(May 2014) 2. The Beak of the Finch: A Story of Evolution in Our Time, Jonathan Weiner
"On a desert island in the heart of the Galapagos archipelago, where Darwin received his first inklings of the theory of evolution, two scientists, Peter and Rosemary Grant, have spent twenty years proving that Darwin did not know the strength of his own theory. For among the finches of Daphne Major, natural selection is neither rare nor slow: it is taking place by the hour, and we can watch."
"On a desert island in the heart of the Galapagos archipelago, where Darwin received his first inklings of the theory of evolution, two scientists, Peter and Rosemary Grant, have spent twenty years proving that Darwin did not know the strength of his own theory. For among the finches of Daphne Major, natural selection is neither rare nor slow: it is taking place by the hour, and we can watch.
In this dramatic story of groundbreaking scientific research, Jonathan Weiner follows these scientists as they watch Darwin's finches and come up with a new understanding of life itself. The Beak of the Finch is an elegantly written and compelling masterpiece of theory and explication in the tradition of Stephen Jay Gould."
Those amazing and confusing Spring flowers
Flowers are of course some of the most beautiful objects within Nature's realm and they can be considered at a number of emotional and intellectual levels. If one thinks simply of the amazing variations in color and form, flowers can be perceived purely in terms of these aspects without any thought given to how or why they may look like this. There is nothing wrong with this "child-like" appreciation of flowers or nature in general, although it usually leads to a gradual accumulation of knowledge about natural patterns that are observed, and thus a more intellectual approach that involves some directed study. You might argue that asking questions about flowers might diminish their wonder, but I think it is actually the opposite. The more one learns about natural objects, the more fascinating and remarkable they become.
For example in walking around our farm in this glorious Spring-time I am struck by the diversity in form and color of flowers and what this might mean to their function. To take just three examples which are in bloom at this moment in early May, consider the "flowers" of the Fraser magnolia, the cranberry viburnum, and the ox-eye daisy (see attached photos). I put "flowers" in quotes to indicate that these flowers differ considerably in their structure. The magnolia is a very large single flower. The viburnum contains a group of flowers which are not equal- the large white flowers around the edge are sterile and are apparently designed to attract insects to the small fertile hermaphroditic flowers in the center. The familiar daisy (a composite) is a complex group of a large number of flowers which are specialized to produce either ray/petal or disc flowers; but the overall effect is that one is observing a single flower! You can see how these could represent an evolutionary sequence from the more primitive (magnolia) to the more advanced (daisy).
So what is a flower? It is simply a reproductive structure whose sole function is to propagate the species. The wonder lies in the incredibly complex forms and variations in patterns of growth, pollination and seed dispersal. Does the exhilarating riot of color and form exist only because of the eyes of insects and birds with color vision who will pollinate the flowers and disperse the seeds? Probably so, but we can consider ourselves fortunate that we are descended from primates with color vision who needed to be able to distinguish between ripe and green fruits and to distinguish leaf color.
Bill Dunson
Galax, VA & Englewood, FL
The Io moth & caterpillar- some amazing natural designs
On a nature walk this morning at Stump Pass State Park in Englewood, FL, our group came across two caterpillars of the Io moth (see photo). At this stage they are a striking light green, with a red and white stripe along their sides. The younger caterpillars are brown to orange-brown. Although we were tempted to pick this beautiful green caterpillar up, I knew that this species has poisonous spines that can cause a lot of pain. One might assume that the green coloration is for camouflage, although it is so bright that it might even be considered a warning coloration along with the red/white stripes. The branched, poison-bearing spines pack a powerful jolt to any potential predator.
Strangely enough it was about three years ago that I saw the adult of this strange moth at our farm in Galax, VA. The unusually colored adult moth appeared on a window screen one morning where it must have been drawn to the lights the night before (see photos). With the wings closed the moth is cryptic in the right background and would presumably escape detection by most predatory birds. If it is detected and is poked, it opens its wings and reveals a marvelous set of false eye spots (see photo). Many moths have eye spots on their hind-wings that mimic an owl's face or just provide something scary for a bird to think about. But the Io moth has what I consider the most impressive set of eye spots. But even so I am amused that a bird would find this intimidating.
