Homegrown Squash

These heirloom varieties of squash are the literal fruits of my springtime obsession with Cucurbits (the gourd family – almost 1000 species of zucchini, pumpkin, watermelon, cucumber, etc).

This obsession grew thanks to Dr. Lori Shapiro who knows the coolest facts about squash! For instance, before domestication, wild gourds contained bitter toxins. Only megafauna like mammoths could ingest and disperse the seeds of these protected fruits (1). In the Americas, early hunter-gatherers used dried gourds as floats for fishing nets and to hold food and water. They also used fresh wild gourds for the medicinal properties of the bitter compounds (2). The wild gourd (Cucurbita pepo) was the first plant domesticated in the Americas, and the first agriculturalists likely grew them for their nutritious seeds rather than the bitter flesh. Thanks, Lori!

1. Kistler, L., L.A. Newson, T.M. Ryan, A.C. Clarke, B.D. Smith, G.H. Perry. 2015. Adaptive domestication in squashes and gourds. Proceedings of the National Academy of Sciences, 112 (49) 15107-15112.
2. Hart, J.P., R.A. Daniels, C.J. Sheviak. 2004. Do Cucurbita pepo gourds float fishnets? American Antiquity. 69(1) 141-148.

 

Chirpless: Camel Crickets

Camel crickets (Ceuthophilus sp.) enjoy hanging out with humans. Perhaps you provide shelter to some in your garage or basement. These insects lack one major cricket trait though – chirping. Sound production should allow camel crickets to find each other in a dark cave or crawlspace. So, why no chirps?

A Chirp Mystery

One possible reason for the lack of chirps is a high risk of predation. In other species of crickets, those who call more or longer often end up as a snack. ^{1, 2} While I would hope camel crickets are relatively safe from bats and birds in your basement, spiders and mice are the crickets’ major predators. Both possess a solid sense of hearing.

Many crickets have parasites who also seek hosts by sound. Chirps attract female crickets, but they also draw mama parasites searching for a cozy spot to lay eggs. The developing parasitic larvae eat the cricket from the inside, exploding out of its body as they grow. Crickets in areas with these parasites quickly evolve “chirplessness.” Do camel crickets need to worry about these “Alien” chest-bursting scenes? While they do have a doozy of a parasite (an intestinal parasite that weakens the cricket enough to ensure predation), the infections are not related to sound production.

Perhaps camel crickets simply lost their physical ability to chirp. Most crickets produce sound by rubbing their wings together. Camel crickets, though, don’t have wings. In a basement, flying is probably not the most effective means of transportation.

The Scent of a Cricket

So, how do camel crickets find each other without sound? One word: pheromones.

Pheromones are used by many cricket species to indicate dominance, reproductive readiness, and location. Camel crickets release a scent that causes them to congregate. Researchers determined the pheromone is unrelated to reproduction since juveniles move toward the scent too. Nagel and Cade³ think the pheromone prevents camel crickets from drying out. We do know the antennae detect these pheromones. In a rather disturbing experiment, researchers found that camel crickets don’t aggregate when their antennae are lopped off.

 

1. Baily, W.J. & Haythornthwaite, S. (1998). Risks of calling by the field cricket Teleogryllus oceanicus: potential predation by Australian long-eared bats. Journal of Zoology. 244(4) 505-513.
2. Hedrick, A.V. (2000). Crickets with extravagant mating songs compensate for predation risk with extra caution. Proceedings of the Royal Society B 267(1444) 671-675.
3. Nagel, M.G. & Cade, W.H. (1983). On the role of pheromones in aggregation formation in camel crickets, Ceuthophilus secretus (Orthopter: Gryllacrididae). Canadian Journal of Zoology 61(1).

Real Monsters – The Cockatrice

In medieval bestiaries, entries portrayed the cockatrice as a rooster with the tail of a snake. It’s said to hatch from the egg of a cockerel that’s been brooded by a snake or toad. Often interchanged with the basilisk, only a weasel (or Harry Potter) can kill it.

Wow. Crazy, right?  Maybe not so much.

Could poultry grow a snake-ish tail? Considering the evolutionary history of birds and embryonic development, yes. Birds are the last surviving descendants of dinosaurs, and early birds (evolutionarily speaking, not the worm-getting kind) had long tails. Over time, shorter-tailed members of the group prevailed as they flew unimpeded, and with better control, among brush and between branches. Vertebrae that once grew, fused as random genetic mutations delivered more successful flight. Genetically, just a few genes (possibly just one), activated early in development, control vertebral growth and tail elongation (1). So if you can stop that gene from turning on, you might just get a tail.

