Niches

Bugs and Maps

We got a little rain relief last night, 0.29 inches, about twice what Athens got. Meanwhile I've been watching evapotranspiration climbing as the trees leaf out and the temperatures rise. ET has climbed 20-fold in the last month, from a winter's end of usually 0.01" to 0.20" most dry days now. We hardly dare but to skirt around the issue, since there are surely those that but they understood it would suggest that cutting down trees might be a solution to the problem of water reserves. Fortunately them ones are none too bright.

I've been good about letting dragonflies sit in photo folders, but I have to let this one out now. In fact, there are two of them, both individuals spotted on the same day about a thousand feet apart.

If this is a Twelve-spotted Skimmer, Libellula pulchella, then it's new for me and adds to the collection of Libellula.

I like the deep chocolate brown coloration. The twelve spot designation is obvious - three dark brown blotches on each of the four wings.

I'm guessing that the individual above, and this one below, to both be females, although I am not looking at the terminal appendages. I'm going by the new word, "pruinescence", that I learned at bugguide. Pruinescence is the appearance of pigment atop the old which imparts a frosted appearance, and it usually occurs in males as they mature. Common whitetails are great examples of this, but the Libelluidae also sport this trait, and this species shows it as additional frosty white spotting on the wings. So these are either females or immature males.

If you go to google and click on the maps tab, then zero in on your location, you'll probably be presented first with a terrain map (if not, click on that tab). Why should you do that? Because these are very neat, and surely everyone should know their terrain!

Here's the immediate area between Wolfskin Road and Black Snake Road that shows our current property in yellow (very roughly). The contours show that it's situated on the southeast slope of a large hill, and straddles the hollow through which SBS Creek flows. The added blue is Goulding Creek, at the 600 foot contour above sea level. Within the yellow is the house at about 650 feet, and northeast of the yellow is an elliptical peak that marks about 700 feet. As you're driving (or biking) along Black Snake Road, you can look southeast and see the rise of the substantial hill of which we're a part.

The orange boundaries include versions of the property we're considering purchasing. That little contour loop at the north end marks the "deck" that has been featured lately.

A larger view of the area including west Oglethorpe County, in the right 2/3 of the image, and the eastern portions of Clarke (Athens) and Oconee Counties at upper left and lower left, respectively. I think it's particularly neat how the terrain south and east of Wolfskin Road is much more rugged that that north of Hway 78. That's the bicycling area, and by that you would know it even if you hadn't seen it here first.

And finally, an even larger view that now includes Athens at upper left, Watkinsville at lower left, and more of the north and southwest portions of Oglethorpe County (right half).

Three New Box Turtles

Yesterday's walk, a good bit earlier than usual, took me to the deck, that open area of the property we're trying to negotiate, and then back by way of the knoll that sits up to the north of the house. GIGO:

I cheated a bit on the knoll photo above - I shot obliquely into the morning sun so that the contrasts were exaggerated, but it really is that vibrant. The cool season grasses are thick and luxurious and I'm sure I know people who are screaming to get out the mower. But no: walking through the grass disturbs large numbers of tiny moths and other insects. Tiny moths mean tiny caterpillars, and these both serve as food for arthropod and tetrapod predators up the food web, and I'm thinking that that is all to the good. Right now I hear a multitude of the latter expressing their deep appreciation of our forebearance in the matter of mowing.

The visit to the deck was mainly for taking another look at the buckeyes for the developmental abnormalities I mentioned yesterday, but I did admire the Appalachian Ragwort that is coming up through the grasses.

You'll recall that several years ago I decided to document the box turtles that wander the property. None of these gets a name until a second observation, and that's only happened once, with Sylvia, a delightful re-encounter indeed. The last couple of box turtle discoveries have been of inexplicably dead animals, so I was pleased to find one on May 4, and then two yesterday, all happily feeding. None of these resembles the previous finds, and so they're numbers 9, 10, and 11 (neglecting the dead ones). My last find on Sep 4 of last year was the second of only two living turtles spotted in 2007, so this is already a good season!

I'm not sure about including the first one, since it was found across Goulding Creek on the bank opposite the confluence of SBS Creek and Goulding. However, this one may range back across the creek, so I'll keep it.

This one had a very slight concavity to the plastron so it may be a male, but I'm going with female. If so, then we have documented four males and seven females (living).

Nice red markings on the legs! And a few documentary thumbnails.

The next two were found yesterday morning, and I'm wondering if this was just coincidence or if they were more out and about in the early morning.

This female was nestled down in the litter eating some disgusting soft gray thing. She was halfway up the west slope from SBS Creek, fifty feet downstream from Troll Rock. A very oddly shaped turtle!

And another female, this time with red eyes, which are usually considered male characteristics. Her plastron says otherwise. She too, was engaged in a messy breakfast. I found her just above Goulding Creek on the shady floodplain north of the deck area.

Weird Buckeye

Glenn was examining yesterday's collection of buckeye leaves when he found something a little interesting.

