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An interesting observation made by an American biologist H.C. Bumpus (1899) provides a good explanation for normalising selection. Bumpus collected some 136 injured house sparrows after a severe snow and sleet storm with high winds at Woods hole. Of these birds 64 died, resulting in two groups of sparrows, those that were killed by the storm and the ones that survived. Bumpus, made measurements of a number of randomly chosen traits such as wing length, wing span, tarsus length etc and found that those that were killed by the storm had measurements which fell at the ends of the bell shaped curve. In other words, birds which had either mean or close to the rnean measurements were the ones to survive. Normalising selection generally eliminates during a catastrophe or a stressful situation individuals whose traits vary markedly from the mean values. By way of interpreting Bumpus's observations, it could be said that the birds which were blown down easily by the winds had either their wings too long for their body weight and therefore presented a larger surface area or they had too short wings for their body size and therefore could not fly against strong winds. Prjor to the catastrophe the range of individual measurements was larger as compared to the range of measurements that survived the catastroihe. Every catastrophe may narrow down the variability of the population thereby weeding out suboptimal genotypes.
Explain about Cyanocobalamin Cyanocobalamin occurs as dark red crystals or as a crystalline hygroscopic powder of the same colour without odour and taste. Upon standing in the
Explain Fats Fats: As you are already aware, fats are reservoir of calories. In addition to carbohydrates, fats can also be an important source of needed calories.
Packaging Compound feeds, whether in mash or pellet form, are packed in bags or stored in bins. Bags may be filled directly from mixers, pellet coolers or holding bins and wei
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Types of polyembryony
discuss why obelia is considered to be of special interest in zoology as an animal showing an intermediate grade of organisation
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