The second aspect of the cockatrice/basilisk story involved being born from a rooster’s egg. Now, that can’t be true – only hens lay eggs. Well, just like in humans, sex can be confusing. Primary sexual characteristics include sexual organs. In order to lay an egg, the bird would need an ovary. But most people identify hens and roosters by secondary sexual characteristics like coloration, size, and the presence of a comb and wattle. These traits develop because of hormones. If a female bird receives a dose of male hormone, she can produce rooster-like traits. This situation is actually not so rare. Because birds only use one gonad, a disease on the ovary would cause the other to develop. Since testes and ovaries develop from the same structure, the hen could get a dose of male hormone, producing rooster-like traits, and still lay an egg (2).

Brooding by a snake or toad wouldn’t help a chicken egg hatch. However, it’s not unusual to find a snake in a nest. Snakes of course eat eggs, and some birds even use snakes as partners to protect their nests from parasites or rodents.

As for death-by-weasel, the cockatrice/basilisk story is probably getting mixed with a cobra (3). The mongoose, which looks similar to a weasel, has an amazing cellular adaptation that makes them resistant to cobra venom. Many Greek and Egyptian stories (as well as the modern tale of Rikki-Tikki-Tavi) glorify the snake-killing abilities of the mongoose.

So next time you hear of a mystical beast that couldn’t possibly be real, give it a chance. And if you’d like to read more about the cockatrice and its devilish ties, visit awingandaway.

 

1. Rashid DJ, Chapman SC, Larsson HCE, Organ CL, Bebin A-G, Merzdorf CS, Bradley R, and Horner JR 2014. From dinosaurs to birds: a tail of evolution. EvoDevo 2(25)
2. Jacob J and Mather FB. 2000. Sex reversal in chickens. UFL-IFAS. FactSheet PS-53. http://ufdc.ufl.edu/IR00003037/00001
3. Alexander, RM 1963. The evolution of the basilisk. Greece & Rome. 10(2) 170-181.

Bee Bandits

Flowers need bees. A bee’s job is to move pollen from one bloom to another; plants pay for the bee’s service with sweet nectar. Cunningly, some bees have found a way to get a paycheck without the work.

Carpenter bees (Xylocopa sp.) exhibit a behavior called “nectar theft.” Rather than reaching the base of the flower through its opening (and getting a pollen dusting in the process), robber bees bite a hole in the base of the flower to slurp up nectar, bypassing the pollen-yielding anthers entirely.

We can’t necessarily blame them though, as it may be the plant’s own darn fault. Flowers with long tube-like bases are more likely to get robbed since the brawny carpenter bees can’t reach the nectar any other way (1). This relationship may even keep the flower tubes shorter over evolutionary time, since short flowers are more likely to be pollinated (and less likely to be robbed).

In order to deter break-ins, some flowers have evolved thicker flower walls, new toxins, or even special relationships with animal “special forces.” Some tropical flowers produce extra nectar in a special chamber for ants, who act like police in stopping the robber bees (2).

P.S. The bees I watched for this sketch were upstanding citizens – no thievery going on here!

P.S.S. It’s a girl! This bee’s got a black face. Males have a large patch of white on their faces. (http://www.uark.edu/ua/arthmuse/carpbee.html)

1. Navarro L and R Mendel. 2009. Relationship between floral tube length and nectar robbing in Duranta erecta L. (Verbenaceae). Biological Journal of the Linnean Society. 96 (2) 392-398.
2. Gerling D, HHW Velthuis, and A Hefetz. 1989. Bionomics of the Large Carpenter Bees of the Genus Xylocopa. Annual Review of Entomology. 34:163-190.

 

Dinosaur Snowflakes

Want to make your own Dinosaur Snowflakes? (Ok, one is a trilobite, not a dinosaur. But trilobites are just as cool.) Patterns are available online – they’re free!  Enjoy!

I created these patterns for Darwin Day fun at the NC Museum of Natural Sciences. What a great way to celebrate Darwin’s Birthday!

Happy Darwin Day!!!

Barnacles. Not that appealing, right? Charles Darwin probably would have agreed… until he ran into a small problem. He found a new species of barnacle on his trip around the world and couldn’t place it into a taxonomic category. So, Darwin ended up examining, dissecting and analyzing every known species of barnacle, re-ordering the entire crustacean sub-class to figure out where his little guy fit.

It took 8 years… of barnacles… and microscopes. Turns out that Darwin’s newly discovered species (which he politely called “Mr. Arthrobalanus”) was the smallest barnacle in the world. With close and careful observation, Darwin also realized that some species of barnacle, thought to consist only of females, actually housed minuscule males inside small compartments of the feminine form. However, the most influential aspect of such this detailed study was the realization that immense variation occurs within and among species (variation being a key component in natural selection). Those barnacles changed not just biology, but our understanding of the world.

February 12, 2016 is Darwin’s 207th Birthday. Enjoy some cake (and maybe even send some love to Mr. Arthrobalanus)!

 

Interested in learning more about Darwin? I recommend three books: The Autobiography of Charles Darwin,  The Voyage of the Beagle, and Origins: Selected Letters of Charles Darwin (although all of Darwin’s letters can be found online at the Darwin Correspondence Project).

