The intensity of mating competition and the potential benefits for female of mating with certain ... more The intensity of mating competition and the potential benefits for female of mating with certain males can be influenced by several extrinsic factors, such that behavioral decisions can be highly context-dependent. Short-lived species with a single reproductive season are a unique model to study context-sensitive mating decisions. Through exhaustive sampling in the field and simultaneous choice tests in the laboratory, we evaluated operational sex ratio (OSR) and female mate choice at the beginning and end of the reproductive season in the annual killifishAustrolebias reicherti. We found seasonal change in both OSR and female mate choice. At the start of the reproductive season the OSR did not deviate from parity, and females preferred larger males. Later in the reproductive season, while the proportion of males in the ponds decreased, females became unselective with respect to male size. The particular biological cycle of annual killifish, where both life expectancy and mating oppo...
Prey require information if they are to respond to predation threat in a risk-sensitive manner. O... more Prey require information if they are to respond to predation threat in a risk-sensitive manner. One way that individuals can obtain this information is through the predator-mediated, threat-induced behavior of conspecifics. We examined such a possibility in a refuge-seeking species, the sand fiddler crab (Uca pugilator). Crabs were either exposed directly to a simulated predation threat (a moving cylinder) or the threat-induced response of a near neighbor.
A ubiquitous feature of animal mating systems is that males compete for females in order to repro... more A ubiquitous feature of animal mating systems is that males compete for females in order to reproduce. One of Darwin's (1871) great insights was that traits leading to variation among males in their ability to secure mates, either because of their attractiveness to females or their efficacy in dispatching rivals males, could evolve by sexual selection.
Abstract Once thought rare in animal taxa, hybridization has been increasingly recognized as an i... more Abstract Once thought rare in animal taxa, hybridization has been increasingly recognized as an important and common force in animal evolution. In the past decade, a number of studies have suggested that hybridization has driven speciation in some animal groups. We investigate the signature of hybridization in the genome of a putative hybrid species, Xiphophorus clemenciae, through whole genome sequencing of this species and its hypothesized progenitors. Based on analysis of this data, we find that X.
In many species, individuals of both sexes have developed a variety of visual signals and behavio... more In many species, individuals of both sexes have developed a variety of visual signals and behavioral patterns with which to broadcast their quality as mating partners (1). The complexity of these signals makes it difficult to distinguish those that are most important in mate selection. Animated models offer a solution to this problem by allowing for the alteration of single parameters in the complex stimulus presented.
A century of research into both behavior and genetics in Xiphophorus has yielded important insigh... more A century of research into both behavior and genetics in Xiphophorus has yielded important insights into the genetic architecture underlying sexual behavior, particularly as concerns male courtship and mating strategies. Two Y-linked loci underlie much of the variation in male mating strategies, possibly reflecting selection for modularization. Courtship behavior elements, in contrast, are under polygenic control.
Abstract The visual and auditory systems are two major sensory modalities employed in communicati... more Abstract The visual and auditory systems are two major sensory modalities employed in communication. Although communication in these two sensory modalities can serve analogous functions and evolve in response to similar selection forces, the two systems also operate under different constraints imposed by the environment and the degree to which these sensory modalities are recruited for non-communication functions.
Holland and Rice (1998) propose a model of the evolution of elaborate male traits and female pref... more Holland and Rice (1998) propose a model of the evolution of elaborate male traits and female preferences. A series of empirical studies has demonstrated" antagonistic coevolution" of the sexes in Drosophila melanogaster, in part due to the evolution of sperm toxicity and female resistance to this toxicity (eg, Rice 1996). Holland and Rice extend this observation to a more general model for the evolution of male and female traits.
Abstract: Sexually dimorphic traits in many mate recognition systems have evolved in response to ... more Abstract: Sexually dimorphic traits in many mate recognition systems have evolved in response to preexisting female biases. These biases are often quite general in form and are likely to be shared by predators, thereby imposing a cost on male trait expression. The Mexican tetra Astyanax mexicanus (Pisces: Characidae), a visual predator of swordtail fishes, exhibits the same visual preferences for male body size morphs as do females.
