A Presentation to the Northern Virginia Chapter
of the Sierra Club
You're members of quite an historic organization. John Muirs' Sierra Club. The organization he helped form in 1892, being the first President and presiding as such for the duration of his life.
How recent we as a nation have settled our country. In just over a hundred years before John Muir's time, in 1775, Daniel Boone had blazed his "Wilderness Road" through the Cumberland Gap. The following year, the town of Boonesboro was formed, just 24 hours after the first shots were fired in Lexington and Concord in 1776.
In 1802, Thomas Jefferson purchased the Louisiana Territory, and the Manifest Destiny movement to "conquer and settle the continent" began.
Trappers roamed the west, making legends of persons like Jedediah Smith and Jeremiah Jones in the 1820's and 1830's. Then came the Missionaries, with the first settlers close behind, lead by the former fur traders.
By the mid 1800''s, the concept of the romantic wilderness began to take hold in the minds of the genteel public, with a national pride generated in the vast unknown lands to the west providing an asset and source of national self-esteem.
And, in 1850, there were 9 billion Passenger Pigeons flying across the heartland of America.
American writers, such as William Cullen Bryant and James Fenimore Cooper wrote of the romantic wilderness, followed by the transcendentalist movement of William Thoreau and Ralph Waldo Emerson. The Hudson Valley artists, led by Thomas Cole and Frederic Church, produced beautiful landscapes of their visits to the untamed west, and a generation of coffee table landscape books became the rage.
Monthly periodicals like Century, Atlantic Monthly, and Harper's Magazine all featured stories about the beautiful wilderness and of those that traveled through these areas. John Muir contributed in this cause with the publishing of fifteen articles
New clubs like the Boone and Crockett Club (started by TDR) and the Sons of Daniel Boone sprung up in the late 1800's. The Boy Pioneers was started for the youth of America to learn of their fathers natural values, shortly later followed by Sir Robert Baden-Powell's establishment of the Boy Scouts in 1907.
It was clearly, an age of enlightenment regarding the values of this changing country and it's people.
John Muir reflected the sentiment of much of the country in his desire to preserve what was left of the natural scenic wonders of the west. But he saw more than just aesthetic beauty in the natural world. He was one of the few who saw natural communities. He saw the inter-connected web of life among the plants, fungi and animals and the dependence of each of the members of the ecosystem on each other. Unlike many naturalists who praised only certain geographic areas, Muir lauded the universe. He was, in fact, one of the early advocates of ecology.
Muir wrote, "When we contemplate the whole globe as one great dewdrop, striped and dotted with continents and islands, flying through space with other stars all singing and shining together as one, the whole universe appears as an infinite storm of beauty". He viewed the universe as a grand harmonious whole, and he visualized his own place in the cosmos with the following early signature, "John Muir, earth-planet, Universe".
Ecology is a term we're all familiar with. Although the term ecology was first coined by Ernst Haeckel in 1869, the science of ecology as we know it was formulated by Eugene Odum and his brother, Howard, in the late 1940's, culminating in his classic textbook, "Fundamentals of Ecology", published in 1953. Odum saw nature as shaped more by physics than by biology; nature as a vital flow of energy from recycled chemicals moving through a thermodynamic system. He viewed energy as a currency shared among the earth's various life forms, and defined ecosystems as living organic communities within their physical settings. Odum, like Muir, saw the earth, in fact, the entire universe, as a series of interlocking ecosystems. Each one embraced a unique strategy of development directed toward achieving as large and diverse an organic structure as is possible within the limits set by the available energy input and the prevailing physical conditions of existence.
Energy from the sun's light is changed to chemical energy in plant mitochondria. This energy is transferred in the form of food. The energy is changed to a different chemical energy in animal protoplasm after an animal eats the plant. Finally, it changes again when the animal dies and its body rots. Bacteria and other organisms in the soil break down the compounds into simple nutrients. These go into the soil and growing plants take them in through their roots as food. The series of stages that energy goes through in the form of food is called the food chain.
Just as a car engine mixes gasoline with oxygen and burns it to produce energy in the form of heat, your body mixes its fuels; carbohydrates, fats, and proteins, with oxygen to produce heat or chemical energy. This bodily combustion is called metabolism.
Ecology is the study of living things and the relationships they have to each other and to their environment. It is studied through the movement of energy, food and other nutrients through the ecosystem.
Every time we walk in the woods, we're looking at the life forms that have successfully found ways of efficiently using the available energy. But what we see now is only a moment in the continuum of life forms that have existed since the beginning of life on earth. As the physical environment changes, so the life forms adapt to better take advantage of the available energy in the new environment. Since the beginnings of life on earth, all biological life has continually evolved into more efficient and more complex life forms to better enhance their ability to eat, survive, and reproduce.
