It has been a long, cold spring this year in New England. I’m all in favor of appropriately cold New England winters, of which there have been disturbingly few of late, but isn’t it wonderful when the world comes into bloom again? Blooming early in the spring before the leaves have built up on the trees is a good (and commonly adopted) strategy for wind-pollinated plants because abundant foliage reduces wind speed and can act as an effective but unwanted barrier standing in the pollen’s path to a female flower. Wind-pollinated plants are not the only spring bloomers, however. Many of the loveliest woodland flowers bloom in spring, and most of these are insect-pollinated. Why now? Most insect-pollinated flowers rely on visual cues (and frequently olfactory cues as well), and it may be easier for insects to appreciate the showy colors of woodland flowers before the deep shade of summer sets in.Given the length of the greenless New England winter, it is perhaps not surprising that spring blooms appear to hold a special place in the hearts of many New Englanders. May Sarton, who spent much of her early life near where I sit in Cambridge, describes the slightly manic feeling that arises from the long-awaited release from winter in this excerpt from her wonderfully evocative poem "March-Mad":
It is a naked time that bares
Our slightly worn-down hopes and cares,
And sets us listening for frogs,
And sends us to seed catalogues
To bury our starved eyes and noses
In an extravagance of roses,
And order madly at this season
When we have had enough of reason.Emerson, transcendentalist extraordinaire and another Massachusetts denizen, had a special fondness for theNew England native rhodendron known as rhodora. In his poem of the same name, he views the spring beauty of the rhodora flower as a link between man, nature, and the divine.
In May, when sea-winds pierced our solitudes,
I found the fresh Rhodora in the woods,
Spreading its leafless blooms in a damp nook,
To please the desert and the sluggish brook…
Rhodora! if the sages ask thee why
This charm is wasted on the earth and sky,
Tell them, dear, that if eyes were made for seeing,
Then Beauty is its own excuse for being:
Why thou wert there, O rival of the rose!
I never thought to ask, I never knew:
But, in my simple ignorance, suppose
The self-same Power that brought me there brought you.And with that, I’m heading outdoors to enjoy some of the New England spring myself.
# Posted by Amity Wilczek on 5/31/03; 5:36:44 PM - Comments [0]
It’s not necessarily just that boys die more easily, however. For instance, sex ratios in excess of 4 infant boys to 3 girls were documented for the "upper strata" of European society in the early part of the century (a trend that is not explained by post-birth infanticide). We know that male conceptuses (that is, fertilized eggs that may or may not go on to produce successful embryos) are more common than female conceptuses, but not in this wretched excess. So what’s going on? Are daughters more vulnerable when times are good? It seems a logical question, but as far as I know it has not been studied. In general, the mechanism by which human mothers "choose" the sex of their unborn offspring remains shrouded in mystery.
We’ve known for a long time that baby boys (in humans) are much more delicate than baby girls. In hard times, infant boys prove much more vulnerable. This can cause sex ratios to be skewed towards females. Evidence is accumulating that the increased male vulnerability can extend back into the womb, as this recent study of mothers in Ethiopia confirms, so fewer boys are born to malnourished mothers.
In antechinuses, small Australian marsupials (shown above), mothers get to make very obvious, active choices about the sex of their offspring. Like many marsupials, antechinus babies crawl out of the womb and into the pouch very early in development. These very small babies then attach to a teat, and most of their development and growth takes place in their mother’s pouch. Antechinus moms frequently produce more babies than they have teats. Mothers pick off and eat the extras that are either too slow or undesirable for other reasons. Sounds gross, but it’s a good way to perform a quick quality check before investing a lot more in inferior offspring when you could be giving resources to really good kids. Mothers are also very picky about the sex of their offspring, and this is in part related to their odd lifestyle. Fertile males live a single year, while females frequently live and breed for two (or rarely three). Each year a frenzied mating period occurs in which males compete violently for females. While only the bigger males successfully mate, all males die during or immediately following their (literally) massive testosterone fest. In this system, there’s not much point in investing in small sons who are unlikely to win a mate. Old – that is, second year – mothers almost never produce sons. First year mothers usually produce either no sons or lots of sons depending on (do you sense a trend yet?) how healthy they are themselves.
Thankfully for our delicate sensibilities, in humans both the mating rituals and the process of offspring sex ratio adjustiment are a whole lot more subtle.
# Posted by Amity Wilczek on 5/29/03; 5:13:56 PM - Comments [0]
At lengths of up to 40 feet, the colossal squid is the largest squid ever observed. In fact, according to New Zealand squid specialist Steve O'Shea the colossal squid is "not just larger but an order of magnitude meaner" than the giant squid. What an order of magnitude of mean looks like has always been a mystery to me, but to O’Shea it apparently looks something like the 25 or so unusual, sharp, nasty hooks that adorn each of the colossal squid’s tentacles. Even without the extra grip from hooks, squid and octopuses can accomplish some pretty spectacular pull with their arm suckers. Many, many years ago I wrestled with a hookless, cat-sized octopus myself at Catalina’s Institute for Marine Research (CIMI), and I was amazed at the force that the altogether squishy-looking creature mustered up in order to keep its hold on me.
