Sexual Selection

Many insects are sexually dimorphic, usually with the male adorned with secondary sexual characteristics, some of which have been noted above in relation to courtship display. In many insect mating systems, courtship can be viewed as intraspecific competition for mates, with certain male behaviors inducing female response in ways that can increase the mating success of particular males. Because females differ in their responsiveness to male stimuli, females can be said to choose between mates, and courtship thus is competitive. Female choice might involve no more than selection of the winners of male-male interactions, or may be as subtle as discrimination between the sperm of different males (section 5.7). All elements of communication associated with gaining fertilization of the female, from long-distance sexual calling through to insemination, are seen as competitive courtship between males. By this reasoning, members of a species avoid hybrid matings because of a specific-mate recognition system that evolved under the direction of female choice, rather than as a mechanism to promote species cohesion.

Understanding sexual dimorphism in insects such as staghorn beetles, song in orthopterans and cicadas, and wing color in butterflies and odonates helped Darwin to recognize the operation of sexual selection - the elaboration of features associated with sexual competition rather than directly with survival. Since Darwin's day, studies of sexual selection often have featured insects because of their short generation time, facility of manipulation in the laboratory, and relative ease of observation in the field. For example, dung beetles belonging to the large and diverse genus Onthophagus may display elaborate horns that vary in size between individuals and in position on the body between species. Large horns are restricted nearly exclusively to males, with only one species known in which the female has better-developed protuberances than conspecific males. Studies show that females preferentially select males with larger horns as mates. Males size each other up and may fight, but there is no lek. Benefits to the female come from long-horned males' better defensive capabilities against intruders

Beekeeping for Beginners

Beekeeping for Beginners

The information in this book is useful to anyone wanting to start beekeeping as a hobby or a business. It was written for beginners. Those who have never looked into beekeeping, may not understand the meaning of the terminology used by people in the industry. We have tried to overcome the problem by giving explanations. We want you to be able to use this book as a guide in to beekeeping.

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