Sex–specific effects of carotenoid intake on the immunological response to allografts in guppies (Poecilia reticulata)

Abstract

Rarely are the evolutionary origins of mate preferences known, but, recently, the preference of female guppies (Poecilia reticulata) for males with carotenoid-based sexual coloration has been linked to a sensory bias that may have originally evolved for detecting carotenoid-rich fruits. If carotenoids enhance the immune systems of these fishes, as has been suggested for other species, this could explain the origin of the attraction to orange fruits as well as the maintenance of the female preference for orange males. We used the classic immunological technique of tissue grafting to assay a component of the immune response of guppies raised on two different dietary levels of carotenoids. Individual scales were transplanted between pairs of unrelated fishes, creating reciprocal allografts. Transplanted scales were scored on a six-point rejection scale every day for 10 days. Five days later, the same pairs of fishes received a second set of allografts and were scored again. Compared with low-carotenoid-diet males, high-carotenoid-diet males mounted a significantly stronger rejection response to the second allograft but not to the first allograft. High-carotenoid-diet females, however, showed no improvement in graft rejection compared with low-carotenoid-diet females. To our knowledge, this is the first experimental evidence for sex-specific effects of carotenoid consumption on the immune system of a species with carotenoid-based sexual coloration. These results are consistent with the hypothesis that the mate preference for carotenoid coloration is maintained by the benefits to females of choosing healthy mates, but they cast doubt on the idea that the benefits of carotenoid consumption, per se, could account for the origin of the preference. The sex-specificity of carotenoid effects on allograft rejection in guppies provides indirect support for the general hypothesis that males pay an immunological cost for sexual ornamentation.

Carotenoid trade-off between parasitic resistance and sexual display: an experimental study in the blackbird ( Turdus merula )

“…Many studies have confirmed the immunostimulant properties of carotenoids (Chew 1993;Van Poppel et al 1993;McGraw & Ardia 2003;Grether et al 2004). However, few works have addressed directly whether carotenoid availability enhances parasitic resistance.…”

“…In addition, previous experimental studies using parasites have found that (i) controlled infections reduce the expression of carotenoid-based ornamentation (Hill & Brawner 1998;Brawner et al 2000;Horak et al 2004), (ii) parasite eradication positively affects carotenoidbased ornamentation (Martinez-Padilla et al 2007), and (iii) expression level of ornaments may indicate males' ability to clear parasite infection (Lindströ m & Lundström 2000). Furthermore, newly developed methods, which allow measurement of the magnitude of the immune response to various antigens (see Adamo (2004) for a review), made it possible to identify a positive relationship between carotenoid-based coloration and various immune effectors (Blount et al 2003;McGraw & Ardia 2003 and references therein), and have also shown that immune defence and sexual attractiveness are constrained by carotenoid availability (Blount et al 2003;Grether et al 2004;McGraw & Ardia 2004). However, the potential link between parasitic infection and expression of secondary sexual traits needs further investigation because both parasites themselves and parasitic resistance may affect ornamentation in different ways.…”

Carotenoid availability affects the development of a colour-based mate preference and the sensory bias to which it is genetically linked

“…Animals are unable to synthesize these pigments (Goodwin 1984), and in some species, including guppies, a trade-off exists between the use of ingested carotenoids in colouration and in the immune system (Olson & Owens 1998;Blount et al 2003;Faivre et al 2003;McGraw & Ardia 2003;Grether et al 2004). The primary source of carotenoids for guppies in nature is unicellular algae, the availability of which is largely a function of the openness of the forest canopy (i.e.…”

Efectos Ecotoxicologicos Del Cartap Sobre Poecilia Reticulata "Guppy'' (Poecilidae) Y Paracheirodon Innesi "Neon Tetra'' (Characidae)

“…Es considerada una especie de importancia ornamental por la acuarofilia mundial (Balon 2004). Se han realizado en P. reticulata diversos estudios en el ámbito del aprendizaje y del comportamiento reproductivo (Brosnan et al 2003, Croft et al 2003, Grether et al 2003, así como modificaciones en el comportamiento por acción de pesticidas organofosforados (Selvi et al 2004). Paracheirodon innesi (Myers, 1936) "Neon Tetra" (Characidae), es una especie amazónica, domesticada y conocida por los acuaristas a nivel mundial (Balon 2004).…”