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

System that permits movement and fixation to echinoderms, What is the syste...

What is the system that permits movement and fixation to echinoderms? The system that allows movement and fixation to substrates in echinoderms is known as the ambulacral syste

How b and t cells recognize antigen are true explain, Which of the followin...

Which of the following statements about how B and T cells recognize antigen are true? a. B cells only recognize antigen presented by class I or class II MHC molecules. b. Both cell

Define antiketogenic effect of carbohydrate, Define Antiketogenic Effect of...

Define Antiketogenic Effect of Carbohydrate? Presence of carbohydrates is necessary for normal fat metabolism. In the absence of sufficient carbohydrates, larger amounts of fat

Why does the urinary volume increase, Why does the urinary volume increase ...

Why does the urinary volume increase when alcoholic beverages are ingested? Alcohol inhibits the ADH (antidiuretic hormone) secretion by the hypophysis. Low ADH decreases the t

Phyletic lineage, Ask questiona brief assignment on it #Minimum 100 words a...

Ask questiona brief assignment on it #Minimum 100 words accepted#

Fluoride - mineral elements, FLUORIDE It is mostly available in drin...

FLUORIDE It is mostly available in drinking water. Fluoride is essential for the formation of enamel of the teeth. Deficiency of fluoride causes weakness of enamel.

Bty100, 1. (a) Which physicochemical properties need to be regulated by the...

1. (a) Which physicochemical properties need to be regulated by the cell? Define chemical equilibrium and discuss how it is maintained by the cell. (b) Differentiate between facili

Define health effects related to probiotics, Define Health Effects related ...

Define Health Effects related to Probiotics? Several lines of evidence support the conclusion that normal gut microflora are involved in resistance to disease, especially gastr

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