Reproduction Essays - Behavior, Sexual Reproduction, Mating

Reproduction For some time she had watched his movements, appearing coyly in his haunts. And now, had it paid off? Doubtless, he was in love. His muscles were taut; he swooped through the air more like an eagle than a Greylag gander. The only problem was, it was not for her that he then landed in a flurry of quacks and wingbeats, or for her that he dashed off surprise attacks on his fellows. It was, rather, for another - for her preening rival across the Bavarian lake. Poor goose. Will she mate with the gander of her dreams? Or will she trail him for years, laying infertile egg clutches as proof of her faithfulness? Either outcome is possible in an animal world marked daily by scenes of courtship, spurning and love triumphant. And take note: these are not the imaginings of some Disney screen-16 writer. Decades ago Konrad Lorenz, a famed Austrian naturalist, made detailed studies of Greylags and afterwards showed no hesitation in using words like love, grief and even embarrassment to describe th e behavior of these large, social birds. At the same time he did not forget that all romance - animal and human - is tied intimately to natural selection. Natural selection brought on the evolution of males and females during prehistoric epochs when environmental change was making life difficult for single-sex species such as bacteria and algae. Generally, these reproduced by splitting into identical copies of themselves. New generations were thus no better than old ones at surviving in an altered world. With the emergence of the sexes, however, youngsters acquired the qualities of two parents. This meant that they were different from both - different and perhaps better at coping with tough problems of survival. At the same time, nature had to furnish a new set of instincts which would make "parents" out of such unreflective entities as mollusks and jellyfish.. The peacock's splendid feathers, the firefly's flash, the humpback whale's resounding bellow - all are means these anima ls have evolved to obey nature's command: "Find a mate. Transmit your characteristics through time!" But while most males would accept indiscriminate mating, females generally have more on their minds. In most species, after all, they take on reproduction's hardest chores such as carrying young, incubating eggs and tending newborns. Often they can produce only a few young in a lifetime. (Given half a chance, most males would spawn thousands.) So it's no surprising that the ladies are choosy. They want to match their characteristics with those of a successful mate. He may flap his wings or join a hockey team, but somehow he must show that his offspring will not likely be last to eat or first in predatory jaws. Strolling through the Australian underbrush that morning, she had seen nothing that might catch a female bowerbird's eye. True, several males along the way had built avenue bowers - twin rows of twigs lined up north and south. True, they had decorated their constructions wit h plant juices and charcoal. Yet they displayed nothing out front! Not a beetle's wing. Not a piece of flower. Then she saw him. He stood before the largest bower and in his mouth held a most beautiful object. It was a powder blue cigarette package, and beneath it there glinted a pair of pilfered car keys. Without hesitation she hopped forward to watch his ritual dance. Males have found many ways to prove their worth. Some, like bowerbirds, flaunt possessions and territory, defending these aggressively against the intrusion of fellow males. Others, like many birds and meat-eating mammals, pantomime nest building or otherwise demonstrate their capacity as dads. Still others, however, do nothing. Gentlemen may bring flowers, but most male fish just fertilize an egg pile some unknown female has left in underwater sand. For a fish, survival itself is a romantic feat. For other species, though, love demands supreme sacrifices. Shortly after alighting on the back of his mate, the male praying mantis probably had no idea what was in store. This would have been a good thing too, because as he continued to fertilize his partner's eggs, she twisted slowly around and bit off his head. She continued to put