The females of several internal fertilizers are able to store sperm for a long time, reducing the... more The females of several internal fertilizers are able to store sperm for a long time, reducing the risk of sperm limitation. However, it also means that males can attempt to mate outside females' receptive period, potentially increasing the level of sperm competition and exacerbating sexual conflict over mating. The guppy (Poecilia reticulata), an internally fertilizing fish, is a model system of such competition and conflict. Female guppies accept courtship and mate consensually only during receptive periods of the ovarian cycle but receive approximately one (mostly forced) mating attempt per minute both during and outside their sexually receptive phase. In addition, females can store viable sperm for months. We expected that guppy females would disfavour sperm received during their unreceptive period, possibly by modulating the quality and/or quantity of the components present in the ovarian fluid (OF) over the breeding cycle. Ovarian fluid has been shown to affect sperm veloc...
AUTHOR(S)= Evans, JP \ Pilastro, A. \ ; YEAR=cop. 2011; PUBLISHER= The University of Chicago Pres... more AUTHOR(S)= Evans, JP \ Pilastro, A. \ ; YEAR=cop. 2011; PUBLISHER= The University of Chicago Press, Chicago, IL [etc.].
ABSTRACT Sexual selection can operate both before and after mating. For males, selection will fav... more ABSTRACT Sexual selection can operate both before and after mating. For males, selection will favor a suite of traits involved in mate acquisition (precopulatory) and in the competition among ejaculates to fertilize eggs (postcopulatory). Sperm competition theory predicts a trade-off between investment in pre- and postcopulatory traits, thus generating negative correlations between traits that function during both episodes of selection. However, such trade-offs can be difficult to detect because they are typically sensitive to the pool of resources available for allocation to competing functions. Although theory predicts that trade-offs will be more apparent when resources are limiting, there have been few attempts to test this prediction. In our study, we used the freshwater fish, Poecilia reticulata, to examine how both pre- and postcopulatory sexually selected traits simultaneously respond to manipulations of diet quantity by comparing behavioral, ornamental, and ejaculate traits between males assigned at random to either a ad libitum or a restricted food diet. We also explore how the relationships between traits that function during pre- and postcopulatory episodes of selection are affected by these treatments. Our results reveal that diet manipulations influenced the expression of both precopulatory (sexual behavior and ornamentation) and postcopulatory sexually selected traits (sperm viability), reinforcing the importance of resource acquisition in sexual selection. However, our data do not support the hypothesis that males trade off their allocation toward these pre- and postcopulatory sexually selected traits. Instead, changes in the expression of pre- and postcopulatory sexually selected traits appear to occur independently.
... 19: 213-218 (1995) The use of feather length as a method for measuring the wing shape of pass... more ... 19: 213-218 (1995) The use of feather length as a method for measuring the wing shape of passerines Andrea Pilastro*, Ivan Farronato0 and ... tra i dati raccolti in campagna su animali vivi con quelli ottenibili dalle pelli di museo, a causa della deformazione dell'ala che si osserva ...
Postcopulatory sexual selection comprises both sperm competition, where the sperm from different ... more Postcopulatory sexual selection comprises both sperm competition, where the sperm from different males compete for fertilization, and cryptic female choice, where females bias sperm use in favour of particular males. Despite intense current interest in both processes as potential agents of directional sexual selection, few studies have attributed the success of attractive males to events that occur exclusively after insemination. This is because the interactions between pre- and post-insemination episodes of sexual selection can be important sources of variation in paternity. The use of artificial insemination overcomes this difficulty because it controls for variation in male fertilization success attributable to the female's perception of male quality, as well as effects due to mating order and the relative contribution of sperm from competing males. Here, we adopt this technique and show that in guppies, when equal numbers of sperm from two males compete for fertilization, relatively colourful individuals achieve greater parentage than their less ornamented counterparts. This finding indicates that precopulatory female mating preferences can be reinforced exclusively through postcopulatory processes occurring at a physiological level. Our analysis also revealed that relatively small individuals were advantaged in sperm competition, suggesting a possible trade-off between sperm competitive ability and body growth.
