In biological science, there are a figure of biological fluctuations which occurs in a assortment of beings from cells to individual or a group of beings of the same species ( Cullen. 2009 ) . These may non be noticeable whereas in some instances are noticeable, i.e. coloring material of tegument. Variations are caused by either familial differences ( besides known as genotypic fluctuation ) or environmental factors which affect the look of a familial phenotype ( besides known as phenotypic fluctuation ) or may even be a combination of the two. These fluctuations could attest as physical visual aspects, birthrate, biochemistry and other measureable characterises such as tallness and weight of an being. ( Cumming. 2011 )

Genotypic fluctuations occur when there is a difference in the figure or construction of the chromosomes. ( Deshek and Harrison. 2006 ) Variations could besides happen when there is a difference in the cistrons carried by the chromosomes. An illustration of familial fluctuation is human blood groups, oculus coloring material, and organic structure construction and besides if an being is immune to disease i.e. some persons who have sickle cell anemia have the same cistron which is shown to hold increased opposition malaria ( Cumming. 2011 ) .

Environmental caused fluctuations could be caused by either one or several combined factors such as ; clime, nutrient supplies, and even competition exhibited by other beings which live in the same home ground. This type of fluctuation would therefore find an being ‘s phenotypic fluctuation ( Deshek and Harrison. 2006 ) .

A combination of the two biological fluctuations ( genotypic fluctuation and phenotypic fluctuation ) could be the tallness of an person, where the tallness of an person is an familial features but the handiness of foods in the environment would find the person ‘s existent tallness ( Farris, M. 2008 ) .

We Will Write a Custom Essay Specifically
For You For Only $13.90/page!

order now

In the carnal land the biological fluctuation of colorss alterations in species is frequently recorded. An illustration would be the north-polar fox where this type of fox could alter its pelt coloring material when alterations in the environment occur, i.e. from a warm season to a cold season. Environmental factors such as visible radiation and temperature alterations would enable the artic fox to alter from brown ( warm season ) to white ( cold season ) , this provides a natural advantage of disguise and besides provides version to the north-polar cold ( Naughton. 2012 ) .

Biological fluctuation is found in a figure of different beings, environmental factors would greatly impact the biological fluctuations of beings of the same species. Periwinkle shells, Littorina Littorea, show biological fluctuation in tallness, mass and aperture, where moving ridge exposure is one of the chief factors which would impact the periwinkle size distribution ( Boulding, Holst, & A ; Pilon, 1999 ) , the periwinkle shells would therefore to accommodate to the rough home ground. The periwinkle size would change due to the ecological affects such as: the periwinkle, ( are herbivorous grazers ) , display a size dependent graze rates ( Geller. 1991 ) , ( which would cut down the interspecific competition due to obtaining smaller nutrient beginnings than larger beings ( Byers. 2000 ) , and besides there would be a differential choice of home grounds by age ( Saier. 2000 ) to obtain the most from a home ground.


The stuffs used to transport out the experiment were, 50 Winkle shells, Vernier calipers were used to mensurate the periwinkles height and aperture, electronic balance was used to mensurate the mass of the periwinkle.


There were 50 winkle shells were used where in the experiment, the measuring of each shells height and aperture was measured to the nearest 0.1mm utilizing vernier calipers. Vernier calipers ( Fig 3 ) are an instrument which were used to mensurate the precise internal and external distances of the peri-winkle shells highly accurately.

Fig 3: shows a diagram of a manual Vernier caliper used to mensurate objects external distances, and internal distances. hypertext transfer protocol: //

The Vernier calipers consists of two jaws which are the external and internal jaws ; the external jaw was used to mensurate the exterior diameter i.e. tallness, of the peri-winkle shell ( from the aperture to the vertex ) while the interior jaw was used to mensurate the internal diameter i.e. the aperture, of the shell.

To obtain a reading with the Vernier calipers, the measurings must foremost be understood. The 1cm grade on the vernier caliper is equal to 10mm on a fixed caliper, for illustration if the graduated table is adjusted ( to the right ) by 2mm off from the 10mm grade, this would read as 12mm ( 10mm + 2mm = 12mm ) .

Another illustration for reading the graduated table was:

The caliper must foremost be zeroed on the skiding Vernier graduated table. Read the figure from the fixed graduated table ( when a measuring is being taken ) . If the value is between two values, the lower value must be read.

