Interlocus sexual conflict
Encyclopedia
Interlocus sexual conflict is a type of sexual conflict
that occurs through the interaction of a set of antagonistic allele
s at one or more different loci
in males and females, resulting in the deviation of either or both sexes from the fitness
optima for the traits.
Interlocus sexual conflict involves a co-evolutionary arms race between the two sexes in which either sex evolves a set of antagonistic adaptations that are detrimental to the fitness
of the other sex. Interlocus sexual conflict can occur over aspects of male–female interactions such as mating frequency, fertilization, relative parental effort, female remating behavior, and female reproductive rate.
is the location of the interacting antagonistic alleles. Conflict in which the antagonistic alleles are located at the same locus is termed intralocus sexual conflict
, and conflict in which the antagonistic alleles are located at different loci in both sexes is termed interlocus sexual conflict. Intralocus sexual conflict
occurs when males and females undergo different selective pressures at the same locus, resulting in either sex limiting the evolution of the other sex. In contrast, interlocus sexual conflict occurs when males and females undergo different selective pressures at different loci, potentially leading to agonistic coevolution.
at one locus in males increases their fitness
while reducing the fitness of the females interacting with them, the females would evolve a counter-adaptation at a different locus
to reduce the harm. In other words, females may exhibit resistance by developing favorable traits to reduce the direct costs implemented by males. For interlocus sexual conflict to be a valid cause of agonistic coevolution, the harm induced by the males across all loci has to outweigh the indirect benefits that the females gain by interacting with males.
are not categorized into interlocus sexual conflict and intralocus sexual conflict
as the genetic locations of the interacting alleles are not known or specified. Nonetheless, certain experimental results have provided evidence of interlocus sexual conflict as a putative cause of agonistic coevolution.
In the yellow dung fly Scathophaga stercoraria, females can be injured in the battles between males suitors. Males are selected to evolve traits for competitive ability that would increase their reproductive success
, but females would evolve a set of antagonistic adaptations to reduce their chances of being injured in battles between the males. Therefore, there is an interlocus sexual conflict in males and females that could possibly lead to an “unresolvable evolutionary chase” when a novel trait in males increases their competitive ability while harming the females.
In a laboratory study of Drosophila melanogaster
, a mutation
that reduces the attractiveness of females is introduced into the genome
of the experimental females. By reducing the attractiveness of the females expressing the trait, the mutation provides females with resistance to the direct costs of re-mating and male courtship. The results of this experiment show that the resistance allele significantly accumulated in the experimental group, suggesting that the direct costs of male-courtship are greater than the indirect benefits of male-courtship and thereby providing evidence for interlocus sexual conflict.
The lack of categorization of most examples of sexual conflict
might prompt future research to establish the genetic location of the interacting alleles in the experimental studies of sexual conflict
and ultimately differentiate between examples of interlocus sexual conflict and intralocus sexual conflict
.
Sexual conflict
Sexual conflict occurs when the two sexes have conflicting optimal fitness strategies concerning reproduction, particularly the mode and frequency of mating, leading to an evolutionary arms race between males and females. The conflict encompasses the actions and behaviors of both sexes to influence...
that occurs through the interaction of a set of antagonistic allele
Allele
An allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation...
s at one or more different loci
Locus (genetics)
In the fields of genetics and genetic computation, a locus is the specific location of a gene or DNA sequence on a chromosome. A variant of the DNA sequence at a given locus is called an allele. The ordered list of loci known for a particular genome is called a genetic map...
in males and females, resulting in the deviation of either or both sexes from the fitness
Fitness (biology)
Fitness is a central idea in evolutionary theory. It can be defined either with respect to a genotype or to a phenotype in a given environment...
optima for the traits.
Interlocus sexual conflict involves a co-evolutionary arms race between the two sexes in which either sex evolves a set of antagonistic adaptations that are detrimental to the fitness
Fitness (biology)
Fitness is a central idea in evolutionary theory. It can be defined either with respect to a genotype or to a phenotype in a given environment...
of the other sex. Interlocus sexual conflict can occur over aspects of male–female interactions such as mating frequency, fertilization, relative parental effort, female remating behavior, and female reproductive rate.
Interlocus versus intralocus sexual conflict
The genetic basis of the distinction between interlocus sexual conflict and intralocus sexual conflictIntralocus sexual conflict
Intralocus sexual conflict is one of two genetic forms of sexual conflict . It occurs when selection on a shared allelic trait in one sex displaces the other sex from its phenotypic optimum...
is the location of the interacting antagonistic alleles. Conflict in which the antagonistic alleles are located at the same locus is termed intralocus sexual conflict
Intralocus sexual conflict
Intralocus sexual conflict is one of two genetic forms of sexual conflict . It occurs when selection on a shared allelic trait in one sex displaces the other sex from its phenotypic optimum...
