Studies on “clonal in ver te brates,” which are all ge net ic ally iden ti cal and would thus be ex pected to show lim it ed dif fer ences in behav ior, are “nonex is ten t,” they added, report ing their find ings in the March 1 on line issue of the jour nal De vel op men tal Psy cho bi ology.
“This is sur pris ing giv en the ob vi ous ad vantages of us ing in ver te brates/clones to tack le the cru cial ques tion why such con sist ent behav ioral dif fer ences ex ist,” they went on. Per son al ity dif fer ences not at trib ut a ble to genes are gen er ally pre sumed to be due to the en vi ron ment in which an or gan ism formed, though there is al so a grow ing apprecia t ion of epige net ic fac tors—chem ical dif fer ences that are not ge net ic, but that in flu ence gene ac ti vity.
Pea aphids, sci entifically named Acyr tho si phon pi sum, are pale little in sects ty pi cally less than a sixth of an inch (half a cen ti me ter) long that feed on pea plants and their rel a tives. A clus ter of aphids in fest ing a giv en plant is typ ic ally a ge net ic ally iden ti cal, or clonal, group pro duced by one moth er with out sex, al though aphids can al so re produce sex u ally at cer tain phases.
When a pea aphid is threat ened by a preda tor—of which the spe cies has sev er al includ ing wasps and grub s—it gives off a chem i cal alarm sig nal that alerts near by aphids. They may re spond in sev er al ways: they can walk away, drop off the plant or seem ingly ig nore the sig nal. The re search ers, Wiebke Schuett and col leagues, found that pea aphids can be di vid ed in to one of three cat e gories: con sist ent “drop pers,” con sist ent “non-droppers,” and some that be have un pre dict a bly.
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