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Evo­lu­tion


A Col­lec­tion of News by Moos


201212Jun19:52

Pre­dict­ing the for­ma­tion of new species

Infor­ma­tion
pub­lished 12 June 2012 | mod­i­fied 25 July 2012
Archived

When ani­mals or plants col­o­nize new habi­tats, a num­ber of new species may evolve from a sin­gle ances­tor. But it is dif­fi­cult to pre­dict on the basis of envi­ron­men­tal con­di­tions or species-​specific traits alone whether and to what extent diver­si­fi­ca­tion will occur.

An Eawag study of African lake cich­lids has now shown what com­bi­na­tion of extrin­sic fac­tors and intrin­sic traits leads to high rates of spe­ci­a­tion, thus pro­mot­ing biodiversity.

Why do some groups of species diver­sify – in just a few thou­sand years – to the point of form­ing a wide vari­ety of new species, while oth­ers remain essen­tially unchanged for mil­lions of years? This is one of the key ques­tions for sci­en­tists inves­ti­gat­ing the emer­gence and decline of bio­di­ver­sity. From var­i­ous stud­ies, it is known that spe­ci­a­tion is influ­enced both by envi­ron­men­tal fac­tors (e.g. habi­tat diver­sity, cli­mate) and by species-​specific traits (e.g. col­oration, behav­iour pat­terns). How­ever, lit­tle is known about how the extrin­sic and intrin­sic fac­tors interact.

CichlidThese inter­ac­tions have now been explored in more detail by a team of researchers led by Eawag and the Uni­ver­sity of Bern. In a study pub­lished in the lat­est issue of Nature, they demon­strate for cich­lids from 46 African lakes that the prob­a­bil­ity of diver­si­fi­ca­tion, or “adap­tive radi­a­tion”, depends on a com­bi­na­tion of envi­ron­men­tal fac­tors and sex­ual selec­tion. African cich­lids are par­tic­u­larly suit­able for this type of study because of the extremely high species rich­ness that devel­oped over time from what was orig­i­nally a small num­ber of species in large African lakes. For Lakes Vic­to­ria and Malawi alone, more than 800 endemic cich­lid species have been recorded.

Accord­ing to the study, diver­si­fi­ca­tion is more likely to occur in deep lakes and in areas with rel­a­tively high solar radi­a­tion. By con­trast, lake size has prac­ti­cally no influ­ence on the like­li­hood of spe­ci­a­tion – which is sur­pris­ing, as spe­ci­a­tion in ter­res­trial species is known to depend in part on the avail­able habi­tat area. Among the species-​specific traits, the inten­sity of sex­ual selec­tion (mate choice) was shown to be a key fac­tor, as indi­cated by the asso­ci­a­tion between sex­ual dichro­ma­tism (dis­tinc­tive col­oration of males and females) and diversification.

If the rel­e­vant eco­log­i­cal fac­tors coin­cide with sex­ual selec­tion, the diver­gence of species is most likely to occur. The spe­ci­a­tion process is thus, to a cer­tain extent, pre­dictable. At the same time, these find­ings also make it pos­si­ble to pre­dict adverse impacts of human activ­i­ties on bio­di­ver­sity – for exam­ple, if the hab­it­able depth of lakes is altered as a result of pol­lu­tion or the low­er­ing of water lev­els rates of species for­ma­tion will decline and exist­ing species diver­sity is expected to collapse.

The above news item is reprinted from mate­ri­als avail­able at EAWAG aquatic research via Sci­enceDaily. Orig­i­nal text may be edited for con­tent and length.

(Source: EAWAG, 10.06.2012)

Goal: 7000 tigers in the wild

Tiger range countries map

Tiger map” (CC BY 2.5) by Sander­son et al., 2006.

about zoos and their mis­sion regard­ing breed­ing endan­gered species, nature con­ser­va­tion, bio­di­ver­sity and edu­ca­tion, which of course relates to the evo­lu­tion of species.
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