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Many communal breeders are characterized by a conflict over who gets to reproduce, with dominant individuals often claiming the largest share of reproduction in the group. How do dominants control breeding in these species? Although infanticide has often been invoked as a means of control, previous theoretical work on indiscriminate killing of young did not support this idea. There is, however, increasing evidence from field studies in both vertebrates and insects that infanticidal individuals can discriminate between their own offspring and those of other group members, and thus avoid the risk of accidentally killing their own progeny. In a simple game-theoretical model we demonstrate that the capacity for discriminate infanticide can promote high reproductive skew even though few or no offspring are actually killed. When discrimination is good and offspring are cheap to produce, the threat of infanticide prevents the subordinate cobreeder from adding many young to the joint brood, and no killing need occur. High levels of infanticide tend to occur only when discrimination is poor, costs of offspring production are low and/or relatedness is low. 相似文献
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Joseph Gyekis David A. Blizard Joseph T. Stout David J. Vandenbergh Gerald E. McClearn Reinmar Hager 《Evolutionary biology》2011,38(4):434-440
Trade-offs occur when two traits have opposing fitness effects such that positive selection on one trait is constrained by
the negative fitness consequences of the other trait. To understand why trade-off may arise we need to study the genetic and
non-genetic factors that influence associated traits because these may respond differently to selective pressure. Research
into trade-offs has largely focused on the genetic basis of associated traits, yet both maternal effects and epigenetic effects
have recently been shown to affect life history traits that play a role in trade-offs. In this study, we analyze genetic,
epigenetic and life-history predictors of one of the most important trade-offs, that between offspring number and offspring
mortality. Using a large-scale 3-generational intercross between two divergent mouse lines C57BL/6J and DBA/2J, we show that
litter size differences between these lines, although significant, are surprisingly not the most important predictors of mortality.
Offspring genotype, maternal effects and their interactions are the most influential factors determining mortality. We found
significant paternal effects suggesting an important influence of paternal care or potentially the role of imprinted genes.
Perhaps contrary to expectations our results further show that the trade-off between offspring number and mortality is not
just a simple function of the two factors yielding, on average, an ‘optimal’ litter size at weaning. Indeed if one focused
on litter size and mortality alone, the slope of relationship is the same for the two lines, yet they differ in the number
of young at weaning. Our study reveals that a perceived trade-off between two traits is governed by a more complex set of
interactions between genetic and non-genetic effects. 相似文献
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Summary Cr could be demonstrated in reaction products of adrenaline and noradrenaline with K2Cr2O7 by spot test analysis. The strong contrast of amine granules in the electron microscope partly may be due to the presence of Cr within them. When KJO3 is used for oxydizing amines, only a slight contrast of granules can be observed in the electron microscope.
Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.
Zur Zeit Gast am Anatomischen Institut der Universität Tübingen. Ständige Adresse: Institut für Histologie und Embryologie der Tierärztlichen Hochschule Wien. 相似文献
Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.
Zur Zeit Gast am Anatomischen Institut der Universität Tübingen. Ständige Adresse: Institut für Histologie und Embryologie der Tierärztlichen Hochschule Wien. 相似文献
519.
Discrete red patches of water were observed in South San FranciscoBay (USA) on 30 April 1993, and examination of live samplesshowed that this red tide was caused by surface accumulationsof the pigmented ciliate Mesodinium rubrum. Vertical profilesshowed strong salinity and temperature stratification in theupper 5 m, peak chlorophyll fluorescence in the upper meter,and differences in the small-scale density structure and fluorescencedistribution among red patches. Events preceding this Mesodiniumred tide included: (i) heavy precipitation and run-off, allowingfor strong salinity stratification; (ii) a spring diatom bloomwhere the chlorophyll a concentration reached 50 mg m3;(ii) depletions of dissolved inorganic N and Si in the photiczone; and (iv) several days of rapid warming and stabilizationof the upper surface layer. These conditions may be generalprerequisites for M.rubrum blooms in temperate estuaries.
1Present address: Station Marine d'Endoume, Centre d'Oceanologiede Marseille, rue Batterie des Lions, 13007 Marseille, France 相似文献
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