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Sexual conflict

Publications filtered by: Sexual conflict

La evolución de la poliandria
Garcia-Gonzalez, F. 2012 La evolución de la poliandria Investigación y Ciencia 429:9-12
Abstract
Durante siglos se ha considerado que la relación sexual dominante en el mundo animal era la monogamia. Sin embargo, en las últimas décadas, la aplicación sistemática de los análisis de paternidad al estudio del comportamiento ha puesto de manifiesto la amplia presencia de otro fenómeno: la poliandria, el apareamiento de una hembra con varios machos en el transcurso de un mismo episodio reproductivo. Si tomamos como ejemplo uno de los iconos tradicionales de la monogamia, las aves que forman parejas estables, descubrimos que las hembras de más del 70 por ciento de las especies de este grupo copulan con otros machos. Y esto no es una excepción: la poliandria es la norma en un gran número de grupos animales. La poliandria comporta una serie de implicaciones evolutivas de gran calibre y, por ello, su estudio atrae la atención de investigadores en todo el mundo. La consecuencia más importante del comportamiento poliándrico se puede ilustrar con un trabajo clásico que estudió el comportamiento sexual de un grupo de macacos a lo largo de ocho años. El macho dominante del clan consumó el 70 por ciento de las cópulas, mientras que el segundo en el orden de jerarquía apenas participó en el 14 por ciento de ellas. En cambio, el número de descendientes engendrado por el macho dominante resultó ser la mitad que el de su subordinado. De ello se desprende que, en los machos, el éxito en el apareamiento no garantiza el éxito en la procreación cuando impera la poliandria.
Sexual Selection and Experimental Evolution
Garcia-Gonzalez, F. & Simmons, L. W. 2011 Sexual Selection and Experimental Evolution Encyclopedia of Life Sciences (ELS). John Wiley & Sons, Ltd. Chichester. DOI:10.1002/9780470015902.a0022859.
Abstract
Sexual selection is a potent force shaping multiple aspects of the interaction between the sexes, including the characters underlying reproductive success and sexual conflict, and may play an important role in determining the viability of populations. Experimental evolution is a methodological approach in which researchers either act as selective agents or establish the selective pressures operating on individuals to investigate changes in traits across generations and the genetic underpinning of these changes. Experimental evolution replicates the evolutionary process under controlled conditions and, by doing so, offers exceptional insights into the role of variation, selection and adaptation in evolution. Applied to the study of pre-copulatory (before mating) and postcopulatory (after mating) sexual selection, experimental evolution proves critical to understand the evolutionary consequences of male–malecompetition and femalemate choice, and the repercussions of concurrent or divergent interests between the sexes in regard to reproduction.
Experimental evolution: life in the fast line
Garcia-Gonzalez, F. & Simmons, L. W. 2011 Experimental evolution: life in the fast line The Conversation
Male-induced costs of mating for females compensated by offspring viability benefits in an insect
Garcia-Gonzalez, F. & Simmons, L. W. 2010 Male-induced costs of mating for females compensated by offspring viability benefits in an insect Journal of Evolutionary Biology, 23: 2066-2075
Abstract
Sexual conflict facilitates the evolution of traits that increase the reproductive success of males at the expense of components of female fitness. Theory suggests that indirect benefits are unlikely to offset the direct costs to females from antagonistic male adaptations, but empirical studies examining the net fitness pay-offs of the interaction between the sexes are scarce. Here, we investigate whether matings with males that invest intrinsically more into accessory gland tissue undermine female lifetime reproductive success (LRS) in the cricket Teleogryllus oceanicus. We found that females incur a longevity cost of mating that is proportional to the partner’s absolute investment into the production of accessory gland products. However, male accessory gland weight positively influences embryo survival, and harmful ejaculate-induced effects are cancelled out when these are put in the context of female LRS. The direct costs of mating with males that sire offspring with higher viability are thus compensated by direct and possibly indirect genetic benefits in this species.
Evolución en acción: estudios de evolución experimental en el contexto de la selección sexual. In: Dopazo, H. and Navarro, A. (Eds). Adaptación y Evolución. 150 años después del Origen de las Especies.
Garcia-Gonzalez, F. 2009 Evolución en acción: estudios de evolución experimental en el contexto de la selección sexual. In: Dopazo, H. and Navarro, A. (Eds). Adaptación y Evolución. 150 años después del Origen de las Especies Sociedad Española de Biología Evolutiva-Obrapropia S. L., Valencia.
Abstract

