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Greater Fecundity (greater + fecundity)
Selected AbstractsDiet and social conditions during sexual maturation have unpredictable influences on female life history trade-offsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 3 2009E. L. B. BARRETT Abstract The trade-off between gametes and soma is central to life history evolution. Oosorption has been proposed as a mechanism by which females can redirect nutrients invested in oocytes into survival when conditions for reproduction are poor. Although positive correlations between oocyte degradation and lifespan have been documented in oviparous insects, the adaptive significance of this process in species with more complex reproductive biology has not been explored. Further, environmental condition is a multivariate state, and combinations of environmental stresses may interact in unpredictable ways. Previous work on the ovoviviparous cockroach, Nauphoeta cinerea, revealed that females manipulated to mate late relative to sexual maturation experience age-related loss in fecundity because of loss of viable oocytes via apoptosis. This loss in fecundity is correlated with a reduction in female mate choice. Food deprivation while mating is delayed further increases levels of oocyte apoptosis, but the relationship between starvation-induced apoptosis and life history are unknown. To investigate this, virgin females were either fed or starved from eclosion until provided with a mate at a time known to be suboptimal for fertility. Following mating, females were fed for the duration of their lifespan. We measured lifetime reproductive performance. Contrary to predictions, under conditions of delayed mating opportunity, starved females had greater fecundity, gave birth to more high-quality offspring and had increased longevity compared with that of fed females. We suggest that understanding proximal mechanisms underlying life history trade-offs, including the function of oocyte apoptosis, and how these mechanisms respond to varied environmental conditions is critical. [source] Sexual selection maintains whole-body chiral dimorphism in snailsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2007M. SCHILTHUIZEN Abstract Although the vast majority of higher animals are fixed for one chiral morph or another, the cause for this directionality is known in only a few cases. In snails, for example, rare individuals of the opposite coil are unable to mate with individuals of normal coil, so directionality is maintained by frequency-dependent selection. The snail subgenus Amphidromus presents an unexplained exception, because dextral (D) and sinistral (S) individuals occur sympatrically in roughly equal proportions (so-called ,antisymmetry') in most species. Here we show that in Amphidromus there is sexual selection for dimorphism, rather than selection for monomorphism. We found that matings between D and S individuals occur more frequently than expected by chance. Anatomical investigations showed that the chirality of the spermatophore and the female reproductive tract probably allow a greater fecundity in such inter-chiral matings. Computer simulation confirms that under these circumstances, sustained dimorphism is the expected outcome. [source] Growth and reproductive biology of the foxfish Bodianus frenchii, a very long-lived and monandric protogynous hermaphroditic labridJOURNAL OF FISH BIOLOGY, Issue 3 2010S. Cossington Samples of the foxfish Bodianus frenchii, collected over reefs on the lower west and south coasts of Western Australia, contained individuals ranging up to 78 years old. Although B. frenchii is far smaller than many other species within the Labridae, its maximum age is the greatest yet recorded for this highly speciose family and, together with Achoerodus gouldii, provides an example of a temperate hypsigenyine with exceptional longevity. Length and age compositions of females and males and the histological characteristics of gonads of a wide length range of individuals demonstrated that B. frenchii is a protogynous hermaphrodite. Furthermore, as, on both coasts, the length of the smallest male was greater than that at which all females had become mature, B. frenchii is a monandric protogynous hermaphrodite, i.e. all of its males are derived from functional females. Attainment of maturity by females is related more to length than age, whereas the reverse is true for sex change. On the basis of Schnute growth equations and length-to-body mass regression equations, the predicted length at age and body mass at length of fish on the south coast were greater than those on the west coast throughout life. Although B. frenchii spawns daily during the main spawning season, which extends from October to February on both coasts, its fecundity at any given length is substantially greater on the south than on the west coast. The more rapid growth of juveniles and earlier attainment of maturity by B. frenchii on the south coast than on the warmer west coast, together with maturation at a similar size on both coasts, run counter to the trends observed in many species and certain ecological theories regarding the relationships between life-cycle traits and latitude and temperature. The attainment by B. frenchii of a larger body length at age, of greater body mass at length and of greater fecundity at both length and body mass in fish on the south than on the west coast strongly suggests that conditions on the former, cooler coast are more favourable for this labrid, which belongs to a sub-genus whose other species typically live in cool, deep, temperate waters. [source] Maternal host plant effects on aphid performance: contrasts between a generalist and a specialist species on Brussels sprout cultivarsAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2010Muhammad Tariq 1The performance of the second generation (G2) of alates and apterae of a generalist, Myzus persicae, and a specialist, Brevicoryne brassicae, aphid species reared on Chinese cabbage or cabbage was evaluated on five cultivars of Brussels sprout. 2Aphid performance was influenced both by the type of host on which the parent aphid had been reared and by the host on which it was feeding when reproducing. 3The fecundity of the G2 of alates of both aphid species reared on Chinese cabbage differed significantly between all the cultivars of Brussels sprout and, on average, was 25% higher than those reared on cabbage. These differences were also apparent for the intrinsic rate of increase of B. brassicae but not for M. persicae. 4There was a trend for the G2 of alates from Chinese cabbage to have greater fecundity compared with aphids from cabbage. These differences were significant for the fecundity of the G2 of alates of both aphid species on Brussels sprout cultivars Fillbasket (30% higher), Red Delicious (35% higher) and Winter Harvest (25% higher) than those reared on cabbage. 5The intrinsic rate of increase for the G2 of alates of B. brassicae from Chinese cabbage was significantly different on all Brussels sprout cultivars tested. The intrinsic rate of increase differed significantly between aphids reared on either Chinese cabbage or cabbage on cultivars Oliver and Darkmar-21 (M. persicae) and Red Delicious and Winter Harvest (B. brassicae). The cv. Oliver appeared to be the most consistently good host; Red Delicious was the poorest host overall. [source] The effects of water source and secondary water treatment on flame angelfish Centropyge loriculus (Günther) reproductionAQUACULTURE RESEARCH, Issue 10 2010Chatham K Callan Abstract This study was conducted to determine whether water source and water treatment affected flame angelfish (Centropyge loriculus) reproduction. Flame angelfish broodstock were maintained and monitored for reproductive performance (fecundity, egg fertilization rates and egg viability) in either untreated well-water (WW), sterilized ocean water (OW) or WW treated by intensive recirculation treatment (biological filtration, protein skimming, UV sterilization and mechanical filtration) (RAS). Results of this experiment indicated that although pairs maintained in WW initially exhibited good spawning performance, fecundity, egg fertilization rates and egg viability declined after 25 weeks. Treatment of WW by recirculation did not significantly improve flame angelfish reproductive performance with only moderately improved fecundity compared with pairs in the WW treatment. In contrast, pairs held in sterilized OW exhibited significantly greater fecundity, egg fertilization rates and egg viability from week 25 onwards than pairs in either the WW or RAS treatments. However, in the process of developing OW biosecurity protocols, we found that sterilization of OW using chlorine at levels >25 mg L,1 (30 min) negatively affected flame angelfish egg fertilization rates indicating that alternative methods of water sterilization may be warranted. [source] | ||||||||||