This year two extreme sea creatures were discovered – the colossal squid, Mesonychoteuthis hamiltoni, and the smallest known species of pygmy seahorse, Hippocampus denise.
The new record holder for smallest seahorse, Hippocampus denise, was actually familiar to scientists already. However, these little seahorses had always been mistaken for babies of another, described species, a misconception that continued until biologists noticed that some of the supposed babies were actually minute (15 millimeter) pregnant males. Say what? Yes, I did say pregnant males. Male seahorses have special pouches on their bellies into which the female deposits her eggs with, you guessed it, an extensible organ that she pokes into his tummy. The male incubates the eggs in his swollen brood pouch and nourishes them until they hatch. Despite what the press may declare, males in the animal kingdom at large are frequently care-givers, and in egg-laying animals dads are often the parents who guard the eggs once they’re fertilized. It is, however, unusual for moms to put their eggs directly into a male. That truly is an unusual role reversal.
It’s wonderful to think that even after so many decades of concerted exploration by professional naturalists, there are still new creatures being discovered at a respectable rate. Unfortunately, our rate of discovery is far outmatched by our known rate of destruction of already existing species…"Below the thunders of the upper deep;
Far far beneath in the abysmal sea,
His ancient, dreamless, uninvaded sleep
The Kraken sleepeth: faintest sunlights flee
About his shadowy sides; above him swell
Huge sponges of millennial growth and height;
And far away into the sickly light,
From many a wondrous grot and secret cell
Unnumber'd and enormous polypi
Winnow with giant arms the slumbering green.
There hath he lain for ages, and will lie
Battening upon huge seaworms in his sleep,
Until the latter fire shall heat the deep;
Then once by man and angels to be seen,
In roaring he shall rise and on the surface die."
The Kraken by Alfred Lord Tennyson
# Posted by Amity Wilczek on 5/20/03; 6:45:26 PM - Comments [0]
On a personal note, it’s my father’s birthday today. This serves to remind me how fortunate I am to have grown up with the tremendous support I received from both my scientifically-oriented parents. My father is a constant source of inspiration both because he is so brilliant (you don’t need to take my word for it -- check out his long list of honors and this marvelous essay he recently wrote, to begin with) and because he is never bored or boring. He is endlessly curious. I’ve been astonished to find that this kind of curiosity is sadly lacking among many eminent scientists, who enjoy affirmation over challenge. But, thanks to my dad’s example, I have learned that encouraging others to share their knowledge need say nothing about the depth or paucity of your own understanding. Truly a great inheritance!As for my equally inspiring mother, you can hear from her in her own words at her blog.
# Posted by Amity Wilczek on 5/15/03; 7:59:19 PM - Comments [1]
Moon in Earth's shadow
photo by Fred Espenak
www.mreclipse.comDon’t forget to look up at the skies tonight. If you look up between about 11pm and 12 pm tonight (if you live on the east coast), you’ll be treated to a total lunar eclipse. If it’s cloudy, you can go here to see live webcasts of the eclipse.
# Posted by Amity Wilczek on 5/15/03; 7:55:10 PM - Comments [0]
Creature Feature: Rocky Mountain Locust
Locusts were a major problem for American farmers in the 19th century (you may recall Laura Ingalls Wilder’s vivid account of a locust swarm in "On the Banks of Plum Creek"), but you’re unlikely to hear about locust plagues in the U.S. today. Why? The major pest species of North America is no more. Like its North American compatriot, the passenger pigeon, this once outrageously abundant social animal has gone extinct since the arrival of European settlers.
The Rocky Mountain locust amassed a swarm 1,800 miles long and 110 miles wide in 1875. The very last living specimen ever documented in nature was caught in 1902. If jumbles of dead bugs are your thing, however, you can still find the locust in great abundance in the glaciers of Montana and Wyoming.
What many people don’t realize about locusts is that their swarming behavior is actually quite unusual. Locusts are just grasshoppers gone awry. When certain grasshopper species get too crowded, they (or their offspring) develop differently into a swarming variety that looks remarkably unlike the uncrowded (grasshopper) form of their own species but a lot like the swarming (locust) forms of other species. Shortly after the migrating hordes have decimated all plant life, they once again return to their unassuming grasshopper morphology and can stay that way for many generations. It’s often been a long time before people recognized that the solitary and swarming forms of a grasshopper are representatives of the same species. In the case of the Rocky Mountain locust, both forms are known. So unfortunately, it’s not the case that we’ve managed to tame the nasty locusts and keep them in their placid grasshopper state. They’re gone.
Will the farmers miss the locust? Despite the loss of a common source of humor and commiseration, probably not. (Farmers still have plenty to commiserate about.) And while I don’t go in much for plagues myself, I’m nonetheless a little sad.