To the left is a photo of a normal bract on the branch of a buckeye. In buckeyes, the leaf is palmately compound, with 5-7 leaflets radiating from a central petiole. In painted buckeye both the first leaf and the young inflorescence emerge from the bud. The bracts are a pair of leaflike organs that cover and protect the bud that contains the developing shoot. When spring arrives, the bracts open up and the new leaves expand. Bracts, like leaves, are terminal organs - they don't develop into anything else or act as a source of new growing points. Once their role in protecting the new shoot is over, they senesce and fall off.

You can see how the bracts function in the photo below. They're the curly reddish pair attached to the old twig of last year, and though the new leaves are now greatly expanded you can see how they fit within the enclosure made by those bracts.

But look closely at the tips of the bract at center.

There is a tiny, but perfect palmately compound leaf emerging from the tip of the bract. (This is also true for the other bract in the pair.) Looks like the bract itself is a bit abnormal, more swollen, thicker, and curlier than the normal bract in the first photo.

Glenn suggests that the bract or a patch of cells on the bract have been redefined to act as a petiole. The petiole is the stemlike structure that connects the stem to the blade of a leaf and it will also enclose all the plumbing, the xylem and phloem, that nourishes the leaf blade. Here the bract, or a part of it, seems to be acting as a petiolar source, thereby producing leaves, like a petiole normally does.

This is not necessarily a genetically transmittable mutation; we'll have to go back to look at the plant that produced this branch to see if all the bracts look like this. It is a developmental abnormality, but it could have been produced by environment. Temperature, disease, and other insults can cause one organ to develop as another. Or it might be a somatic mutation in a cell that led to the formation of this pair of bracts, but which mutation has not made it into the germ line that produces pollen or egg. Or, and this would be the jackpot, it might be a mutation that is also included in the gametes and then it would be genetically transmissible.

Mutations that produce changes in body parts fall into the group of homeotic mutations. Homeotic mutations cause identity changes in organs, since body shape is defined by homeotic genes. A part that would normally develop into one organ instead develops into another, so you get the peculiar classic examples of legs growing out of the head of a fly, instead of the proper antennae.

Since mutations in homeotic genes redefine body parts, they're avidly studied. Homeotic genes were first discovered and mapped out thoroughly in animals, and in particular the fruitfly Drosophila, with its enormous collection of spectacular mutations. But the same strategy of using homeotic genes to make a body and to define body parts is also employed in plants, though by a set of genes that is not homologous to that in animals.

And, in plants as well as in animals homeotic mutations have been isolated to map out and understand how the plant body is formed. Mutations in one homeotic gene may convert a petal into a sepal, or a sepal into a leaf. And so a host of such floral mutations in the model mustard plant Arabidopsis thaliana has been exploited, as in fruitflies and other animals, to unravel the molecular genetics of flowering, called the ABC model of floral development.

In plants, homeotic mutations have been unwittingly used as sources for crop and floral varieties. Brocolli and cauliflower, both forms of the species Brassica oleracea, are homeotic mutants that cause inflorescences to arrest and proliferate into chubby edible structures.

Or take cultivated roses, for instance. Cultivated roses have multitudes of petals, but the family Rosaceae is characterized by five petals and many stamens, the male flower parts. Where did all the extra petals come from? The extra petals in the cultivated rose derive from conversion of stamens into petals, and if you look at the innermost petals in the center of a rose you'll probably see some stamens that seem to be halfway in between being a petal and a stamen.

As for this particular buckeye abnormality, even if it is a transmissible mutation it doesn't look to be a very successful experiment. The tiny leaves are already rather parched, and seem to have stopped developing as the supporting tissue of the bract senesces and prepares to fall off.

Dragonfly and Buckeye Hybrids

Something a little different from last year - barred owls are asserting their existence. Yesterday, walking along Goulding Creek about noon, I heard one calling very close by. And just now, taking a little break from writing, one just over the hill toward our neighbors and another farther away, were vociferously warning each other off.

Perhaps you'll forgive yet another dragonfly if I tell you that I've refrained from posting a large number of Absolutely Beautiful Photographs of previously blogged cruisers and clubtails. Or maybe not, but nonetheless here is another one.

My trip yesterday took me to the dry, sunny deck area, which has seemed to net a different complexion of odonates, and introduced me to this one:

It appears to be Libellula auripennis, Golden-winged Skimmer. There is another possibility in Needham's Skimmer but the black legs in this one suggest the former.

Two things: first, the very broad side stripe, unlike the broken segment patterns of so many other dragonflies, perplexed me. And the yellow-white stigma, which is dark-colored in most other dragonflies, was also striking.

A couple of other enlargements accentuating the focus along different planes - the wings in the left thumbnail, and the abdomen in the right one.