Abstract It is well established that changes to the chemical environment can impair development, ... more Abstract It is well established that changes to the chemical environment can impair development, physiology and reproductive biology; by contrast, impacts on communication have not been widely reported. This is surprising given that chemical communication is the most widely used sensory modality in nature, and that variation in the chemical composition of the environment is the rule, not the exception.
Abstract. Analyses of the relationship between female preference and male behaviour have been com... more Abstract. Analyses of the relationship between female preference and male behaviour have been complicated by correlated variation in factors such as male size and appearance. This study examined the effects of systematically manipulating male behaviour, while holding male morphology constant. Female green swordtails were shown video-recorded sequences of the same male engaging in an active courtship display, performing similar levels of feeding activity, and remaining inactive.
Abstract Swordtail fish (Poeciliidae: genus Xiphophorus) are a paradigmatic case of sexual select... more Abstract Swordtail fish (Poeciliidae: genus Xiphophorus) are a paradigmatic case of sexual selection by sensory exploitation. Female preference for males with a conspicuous “sword” ornament is ancestral, suggesting that male morphology has evolved in response to a preexisting bias. The perceptual mechanisms underlying female mate choice have not been identified, complicating efforts to understand the selection pressures acting on ornament design.
Abstract Species recognition can often play a key role in female mating preferences. Far less is ... more Abstract Species recognition can often play a key role in female mating preferences. Far less is known about conspecific mate recognition from the male perspective. In many closely related taxa, females exhibit few obvious visual differences and males might have to attend to chemical cues in mate recognition, a possibility that has rarely been explored in vertebrates. Here, we examine male species recognition via odor cues in the swordtail fish, Xiphophorus birchmanni.
Abstract Mate choice can vary in response to internal or external conditions that alter the costs... more Abstract Mate choice can vary in response to internal or external conditions that alter the costs and benefits of being choosy. The relationship between mate choice and hybridization, however, is not well understood. An important influence on mate choice is the rate at which potential mates are encountered: low rates increase sampling costs, favoring reduced choosiness. We investigated the influence of conspecific encounter rate on female choice in a naturally hybridizing species of swordtail, Xiphophorus birchmanni.
Female mating preferences can be secondarily lost for a number of reasons. We examined the prefer... more Female mating preferences can be secondarily lost for a number of reasons. We examined the preference of female pygmy swordtails, Xiphophorus nigrensis, for the sword, a conspicuous extension of the caudal fin in some males. Females failed to show a preference for conspecific males with swords when presented with live males naturally varying in sword length, with live males of manipulated sword length, and with synthetic animations of males expressing natural variation in sword length.
Many sexually-selected phenotypes involve some form of visual communication. Video-playback techn... more Many sexually-selected phenotypes involve some form of visual communication. Video-playback techniques are a powerful new tool for studying visual signaling systems. Individual aspects of complex stimuli can be reliably manipulated, and stimuli can be repeatedly presented without appreciable variation in their properties. Experimenters can also construct signals which are biologically impossible, but which can be used to ask critical questions about how stimuli are perceived.
Selection favours females that attend to reliable information about male health or genetic qualit... more Selection favours females that attend to reliable information about male health or genetic quality. Male nutritional state can be an important indicator of mate quality since poor nutrition can be related to reduced sperm quality, low sperm quantity and sexually transmitted diseases. Here we show that female swordtail fish, Xiphophorus birchmanni, preferred the chemical cues of males that were well fed over those that had been food deprived.
Abstract Although private communication is considered an important diversifying force in evolutio... more Abstract Although private communication is considered an important diversifying force in evolution, there is little direct behavioural evidence to support this notion. Here, we show that ultraviolet (UV) signalling in northern swordtails (Xiphophorus) affords a channel for communication that is not accessible to their major predator, Astyanax mexicanus, the Mexican tetra. Laboratory and field behavioural experiments with swordtails (X. nigrensis) and predators (A.
