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 rectangular full mucoperiosteal flaps, Explain Rectangular Full Muc...

Explain Rectangular Full Mucoperiosteal Flaps - Endodontic Surgery      a. Releasing and relaxing "vertical" incisions, with the Horizontal incision, b. Causes re

Importance of family and patient education - food allergy, Define Importanc...

Define Importance of Family and Patient Education - Food Allergy? Remember, involvement of the family and all other relevant caretakers along with the patient is crucial for pr

State the layers of retina, State the Layers of retina The retina is c...

State the Layers of retina The retina is coil~posed of ten layers: a) Pigmented epithelium (outermost layer), b) Neusoepithelium, rods and cones (photoreceptors), c) Exte

Rbc & wbc, difference between RBC and WBC for homework

difference between RBC and WBC for homework

Quantitative characters - population density, Quantitative Characters - Pop...

Quantitative Characters - Population Density Density denotes the average number of individuals of a particular species in a unit area. In other words, it represents the numeri

Why is rubella during gestation a threat to the fetus, Q. Why is rubella du...

Q. Why is rubella during gestation a threat to the fetus? If taking place during gestation rubella is a dangerous disease because the virus crosses the contaminates fetus and t

Explain vanishing points., A vanishing point is where parallel lines that m...

A vanishing point is where parallel lines that move off into the distance seem to converge. It's an artifact of perspective. The vanishing point for any set of lines that are paral

Raw material for industry - impacts on biodiversity, Raw Material for Indus...

Raw Material for Industry - impacts on biodiversity The industry, producing goods and services, relies and impacts on biodiversity directly. Much of the raw material that goes

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