The beginnings of life on earth. To create life, from non-life. Perhaps the single most difficult act to understand. This was the issue that scientists in Charles Darwin's time had to address 150 years ago. How did it happen?
In the Earth's early atmosphere of hydrogen, carbon monoxide, ammonia and methane, and in the presence of strong ultraviolet rays and electrical charges in the form of lightning, complex molecules were formed over 3.5 billion years ago. These sugars, nucleic acids and amino acids concentrated in the seas, combining and forming more complex molecules, until eventually, there appeared one that was to be crucial for the further development of life. This was DNA. It's structure endowed it with two key properties. First, it can act as a blueprint for the manufacture of amino acids; and, second, it has the capacity to replicate itself. With this substance, molecules had reached the threshold of something quite new, for these two characteristics of DNA are also those of living organisms such as bacteria.
These first bacteria lived off inorganic chemicals without the aid of any other source of energy. Three types are known and all still exist in extreme conditions in oxygen-free environments. One lives in very salty environments, a second in hot acidic environments, and the third lived off the various carbon compounds found accumulating in the bottoms of the primordial seas. This last group, the methanogens, give off methane, marsh gas. Their life process employed by the methanogens is called fermentation, well known as the means of leavening bread and making alcohol.
These inorganic chemical-consuming bacteria had the early Earth all to themselves for hundreds of millions of years. Eventually, the materials they took from the environment to build and energize themselves would have been finished, and at that point life on Earth might have come to a lingering end. But the crisis was avoided, in fact it was never even a threat, because from the beginning life has been ruled by its inherent capacity to adapt and change as the environment dictates. The cell form, the amino acids, the DNA remain the same, but their arrangements are adapted to take advantage of new circumstances. There is nothing conscious or directed, or even survival-oriented about the procedure. It is simply a matter of the chance mutations between generations producing individual organisms that are better suited than their antecedents to the changing environment. The mutants and their offspring thrive. The old guard either retreats to some place where the environment has remained unchanged, or becomes extinct. This process is called natural selection. Through this process, one hundred foot tall club mosses now grow at our feet, and 90% of all species that have ever appeared on our planet have gone the way of the dodo bird.
Adaptive change is the basis of evolutionary theory. Evolution is not a fight for survival as is often supposed, with success meaning the direct elimination of competing organisms. It is a process by which new organisms and systems constantly arise to better exploit new resources and opportunities.
And mutation is the mechanism by which adaptation occurs.
And perhaps the most important mutation came in the form of photosynthetic molecules. As carbon deposits became more limited and limiting to the first bacteria, those that could mutate to living on alternative food sources would be at a definite advantage. Instead of taking ready-made food from their surrounding, they began to manufacture their own within their cell walls, drawing the necessary energy from the sun. This process is called photosynthesis. And a by-product of this process was oxygen. These bacteria organisms used to be called blue-green algae, but are now referred to as cyanophytes, or just blue-greens.
Eventually, by 2.2 billion years ago, these photosynthetic molecules were the dominant life-form (creating the first mass extinction of the anaerobic bacteria), with an ever-increasing level of waste oxygen being dumped into the seas. In the relatively short period of 200 million years, the dissolved irons in the sea combined with the free oxygens, and precipitated all the iron oxides into sea bottom depositions, now the source of the iron formations our industrial revolution have been based upon.
Once the oceans were swept free of iron, oxygen began to accumulate in the atmosphere, and about one billion years ago, when atmospheric oxygen levels approached 2 % of today's levels, molecules joined together, and formed the ozone layer. This screen prevented most of the deadly ultraviolet rays of the sun from penetrating to the Earth's surface, thus allowing life to approach to the surface of the water, it's edge with the land, and eventually enabled the populating of the land.
Higher oxygen levels, reached around 750 to 550 million years, were achieved by massive mountain building and subsequent sedimentation and burial at sea of organic material. Normally, the amount of oxygen produced in photosynthesis is balanced by the amount of oxygen consumed by respiring organisms, including decomposers. Burial, shields organic remains from respiring organisms, thus disrupting the balance of oxygen production and consumption and if enough organic matter gets buried, tips the balance toward production These enriched levels, approaching the 21% presently maintained, enabled the evolution of large (read that, visible) animals. It was this change in the environment that led to the tremendous Cambrian explosion of 545 million years ago, when every phylum of animals appeared (arthropods, annelids, mollusks, echinoderms, and chordates) except the bryozoans in the amazingly short interval of as little as 5 million years.