... Development and characterization of 11 microsatellite loci for the Mona Island iguana (Cyclur... more ... Development and characterization of 11 microsatellite loci for the Mona Island iguana (Cyclura cornuta stejnegeri). KG ROSAS 1 ,; N. PÉREZ-BUITRAGO 1 ,; JP ACEVEDO 1 ,; N. MARTÍNEZ 1 ,; SM FUNK 1,2 ,; WO MCMILLAN 1,. ... Volume 8, Issue 4, pages 825827, July 2008. ...
... AJ, Castillo-Juarez, H. & Birkhead, TR (2002). Sperm mobility: mechanisms of fertilizing ... more ... AJ, Castillo-Juarez, H. & Birkhead, TR (2002). Sperm mobility: mechanisms of fertilizing efficiency, genetic variation and phenotypic relationship with male status in the domestic fowl, Gallus gallus domesticus. Proceedings of the Royal Society of London B 269, 607612. ...
In some birds, feather ornaments are expressed in nestlings well before sexual maturation, possib... more In some birds, feather ornaments are expressed in nestlings well before sexual maturation, possibly in response to parental favouritism towards high-quality offspring. In species with synchronous hatching, in which nestling ornaments may vary more among than within broods, parents may use this information to adjust their parental allocation to the current brood accordingly. We tested this hypothesis in the rock sparrow, in which a sexually selected yellow feather ornament is also expressed in nestlings. We experimentally enlarged nestlings’ breast patch in a group of broods and sham-manipulated another group of control broods. Nestlings with enlarged ornament were fed more frequently and defended more actively from a dummy predator than their control counterparts. Mothers from the enlarged group were more likely to lay a second clutch and showed a reduced survival to the next breeding season. These results provide one of the first evidences of differential parental allocation among different broods based directly on nestlings’ ornamentation, and the first, to our knowledge, to show a reduction in maternal survival.
The females of several internal fertilizers are able to store sperm for a long time, reducing the... more The females of several internal fertilizers are able to store sperm for a long time, reducing the risk of sperm limitation. However, it also means that males can attempt to mate outside females' receptive period, potentially increasing the level of sperm competition and exacerbating sexual conflict over mating. The guppy (Poecilia reticulata), an internally fertilizing fish, is a model system of such competition and conflict. Female guppies accept courtship and mate consensually only during receptive periods of the ovarian cycle but receive approximately one (mostly forced) mating attempt per minute both during and outside their sexually receptive phase. In addition, females can store viable sperm for months. We expected that guppy females would disfavour sperm received during their unreceptive period, possibly by modulating the quality and/or quantity of the components present in the ovarian fluid (OF) over the breeding cycle. Ovarian fluid has been shown to affect sperm veloc...
AUTHOR(S)= Evans, JP \ Pilastro, A. \ ; YEAR=cop. 2011; PUBLISHER= The University of Chicago Pres... more AUTHOR(S)= Evans, JP \ Pilastro, A. \ ; YEAR=cop. 2011; PUBLISHER= The University of Chicago Press, Chicago, IL [etc.].
ABSTRACT Sexual selection can operate both before and after mating. For males, selection will fav... more ABSTRACT Sexual selection can operate both before and after mating. For males, selection will favor a suite of traits involved in mate acquisition (precopulatory) and in the competition among ejaculates to fertilize eggs (postcopulatory). Sperm competition theory predicts a trade-off between investment in pre- and postcopulatory traits, thus generating negative correlations between traits that function during both episodes of selection. However, such trade-offs can be difficult to detect because they are typically sensitive to the pool of resources available for allocation to competing functions. Although theory predicts that trade-offs will be more apparent when resources are limiting, there have been few attempts to test this prediction. In our study, we used the freshwater fish, Poecilia reticulata, to examine how both pre- and postcopulatory sexually selected traits simultaneously respond to manipulations of diet quantity by comparing behavioral, ornamental, and ejaculate traits between males assigned at random to either a ad libitum or a restricted food diet. We also explore how the relationships between traits that function during pre- and postcopulatory episodes of selection are affected by these treatments. Our results reveal that diet manipulations influenced the expression of both precopulatory (sexual behavior and ornamentation) and postcopulatory sexually selected traits (sperm viability), reinforcing the importance of resource acquisition in sexual selection. However, our data do not support the hypothesis that males trade off their allocation toward these pre- and postcopulatory sexually selected traits. Instead, changes in the expression of pre- and postcopulatory sexually selected traits appear to occur independently.