Here are two additional observations of dragonflies in the genus Libellula, in the Common Skimmer family Libellulidae. At least I hope they've been properly identified:

15 July 2007: Slaty Skimmer, L. incesta, along with Common Sanddragon, Progomphus obscurus.

27 May 2006: Blue Skimmer, L. vibrans.

On to something a bit different that we're just beginning to investigate: "Preliminary Observations on a Possible Cline of Hybrids between Aesculus flava, Yellow Buckeye, and A. sylvatica, Painted Buckeye."

I've noted for the last few years the flowering in the early spring of our resident Painted Buckeye, a small shrub, generally a meter tall or so, that enjoys the moist, shady understory along the steep slopes close to the little SBS Creek. On 20 March 2008 I posted a photo of the emerging leaves and inflorescence.

I resurrected this previously unposted photo of one typical shrub from April 12 of this year, and it links to a closeup of the inflorescence:

A little more data from earlier posts:

16 April 2006 full flower.

20 April 2005 full flower.

Now for the odd part. All those early flowering shrubs are now making fruits here and there (successful fertilization is not a common event), but there are two other populations of buckeyes that are just now flowering. AND they are occurring in two distinctly different areas. One is in the same locations as the early flowering plants, intermixed with them. The other is a thousand feet away and in quite a different environment.

Here is one such specimen, photographed yesterday, nearly a full month after the early-flowering population was photographed.

One thing unusual about this is that it is 50 feet above the usual elevation for the buckeyes we've been calling "painted", it is quite large, 2 meters, and it's not unique - this area has a great many specimens, some much larger. And it's in full sun at an elevation and in an environment that is quite dry. Having attempted some transplants I can at least tentatively say that seed-grown, potted individuals from the shade-loving populations will not survive transfer to drier, sunnier locations.

So we seem to have three populations: one is what we surmise to be "pure" A. sylvatica, growing in the proper shady moist conditions and flowering early.

The other two populations flower a month later. One resembles the "pure" sylvatica population in terms of size and moist/shade preference. The third population of late-flowerers has individuals that are much larger and grow in sunnier, drier conditions.

We suspect that the third population is actually A. flava, Yellow Buckeye, and that the second population is a hybrid between the two species. The hybrid retains the sylvatica shape and preference for moist shade, but has the flava late flowering. Glenn has done an examination of the floral and vegetative characters of some samples I brought back. He suggests that the dry sunny population itself may be a hybrid form, selected for those conditions, in which case those individuals have the flava sun/dry tolerance along with late flowering, but are intermediate in size. He's identified some characters that we can measure as we move from one location to the other. In all this we're wondering: where is the *fourth* population, the original "pure" A. flava?

I should add, quickly, that it's well known that various Aesculus species readily hybridize, and some are even sold as hybrids, selected for appearance. The flava x sylvatica hybrid is known as Aesculus x neglecta. But Red Buckeyes, A. pavia, also hybridize with A. flava, called Aesculus x hybrida, and with A. sylvatica, called "Harbisonii". Throw in Ohio Buckeye (which we don't have here, probably), A. glabra, and you have even more hybrids.

But this natural experiment in hybridization and selection by environment is kind of neat. In addition, it extends the period of time in which heavily nectar-producing tubular flowers are available for the hummingbirds, and I've actually heard them buzzing about in the last couple of days, down in the hollow.

Sunny Insects

I did another tour of the possible land extension yesterday, a hike that if properly undertaken requires a couple of hours to complete. My route takes me from one end of the crude mowed road that connects two fields, one at the south end, and one at the north end, and the things that go on there are completely different from the happenings in the lower, moister, shadier areas.

At the south field, I thought this might be one of the heavy hummingbird mimics at first, but no - it turned out to be a cluster of Variegated Fritillaries, Euptoieta claudia. And not just a pair, but up to five. In this photo you can just barely make out a third individual underneath the lower one.

All three are clearly visible here, the one topmost with wings aflutter. These photos were all taken at 1/200 second exposure, which was fine in the bright sunlight. I've taken to doing that whenever possible now, insisting on the short exposure time, and adjusting the ISO if necessary to keep the aperture small (high 1/f number) for depth of field.

Even 1/200 second isn't sufficient to freeze the wings.

Both of these fields are heavily disturbed, with the earth compacted by the tree cutters and harvesters of ten years ago. But the variety of tough grasses and perennials (currently Golden Ragwort) is surprisingly great. This north field, near Goulding Creek and overlooking it by 40-50 vertical feet, was being patrolled by a number of dragonflies that I had not seen before.

This beauty seems to be one of the common skimmers, a Tramea, or Saddlebags, perhaps a Carolina saddlebag or a red saddlebag.

I'm going mainly by the extraordinary vista of brown pigmentation on the hindwings close to the body, which probably gives the name "saddlebags". It really sets off the wing venation, which is itself multicolored from white above the brown spread to reddish brown along the leading edge of the hindwings.

I saw the first Ebony Jewelwing, Calopteryx maculata, a coupla of weeks ago but now they're very abundant. They've appeared on this blog every year, and who can resist adding another nice female with a pretty green face and thorax?