The intensity of mating competition and the potential benefits for female of mating with certain ... more The intensity of mating competition and the potential benefits for female of mating with certain males can be influenced by several extrinsic factors, such that behavioral decisions can be highly context-dependent. Short-lived species with a single reproductive season are a unique model to study context-sensitive mating decisions. Through exhaustive sampling in the field and simultaneous choice tests in the laboratory, we evaluated operational sex ratio (OSR) and female mate choice at the beginning and end of the reproductive season in the annual killifishAustrolebias reicherti. We found seasonal change in both OSR and female mate choice. At the start of the reproductive season the OSR did not deviate from parity, and females preferred larger males. Later in the reproductive season, while the proportion of males in the ponds decreased, females became unselective with respect to male size. The particular biological cycle of annual killifish, where both life expectancy and mating oppo...
Prey require information if they are to respond to predation threat in a risk-sensitive manner. O... more Prey require information if they are to respond to predation threat in a risk-sensitive manner. One way that individuals can obtain this information is through the predator-mediated, threat-induced behavior of conspecifics. We examined such a possibility in a refuge-seeking species, the sand fiddler crab (Uca pugilator). Crabs were either exposed directly to a simulated predation threat (a moving cylinder) or the threat-induced response of a near neighbor.
A ubiquitous feature of animal mating systems is that males compete for females in order to repro... more A ubiquitous feature of animal mating systems is that males compete for females in order to reproduce. One of Darwin's (1871) great insights was that traits leading to variation among males in their ability to secure mates, either because of their attractiveness to females or their efficacy in dispatching rivals males, could evolve by sexual selection.
Abstract Once thought rare in animal taxa, hybridization has been increasingly recognized as an i... more Abstract Once thought rare in animal taxa, hybridization has been increasingly recognized as an important and common force in animal evolution. In the past decade, a number of studies have suggested that hybridization has driven speciation in some animal groups. We investigate the signature of hybridization in the genome of a putative hybrid species, Xiphophorus clemenciae, through whole genome sequencing of this species and its hypothesized progenitors. Based on analysis of this data, we find that X.
In many species, individuals of both sexes have developed a variety of visual signals and behavio... more In many species, individuals of both sexes have developed a variety of visual signals and behavioral patterns with which to broadcast their quality as mating partners (1). The complexity of these signals makes it difficult to distinguish those that are most important in mate selection. Animated models offer a solution to this problem by allowing for the alteration of single parameters in the complex stimulus presented.
A century of research into both behavior and genetics in Xiphophorus has yielded important insigh... more A century of research into both behavior and genetics in Xiphophorus has yielded important insights into the genetic architecture underlying sexual behavior, particularly as concerns male courtship and mating strategies. Two Y-linked loci underlie much of the variation in male mating strategies, possibly reflecting selection for modularization. Courtship behavior elements, in contrast, are under polygenic control.
Abstract The visual and auditory systems are two major sensory modalities employed in communicati... more Abstract The visual and auditory systems are two major sensory modalities employed in communication. Although communication in these two sensory modalities can serve analogous functions and evolve in response to similar selection forces, the two systems also operate under different constraints imposed by the environment and the degree to which these sensory modalities are recruited for non-communication functions.
Holland and Rice (1998) propose a model of the evolution of elaborate male traits and female pref... more Holland and Rice (1998) propose a model of the evolution of elaborate male traits and female preferences. A series of empirical studies has demonstrated" antagonistic coevolution" of the sexes in Drosophila melanogaster, in part due to the evolution of sperm toxicity and female resistance to this toxicity (eg, Rice 1996). Holland and Rice extend this observation to a more general model for the evolution of male and female traits.
Abstract: Sexually dimorphic traits in many mate recognition systems have evolved in response to ... more Abstract: Sexually dimorphic traits in many mate recognition systems have evolved in response to preexisting female biases. These biases are often quite general in form and are likely to be shared by predators, thereby imposing a cost on male trait expression. The Mexican tetra Astyanax mexicanus (Pisces: Characidae), a visual predator of swordtail fishes, exhibits the same visual preferences for male body size morphs as do females.
