The Remarkable Fossil of the "Fishapod," Tiktaalik, Which Lived About

question 118

Multiple Choice

The remarkable fossil of the "fishapod," Tiktaalik, which lived about 375 million years ago, is a beautiful example of an intermediate form, having the attributes of both fish (scales, fins) and tetrapods (a flat head, mobile neck) . The presence of Tiktaalik and other fossils of other organisms that lived around the same time shows clear evidence that tetrapods were derived from fish, implying, that the grouping "fish" is paraphyletic. Imagine now that there was no fossil record. Would it still be possible to determine whether or not "fish" is paraphyletic?

• A)Yes, because a phylogeny can be constructed using morphological and molecular characters of modern fish and tetrapods.
• B)No, because without a fossil record there is no evolutionary history of fish available for study.
• C)Yes, because Tiktaalik is a species of coelacanth, and so phylogenetic reconstructions can be based on coelacanth characters.
• D)No, because modern fish and modern tetrapods share no synapomorphies.

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Definitions:

ANOVA

Stands for Analysis of Variance, a statistical method used to test differences between two or more means.

Dependent Variables

Variables in an experiment that are expected to change as a result of manipulations to the independent variable.

Independent Variables

Variables that are manipulated or selected by the researcher to determine their effect on the dependent variable.

MANOVA

Multivariate Analysis of Variance, a statistical test that assesses for differences in multiple dependent variables across one or more factor levels.