, and conflict in which the antagonistic alleles are located at different loci in both sexes is termed interlocus sexual conflict. Intralocus sexual conflict
Intralocus sexual conflict
Intralocus sexual conflict is one of two genetic forms of sexual conflict . It occurs when selection on a shared allelic trait in one sex displaces the other sex from its phenotypic optimum...
occurs when males and females undergo different selective pressures at the same locus, resulting in either sex limiting the evolution of the other sex. In contrast, interlocus sexual conflict occurs when males and females undergo different selective pressures at different loci, potentially leading to agonistic coevolution.
Agonistic coevolution
Interlocus sexual conflict has been proposed as a cause of sexually agonistic coevolution. The model of sexual coevolution is as follows: When an alleleAllele
An allele is one of two or more forms of a gene or a genetic locus . "Allel" is an abbreviation of allelomorph. Sometimes, different alleles can result in different observable phenotypic traits, such as different pigmentation...
at one locus in males increases their fitness
Fitness (biology)
Fitness is a central idea in evolutionary theory. It can be defined either with respect to a genotype or to a phenotype in a given environment...
while reducing the fitness of the females interacting with them, the females would evolve a counter-adaptation at a different locus
Locus (genetics)
In the fields of genetics and genetic computation, a locus is the specific location of a gene or DNA sequence on a chromosome. A variant of the DNA sequence at a given locus is called an allele. The ordered list of loci known for a particular genome is called a genetic map...
to reduce the harm. In other words, females may exhibit resistance by developing favorable traits to reduce the direct costs implemented by males. For interlocus sexual conflict to be a valid cause of agonistic coevolution, the harm induced by the males across all loci has to outweigh the indirect benefits that the females gain by interacting with males.
Examples
Interlocus sexual conflict is potentially widespread across taxa. However, most examples of sexual conflictSexual conflict
Sexual conflict occurs when the two sexes have conflicting optimal fitness strategies concerning reproduction, particularly the mode and frequency of mating, leading to an evolutionary arms race between males and females. The conflict encompasses the actions and behaviors of both sexes to influence...
are not categorized into interlocus sexual conflict and intralocus sexual conflict
Intralocus sexual conflict
Intralocus sexual conflict is one of two genetic forms of sexual conflict . It occurs when selection on a shared allelic trait in one sex displaces the other sex from its phenotypic optimum...
as the genetic locations of the interacting alleles are not known or specified. Nonetheless, certain experimental results have provided evidence of interlocus sexual conflict as a putative cause of agonistic coevolution.
Reproductive success
Reproductive success is defined as the passing of genes onto the next generation in a way that they too can pass those genes on. In practice, this is often a tally of the number of offspring produced by an individual. A more correct definition, which incorporates inclusive fitness, is the...
, but females would evolve a set of antagonistic adaptations to reduce their chances of being injured in battles between the males. Therefore, there is an interlocus sexual conflict in males and females that could possibly lead to an “unresolvable evolutionary chase” when a novel trait in males increases their competitive ability while harming the females.
In a laboratory study of Drosophila melanogaster
Drosophila melanogaster
Drosophila melanogaster is a species of Diptera, or the order of flies, in the family Drosophilidae. The species is known generally as the common fruit fly or vinegar fly. Starting from Charles W...
, a mutation
Mutation (genetic algorithm)
In genetic algorithms of computing, mutation is a genetic operator used to maintain genetic diversity from one generation of a population of algorithm chromosomes to the next...
that reduces the attractiveness of females is introduced into the genome
Genome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
of the experimental females. By reducing the attractiveness of the females expressing the trait, the mutation provides females with resistance to the direct costs of re-mating and male courtship. The results of this experiment show that the resistance allele significantly accumulated in the experimental group, suggesting that the direct costs of male-courtship are greater than the indirect benefits of male-courtship and thereby providing evidence for interlocus sexual conflict.
The lack of categorization of most examples of sexual conflict
Sexual conflict
Sexual conflict occurs when the two sexes have conflicting optimal fitness strategies concerning reproduction, particularly the mode and frequency of mating, leading to an evolutionary arms race between males and females. The conflict encompasses the actions and behaviors of both sexes to influence...
might prompt future research to establish the genetic location of the interacting alleles in the experimental studies of sexual conflict
Sexual conflict
Sexual conflict occurs when the two sexes have conflicting optimal fitness strategies concerning reproduction, particularly the mode and frequency of mating, leading to an evolutionary arms race between males and females. The conflict encompasses the actions and behaviors of both sexes to influence...
and ultimately differentiate between examples of interlocus sexual conflict and intralocus sexual conflict
Intralocus sexual conflict
Intralocus sexual conflict is one of two genetic forms of sexual conflict . It occurs when selection on a shared allelic trait in one sex displaces the other sex from its phenotypic optimum...
.