. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 390 Bulletin Museum of Comparative Zoology, Vol. 148, No. 8 .3r .2 - < 0 - -. I -Fossil Treasure Cay. .3 .5 .6 AXIS I Figure 9. Factor loadings on the first and fourth axis for all samples of Little Bahama Bank cerions. Al- though the fourth axis explains less than 1 per cent of the total variance among samples, it separates both the Treasure Cay populations and the single fossil sample from all others. island itself, while bunching of lines at the northern coast indicates tlie rapid transition from coastal dwarfs
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. 390 Bulletin Museum of Comparative Zoology, Vol. 148, No. 8 .3r .2 - < 0 - -. I -Fossil Treasure Cay. .3 .5 .6 AXIS I Figure 9. Factor loadings on the first and fourth axis for all samples of Little Bahama Bank cerions. Al- though the fourth axis explains less than 1 per cent of the total variance among samples, it separates both the Treasure Cay populations and the single fossil sample from all others. island itself, while bunching of lines at the northern coast indicates tlie rapid transition from coastal dwarfs to interior shells of modest size that we observed in the field. (Though we had noticed the coastal phe- nomenon, we did not expect the regional pattern to be so simple.) We detected no geographic pattern in the vector of resid- uals. 3. Distinction of subareas on Abaco. With more than 30 samples of C. liendaUi from Abaco, we could detect more local patterns of distinction, also correlated with geo- graphic isolation. i) small, ribby shells of Pongo Carpet. We have already reported in detail on a semi-isolated coastal area well within the range of C. hendalli (Gould, ^^'oodruff, and Martin, 1974). Here, along nearly 7 km of eastern coast, we find a small, heavy, fairly ribby morphology partly convergent on C. ahacoewie. (We included only one Pongo Carpet sample in this study; it has the highest loading of any pure C. hendalli sample upon the C. ahacoeme axis—Fig. 6.) This Pongo Caipet morphology is most distinct in its southern area of greatest isolation, and varies in a clinal fashion to- wards "normal" moiphology as it ap- proaches the northern zone of contact. It cannot be distinguished genetically from surrounding populations of standard mor- phology. In fact, it shares with these sur- rounding normal populations the only dis- tinctive genetic marker (the rare Mdh-2''' allele) of its area—Mdh-2'' is fixed in all other populations of C. hendalli. Although these
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