Example 3

This problem concerns snail crushing behaviour in pumpkinseed sunfish. There are two neighbouring lakes with a pumpkinseed sunfish population in each. Wintergreen Lake has a small snail population while Three Lakes II has a large snail population. There were significant differences in the bone and muscle mass of the snail-crushing anatomy of the two populations of sunfish. The extent of morphological differentiation was ranked for the five employed muscles.

Electrical activity patterns were recorded for the five muscles during snail crushing. These measured the relative timing, duration, and intensity of the activity. The five muscles were then ranked according to the extent of functional differentiation between lake populations.

When the lists were compared, little relationship between structure and function was seen.

a)Shows a schematic lateral view of a pumpkinseed sunfish illustrating the pharyngeal jaws(upper=UPJ,lower=LPJ), and some of the muscles that control the pharyngeal jaws. The position of a snail is also shown.
b)Gives the procedural steps involved in analyzing the structure.
c)Gives the procedural steps involved in analyzing the function.
d)Shows a comparison of the ranking lists for structure and function. No relationship between structure and function is seen.

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