The failure of the clock: Why specialized life cycles unravel when the climate breaks tempo

“ There have always been seasons more or less marked, and these have been more or less organically answered by corresponding changes or cycles of change in plants and animals. Rain and drought have in many cases more to do with such changes than variations of temperature. The seasons, again, are less marked in the tropics than in temperate and circumpolar climates. Nevertheless, even near the equator, they exert and have always exerted certain organic influences-have resulted in annual cycles in the life of species. ”

“ In proportion as we recede from the tropics, the more marked do the annual cycles of life thus induced become, many species practically ceasing to exist as such for several months of the year, and being only potentially represented by eggs, germs, or seeds, and sometimes by dormant pregnant females. ”

“ Most juvenile butterfly hunters, unblest by scientific knowledge of insect life, imagine that this and the last owe their difference in size simply to their being old and young individuals of the same name; forgetting—or, rather, never having heard—that butterflies never grow in the slightest degree after once getting their winged form; only as caterpillars do they grow.
The male is distinguished from the female by having only one round black spot, or sometimes none, on each upper wing, whilst the female is spotted as in the engraving. ”

“ It is probable, also, that when hunger presses, most animals will devour anything to stay their hunger, and will die of gradual exhaustion and weakness not necessarily painful, if they do not fall an earlier prey to some enemy or to cold. [11]
Now let us consider what are the enjoyments of the lives of most animals. As a rule they come into existence at a time of year when food is most plentiful and the climate most suitable, that is in the spring of the temperate zone and at the commencement of the dry season in the tropics. They grow vigorously, being supplied with abundance of food ”

“ If we consider each species in the different climates which it inhabits, we shall find perceptible varieties as regards size and form: they all derive an impress to a greater or less extent from the climate in which they live. These changes are only made slowly and imperceptibly. Nature's great workman is Time. He marches ever with an even pace, and does nothing by leaps and bounds, but by degrees, gradations, and succession he does all things ”

“ You have then the ranunculus hederaceus, which botanists regard as a distinct species.
Among animals changes take place more slowly, and it is therefore more difficult to determine their cause. The strongest influence, no doubt, is that of environment. Places far apart are different, and—which is too commonly ignored—a given place changes its climate and quality with time, though so slowly in respect of human life that we attribute to it perfect stability. ”

“ Moreover, each species on the confines of its range, where it exists in lessened numbers, will, during fluctuations in the number of its enemies or of its prey, or in the nature of the seasons, be extremely liable to utter extermination ”

“ But this is a very false view; we forget that each species, even where it most abounds, is constantly suffering enormous destruction at some period of its life, from enemies or from competitors for the same place and food; and if these enemies or competitors be in the least degree favored by any slight change of climate, they will increase in numbers, and, as each area is already stocked with inhabitants, the other species will decrease. ”

“ Though a powerful-looking insect, its flight is by no means swift, and it suffers itself to be captured without difficulty.
The caterpillar is dull pinkish about the back, with three obscure grey-green stripes, a dark line on the sides, and greenish beneath. It feeds on grasses, and has been said to undergo its transformation to the chrysalis in the earth; but this point requires confirmation.
The butterfly is seen from the middle of July till the beginning of September. ”

“ As the imprisoned butterfly approaches maturity, a change is observable in the exterior of the chrysalis, the skin becomes dry and brittle, usually darkens in colour, and if the enclosed butterfly be a strongly marked one, the pattern of its wings shows through, often quite distinctly. ”

“ Until very recently it had always been stated by entomologists, that the Brimstone Butterfly was "double-brooded" (a term meaning that it went through two whole cycles of existence, from the egg to the perfect insect, in one year) , one brood appearing in May, and the other in the autumn.
But it is now established, on very satisfactory evidence, that one brood only is produced, and that, the autumnal one. A considerable number of these survive the winter in some place of concealment, and coming out again in the spring form the so-called spring brood. ”

“ The caterpillar is brown, striped with white, and yellowish tint; head, legs, and thorns, tawny coloured. It feeds on the wild heartsease, also on sainfoin and borage.
The chrysalis is tinted with dull-green and brown, and spotted with gold.
The butterfly is said to be double-brooded—one brood appearing in June, the other in September. The most likely places in which to look for it are clover fields in the south of England, and more especially on the south-east coast. Though still classed among the rarest of British butterflies, it has been found in a great many localities. ”

