The Experts below are selected from a list of 237 Experts worldwide ranked by ideXlab platform
Claudie Doums - One of the best experts on this subject based on the ideXlab platform.
-
Chemical Characterization of Young Virgin Queens and Mated Egg-Laying Queens in the Ant Cataglyphis Cursor: Random Forest Classification Analysis for Multivariate Datasets
Journal of Chemical Ecology, 2018Co-Authors: Thibaud Monnin, Florence Helft, Chloé Leroy, Patrizia D’ettorre, Claudie DoumsAbstract:Social insects are well known for their extremely rich chemical communication, yet their sex pheromones remain poorly studied. In the thermophilic and thelytokous ant, Cataglyphis Cursor, we analyzed the cuticular hydrocarbon profiles and Dufour’s gland contents of queens of different age and reproductive status (sexually immature gynes, sexually mature gynes, mated and egg-laying queens) and of workers. Random forest classification analyses showed that the four groups of individuals were well separated for both chemical sources, except mature gynes that clustered with queens for cuticular hydrocarbons and with immature gynes for Dufour’s gland secretions. Analyses carried out with two groups of females only allowed identification of candidate chemicals for queen signal and for sexual attractant. In particular, gynes produced more undecane in the Dufour’s gland. This chemical is both the sex pheromone and the alarm pheromone of the ant Formica lugubris . It may therefore act as sex pheromone in C. Cursor , and/or be involved in the restoration of monogyny that occurs rapidly following colony fission. Indeed, new colonies often start with several gynes and all but one are rapidly culled by workers, and this process likely involves chemical signals between gynes and workers. These findings open novel opportunities for experimental studies of inclusive mate choice and queen choice in C. Cursor .
-
worker thelytoky allows requeening of orphaned colonies but increases susceptibility to reproductive cheating in an ant
Animal Behaviour, 2018Co-Authors: Claudie Doums, Pierre Federici, Pascaline Chiffletbelle, Thibaud MonninAbstract:In some social insects, workers can produce females asexually through thelytokous parthenogenesis. This allows them to produce replacement queens (i.e. requeening) if the queen has died, but also to compete with the queen to produce females (i.e. reproductive cheating). For the first time, we experimentally tested the role of worker thelytoky under quasinatural conditions in the ant Cataglyphis Cursor, where the queen uses both sexual and thelytokous reproduction. We reared pairs of orphaned and queenright colonies in enclosures for almost 3 months, during which they competed for resources. Orphaned colonies lost more workers than queenright colonies over the course of the experiment, presumably because of the costs of reproductive conflicts between workers. Nevertheless, they produced new queens through worker thelytoky and new colonies through colony fission. This is the first unambiguous demonstration that worker thelytoky allows requeening under natural conditions in this species. We further showed that worker thelytoky results in reproductive cheating in the form of a few workers reproducing in the presence of the queen (in queenright colonies) and a few worker lineages producing more new queens than other lineages (in orphaned colonies). In addition, it also results in rare instances of social parasitism, that is, workers entering and reproducing in foreign colonies. These benefits to workers seem too occasional and too low to drive the evolution of thelytoky in this species. We argue that thelytoky probably evolved in the queen caste, where it allows the production of young queens and confers frequent and large benefits by increasing gene transmission, but is also expressed in workers because of genetic correlations between the two castes.
