Long‐term fitness consequences for offspring of female oviposition decisions in the rose bitterling (Rhodeus ocellatus)

Abstract

Agbali, M. and Smith, C. 2012. Long-term fitness consequences for offspring of female oviposition decisions in the rose bitterling (Rhodeus ocellatus). -Acta Zoologica (Stockholm) 93: 367-372.Female oviposition decisions can have immediate consequences for offspring fitness as well as longer-term effects, either through irreversible disruption to normal development, inducing alternative adult phenotypes, or through 'coping' whereby challenges to development are compensated in the short term, but carry a fitness cost in the adult. We investigated the long-term impacts of oviposition decisions on offspring fitness parameters in the rose bitterling fish (Rhodeus ocellatus). Bitterling lay their eggs in the gills of living freshwater mussels, which complete development inside the mussel gill chamber. Bitterling embryo mortality in mussels is density dependent, and consequently, there are immediate costs associated with using mussels containing high numbers of eggs and embryos. We raised embryos at high and low densities for the first 4 weeks of development and then at a common low density until sexual maturity. Our results showed no effect of density on offspring survival or growth. However, there was an impact of density on age and size at maturity, with embryos raised at high densities becoming sexually mature earlier and at a smaller size. This effect may arise through embryos coping with low oxygen conditions during development. The results are discussed in the context of development and mating system evolution.

Sex differences in the responses to oviposition site cues by a fish revealed by tests with an artificial host

“…These differences may reflect different adaptive priorities for males and females. Thus, while females attend to cues that reflect mussel quality as a site for incubation of young stages (Smith et al, 2001(Smith et al, , 2002Agbali et al, 2010;Agbali & Smith, 2012), males instead appear sensitive to the risk of sperm competition (Spence, Reichard & Smith, 2013), and are insensitive to mussel quality (Smith et al, 2002(Smith et al, , 2003(Smith et al, , 2014bCasalini et al, 2013). A sexual conflict over responses to oviposition sites in R. amarus may, consequently, arise.…”

“…Bitterling eggs are relatively large compared to other similarly sized fish, allowing them to fit in the interlamellar spaces of a mussel gill, and consequently have a high per capita oxygen requirement (Aldridge, 1999). Given that mussels sometimes host well over bitterling eggs (Smith et al, 2001;Kitamura, 2005), competition for oxygen inside the mussel gill can be severe, both among embryos and between embryos and host, and it is notable that embryo mortality rates in mussels are strongly density dependent (Smith et al, 2000(Smith et al, , 2001Agbali & Smith, 2012;, presumably due to asphyxiation (Aldridge, 1999;Kitamura, 2006). Consequently, natural selection is predicted to favour a preference for cues that indicate directly whether a mussel is hosting the eggs and embryos of other females, or indirectly through the decline in quality of a mussel as a result of superparasitism.…”

“…Thus oviposition-site decisions are a key component of the bitterling mating system, with immediate (Smith et al, 2000;Mills & Reynolds, 2002a) and longer-term (Agbali & Smith, 2012) consequences for fitness.…”

Experimental evidence for parasite‐induced over‐winter mortality in juvenile Rhodeus amarus

“…This effect could arise from D. pseudospathaceum ‐infected females with impaired vision suffer an impaired ability to inspect mussels prior to oviposition, and may show sub‐optimal preferences for mussels (Smith et al , ). In this case, the embryos would experience greater density dependent mortality (Smith et al , 2000 b ), or impairment to their development (Agbali & Smith, ; Spence & Smith, ).…”

Histological structure of the female gonads and ovipositor of the European bitterling, Rhodeus amarus (Bloch, 1782) (Cyprinidae: Acheilognathinae)

“…; Konečná et al . ; Agbali and Smith ; Pateman‐Jones et al . ), host–parasite relationships (Bryja et al .…”