Spawning colouration, parasites and habitat selection in Salvelinus alpinus: initiating speciation by sexual selection?

Abstract

The relationship between parasite infection and breeding ornamentation in an Arctic charr Salvelinus alpinus population was examined. Interrelationships between the intensities of parasites with different dietary transmission routes suggested that hosts were segregated by habitat and diet preferences. That is, intensities of parasites transmitted through intermediate hosts that share habitat were, in both sexes, positively interrelated. Negative interrelationships in the intensities of parasites transmitted through different hosts were found only in females. The intensity of breeding colouration was positively correlated with intensities of amphipod-transmitted parasites in both sexes. Intensities of parasites transmitted through copepods showed no relationship to morphological or ornamental characters. Seen in the context of morphology and ornaments of previously described sympatric populations of Arctic charr, these relationships suggested that individual variation in niche background may provide a source for the initial variation in morphology and secondary sexual traits leading to sympatric speciation through sexual selection. # 2005 The Fisheries Society of the British Isles

MHC Adaptive Divergence between Closely Related and Sympatric African Cichlids

“…There is therefore two distinct modes of transmission involved. Thus we cannot rule out the possibility that species differences in susceptibility stems from differences in microhabitat or diet rather than from genetic differences [43]. However, there is substantial overlap in microhabitat and both species feed by combing attached filamentous algae with their specialized bi- and tricuspid teeth [24].…”

Does Breeding Ornamentation Signal Genetic Quality in Arctic charr, Salvelinus alpinus?

“…The Arctic charr (Salvelinus alpinus L.) is a fish species exhibiting a carotenoid-based abdominal ornamentation that is correlated with parasite intensities and immune activity (Skarstein and Folstad 1996;Skarstein et al 2005). The breeding coloration is clearly a sexually dichromatic trait, males being redder than females (Skarstein and Folstad 1996).…”

“…The breeding coloration is clearly a sexually dichromatic trait, males being redder than females (Skarstein and Folstad 1996). The expression of redness can, however, considerably vary among reproductively active fish within both sexes (Skarstein et al 2005;Nordeide et al 2008), though the role of these colours in signalling and mating has yet remained unclear. Nonetheless, because the mating system of Arctic charr is clearly non-resource-based, i.e., neither sex provides parental care after spawning (Sigurjónsdóttir and Gunnarson 1989), mate choice is likely to be based, in addition to potential direct benefits from gamete quality and quantity (see Måsvaer et al 2004;Janhunen et al 2009), on indirect genetic benefits.…”

Conspicuous carotenoid-based pelvic spine ornament in three-spined stickleback populations—occurrence and inheritance

“…We adjusted the final I R -value of the skin fold of the pelvic spines of each fish according to the I R -value of the cardboard in each photo relative to the average I R -value of all photos. Similar methods to quantify colouration have previously been applied by several authors who discussed this method of quantifying colour in ornaments, and gave more details and estimates of repeatability (Yong et al, 2013; Nordeide, Rudolfsen & Egeland, 2006; Villafuerte & Negro, 1998; Nordeide et al, 2008; Skarstein & Folstad, 1996; Skarstein, Folstad & Rønning, 2005; Neff et al, 2008). An alternative method to quantify colour, spectrophotometry, was discarded because of the small size, difficult accessibility of the ornament, and (in some individuals) un-even distribution of the colour at different parts of the spine (Fig.…”