Sylvain Alem - Academia.edu (original) (raw)
Papers by Sylvain Alem
Behavioral Ecology, 2010
... 2003; Danchin and Cézilly 2005; eg, Reinhold et al. ... More recently, though, various modele... more ... 2003; Danchin and Cézilly 2005; eg, Reinhold et al. ... More recently, though, various modelers have proposed that females might sustain certain costs of choice when they receive direct benefits (Kirkpatrick 1985, 1996; Heywood 1989; Grafen 1990; Kirkpatrick and Ryan 1991 ...
Journal of Evolutionary Biology, 2013
Animal Behaviour, 2011
Keywords: Achroia grisella acoustic insect Lepidoptera life history theory pyralid moth sexual se... more Keywords: Achroia grisella acoustic insect Lepidoptera life history theory pyralid moth sexual selection trade-off ultrasound signal Although sexual activity in many animal species is reduced when predation pressure intensifies, such reduction may be attenuated in accordance with age, demography or sexual competition. For example, males in lekking aggregations might forgo evasive behaviour and continue their signalling activity when exposed to predation for various reasons: the pressure to engage in signal competition with neighbours outweighs the risk of a predator attack, the per capita risk of attack is lower on larger leks, signals from neighbours within the lek mask predator cues, or limitations on general attention prevent a lekking male from simultaneously signalling and monitoring predators. We addressed the problem of balancing antipredator behaviour and signal competition in an acoustic pyralid moth, Achroia grisella, in which males gather in leks and broadcast an ultrasonic mating call. There is evidence that A. grisella can be menaced by substrate-gleaning bats and that singing males generally become silent upon perceiving bat echolocation signals or pulsed ultrasound bearing the characteristics of these signals. In this study, the incidence and duration of these silence responses were greatly reduced in lekking males compared with solitary individuals. Moreover, a moderate reduction in silence responses persisted when we broadcast, to individual males, song from a lek followed by bat echolocation stimuli. Thus, while signal masking may play a role in attenuating antipredator behaviour in lekking males, other factors, including signal competition and dilution of predation pressure, are probable influences as well. Ó
Animal Behaviour, 2015
It has been proposed that leks arise because of increased mating benefits in aggregations of disp... more It has been proposed that leks arise because of increased mating benefits in aggregations of displaying males, and some evidence supports this hypothesis. But observations also indicate that lekking aggregations include only a small percentage of the males in a population, implying that certain factors limit lek size. Potential factors include increasing travel costs to find and form large but distant aggregations, greater attraction of predators and higher levels of aggression. Any one of these constraints may cause the number of females arriving at larger leks to decelerate such that per capita male attractiveness, and hence mating success, declines above an optimum lek size. None the less, relatively little empirical work has examined what determines lek size. In particular the possibility that cognitive aspects might constrain lek size has rarely been considered. We studied this question in Achroia grisella, an acoustic moth in which singing males form small aggregations that attract females. We created artificial leks in the laboratory and tested their relative attractiveness to females; we also tested male preferences to form and join such aggregations. Females preferred male aggregations over solitary singers, but the marginal per capita attractiveness of an aggregation of n þ 2 males versus n males waned for n ! 5. Similarly we found that males were attracted to other males singing in the vicinity, but this effect disappeared for n ! 4. We infer that lek size is limited because the marginal per capita attractiveness of larger leks only occurs for small groups. This constraint probably arises because females distinguish leks by overall song rate but are neuroethologically incapable of discriminating rates above a threshold value corresponding to groups of four to six males. These findings emphasize the critical role that neural constraints may play in determining fundamental parameters of complex behaviours such as lekking.
Evolution; international journal of organic evolution, 2014
Fisher's mechanism of sexual selection is a fundamental element of evolutionary theory. In it... more Fisher's mechanism of sexual selection is a fundamental element of evolutionary theory. In it nonrandom mate choice causes a genetic covariance between a male trait and female preference for that trait and thereby generates a positive feedback process sustaining accelerated coevolution of the trait and preference. Numerous theoretical models of Fisher's mechanism have confirmed its mathematical underpinnings, yet biologists have often failed to find evidence for trait-preference genetic correlation in populations in which the mechanism was expected to function. We undertook a survey of the literature to conduct a formal meta-analysis probing the incidence and strength of trait-preference correlation among animal species. Our meta-analysis found significant positive genetic correlations in fewer than 20% of the species studied and an overall weighted correlation that is slightly positive. Importantly, a significant positive correlation was not found in any thorough study that...
