AS Biology please help - Biodiversity?

B

butterkist

New member
The definition for species evenness in my workbook is:

"Species evenness is a measure of the relative abundance of each species in an area. The more similar the population size of each species, the greater the species evenness."

Could someone clarify this a bit more please, as I don't fully understand the definition.

Please, please don't copy information from Wikipedia - I already checked it and its definition too is confusing.

Thank you xxx
 
Pretend there are six species in this area - lay out six plates on a table.
Pretend a Ritz cracker represents one member of that species. Put Ritz crackers on the plates.

Do you have an even number of Ritz crackers on the plates (e.g. roughly the same number on each) ? If so, you have species evenness. Do you have a bunch of crackers on some plates and almost no crackers on the others? In that case you do not have species evenness.

Now - to go a bit further ... even under the best of circumstances, not all species would have the same number of members. So another way of looking at species evenness is to look at the ratio of members to 'ideal' members for each species - if the ratios are even then you have species evenness.
 
species richness = number of species in a habitat

species evenness = is the number/abundance of individuals in each species
 
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