One again we can be amazed by the evolutionary process that can lead to the development of such a remarkable pattern. The variety of animal coloration is a never ending source of wonder.
Bill Dunson
Englewood, FL & Galax, VA
A tiny legume destroyer- the Genista moth
Another one of those things that go on in our backyards without much notice is the occasional destruction of plant leaves by small caterpillars. Sometimes we get annoyed by this and spray the plants or try to figure out what is happening. In recent walks in scrub habitat at Lemon Bay Preserve I have noticed that many of the beautiful sky blue lupines, which are not yet in bloom, are being heavily damaged by a small caterpillar (see photo attached). I was unfamiliar with this species and searched the web to find out that it is well known as a destroyer of various legumes, including lupine and members of the genus Sophora which includes necklace pod in Florida.
The rest of the story is that this caterpillar is immune to the powerful toxins found in legumes, and indeed uses these poisons to defend itself against attacks by predators. If this reminds you of some other famous cases think about monarchs and milkweeds, and zebra butterflies and passion-vines. So here is another case of a larval insect stage making itself toxic by eating a poisonous plant. Consider what this means- that the ability to tolerate the toxins must have evolved over a very long period, and then coloration advertising the toxicity (aposematic or warning coloration) developed. Then predators must recognize the significance of the warning coloration, perhaps specifically or generically. Some predators such as lynx spiders apparently can handle the toxins and eat the caterpillars
Now the adult is distinctively colored (see photo from web) but I do not know if it is protected also.
So if we needed reminding that the natural world is amazingly complex and interesting, here is another case. The deeper we look the more we see, and the more impressive the web of life becomes. So get out there and groove on nature but don't eat the caterpillars!
-Bill Dunson, Englewood, FL
A tale of 2 "nutty" butterflies- the buckeyes
Lemon Bay Preserve in southern Venice, FL, is an interesting place for many reasons, but it has some remarkable butterflies illustrating the role of habitat differences in speciation. For example during a nature walk there yesterday we saw a mangrove buckeye butterfly in a tidal area sitting on some saltwort (see photo). The name is a bit strange since the buckeye tree does not occur here; the tree is named for its large brown nuts which somewhat resemble the eye of a deer/buck. Indeed this butterfly does have 6 distinctive eye-spots, likely useful in deterring predatory birds. Buckeye butterflies often sit in open areas with their wings spread, allowing an observer to admire their unusual coloration. What really excites me about buckeyes at Lemon Bay Preserve is that there are actually two different but closely related species there, the mangrove and common buckeyes. The other photo shows a common buckeye that I found there on another day. If you look carefully you will notice some subtle but distinctive differences between these two sibling species.
The common has lighter or even white borders to the large eye-spot on the fore-wing; in addition the two eye-spots on its hind-wings are much more different in size than in the mangrove buckeye. While these differences are clear, they are not so striking that it is that easy to recognize them in the field.
So what is going on here? How can two closely related species co-exist in the same area without competing? The common buckeye is by far the most widespread in N. America (larvae feed on gerardia, toadflax & plantain) whereas the mangrove buckeye, as its name indicates, is primarily limited to the sub-tropical tidal coastline, and its caterpillar feeds mainly on black mangroves. This situation illustrates one mechanism by which new species originate- habitat specialization within one species splits off a separate species. Whereas speciation normally requires considerable geographic separation, the degree of isolation here is very small and due to juxtaposition of two distinctively different habitats (saline mangroves and adjacent uplands). Sometimes the argument is made that evolution is hard to observe, but here in our backyard we can actually see the end results among two "nutty" buckeye butterflies!
Bill Dunson
Englewood, FL & Galax, VA