Models of indirect (genetic) benefits sexual selection predict linkage disequilibria between gene... more Models of indirect (genetic) benefits sexual selection predict linkage disequilibria between genes that influence male traits and female preferences, owing to non-random mate choice or physical linkage. Such linkage disequilibria can accelerate the evolution of traits and preferences to exaggerated levels. Both theory and recent empirical findings on species recognition suggest that such linkage disequilibria may result from physical linkage or pleiotropy, but very little work has addressed this possibility within the context of sexual selection. We studied the genetic architecture of sexually selected traits by analyzing signals and preferences in an acoustic moth, Achroia grisella, in which males attract females with a train of ultrasound pulses and females prefer loud songs and a fast pulse rhythm. Both male signal characters and female preferences are repeatable and heritable traits. Moreover, female choice is based largely on male song, while males do not appear to provide direct benefits at mating. Thus, some genetic correlation between song and preference traits is expected. We employed a standard crossing design between inbred lines and used AFLP markers to build a linkage map for this species and locate quantitative trait loci (QTL) that influence male song and female preference. Our analyses mostly revealed QTLs of moderate strength that influence various male signal and female receiver traits, but one QTL was found that exerts a major influence on the pulse-pair rate of male song, a critical trait in female attraction. However, we found no evidence of specific colocalization of QTLs influencing male signal and female receiver traits on the same linkage groups. This finding suggests that the sexual selection process would proceed at a modest rate in A. grisella and that evolution toward exaggerated character states may be tempered. We suggest that this equilibrium state may be more the norm than the exception among animal species.
Journal of Evolutionary Biology, 2013
Annales d'Endocrinologie, 2005
Keywords: Achroia grisella acoustic insect Lepidoptera life history theory pyralid moth sexual se... more Keywords: Achroia grisella acoustic insect Lepidoptera life history theory pyralid moth sexual selection trade-off ultrasound signal Although sexual activity in many animal species is reduced when predation pressure intensifies, such reduction may be attenuated in accordance with age, demography or sexual competition. For example, males in lekking aggregations might forgo evasive behaviour and continue their signalling activity when exposed to predation for various reasons: the pressure to engage in signal competition with neighbours outweighs the risk of a predator attack, the per capita risk of attack is lower on larger leks, signals from neighbours within the lek mask predator cues, or limitations on general attention prevent a lekking male from simultaneously signalling and monitoring predators. We addressed the problem of balancing antipredator behaviour and signal competition in an acoustic pyralid moth, Achroia grisella, in which males gather in leks and broadcast an ultrasonic mating call. There is evidence that A. grisella can be menaced by substrate-gleaning bats and that singing males generally become silent upon perceiving bat echolocation signals or pulsed ultrasound bearing the characteristics of these signals. In this study, the incidence and duration of these silence responses were greatly reduced in lekking males compared with solitary individuals. Moreover, a moderate reduction in silence responses persisted when we broadcast, to individual males, song from a lek followed by bat echolocation stimuli. Thus, while signal masking may play a role in attenuating antipredator behaviour in lekking males, other factors, including signal competition and dilution of predation pressure, are probable influences as well. Ó
Theories of lek evolution generally invoke enhanced mating success experienced by males signallin... more Theories of lek evolution generally invoke enhanced mating success experienced by males signalling in aggregations. Reduced predation has also been acknowledged as a potential factor driving lek formation, but its role is more ambiguous. Although lekking is a complex behaviour, few empirical studies have investigated the role of both claims. We studied the potential pressures imposed by mating success and predation in an acoustic moth, Achroia grisella, in which males gather in leks and broadcast a calling song attractive to females. We exploited the ability to manipulate the distribution of singing males in laboratory arenas to create different-sized leks and tested female preferences for these aggregations. Because A. grisella are vulnerable to predation by bats while in flight and on the substrate, we also tested the responses of a potential predator, Rhinolophus ferrumequinum, a bat species that feeds on moths, to the experimental leks. We found that the per capita attractiveness of A. grisella males to females rose with increasing lek size. R. ferrumequinum also oriented toward experimental A. grisella leks, but this attraction did not increase at larger leks. Thus, a male's per capita exposure to predation risk declined as more moths joined the lek. A. grisella males appear to benefit from advertising in larger leks in terms of both increased mate attraction and reduced predation risk. Our results support the idea that multiple factors operating simultaneously may maintain lekking behaviour.