The line on the Vernier graduated table must be found which aligns absolutely with another line on the fixed graduated table. If no lines are absolutely aligned, happen the 1 that would be the cupboards. Read the figure on the Vernier graduated table for this line, the two readings would so be combined to obtain the measuring. Fig 4 shows the fixed reading is 3 millimeter and the Vernier reading is 0.58 millimeter, so when the measuring is combined, 3mm + 0.58, an reply of 3.58 is obtained millimeters ( ehow. 2013 ) .

hypertext transfer protocol: //×800.jpg

Fig 4: shows how to read a value which has been obtained in the fix measuring. ( ehow. 2013 )

To mensurate the tallness of the peri-winkle shells ( fig 5 ) utilizing the Vernier caliper ; the first measure that was taken is to put the caliper to 0, the shell was placed level on the surface and a measuring was taken of the tallness ( fig 5. Labelled as H ) of the shell from the axis of the shell to the aperture. The measuring of the aperture was taken by the internal jaws of the calipers by ; shuting the internal jaws of the caliper ( set to 0 ) so the internal jaws of the calipers was placed into the oral cavity of the shell, the internal jaws were opened and a measuring of the aperture was taken from lip to lip ( fig 5, from a to B ) inside the oral cavity of the aperture. The consequence ( tallness and aperture ) for each shell was so recorded in tabular array ( fig 6 in appendix ) .

hypertext transfer protocol: //

Fig 5: shows the basic measuring processs for the periwinkle shell. Where measurings of the tallness were taken from the axis to the aperture, labelled as H, and the measurings of the aperture were taken from a to b inside the oral cavity. ( Independent research. 2013 )

Each shell was so separately weighed utilizing an electronic top pan balance to mensurate the mass of the periwinkle shell to the nearest 0.01g. To avoid any systematic mistakes, the balance was first zeroed before the measuring was taken for each person shell as to obtain a right reading. The mass for each of the 50 shells was so recorded in a tabular array ( Fig 6 in appendix ) .


These consequences are shown for the shell mass against the shell tallness ( fig 1 ) and besides shell mass against the shell aperture ( fig 2 ) . Using the correlativity coefficient, a additive relationship was identified between the shell mass ( g ) and the undermentioned varibles: shell tallness ( in millimeter ) and shell aperture ( in millimeter ) .

These correlativities were so presented in fig 1 and fig 2.

Fig 1: shows a graph for Shell mass ( g ) against snake pit tallness ( millimeter )

Fig 2: shows a graph for shell aperture ( millimeter ) and shell mass ( g ) .


The R2 value shows if the line of best tantrum for the information points, is strong or weak, the closer the value of R2 is to 1, the stronger the line of best tantrum for the consequences presented whereas the R value shows weather the line of best tantrum has a positive or negative correlativity, this value is known as the correlativity coefficient, depending on conditions the R value is a positive figure ( positive correlativity ) or negation figure ( negative correlativity ) .

Fig 1 shows that there is a additive relationship between shell mass and the shell tallness. Fig 1 shows that the R2 value is 0.774 which shows that the line of best tantrum is comparatively strong for the information points, the graph besides shows a R value of 0.88 which indicates that there is a strong positive correlativity between the shell mass and shell tallness, the information points besides show a grade of preciseness, hence figure 1 indicates that, as the mass of the shells addition there is besides an addition in tallness of the shells, this would therefore indicate that as the tallness additions of the periwinkle littorina Littorea due to environmental factors such as, wave daze ( Raffaelli. 1982 ) , the closer the periwinkles are to the shore, the tallness would increase as there is more wave exposure whereas the smaller periwinkle shells which show a lessening size in tallness and aperture would be found farther off from the shore.

Fig 2 besides shows a additive relationship between the shell mass and the shell aperture. Fig 2 shows a R2 value of 0.056 which shows that the line of best tantrum is comparatively weak for the information points presented. The graph besides shows an R value of 0.24 which indicates line of best tantrum presents a relativity weak positive correlativity since the information points are really much scattered this would therefore indicate that as the mass of the shells addition there is besides a ( comparatively low ) addition in the shell aperture nevertheless the graph does demo some fluctuation with the consequences because some of the information points show that as the mass additions there is non a high addition in shell aperture, for illustration: shell no. 3 ( fig 6 ) has a mass of 3.287g but has a shell aperture of 6.9mm while the bulk of shells with a mass of 3g or higher show a aperture value of 7.7mm or higher. There are besides other fluctuations in fig 2, five of the information points show aperture values which do non transcend 8mm as the shell mass additions, this may therefore indicate that the periwinkle shells which show a aperture value of 8mm or less would hence be found farther off from the shore where there is less wave exposure so the periwinkle would hold in decrease pes size as excess adhesion is non needed comparison to the periwinkle found closer to the shore.