Before we leave the impacts of changing atmospheric oxygen levels, two more interesting events should be mentioned.
During the Carboniferous Period, there was the first explosion of land plants, pumping massive amounts of oxygen into the environment. With a significant amount of the world's surface being a swampland, fallen trees and other organic matter were quickly covered by muds, with the inability of aerobic decompositional processes to withdraw oxygen back out of the atmosphere. Thus, it is speculated, extremely elevated levels of atmospheric oxygen were maintained; possibly at a level of 35%, much greater than today's 21% levels. The impacts of this elevated level would explain the existence of six foot long millipedes, amphibians that were nine to twelve feet long, and the profusion of insect families (increasing from one or two to more than 100 during the Carboniferous, with many being huge, including 2 and 1/2 foot wingspan dragonflies). The oxygen-rich atmosphere was a denser atmosphere that provided more lift and thus made it easier for them to fly. More importantly, the excess oxygen made it easier for insects to breathe. The 2 1/2' wingspan dragonfly would have had a body that was over an inch thick, possible only with such high oxygen levels. Ferns and other club moss-like trees grew enormous because plentiful oxygen made it easier for them to manufacture lignin, their main structural material. And the beginning of the Carboniferous was also when our earliest four-footed ancestors hauled themselves out of the swamps and onto dry land. As they learned to carry their full weight without the help of water and to breathe with feeble lungs instead of gills, drawing in 35 % oxygen with each gulp would have lightened their burden considerably. By reducing the number of times they had to exhale, it would also have helped them avoid dehydration.
It was a different world. It was a 35% oxygen world.
The evolutionary explosion that began in the Carboniferous ended in the ensuing Permian Period. At the close of the Permian, around 250 my ago, an estimated 95% of all species on Earth went extinct, including the giant flying insects. Various causes have been suggested for the mass extinction, from volcanoes (Siberian volcanoes covering areas as large as Alaska have been recorded), to climatic changes to gamma rays released from two neutron stars colliding, to asteroid impacts (although no evidence of this has been found). But it's also true that the atmospheric oxygen level began to decline at the start of the Permian. By the time of the extinction, it became a 15% oxygen world. That may have been a tough change to adapt to. It certainly played a role in the demise of the life forms that had its beginnings in such an oxygen-rich environment.
Evolution continues to change life forms and to adapt to new conditions. Wings have been evolved on three separate occasions; birds, bats, and the pteridactyls of the dinosaur period. But, give us another 100 million years, and let's see where the flying squirrels go. And evolution is known to reverse itself. Three major groups of mammals have returned to the seas. The best example are the wolf-sheep mammals that returned to a life in the sea around 50 million years ago, and eventually became today's whales, porpoises and dolphin (Cetacea). The two other groups include the seals, sea lions, walruses, dugongs and manatees. Snakes have chosen to drop their legs. Ostrich, penguins, and more recently, the cormorants of the Galapagos Islands, have lost their ability to fly.
Evolution is continuing at this time. The Polar Bear is one of the most recent species of Carnivore, having arisen only 250,000 years ago from a northern population of Brown Bears that gave up omnivory to concentrate on seals. The grizzly and Polar Bear can still interbreed and female offspring of their liaisons are certainly fertile, although males may not be.
Another example of diverging species is among the canids of North America.
Coyotes in the southern states have crossbred with the rare Red Wolf for decades. In fact, coyotes, wolves and domestic dogs can all mate and produce fertile offspring. By 1970, seemingly pure Red Wolves were confined to southwestern Louisiana and the south-eastern corner of Texas, and by 1980 they were extinct in the wild. In 1977, a breeding program came up with only 14 judged genetically pure Red Wolves (the rest, totalling 79, were deemed to be either Grey Wolves, Coyotes or Coywolves). By 1988, 80 Red Wolves had been raised and reintroduced to eight locations, including the Smokies. While hailed as a conservation triumph at the time, this rescue has since become the center of a philosophical debate. Scientists analyzed the genetic make-up of Red Wolves that had lived between 1905 - 1930 using skins that had lain fusty in museum vaults. They also analyzed all the candidates for the captive breeding program, from stored blood samples, and the descendants of the 14 judged to be Red Wolves. Their studies showed that none of the candidates rejected as Grey Wolves was in fact a Grey Wolf, being mainly Coyotes or Coywolves. Furthermore the Red Wolves---those that had lived from 1902 - 30 and the modern captive-bred ones---had no genetic characters that could not be found in either Grey Wolves or Coyotes. In fact, they were genetically indistinguishable from Louisiana Coyotes. So, either the Red Wolf had already cross-bred itself out of existence by the late nineteenth century, or it never existed as a true species but was always a hybrid between the Grey Wolf and Coyote.