Behavioral Ecology, 2010
... 2003; Danchin and Cézilly 2005; eg, Reinhold et al. ... More recently, though, various modele... more ... 2003; Danchin and Cézilly 2005; eg, Reinhold et al. ... More recently, though, various modelers have proposed that females might sustain certain costs of choice when they receive direct benefits (Kirkpatrick 1985, 1996; Heywood 1989; Grafen 1990; Kirkpatrick and Ryan 1991 ...
Journal of Evolutionary Biology, 2013
Animal Behaviour, 2011
Keywords: Achroia grisella acoustic insect Lepidoptera life history theory pyralid moth sexual se... more Keywords: Achroia grisella acoustic insect Lepidoptera life history theory pyralid moth sexual selection trade-off ultrasound signal Although sexual activity in many animal species is reduced when predation pressure intensifies, such reduction may be attenuated in accordance with age, demography or sexual competition. For example, males in lekking aggregations might forgo evasive behaviour and continue their signalling activity when exposed to predation for various reasons: the pressure to engage in signal competition with neighbours outweighs the risk of a predator attack, the per capita risk of attack is lower on larger leks, signals from neighbours within the lek mask predator cues, or limitations on general attention prevent a lekking male from simultaneously signalling and monitoring predators. We addressed the problem of balancing antipredator behaviour and signal competition in an acoustic pyralid moth, Achroia grisella, in which males gather in leks and broadcast an ultrasonic mating call. There is evidence that A. grisella can be menaced by substrate-gleaning bats and that singing males generally become silent upon perceiving bat echolocation signals or pulsed ultrasound bearing the characteristics of these signals. In this study, the incidence and duration of these silence responses were greatly reduced in lekking males compared with solitary individuals. Moreover, a moderate reduction in silence responses persisted when we broadcast, to individual males, song from a lek followed by bat echolocation stimuli. Thus, while signal masking may play a role in attenuating antipredator behaviour in lekking males, other factors, including signal competition and dilution of predation pressure, are probable influences as well. Ó
Animal Behaviour, 2015
It has been proposed that leks arise because of increased mating benefits in aggregations of disp... more It has been proposed that leks arise because of increased mating benefits in aggregations of displaying males, and some evidence supports this hypothesis. But observations also indicate that lekking aggregations include only a small percentage of the males in a population, implying that certain factors limit lek size. Potential factors include increasing travel costs to find and form large but distant aggregations, greater attraction of predators and higher levels of aggression. Any one of these constraints may cause the number of females arriving at larger leks to decelerate such that per capita male attractiveness, and hence mating success, declines above an optimum lek size. None the less, relatively little empirical work has examined what determines lek size. In particular the possibility that cognitive aspects might constrain lek size has rarely been considered. We studied this question in Achroia grisella, an acoustic moth in which singing males form small aggregations that attract females. We created artificial leks in the laboratory and tested their relative attractiveness to females; we also tested male preferences to form and join such aggregations. Females preferred male aggregations over solitary singers, but the marginal per capita attractiveness of an aggregation of n þ 2 males versus n males waned for n ! 5. Similarly we found that males were attracted to other males singing in the vicinity, but this effect disappeared for n ! 4. We infer that lek size is limited because the marginal per capita attractiveness of larger leks only occurs for small groups. This constraint probably arises because females distinguish leks by overall song rate but are neuroethologically incapable of discriminating rates above a threshold value corresponding to groups of four to six males. These findings emphasize the critical role that neural constraints may play in determining fundamental parameters of complex behaviours such as lekking.
Evolution; international journal of organic evolution, 2014
Fisher's mechanism of sexual selection is a fundamental element of evolutionary theory. In it... more Fisher's mechanism of sexual selection is a fundamental element of evolutionary theory. In it nonrandom mate choice causes a genetic covariance between a male trait and female preference for that trait and thereby generates a positive feedback process sustaining accelerated coevolution of the trait and preference. Numerous theoretical models of Fisher's mechanism have confirmed its mathematical underpinnings, yet biologists have often failed to find evidence for trait-preference genetic correlation in populations in which the mechanism was expected to function. We undertook a survey of the literature to conduct a formal meta-analysis probing the incidence and strength of trait-preference correlation among animal species. Our meta-analysis found significant positive genetic correlations in fewer than 20% of the species studied and an overall weighted correlation that is slightly positive. Importantly, a significant positive correlation was not found in any thorough study that...