# Posted by Amity Wilczek on 5/1/03; 6:26:15 PM - Comments [0]
Seeing wings in a different light
Forest-dwelling butterfly
Heliconius cydno
Left wing under regular light
Right wing showing polarized iridescenceTwo closely related species of butterfly respond differently to females depending on the light conditions. The forest-dwelling butterflies appear to use polarized light to find mates. Meadow-dwelling butterflies, on the other hand, don’t.
In the forest environment, light intensity is patchy and it may be difficult to see wing coloration caused by pigments. Polarized signals from wing iridescence may show up more clearly in these kinds of environments. So will we see a general pattern in which species of butterflies that occur in meadows are more colorful but species in forests are more iridescent? That would be a nice confirmation of this hypothesis.
If you’re curious about polarized light, light scattering, and iridesence, you should check out this beautifully illustrated website devoted to the science of color. Heck, check it out anyway.
# Posted by Amity Wilczek on 4/30/03; 6:16:34 PM - Comments [0]
Wallace McAnulty with his
54lb grass carp.Frequently when an alien invader (read introduced plant or other pest, in this case) becomes noxious, people are inclined to bring in predators or parasites that eat the invader in its native area in the hope of sorting things out. Sometimes this works. Frequently it doesn’t. And then, just to make things a little more risky, people occasionally decide to introduce instead things that might possibly be interested in eating the invader (but don’t necessarily do so anywhere else in nature). The difficulty in both cases is figuring out how to control the second introduced species so that it doesn’t run rampant after it’s dealt with the unwanted pest.
At Lake Austin in Texas, locals have decided to bring in a massive fish – the grass carp – to clear up a truly nasty, introduced water weed that has been choking favorite swimming areas and spreading rapidly. Weighing in at up to 400 lbs, the grass carp is a fast-growing, greenery-eating machine.
This may sound like a recipe for ecological disaster, but the state of Texas thinks it has its bases covered. How is that? Texas only allows the introduction of genetically modified grass carp that are certified triploid (that is, having three complete sets of chromosomes instead of the usual two). Unlike mammals, many fish and amphibians seem to be perfectly happy with extra sets of chromosomes until it comes time to make eggs and sperm. Then the odd chromsome composition mucks things up. The triploid fish are therefore healthy plant-munchers but will never make any baby fish.
Disaster averted? Well, maybe. There are many different triploid fish known as gynogenotes that have figured out how to reproduce asexually as all-female species. Gynogenotes avoid the problem of odd chromosome composition by a weird, alternative strategy of egg production in which sperm from their own species are not needed to produce baby fish. Even some carp species are able to do this! Is this deviant stategy likely to spring up in the triploid grass carp? Probably not, but nature is wild and mysterious…I for one wouldn’t like to be the biologist encouraging their introduction.
# Posted by Amity Wilczek on 4/27/03; 5:23:40 PM - Comments [0]
Creature Feature: The Mimic Octopus
It’s not unusual for harmless species to mimic nasty ones in order to trick their predators…but it is unusual for an animal to mimic any of a number of nasty species depending on its mood. Nonetheles, that’s what biologist and octopus expert Mark Norman claims to have found in this Indonesian octopus. It mimics a poisonous sea snake, a poisonous flatfish, or a poisonous lionfish (pictured above – both the actual fish and the octopus) as it pleases. You can check out still photos at National Geographic, or see some beautiful quicktime movies of the octopus in action. No matter whether or not you buy the mimicry story, the octopus's ability to rapidly, dramatically alter its appearance is nonetheless a spectacular feat.
# Posted by Amity Wilczek on 4/24/03; 6:58:24 PM - Comments [1]
My Favorite Mutant: Polydactyly in Cats
Polydactylous cats have attained a certain fame for the large colony of feral cats in the Florida Keys that was established by -- or at least credited to --Hemingway.
This delightful creature is Bombadil, my polydactylous cat. He looks as though he has two paws (one large and one small) on each of his front feet. These paws are semi-opposable, and he does use them to grasp objects.
Polydactyly, or the presence of extra toes, is typically inherited in a predictable fashion. If you have a parent cat with too many toes, about half of that cat's offspring will have too many toes too. Although common in domesticated cats, it has also been documented in large, wild cats.
Polydactyly, or the presence of extra toes, is typically inherited in a predictable fashion. If you have a parent cat with too many toes, about half of that cat's offspring will have too many toes too. Although common in domesticated cats, it has also been documented in large, wild cats. Polydactylous cats have attained a certain fame for the large colony of feral cats established by -- or at least credited to --Hemingway in the Florida Keys.
You may notice that Bombadil also has two differently colored eyes. Less is known about the genetic basis of being "odd-eyed," as this condition is known. However, odd-eyed cats are always white. Curious.
While Bombadil is a very odd cat, his brother (who also lives with us) is a conventional tabby cat with no extraneous toes.
# Posted by Amity Wilczek on 4/24/03; 6:42:02 PM - Comments [0]
This Page was last updated: Saturday, May 31, 2003 at 5:36:44 PM
This page was originally posted: 5/31/2003; 5:36:44 PM.
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