Observation of bumpus, Biology

Assignment Help:

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.


Related Discussions:- Observation of bumpus

Explain the cultural practices of single crop, Explain the Cultural Practic...

Explain the Cultural Practices of single crop Continuous cultivation of a single crop over years on the same site causes accumulation of a particular group of microbes, which d

What is the endocrine function of the placenta, Q. What is the endocrine fu...

Q. What is the endocrine function of the placenta? The placenta is not a permanent gland of the endocrine system other than this it also has endocrinal function. The placenta p

Functions of iron in the body, functions of iron in the body: Iron i...

functions of iron in the body: Iron is the major component in haemoglobin. It helps to carryout oxygen from lungs to the tissues. About 60 to 70% of Iron in the body i

Parasitology, how nematodes adapted to their mode of feedings

how nematodes adapted to their mode of feedings

Lymphatic drainage of the heart, The heart is drained by vessels that trave...

The heart is drained by vessels that travel in the interventricular and atrioventricular grooves. One set runs in the anterior part of the atrio-ventricular groove. The vessels of

Agro industrial-chelating agents, Chelating agents Oxalates: Only a ...

Chelating agents Oxalates: Only a few plants contain sufficient amounts of sodium and potassium oxalate to be considered toxic. Moreover, ruminants that consume these plants

Elaborate evolution by natural selection , Elaborate Evolution by Natural S...

Elaborate Evolution by Natural Selection ? The conelaboratecept of natural selection lies at the heart of Darwin's Theory of Evolution. Darwin understood that plants and animal

What do you mean by somites, Q. What do you mean by somites? Somites ar...

Q. What do you mean by somites? Somites are differentiated portions of mesodermal tissue longitudinally distributed along the embryo and the somites originate the muscle portio

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd