Regulation of Yolk-Androgen Concentrations by Plasma Prolactin in the American Kestrel

Sockman, Keith W.; Schwabl, Hubert; Sharp, P. J.

doi:10.1006/hbeh.2001.1715

Cited by 40 publications

(20 citation statements)

References 41 publications

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“…Mothers commonly transfer hormones that influence growth into eggs, and several studies have documented differential maternal allocation in relation to egglaying order (Schwabl 1996b;Eising et al 2001;Reed and Vleck 2001;Royle et al 2001) and offspring sex (Schwabl et al 1997;Petrie et al 2001). Moreover, maternal hormones, such as steroids, may differentially affect prenatal and postnatal growth of males and females (Gatford et al 1998;Henry and Burke 1999) and fluctuations in maternal hormones during egg laying (e.g., due to social interactions; Whittingham and Schwabl 2002), correlates with maternal transfer of hormones into eggs (Zadworny et al 1986;Schwabl 1996a;Sockman et al 2001). Thus, the link between the sex-biased FIG.…”

Section: Discussionmentioning

confidence: 99%

The Evolution of Sexual Size Dimorphism in the House Finch. V. Maternal Effects

et al. 2003

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Abstract. The phenotype of a mother and the environment that she provides might differentially affect the phenotypes of her sons and daughters, leading to change in sexual size dimorphism. Whereas these maternal effects should evolve to accommodate the adaptations of both the maternal and offspring generations, the mechanisms by which this is accomplished are rarely known. In birds, females adjust the onset of incubation (coincident with the first egg or after all eggs are laid) in response to the environment during breeding, and thus, indirectly, determine the duration of offspring growth. In the two house finch (Carpodacus mexicanus) populations that breed at the extremes of the species' distribution (Montana and Alabama), females experience highly distinct climatic conditions during nesting. We show that in close association with these conditions, females adjusted jointly the onset of incubation and the sequence in which they produced male and female eggs and consequently modified the growth of sons and daughters. The onset of incubation in newly breeding females closely tracked ambient temperature in a pattern consistent with the maintenance of egg viability. Because of the very different climates in Montana and Alabama, females in these populations showed the opposite patterns of seasonal change in incubation onset and the opposite sex bias in egg-laying order. In females with breeding experience, incubation onset and sex bias in laying order were closely linked regardless of the climatic variation. In nests in which incubation began with the onset of egg laying, the first-laid eggs were mostly females in Montana, but mostly males in Alabama. Because in both populations, male, but not female, embryos grew faster when exposed to longer incubation, the sex-bias produced highly divergent sizes of male and female juveniles between the populations. Overall, the compensatory interaction between the onset of incubation and the sex-biased laying order achieved a compromise between maternal and offspring adaptations and contributed to rapid morphological divergence in sexual dimorphism between populations of the house finch breeding at the climatic extremes of the species range.

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Section: Discussionmentioning

confidence: 99%

The Evolution of Sexual Size Dimorphism in the House Finch. V. Maternal Effects

et al. 2003

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“…synthesis of prolactin, a pituitary hormone that is also involved in controlling proliferation of oocytes and the synthesis of follicular steroids (Etches et al 1979;Tabibzadeh et al 1995;Sockman & Schwabl 1999;Sockman et al 2001).…”

Section: Evidence For the Baldwin Effect's Processes (A) Environmentamentioning

confidence: 99%

Evolutionary significance of phenotypic accommodation in novel environments: an empirical test of the Baldwin effect

Badyaev

2009

Phil. Trans. R. Soc. B

164

123

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When faced with changing environments, organisms rapidly mount physiological and behavioural responses, accommodating new environmental inputs in their functioning. The ubiquity of this process contrasts with our ignorance of its evolutionary significance: whereas within-generation accommodation of novel external inputs has clear fitness consequences, current evolutionary theory cannot easily link functional importance and inheritance of novel accommodations. One hundred and twelve years ago, J. M. Baldwin, H. F. Osborn and C. L. Morgan proposed a process (later termed the Baldwin effect) by which non-heritable developmental accommodation of novel inputs, which makes an organism fit in its current environment, can become internalized in a lineage and affect the course of evolution. The defining features of this process are initial overproduction of random (with respect to fitness) developmental variation, followed by withingeneration accommodation of a subset of this variation by developmental or functional systems ('organic selection'), ensuring the organism's fit and survival. Subsequent natural selection sorts among resultant developmental variants, which, if recurrent and consistently favoured, can be inherited when existing genetic variance includes developmental components of individual modifications or when the ability to accommodate novel inputs is itself heritable. Here, I show that this process is consistent with the origin of novel adaptations during colonization of North America by the house finch. The induction of developmental variation by novel environments of this species's expanding range was followed by homeostatic channelling, phenotypic accommodation and directional cross-generational transfer of a subset of induced developmental outcomes favoured by natural selection. These results emphasize three principal points. First, contemporary novel adaptations result mostly from reorganization of existing structures that shape newly expressed variation, giving natural selection an appearance of a creative force. Second, evolutionary innovations and maintenance of adaptations are different processes. Third, both the Baldwin and parental effects are probably a transient state in an evolutionary cycle connecting initial phenotypic retention of adaptive changes and their eventual genetic determination and, thus, the origin of adaptation and evolutionary change.

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“…In birds, propensity to incubate is regulated by prolactin (PRL), a pituitary hormone that also affects the production and metabolism of steroids by the ovary (Etches et al 1979;Rozenboim et al 1993;Tabibzadeh et al 1995;Sockman et al 2001;Vleck 2002). Thus, when ambient temperature at the time of egg-laying favours early onset of incubation (Hébert 2002), it results in the overlap between high secretion of PRL and oogenesis, such that high concentrations of PRL, necessary for egg incubation by the female, could constrain the sex-specific steroid requirements of growing follicles (Johnson 1990;Tabibzadeh et al 1995;Chaudhuri & Maiti 1998;Sockman & Schwabl 1999).…”

Section: Introductionmentioning

confidence: 99%

Adaptive sex differences in growth of pre-ovulation oocytes in a passerine bird

et al. 2005

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Maternal modification of offspring sex in birds has strong fitness consequences, however the mechanisms by which female birds can bias sex of their progeny in close concordance with the environment of breeding are not known. In recently established populations of house finches (Carpodacus mexicanus), breeding females lay a sex-biased sequence of eggs when ambient temperature causes early onset of incubation. We studied the mechanisms behind close association of incubation and sex-determination strategies in this species and discovered that pre-ovulation oocytes that produce males and females differed strongly in the temporal patterns of proliferation and growth. In turn, sex-specific exposure of oocytes to maternal secretion of prolactin and androgens produced distinct accumulation of maternal steroids in oocyte yolks in relation to oocyte proliferation order. These findings suggest that sex difference in oocyte growth and egg-laying sequence is an adaptive outcome of hormonal constraints imposed by the overlap of early incubation and oogenesis in this population, and that the close integration of maternal incubation, oocytes' sex-determination and growth might be under control of the same hormonal mechanism. We further document that population establishment and the evolution of these maternal strategies is facilitated by their strong effects on female and offspring fitness in a recently established part of the species range.

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Regulation of Yolk-Androgen Concentrations by Plasma Prolactin in the American Kestrel

Cited by 40 publications

References 41 publications

The Evolution of Sexual Size Dimorphism in the House Finch. V. Maternal Effects

The Evolution of Sexual Size Dimorphism in the House Finch. V. Maternal Effects

Evolutionary significance of phenotypic accommodation in novel environments: an empirical test of the Baldwin effect

Adaptive sex differences in growth of pre-ovulation oocytes in a passerine bird

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