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Members belonging to different species refrain from mating because of the behavioural differences between them. Such behavioural differences usually centre around specific courtship patterns which the species have evolved. The behaviour patterns are more conspicuous in animals rather than in plants. And among animals, once again, the courtship behaviour is more pronounced among terrestrial and fresh water organisms than in marine forms. Mayr points out that in those forms where there is an elaborate courtship behaviour the interspecific hybrids are rare. Closely related species that do not have pair-binding courtship rituals do commonly give rise to hybrids. Mayr is of the opinion that in species where there is a courtship behaviour pattern, the "engagement" may be broken if the pairs do not belong to the same species, A detailed study of the courtship behaviour of six species of Drosophila showed that courtship and mating could be divided into six phases. If there is incompatibility at any one of these six phases, the potential mates break off and the courtship is discontinued. Under laboratory conditions, the interspecific crosses have not been successful and the courtship was terminated even in the first stage. What is more interesting here is that even to a trained observer differences in courtship behaviour exhibited by different species may appear to be trivial and insignificant. But the species recbgnise the specific signals and respond suitably. In certain other forms differences in courtship behaviour between species could be very pronounced, The courtship dances of the different species of Uca (shore crab) could be recognised from a distance. This is also true of mating dances of salamanders, turtles and birds.
Describe cardiac rewabilptation and its various effects ? A survival benefit cannot be attributed solely to exercise training because many studies involved multifunctional inte
Q. Counselling for day to day Management? As we know that diabetes is a chronic disease, a major part of its control requires counselling the patient and his family for day to
Using the words 'cilia' and 'mucus', describe, very briefly, how the body gets rid of dust which enters the lungs. The lining of the air passages makes mucus which traps dust p
Define influence of polyphenols on Carbohydrates? Binding of proteins may indirectly affect carbohydrate absorption. Inhibition of amylolytic enzymes and subsequent reduction o
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Dot blot is the technique for measuring the amount of one perticular DNA or RNA in the highly complex mixture. The samples are spotted onto the hybridization membrane (like nitroc
Q. What are the functions of glucagon and insulin for the blood glucose control? Glucagon increases insulin and glycemia reduces it. They are antagonistic pancreatic hormones.
Q. What is a nutrient? A nutrient is every substance used in the metabolism and which is obtaining from the diet. For example, essential amino acids and vitamins are nutrients.
what is the advantage of being dark skinned?
Researchers (Helle et al., 2004) analyzed rates of twin births in the Sami population of Northern Scandinavia during the eighteenth and nineteenth centuries. They found that (1) a
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