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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.
Physical Weathering Mechanical forces acting upon the rocks cause physical weathering. Temperature fluctuations cause expansion and contraction of rock surface resulting in the
GRAFFIAN FOLLICLE - It appears as knob or stigma in medulla. It is round, discovered by Graff. It is covered by 2 layers - thecae externa & theca interna. From theca i
A newborn baby with a patent foramen ovale or a ventricular septal defect might be cyanotic (blue). Will a two-year-old with these defects also be cyanotic? Explain your answer.
How membrane maintained impermeability to potassium At 1 AM, an impermeable membrane divides a 1 liter solution of 1M NaCl in the left compartment from a 1 liter solution havin
what is flora?
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Polysaccharides and Oligosaccharides are both parts of carbohydrate molecules, but they vary in complexity and size. The Oligosaccharides are much easier and smaller, according to
Q. Define the term Behaviour Change Communication? Behaviour Change Communication (BCC) is an interactive process with communities to develop specific messages and methods usin
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