. Carnegie Institution of Washington publication. VARIATION AND HEREDITY OF BODY-LENGTH. 13 VARIATION AND HEREDITY OF BODY-LENGTH. The variation in size in some of the species is really extraordinary. It is relatively slight in Epilachna, Adalia, Harmonia, Anatis, Cycloneda, Paranaemia, Megilla, and Anisosticta. But in Hippodamia and Coccinella H. convergens and C. novemnotata stand out as greatly more variable than their co-species (fig. 2). It is easy to see why Epilachna should not be so highly variable, since the food-supply rarely becomes short for the indi- vidual larva. The aphid supply
. Carnegie Institution of Washington publication. VARIATION AND HEREDITY OF BODY-LENGTH. 13 VARIATION AND HEREDITY OF BODY-LENGTH. The variation in size in some of the species is really extraordinary. It is relatively slight in Epilachna, Adalia, Harmonia, Anatis, Cycloneda, Paranaemia, Megilla, and Anisosticta. But in Hippodamia and Coccinella H. convergens and C. novemnotata stand out as greatly more variable than their co-species (fig. 2). It is easy to see why Epilachna should not be so highly variable, since the food-supply rarely becomes short for the indi- vidual larva. The aphid supply is, on the other hand, very uncertain, and it is a great advantage for a species to undergo metamorphosis when the food falls short, even though undersized. But why are not all the aphidivorous species highly variable, then? Again we may say that Adalia is more constant because of its short larval period, which makes it less likely to suffer from limitation of the food-supply; but why, then, is the large Anatis / \/. \l 56 57 58 59 00 61 62 63 64 65 66 67 08 69 70 71 73 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 01101 1 2 3 4 11 4 11 17 11 14 15 9 13 9 8 1 2 0 0000000 0 = 154 00000 00 0 1205 1 36 8 6 10 16 11 9 14 9 13 16 14 12 9 35: 0=175 lot males ; 175 f>'imiles. FIG. 2.—Variation ol'length ol' of JIij>i>ml<i»ti<i convergens, Fail-field, Washington, l!K).j. relatively constant? To determine if shortage of food-supply really could reduce the size, I experimented upon Epilachna, which one would expect would be most resistant to such treatment. I was able to get healthy beetles of only mm. in length of elytra, while mm. is not rare in nature. I believe, then, that the greater part of the variation in size is modificational. In addition to the factors mentioned above, it seems possible that H. convergens and C. novemnotata resort to a greater variety of aphids, the season of some of which is of short Please note that these image
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