Evolution is fluid over time. Life forms constantly change in response to environmental and biological changes. Just as biology is dynamic, so, too, is our physical environment. Over the last billion years, the African plate has hit our North American plate twice. The plates, as well, have moved relative to the equator, including a time when dinosaurs roamed, that we here in Virginia, were very close to the equator. Beyond these major events, wobbles in the earth's axis, and ocean current changes due to tectonic plate locations are a few of the sources of significant climate changes. The most recent to affect our region has been the Pleistocene Ice Age. In fact, we are still living in this Ice Age. Fortunately, we are living in an interglacial period of warmth
At the height of the most recent Wisconsin glaciation, some 18,000 years ago, our forests were dominated by spruce and fir forests. The deciduous trees, such as maples and chestnut, were notably absent from the eastern forests. They had retreated to "refugium" probably in the lower stretches of the Mississippi River in Louisiana. The hemlocks and white pine, being more cold-tolerant, were safely esconced in refugium in the southern Appalachians. From 10,000 to 4,000 years ago, as this last glaciation released its grip on the North American continent, these deciduous species have slowly increased their range, with the boreal forest transitional line slowly moving both north and up to higher elevations.
As these coniferous forests became isolated islands on high elevation summits, divergent evolution has caused the production of new species. The balsam fir (Abies balsamea) on several peaks in Virginia and West Virginia has evolved into a slightly differing form (Abies intermedia). However, further south, the firs show even greater differences, forming a young endemic (found nowhere else in the world) species, the Fraser fir (Abies fraseri).
The faunal populations also become stranded. If you read Maurice Brook's "The Appalachians", you will learn about the tremendous diversity of salamanders that, stranded on these summits for thousands of generations, have evolved into 25 separate endemic species. These include the Shenandoah, Cheat Mountain, Peaks of Otter, and Cow Pasture salamanders, among others.
Another interesting story involves a relic population of snowshoe hares stranded in West Virginia. They not only change color at the same time as northern individuals, but also exhibit explosive population cycles with periods of 9 to 11 years that coincide almost exactly with those exhibited by populations in New England and eastern Canada, over 600 miles away.
Still another effect on our forests resulting from the glaciation impacts the bird populations. As the ice sheet covered the northern forests, the available Southern forests were split into eastern and western ranges separated by a large, uninhabitable prairie. In this manner, we now have the Eastern yellow-shafted and Western red-shafted flickers; the Eastern Myrtle and Western Audubon's warbler. Where they merge in the Midwest today, there is some interbreeding occurring. Are they different species? Depends on whether you are a lumper or a splitter.
To me, the most interesting relics in our forests are the existence of certain extremely large seeded fruits, such as the paw paw, the Kentucky coffee tree and the Osage orange. The seeds are just too large to be evolved for digestion by the existing mammals. And how about those over-sized thorns on hawthorns and locust trees? The thorns are spaced too far apart to prevent todays mammals from eating between the thorns. The generally accepted answer is the former existence of megafauna. It is known that 35 to 40 large North American mammals became extinct about 12 to 10 thousand years ago. These included mastodons, mammoths, giant sloths and beaver, dire wolves, camel, horses, shrub and musk oxen, lion and, of course, the saber-tooth tiger. This happened at the same approximate time that the continent was changing from an oceanic climate of mild summers and winters (associated with the Wisconsin glaciation), to a continental climate of hot summers and cold winters (ever live in Chicago?). It is postulated that this stressful environment changed the vegetation, putting the megafauna at a competitive disadvantage with the smaller mammals. It is also acknowledged that at this time, the North American continent was being populated by another predaceous mammal, who had a tremendous competitive edge over all other mammals. Certainly, both factors played roles in the extinction of these species. Perhaps the diseases introduced by Asian man had as significant impact on these large megafauna as they did on the native Indians.
All of today's life forms can be placed into six kingdoms; Monera, Archaebacteria, Protista, Fungi, Plantae and Animalia.
Monera are generally bacteria including the blue-greens (cyanophytes) and spirochetes, causing diseases like syphilis and Lyme disease.
Archaebacteria are a primitive form of bacteria including some methane inhabitants; leftovers from the first life forms that existed prior to the aerobic photosynthesizers (mentioned earlier) and those living in the most extreme environments like highly concentrated brine pools and hot springs.