-
ORIGINAL PAPER Aggressions and size-related fecundity of queenless workers in the ant Cataglyphis Cursor
2016Co-Authors: Johanna Clemencet, Pierre Federici, Quentin Rome, Claudie DoumsAbstract:Abstract In social hymenoptera, the reproductive division of labor is often linked to differences in individual body size with the reproductive caste (the queen) being larger than the workers. Likewise, the reproductive potential may vary with size within the worker caste and could affect the evolution of worker size in social insects. Here, we tested the relationship between worker size and reproductive potential in the facultative parthenogenetic ant Cataglyphis Cursor. Colonies are headed by a multiply mated queen, but workers can produce gynes (virgin queens) and workers by thelytokous parthenogenesis after the queen’s death. We observed the behaviour of workers (n=357) until the production of gynes (212 h over 3 months) in an orphaned colony (mated queen not present). The size of workers was measured, and their paternal lineage determined using six microsatellite markers, to control for an effect of patriline. Larger workers were more likely to reproduce and lay more eggs indicating that individual level selection could take place. However, paternal lineage had no effect on the reproductive potential and worker size. From the behav-ioural and genetic data, we also show for the first time in this species, evidence of aggressive interactions among workers and a potential for nepotism to occur in orphaned colonies, as the five gynes produced belonged to a single paternal lineage
-
No evidence of pre-copulatory mate choice by gynes in the facultatively parthenogenetic ant Cataglyphis Cursor
Insectes Sociaux, 2015Co-Authors: Florence Helft, Claudie Doums, Thibaud MonninAbstract:Virgin queens (gynes) of the ant Cataglyphis Cursor mate on the ground at the nest entrance, where they benefit from the protection of nestmate workers. By carrying out mating tests in the laboratory, we show that gynes mate with the first males they encounter, suggesting the absence of pre-copulatory mate choice by gynes. This is in agreement with the recent finding that workers behave aggressively towards foreign males and could thereby exercise a form of inclusive mate choice, which could replace pre-copulatory mate choice by gynes.
-
first evidence of inclusive sexual selection in the ant Cataglyphis Cursor worker aggressions differentially affect male access to virgin queens
Ethology, 2015Co-Authors: Florence Helft, Claudie Doums, Thibaud MonninAbstract:Sexual selection typically shapes the traits of individuals capable of reproduction. However, in social species, it may also affect the behaviour of non-reproductive individuals if this increases their inclusive fitness. We examined the potential role of workers during mating in the polyandrous ant Cataglyphis Cursor. In this species, mating takes place on the ground near the nest entrance, and workers chase away foreign males trying to mate with young queens (gynes). We investigated the effects of worker aggression on male mating attempts by placing three or four males in the presence of one foreign gyne and 20 of her nestmate workers and contrasted this with a second group of 3–4 males in the presence of another gyne without nestmate workers (n = 8 paired replicates). Workers strongly attacked males (more than 20 aggressions per minute), although this did not affect the total number of mating attempts by the 3– 4m ales or the skew in the number of mating attempts among these males. However, there was an interaction between worker aggression and relative male weight, as relatively heavy males attempted to mate more often than lighter males in the absence of worker whereas the reverse occurred in the presence of workers. Our study is the first to experimentally test the potential role of non-reproductive individuals in sexual selection. It shows that workers could potentially change male mating success by disfavouring heavier males.
Serge Aron - One of the best experts on this subject based on the ideXlab platform.
-
2006: Local resource competition and sex ratio in the ant Cataglyphis Cursor
2014Co-Authors: Morgan Pearcy, Serge AronAbstract:The local resource competition (LRC) hypothesis predicts that wherever philopatric offspring compete for resources with their mothers, offspring sex ratios should be biased in favor of the dispersing sex. In ants, LRC is typically found in polygynous (multiple queen) species where foundation of new nests occurs by budding, which results in a strong population structure and a male-biased population-wide sex ratio. However, under polygyny, the effect of LRC on sex allocation is often blurred by the effect of lowered relatedness asymmetries among colony members. Moreover, environmental factors, such as the availability of resources, have also been shown to deeply influence sex ratio in ants. We investigated sex allocation in the monogynous (single queen) ant Cataglyphis Cursor, a species where colonies reproduce by budding and both male and female sexuals are produced through parthenogenesis, so that between-colony variations in relatedness asymmetries should be reduced. Our results show that sex allocation in C. Cursor is highly male biased both at the colony and population levels. Genetic analyses indicate a significant isolation-by-distance in the study population, consistent with limited dispersal of females. As expected from asexual reproduction, only weak variations in relatedness asymmetry of workers toward sexual offspring occur across colonies, and they are not associated with colony sex ratio. Inconsistent with the predictions of the resource availability hypothesis, the male bias signifi-cantly increases with colony size, and investment in males, but not in females, is positively correlated with total investment in sexuals. Overall, our results are consistent with the predictions of the LRC hypothesis to account for sex ratio variation in this species. Key words: dispersal, Formicidae, relatedness, sex allocation, thelytoky. [Behav Ecol 17:569–574 (2006)
