This study has the potential to help astronomers better understand how star variability plays a role in finding habitable exoplanets, specifically around stars that are different from our Sun.

Young stars buried deep in molecular clouds are bathed in ultraviolet radiation, but they shouldn't be. Protostars are too cold and dim to produce UV light themselves, yet James Webb Space Telescope observations of five stellar nurseries in Ophiuchus reveal its unmistakable signature affecting the surrounding gas. Astronomers tested the obvious explanation that nearby massive stars illuminate these birthplaces but subsequently ruled it out. The UV radiation must be coming from inside the star forming regions themselves, forcing a fundamental rethink of how stars are born.

What is the importance of studying explosive volcanism on Venus? This is what a recent study published in the Journal of Geophysical Research: Planets hopes to address as a team of scientists investigated the potential altitudes of explosive volcanism on Venus. This study has the potential to help scientists better understand the present volcanic activity on Venus, along with gaining insight about its formation and evolution and other planetary bodies throughout the solar system and beyond.

Scientists have long tried to uncover the perilous journey humans took to reach the ancient land mass that now makes up Australia. Now, a genetic study has edged us closer to understanding how and when they achieved this