Protista are single-celled free-living organisms, including the microscopic creatures responsible for giardia and malaria.
Fungi includes mushrooms, molds and yeasts. Fungi used to be included in with the Plantae Kingdom, but research now shows that fungi share more genetic information with animals than with plants. In fact, we humans have more in common with fungi than with plants.
Plantae includes most algae, lichen, spore-bearing fern and fern allies, gymnosperms, such as conifers, and angiosperms; the flowering plants (further broken down into monocots and dicots).
Animalia includes approximately 22 major phyla including sponges, coelenterates (jellyfish, sea anemones, corals), nematodes (roundworms and elephantitus), annelids (earthworms), echinoderms (marine starfish, sea urchins and sea lilies), mollusks (clams, squid, octopus, snails and slugs), arthropods (Insects; millipedes, centipedes, beetles, dragonflies, bugs, butterflies, ants and bees, Arachnids; daddy long-legs, mites/ticks, spiders and scorpions, Crustaceans; lobsters, sowbugs, crabs/shrimp), and chordates (fish, amphibians, reptiles, birds and mammals).
These six kingdoms have worked out some interesting methods of survival. In the evolution of life, cooperation among organisms is probably at least as important as competition. The first complex single-celled creature, eukaryotes probably appeared when a host bacterium engulfed a smaller bacterium, perhaps one that could use photosynthesis to turn sunlight into energy.
Of course, everyone is familiar with the lichens. Each kind of lichen is made up of a particular kind of fungus and a particular kind of alga. The fungus provides support, salts and water, while the alga carries on its business of manufacturing starch. Interestingly, each lichen has its own botanical name as does the individual alga and fungus. In these individual species, some of the algae and fungi can live separately, but most of the fungus cannot live without its alga.
Mycorrhizal fungi are fungal species, which aid plants in taking up nutrients. It is a mutualistic symbiosis between plant and fungus. It has been estimated that 70% of all flowering plants are dependent to some degree on these mycorrhizal relationships. All conifers, beech and birch and most of the orchids cannot survive without the mycorrhizal fungi. Surprisingly, even some mushrooms; themselves fungi, require these mycorrhizal fungi. Some of these include the amanitas, boletes and chantarelles. Speaking of mushrooms, be careful with mushrooms. In 1963, the executive chef for Le Bistro in Washington, a frenchman, took his family on a Memorial Day mushroom hunt in Rock Creek Park. The mushrooms he cooked for his family cost the life of his ten year old son. Only 5 % of mushrooms are poisonous, but remember, when untreated, few people have ever died of copperhead bites, one out of ten may die from a black widow bite, one of eight statistically have died from rattlesnake bites, but nine out of ten will die from consuming amanita mushrooms, a common summer mushroom in the eastern deciduous forests. (But squirrels, chipmunks and turtles can eat them with no ill effects.)
In the Plant Kingdom, you've got plants that when attacked by insects, will release hormones that not only repel the pests, but the hormones are received through the air by neighboring plants, which will in turn, produce their own hormones. Other plants produce hormones that make the insects feel completely full and satiated, other hormones cause insect indigestion. Some species, like corn and bean plants even summon mercenaries; when certain species of caterpillars munch the leaves, the plants emit chemicals that attract parasitic wasps, that lay their eggs on the caterpillars. And we're all familiar with the chemicals that are emitted from nettles that teach us to leave well enough alone.
Angiosperms took advantage of the mobility of animals to transport their pollen far and wide. The animals that acted as transfer agents fed on the products of the flower and became ever more efficient grazers, while the plants they visited evolved better methods of dispersing and receiving pollen. Thus the two adapted to each other in a magnificent co-evolutionary process. Nectar and pollen are the rewards to the pollinators. Pollen, the male reproductive organ, can either be eaten or transferred from flower to flower, while nectar, totally unnecessary to the plant, provides an excellent incentive for the pollinator to visit. Many of our spring ephemeral flowers assure the dispersal of their seeds through the production of fleshy attachments on their seeds. These attachments, or eliosomes, are carried back to ant colonies to be eaten, with the seed left unharmed. Similarly, the fleshy endosperm of fruits covering the hard seeds, like apples, grapes, and berries, is energy spent by the plant solely directed to attracting bird and mammal dispersers.
Orchids, the highest evolved of the monocots, have developed the most extreme examples of co-evolution. For example, one species of orchid (intent on encouraging a type of male wasp) produces flowers that look like the female wasps, produces scents that replicate the pheromones of the female, and flowers just before the females wasps have hatched to avoid competition with the females.