Five Reasons Why This Beetle Should Win the Best Insect Award

I recently ran across this gorgeous beetle while hanging out with writer Scott Huler on his ambitious Lawson Trek. I didn’t know what species it was, but figured it would be pretty easy to ID when I got home (it was). As I began researching this insect, I quickly realized that the Patent-Leather Beetle (Odontotaenius disjunctus) should be nominated for a Best Insect Award.
Here’s why:

1. Great Personality
This very large beetle with scary looking mouthparts won’t hurt you. It rarely flies and it’s a pretty slow walker… so no sudden movements and no buzzing around your head. I like that in an insect. And those horrifying chompers? They’re used to chew through logs, not people. Thank you, evolution.

2. Cool Appearance
Ooo, shiny! Plus, it’s a terrific insect for anatomy practice. First, no microscope needed. Second, that clear-cut case of head, thorax, abdomen? Not so fast. The abdomen-looking structure is actually a grooved set of hardened wings called elytra. And that thorax-looking structure? Well, it is PART of the thorax. The other section is underneath those elytra. Way to keep things interesting!

3. No Sexism
Both males and females contribute to rearing their young and keeping the home safe and tidy. This social structure is not common among beetles (see another post about equality-minded beetles).

4. Ecological Service
Patent-leather beetles don’t just raise their family in logs. They also eat and decompose the wood, recycling nutrients back to the forest floor.

5. Kiss Language
These beetles communicate with each other through a number of different calls. Many calls sound like the noise you make when blowing someone a kiss. Larval patent-leather beetles even have a modified third set of legs that create noises to communicate with parents (“Ma, I’m hungry!” “Watch me, Dad!”)

Want to learn more about the awesome Patent-leather beetles (and hear their kiss-calls)? Here’s a great resource from the University of Florida.

Wildflower Stories: Ast(er)ounding!

Favorite flower? Daisy (an Aster, like these).
Not only is it humble and cute, it’s a bargain. For each daisy you buy, you get hundreds of flowers. The disk part of each “flower” is actually a composite of scores of tiny flowers. Look close – you’ll see.

And the “petals” of a daisy? Each one is actually a whole flower too! The single petal plucked for “loves me” or “loves me not” is actually 5 petals fused over evolutionary time. If you look at the tips, you can still see some divisions.

Here’s another example of an aster – purple coneflower!

Educational Activity: dissect an aster and see all the mini-flowers for yourself!

Roly Poly Irony

What’s the #1 killer of Roly Polies (Armadillidium vulgare)? I’ll give you a few hints… it’s not hungry birds, shoes, or tiny heart attacks.

It’s drowning.

The irony is that Roly Polies are crustaceans (not bugs, millipedes, lice or small organic tanks). Their closest relatives include shrimp and lobster.

Roly Polies like moisture – they retreat to damp areas and burrow underground in case of drought. They roll up as a defense against dehydration (and when you poke them). Ah, the wonders of evolution on land. All this protection against desiccation, but no ability to survive in water.

So now that you know Roly Polies are crustaceans, don’t try to rescue them by putting them back in the sea. We’re about 300 million years too late for that!

SOURCE :Population Characteristics of the Terrestrial Isopod Armadillidium Vulgare in California Grassland by Oscar H. Paris and Frank A. Pitelka
Ecology  Vol. 43, No. 2 (Apr., 1962) , pp. 229-248
Stable URL: http://www.jstor.org/stable/1931979

Oak Scale – Sitting There Like a Tiny Bump on a Log

See that tiny bump on the branch? You’re looking at a mom protecting hundreds of babies. Well, actually, the mama Oak Scale insect (Parthenolecanium quercifex) is dead now, but her exoskeleton is still harboring those little eggs underneath. When those baby Scales hatch around the end of May, the tiny darlings will move out to the oak leaves and begin to SUCK THAT POOR TREE DRY. They sniff out the precious sugar-water flowing through veins in leaves, insert their straw-like mouth parts and drink up. As the year progresses, Scales grow and mate. Mama lays her eggs beneath her and dies, making way for next May’s new generation.
(These are the eggs… um, on my kitchen table. Didn’t realize they’d pop out like that when I lifted the mama Scale off. Oops.)

In the insect’s defense, healthy trees can resist Scale infestations. Some leaves and twigs may fall off – that’s all. But trees that are weakened (by physical damage, drought, chemicals, etc.) can be killed by the insects.

Cool Climate Change research recently found that densities of Oak Scale are up to 13x higher in warm urban areas! (1) Since things are getting toastier here on Earth, we may want to get more familiar with the life & times of the Oak Scale.

1. Meineke EK, Dunn RR, Sexton JO, Frank SD (2013) Urban Warming Drives Insect Pest Abundance on Street Trees. PLoS ONE 8(3): e59687. doi:10.1371/journal.pone.0059687