Question

Calculate the mean (average) persistence times for species with planktonic larvae and species with nonplanktonic larvae.

Short answer

The mean persistence time for species with planktonic larvae is 4.6 million years, and the mean persistence time for nonplanktonic larvae is 1.6 million years.

Step-by-step solution

Planktonic and nonplanktonic larval stage

One of the life stages of invertebrate organisms that allows the species to disperse is the planktonic larval stage. The growth of the larvae occurs at adrift at sea. In contrast, nonplanktonic larvae develop at the benthic layer of the sea and do not show much dispersion.

Calculation of mean or average

The mean or average is calculated by adding given scores or data and dividing the sum of the data by the number of scores or data.

Average of species with planktonic larvae and nonplanktonic larvae

Mean persistence time of species with planktonic larvae equals sum of persistence time of planktonic larvae species divided by the total number of bars.

\(\frac{{6.12 + 6.12 + 6.12 + 1.08 + 1.44 + 6.12 + 0.17 + 7.92 + 2.16 + 6.12 + 6.12 + 7.20 + 3.24}}{{13}} = 4.6\)

Hence, the average persistence time of planktonic larvae species is 4.6 million years.

The mean persistence time of species with nonplanktonic larvae equals the sum of the persistence time of nonplanktonic larvae divided by total number of bars.

\(\frac{{1.80 + 1.80 + 6.12 + 1.08 + 2.52 + 2.52 + 0.72 + 1.44 + 1.44 + 4.68 + 2.88 + 1.80 + 1.80 + 1.80 + 1.80 + 1.08 + 1.08 + 1.08 + 1.08 + 1.08 + 1.08 + 1.08 + 0.72 + 0.72 + 0.72 + 0.72 + 2.16}}{{28}} = 1.77\)

Hence, the average persistence time of nonplanktonic larvae species is 1.7 million years.