It now appears that as many as 20% of all animal-pollinated flowering plants actually change colors to tell the pollinators which flowers still have nectar (and pollen) and which ones have already been tapped. Color changes may be subtle; just turning a little faded, to as dramatic as turning from yellow to red.
And the blue misty vapor of the Blue Ridge and the smoke of the Smokies? It turns out that these are hydrocarbons produced by the plants protects them from heat stress that damages the photosynthetic functions of the plants. In kudzo, for example, over 50% of the available carbon in the plant that could go to producing sugars, are used in producing these isoprene compounds.
Let's not forget the carnivorous plants, living in wet, nitrogen-poor areas, supplement their nitrogen uptake by resorting to attracting and eating insects. (P.S., hamburger won't work; the food must be wriggling to activate the plants metabolic functions.)
Populations of fireflies in the Smokies, covering a whole valley, in unison, not only send out five to eight flashes, but will stop for a quarter of a minute, and then together do it again, They occasionally are known to flash in synchronous waves that ripple down the hillside like waterfalls of light.
Silk made by spiders that is stronger than any known natural or synthetic fiber.
You've got female spiders that eat their mates and young spiderlings that eat their mother. And males that throw themselves into the mouths of the cannabalistic females. In each of these cases, death is endured in return for the opportunity of more offspring.
Butterflies that overwinter as winged adults. If you go out today, you might find the purple mourning cloak, edged in yellow, and maybe the yellow-spotted commas or the question marks. And nearly fifty moths that are active throughout the winter. These can be frozen solid and survive. On the other extreme, monarchs have evolved that migrate as much as 2,000 miles from New England to central Mexico.
The metamorphism from caterpillar to butterfly or moth is an interesting phenomenon. When the egg first hatches, two life forms begin to divide into molecular gametes; one, being the caterpillar, the other being the adult. Actually, the adult gametes forms in many different growth points on the caterpillar. After a few divisions, the adult gametes stops dividing and becomes dormant, while the caterpillar continues to divide until it begins to feed. At that point, its body cells divide no more. Instead, they simply enlarge until, by the time the caterpillar was full grown, they are vastly distended and many thousand times bigger than their original size. At the time of metamorphosis; either in the butterflies' chrysalis, or the moths' cocoon, the dormant adult growing points (the gametes), on the caterpillar, reactivates and literally, consumes the caterpillar as fuel as it grows into the adult butterfly or moth.
Ants that grow fungi on leaves they bring into their nests for food. Ants that make slaves of aphids, stroking them to produce their secretions used as food by the ants. Specialized ants that are used only as physical containers to hold nectar for the others to use. And then there's parasitic flies, that lay eggs near the ant's nest, producing chemical scents that mimic the ants. The ants take the orphaned eggs into the nest, presuming they are ant larvae, the eggs hatch, and the fly larvae make great meals of the ant larvae.
Let's talk about sex. Some plants, like the Jack-in-the-Pulpit, red and striped maple, can change sex from year to year. Hermaphroditic slugs, snails and worms have both male and female organs. Lizards and snakes have two penises. No one has a clue why. And the hemlock wooly adelgids and the balsam wooly adelgids have no males; a unique situation called parthenogenisis, a practice shared by all aphids much of the time. Females producing females, the descendants of a single individual forming total populations from natural clones. This phenomenon is shared by a few fish, most pussytoes plants, the mountain Jefferson Blue-spotted Salamander, and a dozen New World species of whiptail lizards. There's even one species of fish that not only is hermaphroditic, but fertilizes itself.
Pit vipers, including copperheads, water moccasins and rattlesnakes, the most advanced of the reptiles, are armed with infra-red heat sensing organs. The infra-red senses developed not as aids to feeding but as defensive organs originally used to sense the size of, and thus the potential threat posed by encountered animals. And the toxic venom breaks digests the prey before it can putrefy and poison the snake. The forked tongue, like paired ears or eyes, provides a stereo smell that gives snakes the agility to sense not only the presence of some chemical but also its location. However, king snakes and opossum are immune to the toxins in the serum, and thus are common predators of the pit vipers.
And speaking about defense mechanisms, how about the horned toads of Oklahoma and the southwest that squirts red liquid out of it's eye socket. Or, for that matter, turkey vultures that emit foul-smelling projectile vomit (a trait discovered first hand by a Park biologist trying to remove one caught in a bear trap). And although you can't get warts from toads, they do possess poisonous paratoid glands that afford them an adequate defense. However, the exception in this case is the hog-nosed snake, whose diet is principally nothing but toads.
