FIGURE 7.
Variation of shell ornamentation index (expressed by OI) along the latitudinal gradient. (a) Northern hemisphere in 10° latitudinal bin from different coastlines; (b) Southern hemisphere in 10° latitudinal bin from different coastlines. Trend gradient and the corresponding p‐value were tested by the Cochran–Armitage trend test, with adjusted p‐values shown in parentheses.