Agriopus hispidus See Pigfishes

Albicore CD's *spelling for Albacore,' i.e. Thunnus alalunga (Bonnaterre, 1788).

As noted by CD, Albacore feed on flying fishes, which feed on small *crustaceans (Journal, Dec. 6, 1833). What supported the latter, i.e. the basis of pelagic *food webs, eluded him, however, as *phytoplankton had not yet been discovered. (See also Plankton.)

Aleuteres spp. See Filefishes.

Algae Aclass of plants including the ordinary seaweeds and the filamentous freshwater weeds (Origin VI, p. 430; see Blennies; Damselfishes; Kelp; Lizards; Parrotfishes; Plankton).

Alosa See Herrings.

Altruism An action by, or feature, of a given individual, appearing to benefit a different and unrelated individual.

Altruism represented a serious problem for CD's theory of *natural selection. Thus, after reading in McClelland (1839, p. 230) that Fishes are bright to be caught, he noted: I must utterly deny this. - If this could be passed -farewell my thesis (Marginalia 550). CD then developed this point: It has been asserted that animals are endowed with instincts, not for their own individual good or for that of their own social bodies, but for the good of other species, though leading to their own destruction: it has been said that fishes migrate that birds & other animals may prey on them;2 this is impossible on our theory of the natural selection ofself-profitable modifications ofinstinct. But I have met with no facts, in support of this belief worthy of consideration. (*BigSpecies Book p. 520; n. 2 cites Linnaeus (1762), p. 389, and Alison (1847), pp. 7,15).

CD rightly saw in altruism a clear test of his theory (see also Difficulties), which thus meets *Popper's criterion of falsifiability: As in nature selection can act only through the good of the individual, including both sexes, the young, & in social animals the community, no modification can be effected in it for the advantage of other species; & if in any organism structure formed exclusively to profit other species could be shown to exist, it would be fatal to our theory. Yet how often one meets with such statements, as that the fish in the Himalayan rivers are bright-coloured, according [to] an excellent naturalist, that birds may catch them! How the fish came to be bright-coloured I can no more pretend to explain than how the *Gold-fish, which Mr *Blyth Ā«informs me he> believes to be a domestic *variety of a dull-coloured Chinese fish, has gained its golden tints, or than how the *Kingfisher, which preys on these fish, comes to be so brilliantly *coloured, without, as far as we can see, any direct relation to its habits. (Big Species Book, p. 382; the excellent naturalist is McClelland, cited above. Seealso Handicap principle.)

Strangely enough, a Russian school of self-described 'Darwinian' evolutionists emerged which saw altruism of the kind CD rejected as the motor of *evolution (Todes 1989; Sapp 1994). This school included a noted ichthyologist, Karl Fedorovich Kessler, who interpreted fish reproduction, schooling and migrations as forms of'mutual aid' (Todes 1989, pp. 109-12).

'Mutual aid' is tempting, though it is not what seems to be happening in nature. Rather, the detailed study by Hamilton (1964) and others, first of social insects, then of other social animals, demonstrated conclusively that 'helping,' for an animal, can lead to increased survival and reproduction of kin, i.e. siblings, cousins, etc. Their increased fitness increases the 'inclusive fitness' of the helper, thus compensating for the cost ofhelping, which can go, for example in the worker caste among euso-

cial insects, as far as forgoing reproduction. Or put differently: an animal can opt to spread its genes by helping its relatives reproduce successfully, and thereby spread the shared genes, which can be seen as the ones that 'selfishly' benefit from the whole arrangement (Dawkins 1989).

Thus, CD need not have worried about altruism ultimately undermining his theory. In fact, altruism became one of the exceptions that probed the rule.

Amblyopsis See Cavefishes.

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