And I love the amphibians, like the wood frog, that are found above the Arctic Circle, the gray treefrogs, spring peepers and upland chorus frogs that has the ability to be frozen in a block of ice, which you can then thaw with no ill effects to the creatures. And many of our frogs, after eating ants and bees that contain nasty toxins, will throw up their actual stomachs to be wiped off by their right hands. Reptiles get into this act, too. Box turtles, painted turtles, garter snakes, and some lizards are also able to endure freezing.
In the bird order, American cowbirds and European cuckoos lay eggs in nest of other species, whose eggs hatch in short order with the young birds pushing the surrogate mothers' natural eggs (or young) out of the nest.
Hawks patrolling the skies during the day and owls to take over at night. Birds catching insects during the day, and bats in the evenings. Anhingas that fish under water in the tropics, penguins that have made a living in the waters of Antartica and Arctic tern migrations of 6,000 miles speak of natures' flexibility.
In the Order of mammals, the sex lives, again, seem to be particularly interesting. Delayed fertilization, where sperm is stored overwinter in the females is the typical pattern among temperate North American bats. This adaptation fits these mammals with a long winter dormant period. Insemination occurs in the fall, when the bats are well fed and active, as opposed to the following spring when the animals are in their poorest conditions and when food may not yet be abundant. Ovulation occurs almost immediately upon emergence from dormancy, rather than being delayed until after males attain breeding condition and copulation occurs.
Delayed implantation is another adaptation, where fertilization occurs normally, but at an early stage of development, the blastocyst becomes dormant. Species with this pattern include black, grizzly, and polar bear, most of the weasel family, some seals, bats and roe deer. The advantage to these mammals are basically the same as those practicing delayed fertilization. In the case of black bear, fall mating would take valuable time from the critical need to bulk up on acorns and other foods, putting the bear in a stressed condition prior to its winter dormancy. Mating is done after spring feeding and allows the cubs the opportunity to spend the second winter with the sow before being forced out on its own. Delayed implementation is stretched to its maximum in the case of the fisher, recently reintroduced to WVA and PA. A long delayed implantation results in a birth a year after mating (an average of 352 days, including a gestation period of 30-50 days). The female is quickly inseminated again (in fact, she is not pregnant for only about ten days), so that birthing takes place every year.
Deer do not need such unusual birthing practices since their food is available year-round. However, they have their own unique adaptations.
Deer and other grazing ruminants have four stomachs, to allow them to grab a lot of the nutrient-poor grass found in the open, store it quick, and enable it to run back into the safety of the woods and brush, to regurgitate the partially digested food, and then chew it's cud, to capture the remaining nutrients.
Another way to get more from the available food, is to practice coprophagy, like rabbits, meadow voles and beaver, who eat their partially digested feces directly from their anus. By the way, our native rabbits do not live in, or dig burrows. They scrap depressions on the surface called forms. In the winter, they occasionally will move into the entrance of a groundhog burrow, sharing it with other residents deeper within.
Or, within the carnivores, bobcats and lynx, being totally dependent on easily converted meats, have guts only four times their body length, while foxes and wolves, facing the problems of omnivory, including harder to digest vegetative material, have guts five times their body length.
In the nature of evolution, skunks and porcupine share similar niches. Skunks are to the weasel family as porcupine are to the rodent family. Both have developed unique forms of protection that enable them to slowly waddle around in search of food, relatively safe from predators. Of course, there's always the species that has evolved to take advantage of the situation. For example, skunks have to deal with owls. Owls have no hesitation attacking skunks. Owls have very poor olfactory senses. In fact, if you ever find road kill owls, they almost always smell of skunk. And the porcupine is the preferred food of the fisher, the largest member of the weasel family native to our Appalachians.
In the Pacific northwest, you've got red tree voles, that spend generations in the trees that never touch the ground. And in our West Virginia spruce forests, we have northern water shrews that spend most of their time hunting underwater or literally, running across the surface, held up by the water's surface tension. Speaking of shrews, right here in Fairfax County you can find the smallest mammal in the world, the pygmy shrew, two and a half inches in length and weighing about the same as a dime. This creature is so small, it is known to back down from a confrontation with an earthworm.
The weasels present an interesting adaptation for winter survival. We have three weasels in this area; the long-tailed, the short-tailed (or ermine), and the least weasel. North of our Virginia mountains, all three species molt to a white coat in winter. This pelage helps them blend in with the snow cover. Yet, the tails on both of these species are tipped in black. This aids them by distracting hawks and owls, who focus on the tail and will often enable the weasels to escape. However, the smallest of the three weasels, the least weasel, being only six inches long, does not benefit from a black-tipped tail, and, therefore, doesn't have one. Incidentally, after our past few winters, it's obvious that we don't have a reliable winter snow cover. South of the Mason-Dixon line, all three weasels maintain a brown pelage all year round, while those of the Dolly Sods/Spruce Knob area tend to have a mottled brown and white winter coat.