Los estudios de evolución experimental constituyen una herramienta de extrema utilidad para comprender los procesos evolutivos a nivel intra-específico. Este artículo expone, a grandes rasgos, en qué consiste la evolución experimental y qué información ofrece. Se resalta el caso particular de estudios que utilizan esta aproximación metodológica para avanzar en el conocimiento de la selección sexual y de sus consecuencias evolutivas. Se muestra con algunos ejemplos cómo los estudios de evolución experimental contribuyen de manera significativa a mejorar la comprensión de la evolución de caracteres que determinan el éxito en el apareamiento y la fecundación, o de las diferencias entre los sexos.

Selección sexual post-cópula y la evolución de la poliandria. In: Dopazo, H. and Navarro, A. (Eds). Adaptación y Evolución. 150 años después del Origen de las Especies.
Garcia-Gonzalez, F. 2009 Selección sexual post-cópula y la evolución de la poliandria. In: Dopazo, H. and Navarro, A. (Eds). Adaptación y Evolución. 150 años después del Origen de las Especies Sociedad Española de Biología Evolutiva-Obrapropia S. L., Valencia
Abstract

En un gran número de especies las hembras se aparean de manera poliándrica (con varios machos durante un mismo episodio reproductivo). Este comportamiento tiene consecuencias evolutivas de suma importancia, incluyendo que posibilita la continuación de la selección sexual más allá del apareamiento. Por ello, la comprensión del significado adaptativo de la poliandria ha suscitado gran interés entre los biólogos evolutivos. Aquí se exponen, a grandes rasgos, las principales hipótesis que se han sugerido para explicar el apareamiento múltiple femenino desde una perspectiva evolutiva, y se discuten brevemente algunos retos pendientes en este área. Se destaca el hecho de que existen procesos de selección sexual post-cópula que pueden jugar un papel fundamental en la adquisición de beneficios de naturaleza genética por parte de las hembras poliándricas.

Female crickets trade offspring viability for fecundity
Simmons, L. W. & Garcia-Gonzalez, F. 2007 Female crickets trade offspring viability for fecundity Journal of Evolutionary Biology, 20: 1617-1623
Abstract
A growing number of studies are suggesting that females can improve the viability of their embryos by mating with multiple males. However, the reason why females should have low rates of embryo viability is puzzling. Here we conduct a quantitative genetic study of maternal effects on embryo viability in the field cricket Teleogryllus oceanicus. After controlling for female body size, we find significant additive genetic variance for ovary weight, a measure of fecundity, and egg hatching success, a measure of embryo viability. Moreover, we show a genetic trade-off between these traits that is predicted from life-history theory. High rates of embryo mortality in this highly fecund species might therefore be explained by selection favouring an optimum balance between fecundity and embryo viability that maximizes maternal fitness. Paternal effects on female fecundity and embryo viability are often seen as benefits driving the evolution of polyandrous behaviour. However, we raise the alternative possibility that paternal effects might shift females from their naturally selected optimum, and present some support for the notion that sexual conflict over a female’s optimal fecundity and embryo viability might generate antagonistic coevolution between the sexes.
¿Quién se ocupa de las crías?
Gomendio, M. & Garcia-Gonzalez, F. 2005 ¿Quién se ocupa de las crías? Quercus, 232: 46-51
Abstract
El cuidado de las crías no siempre recae sobre el mismo sexo. En los mamíferos, las hembras actúan como madres sacrificadas. En otros casos es el padre el que asume esta responsabilidad, como ocurre en algunas especies de peces. Entre las aves suele ser una tarea compartida por machos y hembras. Puesto que todas las combinaciones son posibles, cabe preguntarse ¿qué factores determinan que uno u otro sexo se ocupe de las crías?
Sperm competition mechanisms, confidence of paternity, and the evolution of paternal care in the golden egg bug (Phyllomorpha laciniata)
Garcia-Gonzalez, F., Núñez, Y., Ponz, F., Roldán, E. R. S., and Gomendio, M. 2003 Sperm competition mechanisms, confidence of paternity, and the evolution of paternal care in the golden egg bug (Phyllomorpha laciniata) Evolution, 57:1078-1088
Abstract