-
fertile diploid males in the ant Cataglyphis Cursor a potential cost of thelytoky
Behavioral Ecology and Sociobiology, 2013Co-Authors: Claudie Doums, Pierre Federici, Johanna Clemencet, Laurent Cournault, Camille Ruel, Serge AronAbstract:Under the hymenopteran single-locus complementary sex-determination system, production of diploid males results from homozygosity at the sex-determiner locus. This arises when both parents transmit identical alleles at the locus to the offspring. In species reproducing asexually through thelytokous parthenogenesis, production of diploid males may also occur when the sex locus undergoes recombination and becomes homozygous in the offspring. Diploid males represent a substantial genetic load in hymenopteran populations because they often produce unviable sperm or sire sterile triploid female offspring. In the Mediterranean ant Cataglyphis Cursor, the queen and workers can produce female offspring through automictic thelytokous parthenogenesis with central fusion, a mode of parthenogenesis that increases homozygosity. We report, for the first time, the presence of about 39 % of colonies producing adult diploid males (seven colonies out of 18). Overall, 8 % of adult males were diploid (12 diploid males out of the 146 males genotyped). Genotyping workers from the seven colonies producing diploid males showed that three diploid males were sons of queens and produced by thelytoky, six were probably sons of workers also produced by thelytoky and three were non-natal. Furthermore, the mating of a diploid male with two virgin queens in the laboratory led to the production of sterile triploid workers, which shows that diploid males in C. Cursor are fertile, mate successfully and produce viable and functional but probably sterile female offspring. Because diploid males originate from thelytokous reproduction, they are only produced during sexual production and hence do not impair colony growth, which could explain why they are not removed at early brood stages.
-
Genetic polyethism in the polyandrous desert ant Cataglyphis Cursor
Behavioral Ecology, 2012Co-Authors: Pierre-andré Eyer, Julien Freyer, Serge AronAbstract:Several genetic and nongenetic hypotheses have been formulated to account for the evolution and maintenance of multiple mating by females (polyandry) in social Hymenoptera. A major hypothesis argues that polyandry allows production of genetically diverse workers varying in their inclination to perform different tasks, thereby enhancing division of labor and colony task efficiency. We tested the relationship between patriline, worker size, and task specialization in the ant Cataglyphis Cursor, a species showing natural variation in queen mating frequency. Our results reveal a significant association between patriline and task preference: workers belonging to different patrilines differ in their propensity to perform a given task (foraging, nest construction, waste management, or food storage). Furthermore, we found that worker size is closely associated with task specialization but not with paternal origin. Overall, these results show that task performance is at least partly genetically influenced in the ant C. Cursor, which is a key prerequisite for polyandry to improve division of labor in social insects. Keywor ds: division of labor, genetic polyethism, polyandry, polymorphism, social insect. [Behav Ecol]
-
Genetically mediated division of labor in the polyandrous desert ant Cataglyphis Cursor
2012Co-Authors: Pierre-andré Eyer, Serge AronAbstract:Several genetic and non-genetic hypotheses have been formulated to account for the evolution and maintenance of multiple mating by females (polyandry) in social Hymenoptera. A major hypothesis argues that polyandry allows production of a genetically diverse worker force, enhancing division of labor and colony task efficiency. We tested the relationship between patriline, worker size and task specialization in the desert ant Cataglyphis Cursor, a species showing natural variation in queen mating frequency. Our results show a significant association between patriline and task preference: workers belonging to different patrilines differ in their propensity to perform a given task (foraging, nest construction, waste management or food-storage). Furthermore, we found that worker size is closely associated with task specialization, but not with paternal origin. Overall, these results indicate that division of labor is at least partly genetically influenced in the ant Cataglyphis Cursor, lending support to the ‘polyandry for a more efficient polyethism’ hypothesis.
-
ant queens adjust egg fertilization to benefit from both sexual and asexual reproduction
Biology Letters, 2011Co-Authors: Serge Aron, Iris Timmermans, Morgan PearcyAbstract:An enduring problem in evolutionary biology is the near ubiquity of sexual reproduction despite the inherent cost of transmitting only half the parent's genes to progeny. Queens of some ant species circumvent this cost by using selectively both sexual reproduction and parthenogenesis: workers arise from fertilized eggs, while new queens are produced by parthenogenesis. We show that queens of the ant Cataglyphis Cursor maximize the transmission rate of their genes by regulating the proportion of fertilized and parthenogenetic eggs laid over time. Parthenogenetic offspring are produced in early spring, when workers raise the brood into sexuals. After the mating period, queens lay mostly fertilized eggs that will be reared as the non-reproductive caste.
