Fig. 3: Condition-dependent sex determination and sex change.

a Density-dependent sex determination potentially affecting ASR in (1) the nematode Romanomermis culicivorax, (2) temperate eels, (3) the pejerrey, (4) the brook lamprey, (5) the European sea bass and (6) the zebrafish Danio rerio. In all the above-mentioned species, more males are produced at high density. b Socially induced sex change occurs in various species such as (7) protandrous clownfishes, protogynous (8) wrasses (e.g., Thalassoma bifasciatum) and (9) Potter’s angelfish as-well as bi-directional sex change as exemplified in (10) the blue-banded goby. Other examples of socially controlled sex change were observed in both crustaceans and amphibians: (11) Northern shrimp exhibit protandrous sex change that occurs at small size when the density of females in the population is high. Protogynous sex change was also observed in (12) captive reed frogs and its occurrence is linked to local male density. Hence, for most sex changing species, those individuals that do not change sex are more numerous. Note that the direction of the arrow in the right panel (b) indicates the direction of sex change: orange from male to female (protandrous) and maroon from female to male (protogynous). Drawing by Pierre Lopez (MARBEC) based on data from refs. ^{71,72,73,74,75,76,77,78,79,80,81,82,169}.