Theoretical models predict how paternal effort should vary depending on confidence of paternity and on the trade-offs between present and future reproduction. In this study we examine patterns of sperm precedence in Phyllomorpha laciniata and how confidence of paternity influences the willingness of males to carry eggs. Female golden egg bugs show a flexible pattern of oviposition behavior, which results in some eggs being carried by adults (mainly males) and some being laid on plants, where mortality rates are very high. Adults are more vulnerable to predators when carrying eggs; thus, it has been suggested that males should only accept eggs if there are chances that at least some of the eggs will be their true genetic offspring. We determined the confidence of paternity for naturally occurring individuals and its variation with the time. Paternity of eggs fertilized by the last males to mate with females previously mated in the field has been determined using amplified fragment length polymorphisms (AFLPs). The exclusion probability was 98%, showing that AFLP markers are suitable for paternity assignment. Sperm mixing seems the most likely mechanism of sperm competition, because the last male to copulate with field females sires an average of 43% of the eggs laid during the next five days. More importantly, the proportion of eggs sired does not change significantly during that period. We argue that intermediate levels of paternity can select for paternal care in this system because: (1) benefits of care in terms of offspring survival are very high; (2) males have nothing to gain from decreasing their parental effort in a given reproductive event because sperm mixing makes it difficult for males to reach high paternity levels and males are left with no cues to assess paternity; (3) males cannot chose to care for their offspring exclusively because they can neither discriminate their own eggs, nor can they predict when their own eggs will be produced; and (4) males suffer no loss of further matings with other females when they carry eggs. Thus, our findings do not support the traditional view that paternal investment is expected to arise only in species where confidence of paternity is high. The results suggest that females maximize the chances that several males will accept eggs at different times by promoting a mechanism of sperm mixing that ensures that all males that have copulated with a female have some chance of fathering offspring, that this probability remains constant with time, and that males have no cues as to when their own offspring will be produced.

Harm to females increases with male body size in Drosophila melanogaster
Pitnick, S. & Garcia-Gonzalez, F. 2002 Harm to females increases with male body size in Drosophila melanogaster Proceedings of the Royal Society of London B, 269: 1821-1828
Abstract

Previous studies indicate that female Drosophila melanogaster are harmed by their mates through copulation. Here, we demonstrate that the harm that males inflict upon females increases with male size. Specifically, both the lifespan and egg-production rate of females decreased significantly as an increasing function of the body size of their mates. Consequently, females mating with larger males had lower lifetime fitness. The detrimental effect of male size on female longevity was not mediated by male effects on female fecundity, egg-production rate or female-remating behaviour. Similarly, the influence of male size on female lifetime fecundity was independent of the male-size effect on female longevity. There was no relationship between female size and female resistance to male harm. Thus, although increasing male body size is known to enhance male mating success, it has a detrimental effect on the direct fitness of their mates. Our results indicate that this harm is a pleiotropic effect of some other selected function and not an adaptation. To the extent that females prefer to mate with larger males, this choice is harmful, a pattern that is consistent with the theory of sexually antagonistic coevolution.

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