Morgan Pearcy - One of the best experts on this subject based on the ideXlab platform.
-
2006: Local resource competition and sex ratio in the ant Cataglyphis Cursor
2014Co-Authors: Morgan Pearcy, Serge AronAbstract:The local resource competition (LRC) hypothesis predicts that wherever philopatric offspring compete for resources with their mothers, offspring sex ratios should be biased in favor of the dispersing sex. In ants, LRC is typically found in polygynous (multiple queen) species where foundation of new nests occurs by budding, which results in a strong population structure and a male-biased population-wide sex ratio. However, under polygyny, the effect of LRC on sex allocation is often blurred by the effect of lowered relatedness asymmetries among colony members. Moreover, environmental factors, such as the availability of resources, have also been shown to deeply influence sex ratio in ants. We investigated sex allocation in the monogynous (single queen) ant Cataglyphis Cursor, a species where colonies reproduce by budding and both male and female sexuals are produced through parthenogenesis, so that between-colony variations in relatedness asymmetries should be reduced. Our results show that sex allocation in C. Cursor is highly male biased both at the colony and population levels. Genetic analyses indicate a significant isolation-by-distance in the study population, consistent with limited dispersal of females. As expected from asexual reproduction, only weak variations in relatedness asymmetry of workers toward sexual offspring occur across colonies, and they are not associated with colony sex ratio. Inconsistent with the predictions of the resource availability hypothesis, the male bias signifi-cantly increases with colony size, and investment in males, but not in females, is positively correlated with total investment in sexuals. Overall, our results are consistent with the predictions of the LRC hypothesis to account for sex ratio variation in this species. Key words: dispersal, Formicidae, relatedness, sex allocation, thelytoky. [Behav Ecol 17:569–574 (2006)
-
ant queens adjust egg fertilization to benefit from both sexual and asexual reproduction
Biology Letters, 2011Co-Authors: Serge Aron, Iris Timmermans, Morgan PearcyAbstract:An enduring problem in evolutionary biology is the near ubiquity of sexual reproduction despite the inherent cost of transmitting only half the parent's genes to progeny. Queens of some ant species circumvent this cost by using selectively both sexual reproduction and parthenogenesis: workers arise from fertilized eggs, while new queens are produced by parthenogenesis. We show that queens of the ant Cataglyphis Cursor maximize the transmission rate of their genes by regulating the proportion of fertilized and parthenogenetic eggs laid over time. Parthenogenetic offspring are produced in early spring, when workers raise the brood into sexuals. After the mating period, queens lay mostly fertilized eggs that will be reared as the non-reproductive caste.
-
multiple mating in the ant Cataglyphis Cursor testing the sperm limitation and the diploid male load hypotheses
Insectes Sociaux, 2009Co-Authors: Ingrid Timmermans, Morgan Pearcy, D Allard, Serge AronAbstract:Multiple mating (i.e., polyandry) by queens in social Hymenoptera is expected to weaken social cohesion since it lowers within-colony relatedness, and hence, indirect fitness benefits from kin selection. Yet, there are many species where queens mate multiply. Several hypotheses have been put forward to explain the evolution and maintenance of polyandry. Here,we investigated the ‘sperm limitation’ and the ‘diploid male load’ hypotheses in the ant Cataglyphis Cursor. Genetic analyses of mother-offspring combinations showed that queens mate with up to 8 males, with an effective mating frequency of 3.79. Significant paternity skew (unequal contribution of the fathers) was detected in 1 out of 5 colonies. The amount of sperm stored in the spermatheca was not correlated with the queen mating frequency, and males carry on average enough sperm in their seminal vesicles to fill one queen’s spermatheca. Analyses of the nuclear DNA-content of males also revealed that all were haploid. These results suggest that the ‘sperm limitation’ and the ‘diploid male load’ hypotheses are unlikely to account for the queen mating frequency reported in this ant. In light of our results and the life-history traits of C. Cursor, we discuss alternative hypotheses to account for the adaptive significance of multiple mating by queens in this species.
-
local resource competition and sex ratio in the ant Cataglyphis Cursor
Behavioral Ecology, 2006Co-Authors: Morgan Pearcy, Serge AronAbstract:The local resource competition (LRC) hypothesis predicts that wherever philopatric offspring compete for resources with their mothers, offspring sex ratios should be biased in favor of the dispersing sex. In ants, LRC is typically found in polygynous (multiple queen) species where foundation of new nests occurs by budding, which results in a strong population structure and a male-biased population-wide sex ratio. However, under polygyny, the effect of LRC on sex allocation is often blurred by the effect of lowered relatedness asymmetries among colony members. Moreover, environmental factors, such as the availability of resources, have also been shown to deeply influence sex ratio in ants. We investigated sex allocation in the monogynous (single queen) ant Cataglyphis Cursor, a species where colonies reproduce by budding and both male and female sexuals are produced through parthenogenesis, so that between-colony variations in relatedness asymmetries should be reduced. Our results show that sex allocation in C. Cursor is highly male biased both at the colony and population levels. Genetic analyses indicate a significant isolation-by-distance in the study population, consistent with limited dispersal of females. As expected from asexual reproduction, only weak variations in relatedness asymmetry of workers toward sexual offspring occur across colonies, and they are not associated with colony sex ratio. Inconsistent with the predictions of the resource availability hypothesis, the male bias significantly increases with colony size, and investment in males, but not in females, is positively correlated with total investment in sexuals. Overall, our results are consistent with the predictions of the LRC hypothesis to account for sex ratio variation in this species. Copyright 2006.
-
thelytokous parthenogenesis and its consequences on inbreeding in an ant
Heredity, 2006Co-Authors: Morgan Pearcy, Olivier J Hardy, Serge AronAbstract:Thelytokous parthenogenesis, that is, the production of diploid daughters from unfertilized eggs, may involve various cytological mechanisms, each having a different impact on the genetic structure of populations. Here, we determined the cytological mechanism of thelytokous parthenogenesis and its impact on inbreeding in the ant Cataglyphis Cursor, a species where queens use both sexual and asexual reproduction to produce, respectively, workers and new queens. It has been suggested that thelytokous parthenogenesis in C. Cursor might have been selected for to face high queen mortality and, originally, to allow workers to replace the queen when she passes away. We first determined the mode of thelytokous parthenogenesis by comparing the rate of transition to homozygosity at four highly polymorphic loci to expectations under the different modes of parthenogenesis. Our data show that thelytoky is achieved through automictic parthenogenesis with central fusion. We then estimated the proportion of colonies headed by worker-produced queens in a natural population. We designed a model linking the observed homozygosity in queens to the proportion of queens produced by workers, based on the assumption that (i) parthenogenesis is automictic with central fusion and (ii) queen lineage is asexually produced, resulting in an increase of the inbreeding over generations, whereas workers are sexually produced and therefore not inbred. Our results indicate that more than 60% of the colonies should be headed by a worker-produced queen, suggesting that queen's lifespan is low in this species.
Johanna Clemencet - One of the best experts on this subject based on the ideXlab platform.