The size of the periwinkle, Littorina Littorea, shell size is genetically determined nevertheless environmental factors may hold an consequence on the phenotypic look of the shell. Environmental factors such as moving ridge exposure, interspecies competition, predation and besides nutrient handiness would hold an consequence on the shell size ( Lawrence. 2001 ) . Shells with an addition tallness combined with the increased aperture would therefore indicate that the periwinkle would hold been found much closer to the shore due to environmental factors, such as moving ridge exposure, where the excess tallness of the shells would defy excess moving ridge exposure whereas the addition in aperture would enable an addition in foot size for greater adhesion ( Raffaelli. 1982 ) to the soft deposit found closer to the shore, moreover the shells would hold adapted to accommodate the environment factors found in the country.

However there may some fluctuations in the consequences obtained ( i.e. fig 2 ) , where this comparatively low sample size of the shells may non hold been plenty to find the ( overall ) existent size of the periwinkle shells aperture or tallness, where the experiment could hold been improved by: a larger sample could hold been taken to acquire a much clearer overview of the periwinkles in the environment.


There does look to be a really strong nexus between the shell mass and the shell tallness, and at that place seems to be a comparatively weak nexus between the shell mass and shell aperture. Examples of size fluctuations for the periwinkle shells shows how the shells became adapted to their environment where this would reason with Charles Darwin ‘s theory of development, where these fluctuations would happen for the endurance and reproduction of the species so the altered cistrons, hence would go through onto the following coevals of periwinkle Littorina Littorea.

Entire word count: 1,991


Boulding, E. G. , Holst, M. , & A ; Pilon, V. ( 1999 ) . Changes in choice on univalve shell size and thickness. Journal of Experimental Marine Biology and Ecology, 232: 217-239.

Buffler, A. ( 2003 ) . Using the Vernier calipers and micrometre screw gage. [ Online ] . Available at: hypertext transfer protocol: // ( Accessed on 17th March 2013 )

Cullen, K. E. ( 2009 ) . Encyclopaedia of Life Sciences. New York: Info base Publishing. Pp. 70

Cumming, M. R. ( 2011 ) . Human Heredity: Principles and Issues. USA: Cengage Learning. Pp. 426

Cumming, M. R. ( 2011 ) . Human Heredity: Principles and Issues. USA: Cengage Learning. Pp. 98

Deshek, V. W. and Harrison, M. ( 2006 ) Plant Cell Biology. USA: Science Publishers. Pp. 261

Lawrence, J. M. ( 2001 ) . Edible Sea Urchins: Biology and Ecology: Biology and Ecology. Amsterdam: Elsevier Science. Pp. 169

Farris, M. ( 2008 ) . The Altitude Experience: Successful Trekking and Climbing above 8000 pess. United statess: Globe Pequot. Pp. 15, 16

Geller, J. B. ( 1991 ) . Gastropod grazers and algal colonisation on a bouldery shore in northern California: the importance of the organic structure size of grazers. Journal of Experimental Marine Biology and Ecology, 150: 1-17.

Independent research. ( 2013 ) . NAHANT Those Curiously Interesting Snails. [ Online ] . Available at: hypertext transfer protocol: // ( accessed on 17th March 2013 )

McKenzie, G. ( 2013 ) . How to Read Calipers On Micrometres. [ Online ] . Available at:

hypertext transfer protocol: // ( Accessed on 17th March 2013 )

Naughton, D. ( 2012 ) . The Natural History of Canadian Mammals. Canada: University of Toronto Press. Pp. 391-392

Saier, B. ( 2000 ) . Age-dependent zonation of the periwinkle Littorina Littorea ( L. ) in the Wadden Sea. Helgol Mar Res, 54: 224-229.

Raffaelli, D. ( 1982 ) . Recent ecological research on some European species of Littorina. Journal of Molluscan Studies, 48: 342-354.


I'm Niki!

Would you like to get a custom essay? How about receiving a customized one?

Check it out