What exactly is species evenness?

Species evenness refers to how close in numbers each species in an environment is.

Explanation: For example, let's say there are 15 elephants, 60 zebras and 5 lions on our first sample. The sample from the second states 35 elephants, 25 zebras and 20 lions. The total of both sample 1 and sample 2 become 80. Sample 2 is relatively more evenness than sample 1 . This is because the total number of animals in the sample is quite evenly distributed between the 2 samples. This environment  is not very even though. Species richness is a measure of the number of different kinds of organisms present in a particular area. Evenness compares the similarity of the population size of each of the species present as I mentioned above.

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answer: land bridge theory. land bridge theory held that shifting portions of dry land explained the finding of identical species on different continents. plate tectonic theory eventually eliminated the land bridge theory.

b. heterotroph

explanation: