PiscesLogoSmallerStill Species accumulation tutorial

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The species accumulation curve, which shows the increase in the taxa observed with sampling effort, is an excellent way to summarise the completeness of the sampling effort. In this tutorial we take you through creating observed and smoothed species accumulation curves.

 

First open the data set called hinkley_fish.csv

 

This data set is for the fish community of the Bristol Channel, England. It is a monthly record of fish samples over 184 months. It is one of the largest data sets of its type available.

 

open hinkley fish

 

Now as we initially want to show the species accumulation curve as collected, go to the drop down box at top of the window labelled "Number of random selections of sample order" and change this number to 1. (The default is typically 10, which would automatically undertake 10 random permutations of sample order)

 

random selections

 

 

Now from the Abundance tab choose Species Accumulation.

 

selecting species accumulation

 

A results window will open showing the results. Select the graph tab

 

selecting graph

 

A graph showing the species accumulation will be shown as follows (for this graph we have changed the graph default fonts and line thickness using the graph tools above the plot):

 

species accumulation curve

 

Now this graph clearly shows the gradual deceleration in the acquisition of new species, however, the rate changes through time because of random sampling noise, climatic events etc. We can get a better idea of the general trend by randomly changing the sample order a number of times, and averaging the species accumulation curves produced.

 

To produce this smoothed curve go to the drop-down box at top of the window labelled "Number of random selections of sample order" and change this number to 30. The window showing the species accumulation curve will close down. Click again on Species accumulation under the Abundance tab, select the graph tab, and the following smoothed graph will appear.

 

smoother accumulation

This graph shows the general trend of species acquisition with sampling effort, adjusted for random sample order.