And, speaking of survival adaptations, how is it that one of our most common animals, the only marsupial found in north America; the most primitive of all marsupials; the opossum, is also the slowest, and, shall we say, the least intelligent of mammals. For example, they just don't learn how to avoid being trapped. In like-sized mammals, the size of the opossum brain is a third to half the size of other mammals (Man comes in at 7.5x larger.) In the ranking of the complexity of mammalian social systems, on a scale that starts at 2 for least complex and ranges to 20 for most complex, the opossum earned a 2. Even the young noticeably don't play or interact and are, in general, extremely lethargic. They're are terribly near-sighted (one reason for so many road-kills). When frightened, they freeze, or feign death (not effective against cars). Finally, they are often along roads looking for one of their favorite foods in the form of road kills---often other opossum. And they usually don't survive over a year. Females can have two litters in a year, but rarely live to breed the following year. Almost never does an opossum live to be three years.
On the other hand, as I mentioned before, they are immune to rattlesnake venom. And its well-known trait of feigning death (completely involuntary, lasting up to five minutes or so), defecating, and emitting a foul-smelling greenish ooze from its anal glands is an effective way of avoiding predation.
I guess its very omnivorous diet (it will eat anything), and large fecundity ( two broods per year, with up to 13 per brood, starting at age of 6 to 8 months) give even this creature a niche in our ecosystems.
Which leads us up to the most advanced of the mammal species; Man. Considering geologic time and the time life has existed on earth, Man's dominance has been extremely short and recent. Even 10,000 years ago, Man lived among nature, being an omnivore and passing his life as a hunter-gatherer. At this time, the earth was populated by only about 5 million people. It was at this time, Man started protecting his body with clothes and began the spread from Africa into the European and Asian continents. It was among the Mediterranean regions that Man began his agricultural culture. In this Fertile Crescent, and only here, could agriculture begin. Due to the mild, wet winters and hot, dry summers, the large seeded, self-sowing annuals, like barley and wheat were abundant, forming the basic breads of the culture. Soon, legumes and domestication of native animals (sheep, goats, cattle and pigs) were added. When flax was added, the source of plant fiber for making linen, Man was off to the races.
By 7,000 BC, agriculture reached Greece and Cyprus; Egypt and India was reached by 6,000 BC, central Europe by 5,400 BC, and Britain by about 4,000 BC.
And what an impact Man has made on our ecosystems today. Population growth of 1/4 million persons a day. An acre of tropical rainforest burned every second. Habitat loss, exotic introductions, and selective exploitation of resources, all severely erode the balance of nature. It's like a board game, where you keep taking out species until the whole ecosystem crashes down on the floor.
One hundred years ago, when John Muir was President of the Sierra Club, the Cass timber railroad was running near Elkins WV, 24 hours a day. Muir arrived at a crucial period in America's history; following the squandering of resources in the East but before the final taming of the West. Largely because of his efforts, Yosemite, Rainier, Grand Canyon, Petrified Forest, and many parts of the Sierras all became national preserves. He lived in an ambivalent time of our country's development. While he was alive to see the virgin wilderness of the west, and help the country recognize and save the jewels he cherished, he also saw the destruction of many of the same sites that meant so much to him; Hetch-Hetchy to name the most famous of his losses.
Perhaps John Muir's greatest cause was also his biggest defeat. With Teddy Roosevelt in the White House, Muir was able to prevent the damming of the Hetch-Hetchy valley. But shortly after the election of Woodrow Wilson, the final approval was secured.
John Muir died a year after Hetch-Hetchy, in 1914, the same year as the last Passenger Pigeon .
We, today, must recognize the same ambivalence of our time. Although the world's last ecosystems are still intact, they are truly imperiled. 100 years from now, some scientists predict 50% of the world's species will become extinct. And if that were to happen, whatever could we look forward to for the next 100 years.
Allow me to close with two quotes by Muir.
"The clearest way into the Universe is through a forest wilderness. Climb the mountains and get their good tidings. Nature's peace will flow into you as sunshine flows into trees. The winds will blow their own freshness into you, and the storms their energy, while cares will drop off like autumn leaves."
"Keep close to Nature's heart, yourself; and break clear away, once in a while, and climb a mountain or spend a week in the woods. Wash your spirit clean."