Fig. 1.

The dispersal-related trait diversity of aquatic macroinvertebrates. Taxa that disperse in water include the crustacean genera Potamon (a) and Asellus (arrow in b), planarians (b), the bivalve mollusc genus Unio (c), insect larvae such as the Diptera genus Simulium (d) and Plecoptera genus Leuctra (e), and adult Coleoptera including the dytiscid genus Cybister (f). Such aquatic dispersers may move passively in the drift (c,d) and/or actively crawl or swim (a,b,e,f). Most adult insects have wings and can fly overland (f–n). Wings are morphologically diverse and include various types: one wing pair, as in Diptera such as the syrphid genus Eristalis (g); one pair of wings with elytra for Coleoptera including the genus Enochrus (h) or with hemielytra for Heteroptera such as the genus Hesperocorixa (i); two wing pairs including one pair of small hind wings for Ephemeroptera including the genus Ephemera (j); and two pairs of similar-sized wings for the Trichoptera genus Polycentropus (k), the Megaloptera genus Sialis (i) and the Odonata genera Ischnura (m) and Crocothemis (n). Wings range in size from a few mm in some Diptera (g) up to more than 3 cm (l–n), with the Odonata exemplifying the large morphologies. Taxa vary in the number of eggs produced per female, ranging from tens per reproductive cycle for most Coleoptera and Heteroptera such as the genus Sigara (o) to several hundreds in the egg masses of most Ephemeroptera and Trichoptera, such as those of the genus Hydropsyche (p). Credits: Adolfo Cordero-Rivera (a–g,i,k–n), Jesús Arribas (h), Pere Bonada (j), José Antonio Carbonell (o) and Maria Alp (p).