You discover in a study of a group of five fossil taxa with spines that the mean spine length has increased over time. When you tabulate mean spine lengths for each taxon over time, you obtain the following table. X = Taxon has become extinct
Time interval Taxon 1 Taxon 2 Taxon 3 Taxon 4 Taxon 5
245–214 MYA 2.3 7.0 1.4 5.6 4.8
215–184 MYA 2.4 6.9 1.5 5.4 4.6
185–154 MYA 2.2 7.1 1.3 5.3 4.7
155–124 MYA X 7.2 1.5 5.5 4.9
125–94 MYA X 7.0 X 5.7 4.6
95–65 MYA X 6.8 X 5.6 X
What kind of process is underlying this active evolutionary trend?
What will be an ideal response?
ANS:
lineage sorting
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