JOHNSON and BARNETT: CORRELATION BETWEEN CHARACTERS AND FOOD SUPPLY 



Table 9.-IPVALA photophore counts of Vinciguerria nimbaria from the Philippine and South China seas. Antipodes station positions 

 given in Figure 4. Distance from shore (Philippine Sea stations only) given in rank order from nearest to land to most distant offshore. 



Rr 



rank of mean, R,. = rank of distance offshore. 



Antipodes 

 stations 



65 65.5 66 66.5 67 67.5 68 68.5 69 69.5 70 70.5 71 71.5 72 72.5 



n Mean ± 95% limits R. 



1, 2 



3,4 

 5, 6 



8 

 10 



11, 12 

 13, 14 

 15, 16 

 17, 18 

 19, 20 

 21, 22 



- 1 



1 - 



- 1 



10 

 22 

 28 

 22 



10 

 6 



13 

 6 



26 



14 

 100 



69.80 ± 0.895 

 69.47 ± 0.456 

 69.84 ±0.308 

 69.95 ± 0.374 



70.30 : 

 69.17: 



69.31 : 

 69.83 : 

 69.06 : 

 69.54 : 

 69.59 : 



; 0.420 

 : 0.930 



0.531 

 : 1.124 

 : 0.440 

 : 0.604 



0.209 



4 

 8 

 3 

 2 

 1 



10 

 9 

 5 



11 

 7 

 6 



4 

 5 

 8 

 11 

 10 

 9 

 7 

 6 

 3 

 2 

 1 



sibility and ignore the fourth possibility in our 

 subsequent discussion. 



We believe that the observed meristic variation 

 is the result of genetic differences between 

 populations and not the result of an ecophenotypic 

 effect of food availability conditions on develop- 

 ment of meristic characters. We present evidence 

 available to support this belief, but we note that 

 this evidence is not conclusive. 



A statement of the ecophenotypic explanation is 

 easily made. The meristic variation observed could 

 result if the effect of low food densities upon the 

 development of meristic characters parallels the 

 effect of low temperature, retarding growth rates 

 more than differentiation rates, and lengthening 

 the period of determination of meristic characters. 

 Because the effect of low food availability upon 

 egg maturation appears to be a reduction of egg 

 number and not egg size (Anokhina 1960; Blaxter 

 1969), any ecophenotypic effect of low food density 

 upon meristic characters would have to operate 

 between the onset of feeding and metamorphosis. 

 Riley (1966) and Blaxter (1969), among others, 

 have found for the species they have studied that 

 the time to reach metamorphosis may be sig- 

 nificantly increased by decreasing the density of 

 food. Therefore an indispensable condition of the 

 ecophenotypic explanation is that for the species 

 studied, the final values of meristic counts are de- 

 termined after the onset of feeding. If so, the 

 meristic variation observed might result from a 

 concordant increase in the length of the period of 

 determination of meristic characters with a delay 

 in time to reach metamorphosis in larvae from 

 areas of lower productivity. 



Three facts resulting from the study of the 

 development of the eggs and larvae of Vin- 

 ciguerria lucetia by Ahlstrom and Counts (1958) 

 appear to support the ecophenotypic explanation: 

 1) Ahlstrom and Counts did find a direct rela- 

 tionship between size at metamorphosis (no 

 developmental time scale is available for any of 

 the species studied) and numbers of longitudinal 

 photophores and vertebrae; 2) vertebral ossifica- 

 tion and photophore formation in V. lucetia occur 

 in larvae 11 mm SL or more in size, well after 

 yolk-sac absorption and presumably after the on- 

 set of feeding; and 3) the distances between 

 samples of V. lucetia utilized in construction of 

 Figure 3 are small, much less in most cases than 

 the distances between the eight study areas for 

 the other species discussed in this paper. Yet the 

 results for V. lucetia along the east to west tran- 

 sect lines apparently agree with results for the 

 other mid-water species. We find it difficult to 

 believe that the results for V. lucetia are 

 explainable in terms of genetically distinct 

 populations distributed along these inshore to 

 offshore transects. 



Three lines of evidence appear to contradict the 

 ecophenotypic explanation in favor of the 

 explanation hypothesizing that the observed 

 meristic variation is the result of genetic 

 differences between populations. (1) in Vin- 

 cigusrria lucetia the total number of myomeres 

 are formed in late stage eggs (Ahlstrom and 

 Counts 1958). Since the number of myomeres, 

 vertebra! counts, and longitudinal photophore row 

 counts are usually highly intercorrelated, the 

 ecophenotypic explanation appears to be invalid in 



293 



