Question

At different sites along the coast of California, the following data was recorded:

Species	Site 1 abundance		Site 2 abundance
Mytilus californicus	70		19
Tigriopus californicus	0		290
Strongylocentrotus purpuratus	7		4
Pisaster ochraceus	1		0
Balanus glandula	0		20
Tegula funebralis	24		13
Mopalia muscosa	5		0
Pagurus samuelis	0		13
Pagurus hirsutiusculus	14		27
Pollicipes polymerus	1		4

Use two different indices to compare the sites. First, compute the Jaccard Index.

The Jaccard Index uses presence/absence data (i.e., ignores info about abundance)

SJ = a/(a + b + c), where

SJ = Jaccard similarity coefficient,

a = number of species common to (shared by) quadrats (or sites),

b = number of species unique to the first quadrat, and

c = number of species unique to the second quadrat

Next, compute the Similarity ratio:

Similarity between quadrats i and j is

SR , where

yki = abundance of kth species in quadrat i

Briefly discuss the results of the two computations. Under what conditions would you get similar (or identical answers) for the two indices?

Answer 1

Briefly discuss the results of the two computations. Under what conditions would you get similar (or identical answers) for the two indices?

Solution:-

• The Jaccard index also called Intersection over Union is a statistic used for analyse the similarity and diversity of sample sets.

• The Jaccard coefficient ascertain similitude in the middle of limited example sets, and is characterized as the measure of the convergence separated into the extent of the association of the example sets.

• The Jaccard remove, that compute uniqueness in the middle of test sets, and integral to the Jaccard coefficient that is gotten by subtracting in the Jaccard coefficient from 1 by separating to the distinction of the sizes to the association and that crossing point with two sets by the extent of the association.

• In the given above dates of the coast of California to mantion two site. The site 1 have number of the Tigriopus californicus are zero when contrasted with the site 2 of similar species. As indicated by the Jaccard coefficient site 1 have contain zero species individuals turns into its survivability is less when contrasted with the site 2 for similar species.
• But have rivers case also present as mentioned previously.  The number Mytilus californicus species at site 1 is more(70)as contrasted with the site 2(19),because additionally the resistances of the Mytilus californicus species are more at site 1as contrasted with the site 2.

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