“ Armed with the above simple paraphernalia, viz. net to catch, boxes and pins to contain and detain, the insect hunter may sally forth on any fine summer's day, with a pretty sure prospect of sport, and the chance, at least, of a prize. Much depends, however, on the choice of a day, and the nature of the locality that is to form the hunting ground.
As to weather, it must be remembered that winged insects have a great objection to face a north, or north-east wind, during the prevalence of which you will probably find hardly one stirring, however prolific the locality may at other times be. ”

“ Heat and Temperature Heat is a form of energy. When a substance contains heat, it exhibits the property we measure as temperature—the degree of "hotness" or "coldness". A specific amount of heat absorbed by or removed from a substance raises or lowers its temperature a definite amount. However, the amount of temperature change depends on characteristics of the substance. Each substance has its unique temperature change for the specific change in heat. ”

“ Temperatures also vary with differences in topographical surface and with altitude. These temperature variations create forces that drive the atmosphere in its endless motions.
Diurnal Variation Diurnal variation is the change in temperature from day to night brought about by the daily rotation of the Earth. The Earth receives heat during the day by solar radiation but continually loses heat by terrestrial radiation.Warming and cooling depend on an imbalance of solar and terrestrial radiation. During the day, solar radiation exceeds terrestrial radiation and the surface becomes warmer. ”

“ For example, if a land surface and a water surface have the same temperature and an equal amount of heat is added, the land surface becomes hotter than the water surface. Conversely, with equal heat loss, the land becomes colder than the water.
The Earth receives energy from the sun in the form of solar radiation. The Earth and its atmosphere reflect about 55 percent of the radiation and absorb the remaining 45 percent converting it to heat. The Earth, in turn, radiates energy, and this outgoing radiation is "terrestrial radiation". ”

“ Variations with Topography Not related to movement or shape of the earth are temperature variations induced by water and terrain. As stated earlier, water absorbs and radiates energy with less temperature change than does land. Large, deep water bodies tend to minimize temperature changes, while continents favor large changes. Wet soil such as in swamps and marshes is almost as effective as water in suppressing temperature changes. Thick vegetation tends to control temperature changes since it contains some water and also insulates against heat transfer between the ground and the atmosphere. ”

“ Maximum temperatures of 115°-120° occur over the deserts of northern Africa. In a true tropical climate seasons, in our sense, do not exist. The variations in temperature throughout the year are so slight that the seasons are not classified according to temperature, but depend on rainfall and the prevailing winds. The life of animals and of plants in the tropics, and of man himself, is regulated very largely, in some cases almost entirely, by rainfall. ”

“ Looking back over the past 100,000 years, the earth’s climate periodically has undergone extreme shifts, sometimes in as little as a decade. Such abrupt swings can occur in complex systems when seemingly small shifts in the forces in play suddenly trigger dramatic nonlinear change, such as when a slight drop in temperature can suddenly turn water into ice. ”

“ For with that marvelous climate of all geological time continuing right up to that fatal day when it was "abruptly terminated," and the mammoth and his fellows were caught in the merciless frosts which now hold them, the percentage of all the lucky forms of life, plants, invertebrates, or mammals, which could stand such a change and "persist" into our modern world, must be utterly nonsensical as a test of age even from their standpoint. ”

“ On the confines of its geographical range, a change of constitution with respect to climate would clearly be an advantage to our plant; but we have reason to believe that only a few plants or animals range so far, that they are destroyed by the rigour of the climate alone. Not until we reach the extreme confines of life, in the arctic regions or on the borders of an utter desert, will competition cease. ”

“ The fertile clods with coulters, and subduing{66}
The soil of earth, summon the crops to birth,
They could not of their own accord spring up
Into the bright air. Even then sometimes,
When answering our long toil throughout the land
Every bud puts forth its leaves and flowers,
Either the sun in heaven scorches them
With too much heat, or sudden gusts of rain
Or nipping frosts destroy them, or wind-storms
Shatter them with impetuous whirling blasts.
Furthermore why does Nature multiply
And nourish terrible tribes of savage beasts
By land and sea, dangerous to mankind? ”

“ In the earliest times in which animals and plants lived, the climate over the whole globe appears to have been as warm as, or even warmer than, it is now between the tropics. And the slow change from warmer to colder appears to have been the chief cause of the successive destruction of the different races; and new ones were created, better adapted to the altered condition of the globe ”

“ Nevertheless, so profound is our ignorance, and so high our presumption, that we marvel when we hear of the extinction of an organic being; and as we do not see the cause, we invoke cataclysms to desolate the world, or invent laws on the duration of the forms of life!
I am tempted to give one more instance showing how plants and animals, remote in the scale of nature, are bound together by a web of complex relations. ”