... 19: 213-218 (1995) The use of feather length as a method for measuring the wing shape of pass... more ... 19: 213-218 (1995) The use of feather length as a method for measuring the wing shape of passerines Andrea Pilastro*, Ivan Farronato0 and ... tra i dati raccolti in campagna su animali vivi con quelli ottenibili dalle pelli di museo, a causa della deformazione dell'ala che si osserva ...
Postcopulatory sexual selection comprises both sperm competition, where the sperm from different ... more Postcopulatory sexual selection comprises both sperm competition, where the sperm from different males compete for fertilization, and cryptic female choice, where females bias sperm use in favour of particular males. Despite intense current interest in both processes as potential agents of directional sexual selection, few studies have attributed the success of attractive males to events that occur exclusively after insemination. This is because the interactions between pre- and post-insemination episodes of sexual selection can be important sources of variation in paternity. The use of artificial insemination overcomes this difficulty because it controls for variation in male fertilization success attributable to the female's perception of male quality, as well as effects due to mating order and the relative contribution of sperm from competing males. Here, we adopt this technique and show that in guppies, when equal numbers of sperm from two males compete for fertilization, relatively colourful individuals achieve greater parentage than their less ornamented counterparts. This finding indicates that precopulatory female mating preferences can be reinforced exclusively through postcopulatory processes occurring at a physiological level. Our analysis also revealed that relatively small individuals were advantaged in sperm competition, suggesting a possible trade-off between sperm competitive ability and body growth.
... Development and characterization of 11 microsatellite loci for the Mona Island iguana (Cyclur... more ... Development and characterization of 11 microsatellite loci for the Mona Island iguana (Cyclura cornuta stejnegeri). KG ROSAS 1 ,; N. PÉREZ-BUITRAGO 1 ,; JP ACEVEDO 1 ,; N. MARTÍNEZ 1 ,; SM FUNK 1,2 ,; WO MCMILLAN 1,. ... Volume 8, Issue 4, pages 825827, July 2008. ...
... AJ, Castillo-Juarez, H. & Birkhead, TR (2002). Sperm mobility: mechanisms of fertilizing ... more ... AJ, Castillo-Juarez, H. & Birkhead, TR (2002). Sperm mobility: mechanisms of fertilizing efficiency, genetic variation and phenotypic relationship with male status in the domestic fowl, Gallus gallus domesticus. Proceedings of the Royal Society of London B 269, 607612. ...
In some birds, feather ornaments are expressed in nestlings well before sexual maturation, possib... more In some birds, feather ornaments are expressed in nestlings well before sexual maturation, possibly in response to parental favouritism towards high-quality offspring. In species with synchronous hatching, in which nestling ornaments may vary more among than within broods, parents may use this information to adjust their parental allocation to the current brood accordingly. We tested this hypothesis in the rock sparrow, in which a sexually selected yellow feather ornament is also expressed in nestlings. We experimentally enlarged nestlings’ breast patch in a group of broods and sham-manipulated another group of control broods. Nestlings with enlarged ornament were fed more frequently and defended more actively from a dummy predator than their control counterparts. Mothers from the enlarged group were more likely to lay a second clutch and showed a reduced survival to the next breeding season. These results provide one of the first evidences of differential parental allocation among different broods based directly on nestlings’ ornamentation, and the first, to our knowledge, to show a reduction in maternal survival.
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Papers by Andrea Pilastro