Abstract It is well established that changes to the chemical environment can impair development, ... more Abstract It is well established that changes to the chemical environment can impair development, physiology and reproductive biology; by contrast, impacts on communication have not been widely reported. This is surprising given that chemical communication is the most widely used sensory modality in nature, and that variation in the chemical composition of the environment is the rule, not the exception.
Abstract. Analyses of the relationship between female preference and male behaviour have been com... more Abstract. Analyses of the relationship between female preference and male behaviour have been complicated by correlated variation in factors such as male size and appearance. This study examined the effects of systematically manipulating male behaviour, while holding male morphology constant. Female green swordtails were shown video-recorded sequences of the same male engaging in an active courtship display, performing similar levels of feeding activity, and remaining inactive.
Abstract Swordtail fish (Poeciliidae: genus Xiphophorus) are a paradigmatic case of sexual select... more Abstract Swordtail fish (Poeciliidae: genus Xiphophorus) are a paradigmatic case of sexual selection by sensory exploitation. Female preference for males with a conspicuous “sword” ornament is ancestral, suggesting that male morphology has evolved in response to a preexisting bias. The perceptual mechanisms underlying female mate choice have not been identified, complicating efforts to understand the selection pressures acting on ornament design.
Abstract Species recognition can often play a key role in female mating preferences. Far less is ... more Abstract Species recognition can often play a key role in female mating preferences. Far less is known about conspecific mate recognition from the male perspective. In many closely related taxa, females exhibit few obvious visual differences and males might have to attend to chemical cues in mate recognition, a possibility that has rarely been explored in vertebrates. Here, we examine male species recognition via odor cues in the swordtail fish, Xiphophorus birchmanni.
Abstract Mate choice can vary in response to internal or external conditions that alter the costs... more Abstract Mate choice can vary in response to internal or external conditions that alter the costs and benefits of being choosy. The relationship between mate choice and hybridization, however, is not well understood. An important influence on mate choice is the rate at which potential mates are encountered: low rates increase sampling costs, favoring reduced choosiness. We investigated the influence of conspecific encounter rate on female choice in a naturally hybridizing species of swordtail, Xiphophorus birchmanni.
Female mating preferences can be secondarily lost for a number of reasons. We examined the prefer... more Female mating preferences can be secondarily lost for a number of reasons. We examined the preference of female pygmy swordtails, Xiphophorus nigrensis, for the sword, a conspicuous extension of the caudal fin in some males. Females failed to show a preference for conspecific males with swords when presented with live males naturally varying in sword length, with live males of manipulated sword length, and with synthetic animations of males expressing natural variation in sword length.
Many sexually-selected phenotypes involve some form of visual communication. Video-playback techn... more Many sexually-selected phenotypes involve some form of visual communication. Video-playback techniques are a powerful new tool for studying visual signaling systems. Individual aspects of complex stimuli can be reliably manipulated, and stimuli can be repeatedly presented without appreciable variation in their properties. Experimenters can also construct signals which are biologically impossible, but which can be used to ask critical questions about how stimuli are perceived.
Selection favours females that attend to reliable information about male health or genetic qualit... more Selection favours females that attend to reliable information about male health or genetic quality. Male nutritional state can be an important indicator of mate quality since poor nutrition can be related to reduced sperm quality, low sperm quantity and sexually transmitted diseases. Here we show that female swordtail fish, Xiphophorus birchmanni, preferred the chemical cues of males that were well fed over those that had been food deprived.
Abstract Although private communication is considered an important diversifying force in evolutio... more Abstract Although private communication is considered an important diversifying force in evolution, there is little direct behavioural evidence to support this notion. Here, we show that ultraviolet (UV) signalling in northern swordtails (Xiphophorus) affords a channel for communication that is not accessible to their major predator, Astyanax mexicanus, the Mexican tetra. Laboratory and field behavioural experiments with swordtails (X. nigrensis) and predators (A.
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