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Geir Rudolfsen Rudolf Müller Davnah Urbach Claus Wedekind 《Behavioral ecology and sociobiology》2008,62(4):561-567
The mating behavior and reproductive strategies of Alpine whitefish like Coregonus zugensis (Nüsslin) are poorly understood, probably because they spawn in deep water where direct observations are difficult. In this
study, we interpret life-history and sperm quality traits of fish that we caught from their spawning place. We found that
males invest heavily into gonadal tissue (up to 5.6% of their body weight), which is, in comparison to other fish, consistent
with external fertilization, distinct pairing and moderate to high communal spawning, or no pairing and low to moderate communal
spawning. Sperm competition theory and recent experimental studies on other salmonids predict that males optimize ejaculate
characteristics in relation to the costs of sperm and the level of competition they have to expect: dominant males are predicted
to invest less into ejaculate quality and to have slower spermatozoa than subdominant males. We found that spermatozoa of
older males are slower than those of younger males. Moreover, older males have larger breeding tubercles, a secondary sexual
trait that has, in some previous studies, been found to be linked to good condition and to good genetic quality. Our results
suggest that C. zugensis has age-linked reproductive strategies, that multimale spawning is common, i.e., that sperm competition plays a significant
role, and that older males are on average dominant over younger males at the spawning place. 相似文献
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Numbers of studies in externally fertilizing fish species provide evidence for an effect of ovarian fluid on sperm motility characteristics such as duration of forward mobility, velocity or percent motile sperm cells. Yet, because of variations among females in the quality of their ovarian fluid, such effects might differ between individuals. Additionally, ovarian fluid from different females could also be expected to affect each ejaculate differently, resulting in cryptic female choice. In this study on Artic charr (Salvelnius alpinus), sperm velocity from several males was measured in the diluted ovarian fluid of several females according to a fully balanced crossing design. This design allowed us to estimate variations among females in the effect of their ovarian fluid on the velocity of sperm from different males, and to detect variations among males in the ability of their sperm to swim in ovarian fluid. Sperm velocity was estimated by computer-assisted sperm analysis. Average velocity was found to vary among females, with some females having constantly higher velocity measurements in their ovarian fluid, and among males, indicating that some males had overall faster sperm in ovarian fluid than others. Moreover, variation in sperm velocity was shown to depend on individual female-male interactions. Our results document that females vary in the effect of their ovarian fluid on sperm velocity and that their ovarian fluid may stimulate sperm velocity according to individual characteristics of males. This latter result suggests a potential mechanism for cryptic female choice.
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Davnah UrbachEmail: Phone: +41-31-6313182Fax: +41-31-6314535 |
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