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Alternative Life Histories (alternative + life_history)
Selected AbstractsStrongly female-biased sex allocation in a trivoltine population of Trypoxylon (Trypargilum) opacum Brèthes (Hymenoptera, Crabronidae)ACTA ZOOLOGICA, Issue 4 2010Maria Luisa Tunes Buschini Abstract Buschini, M.L.T. and Bergamaschi, A.C.B. 2009. Strongly female-biased sex allocation in a trivoltine population of Trypoxylon (Trypargilum) opacum Brèthes (Hymenoptera, Crabronidae). ,Acta Zoologica (Stockholm) 91: 433,439. This study was carried in southern Brazil from December 2001 to December 2004. The aim of this paper is to provide additional information on the life-history and sex allocation of this little known species. This wasp's species has two alternative life histories: either they pupated immediately and emerged as adults later in the same season (direct development) or they entered diapause, overwintering and pupating the following spring (delayed development). The numerical sex ratio of overwintering and of direct developing wasps were strongly female biased in 2002, 2003 and 2004. [source] Genetic life history effects on juvenile survival in bluegillJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2007B. D. NEFF Abstract Foraging behaviour under the risk of predation has important consequences on an individual's survivorship and fitness. In bluegill (Lepomis macrochirus), we have recently shown that offspring sired by males of alternative life histories differ in their foraging behaviour. Specifically, offspring sired by ,cuckolder' males take fewer risks during foraging than do offspring sired by ,parental' males. This behavioural difference can have important consequences on the fitness of the two life histories and thus the underlying evolutionary mechanism. Here, we examine the consequences of this behavioural variation on growth rate, condition and survivorship during early development of juveniles. We used split in vitro fertilization to generate maternal half-sibs that differed in sire life history. The resulting 18 455 larvae from 50 families were released into a microcosm with safe and risky foraging areas for approximately 2 months. A total of 262 juveniles (1.4%) survived of which parentage was unambiguously determined using microsatellite genetic markers for 254 (97%). Although we found significant dam effects, there was no difference in apparent growth rate or condition of juveniles sired by males of the two life histories. Of the 25 paired half-sib families, 15 had higher survivorship when sired by a cuckolder male, seven had higher survivorship when sired by a parental male and three had no surviving offspring from either sire. Thus, although growth was similar between the two offspring types, survivorship was not. Combining the differential survivorship estimate with paternity data from natural nests and the frequency of males adopting each life history, we calculated that the cuckolder life history has 1.87 times higher fitness than the parental life history. As such, the life histories likely are not governed by a genetic polymorphism. [source] Variation of reproductive behaviour and success of males adopting different tactics in Atlantic salmonJOURNAL OF FISH BIOLOGY, Issue 2003B. De Gaudemar Six males and five females anadromous Atlantic salmon were released in two sections of the Lapitxuri experimental stream (Southwest France), where they could reproduce naturally. Females had all the same size and age, contrary to males. We focussed our attention on the variation with time of spawning tactics and success of males. Two factors affected male spawning behaviour in the short term. An increase of the OSR increased the level of male competition around redds which resulted in a larger number of males adopting sneaking rather than fighting tactics. Changes in female activities also seemed to be detected by males, since male aggressiveness increased when females were close to oviposition. But whatever their activities, males preferentially courted the earlier spawning female when two females were active at the same time. Fighting in males was confirmed to be the most successful tactic at a given time. However, males adopting sneaking tactic at the beginning of the spawning season could dramatically increase their reproductive success in the long-term. Fighting males invested much more energy in contests than secondary males, which may constitute a handicap in terms of longevity. They could quickly lose their status or strength with time which, although placed in a situation of high OSR, resulted in greater numbers of previously low-ranking males adopting satellite and fighting tactics during the period preceding oviposition. Age more than size affected male status and reproductive success. Females seemed to select their mate directly in relation to their physiological condition, since they only attacked dull coloured males showing obvious wound marks. They also could indirectly choose their mate by repeatedly leaving the redd during the period preceding oviposition in a situation of high OSR. This behaviour might incite male competition and also promoted, by incessant attempts of secondary males to rob the more successful status of primary males, their chance to spawn with fitter males. These results emphasized the importance of environment, physiological condition and energy expenditure in allocation tactics and variations in salmon reproductive success throughout the spawning season. This led us to hypothesize that the choice of sneaking through conditional strategies might provide greater average fitness in salmon alternative life histories. [source] Mammalian prenatal development: the influence of maternally derived moleculesBIOESSAYS, Issue 9 2009Cécile Fligny Abstract Normal fetal development is dependent upon an intricate exchange between mother and embryo. Several maternal and embryonic elements can influence this intimate interaction, including genetic, environmental or epigenetic factors, and have a significant impact on embryo development. The interaction of the genetic program of both mother and embryo, within the uterine environment, can shape the development of an individual. Accumulating data from animal models indicate that prenatal events may well initiate long-term changes in the expression of the embryo genetic program, which persist, or may only become apparent, much later in the individual's life. Also, environmental conditions during prenatal development may prompt the adoption of different developmental pathways, leading to alternative life histories. This review focuses on environmental factors, specifically maternally derived molecules, to illustrate how they can influence in utero embryonic development and, by extension, adult life. [source] | ||||||||||