Models of indirect (genetic) benefits sexual selection predict linkage disequilibria between gene... more Models of indirect (genetic) benefits sexual selection predict linkage disequilibria between genes that influence male traits and female preferences, owing to non-random mate choice or physical linkage. Such linkage disequilibria can accelerate the evolution of traits and preferences to exaggerated levels. Both theory and recent empirical findings on species recognition suggest that such linkage disequilibria may result from physical linkage or pleiotropy, but very little work has addressed this possibility within the context of sexual selection. We studied the genetic architecture of sexually selected traits by analyzing signals and preferences in an acoustic moth, Achroia grisella, in which males attract females with a train of ultrasound pulses and females prefer loud songs and a fast pulse rhythm. Both male signal characters and female preferences are repeatable and heritable traits. Moreover, female choice is based largely on male song, while males do not appear to provide direct benefits at mating. Thus, some genetic correlation between song and preference traits is expected. We employed a standard crossing design between inbred lines and used AFLP markers to build a linkage map for this species and locate quantitative trait loci (QTL) that influence male song and female preference. Our analyses mostly revealed QTLs of moderate strength that influence various male signal and female receiver traits, but one QTL was found that exerts a major influence on the pulse-pair rate of male song, a critical trait in female attraction. However, we found no evidence of specific colocalization of QTLs influencing male signal and female receiver traits on the same linkage groups. This finding suggests that the sexual selection process would proceed at a modest rate in A. grisella and that evolution toward exaggerated character states may be tempered. We suggest that this equilibrium state may be more the norm than the exception among animal species.
Journal of Evolutionary Biology, 2013
Annales d'Endocrinologie, 2005
Keywords: Achroia grisella acoustic insect Lepidoptera life history theory pyralid moth sexual se... more Keywords: Achroia grisella acoustic insect Lepidoptera life history theory pyralid moth sexual selection trade-off ultrasound signal Although sexual activity in many animal species is reduced when predation pressure intensifies, such reduction may be attenuated in accordance with age, demography or sexual competition. For example, males in lekking aggregations might forgo evasive behaviour and continue their signalling activity when exposed to predation for various reasons: the pressure to engage in signal competition with neighbours outweighs the risk of a predator attack, the per capita risk of attack is lower on larger leks, signals from neighbours within the lek mask predator cues, or limitations on general attention prevent a lekking male from simultaneously signalling and monitoring predators. We addressed the problem of balancing antipredator behaviour and signal competition in an acoustic pyralid moth, Achroia grisella, in which males gather in leks and broadcast an ultrasonic mating call. There is evidence that A. grisella can be menaced by substrate-gleaning bats and that singing males generally become silent upon perceiving bat echolocation signals or pulsed ultrasound bearing the characteristics of these signals. In this study, the incidence and duration of these silence responses were greatly reduced in lekking males compared with solitary individuals. Moreover, a moderate reduction in silence responses persisted when we broadcast, to individual males, song from a lek followed by bat echolocation stimuli. Thus, while signal masking may play a role in attenuating antipredator behaviour in lekking males, other factors, including signal competition and dilution of predation pressure, are probable influences as well. Ó
Theories of lek evolution generally invoke enhanced mating success experienced by males signallin... more Theories of lek evolution generally invoke enhanced mating success experienced by males signalling in aggregations. Reduced predation has also been acknowledged as a potential factor driving lek formation, but its role is more ambiguous. Although lekking is a complex behaviour, few empirical studies have investigated the role of both claims. We studied the potential pressures imposed by mating success and predation in an acoustic moth, Achroia grisella, in which males gather in leks and broadcast a calling song attractive to females. We exploited the ability to manipulate the distribution of singing males in laboratory arenas to create different-sized leks and tested female preferences for these aggregations. Because A. grisella are vulnerable to predation by bats while in flight and on the substrate, we also tested the responses of a potential predator, Rhinolophus ferrumequinum, a bat species that feeds on moths, to the experimental leks. We found that the per capita attractiveness of A. grisella males to females rose with increasing lek size. R. ferrumequinum also oriented toward experimental A. grisella leks, but this attraction did not increase at larger leks. Thus, a male's per capita exposure to predation risk declined as more moths joined the lek. A. grisella males appear to benefit from advertising in larger leks in terms of both increased mate attraction and reduced predation risk. Our results support the idea that multiple factors operating simultaneously may maintain lekking behaviour.