-
ORIGINAL PAPER Aggressions and size-related fecundity of queenless workers in the ant Cataglyphis Cursor
2016Co-Authors: Johanna Clemencet, Pierre Federici, Quentin Rome, Claudie DoumsAbstract:Abstract In social hymenoptera, the reproductive division of labor is often linked to differences in individual body size with the reproductive caste (the queen) being larger than the workers. Likewise, the reproductive potential may vary with size within the worker caste and could affect the evolution of worker size in social insects. Here, we tested the relationship between worker size and reproductive potential in the facultative parthenogenetic ant Cataglyphis Cursor. Colonies are headed by a multiply mated queen, but workers can produce gynes (virgin queens) and workers by thelytokous parthenogenesis after the queen’s death. We observed the behaviour of workers (n=357) until the production of gynes (212 h over 3 months) in an orphaned colony (mated queen not present). The size of workers was measured, and their paternal lineage determined using six microsatellite markers, to control for an effect of patriline. Larger workers were more likely to reproduce and lay more eggs indicating that individual level selection could take place. However, paternal lineage had no effect on the reproductive potential and worker size. From the behav-ioural and genetic data, we also show for the first time in this species, evidence of aggressive interactions among workers and a potential for nepotism to occur in orphaned colonies, as the five gynes produced belonged to a single paternal lineage
-
fertile diploid males in the ant Cataglyphis Cursor a potential cost of thelytoky
Behavioral Ecology and Sociobiology, 2013Co-Authors: Claudie Doums, Pierre Federici, Johanna Clemencet, Laurent Cournault, Camille Ruel, Serge AronAbstract:Under the hymenopteran single-locus complementary sex-determination system, production of diploid males results from homozygosity at the sex-determiner locus. This arises when both parents transmit identical alleles at the locus to the offspring. In species reproducing asexually through thelytokous parthenogenesis, production of diploid males may also occur when the sex locus undergoes recombination and becomes homozygous in the offspring. Diploid males represent a substantial genetic load in hymenopteran populations because they often produce unviable sperm or sire sterile triploid female offspring. In the Mediterranean ant Cataglyphis Cursor, the queen and workers can produce female offspring through automictic thelytokous parthenogenesis with central fusion, a mode of parthenogenesis that increases homozygosity. We report, for the first time, the presence of about 39 % of colonies producing adult diploid males (seven colonies out of 18). Overall, 8 % of adult males were diploid (12 diploid males out of the 146 males genotyped). Genotyping workers from the seven colonies producing diploid males showed that three diploid males were sons of queens and produced by thelytoky, six were probably sons of workers also produced by thelytoky and three were non-natal. Furthermore, the mating of a diploid male with two virgin queens in the laboratory led to the production of sterile triploid workers, which shows that diploid males in C. Cursor are fertile, mate successfully and produce viable and functional but probably sterile female offspring. Because diploid males originate from thelytokous reproduction, they are only produced during sexual production and hence do not impair colony growth, which could explain why they are not removed at early brood stages.
-
Worker thermal tolerance in the thermophilic ant Cataglyphis Cursor (Hymenoptera, Formicidae)
Insectes Sociaux, 2009Co-Authors: Johanna Clemencet, Laurent Cournault, A. Odent, Claudie DoumsAbstract:In the thermophilic ant genus Cataglyphis, species differing in their physical caste system have developed alternative mechanisms to face extreme heat by physiological and/or behavioural adaptations. In this study, we tested whether thermal tolerance is related to worker size in the ant Cataglyphis Cursor that presents intermediate worker size compared with previously studied species (size range 3.5–10 mm). Thermal tolerance at two temperatures was tested in the laboratory on colonies originating from two habitats (seaside versus vineyard), known to differ in average worker size. As expected large workers were more resistant to high temperature than small workers, but the effect of worker size on thermal resistance was less pronounced under the more extreme temperatures. The pattern of thermal tolerance was similar in the two habitat types. After controlling for worker size, worker thermal tolerance significantly varied amongst colonies, but this variation was not related to colony size. Our results suggest that a higher thermal tolerance can confer an advantage to larger workers especially during foraging and are discussed in the context of the evolution of worker size in ants.
-
Aggressions and size-related fecundity of queenless workers in the ant Cataglyphis Cursor.
Die Naturwissenschaften, 2007Co-Authors: Johanna Clemencet, Pierre Federici, Quentin Rome, Claudie DoumsAbstract:In social hymenoptera, the reproductive division of labor is often linked to differences in individual body size with the reproductive caste (the queen) being larger than the workers. Likewise, the reproductive potential may vary with size within the worker caste and could affect the evolution of worker size in social insects. Here, we tested the relationship between worker size and reproductive potential in the facultative parthenogenetic ant Cataglyphis Cursor. Colonies are headed by a multiply mated queen, but workers can produce gynes (virgin queens) and workers by thelytokous parthenogenesis after the queen’s death. We observed the behaviour of workers (n = 357) until the production of gynes (212 h over 3 months) in an orphaned colony (mated queen not present). The size of workers was measured, and their paternal lineage determined using six microsatellite markers, to control for an effect of patriline. Larger workers were more likely to reproduce and lay more eggs indicating that individual level selection could take place. However, paternal lineage had no effect on the reproductive potential and worker size. From the behavioural and genetic data, we also show for the first time in this species, evidence of aggressive interactions among workers and a potential for nepotism to occur in orphaned colonies, as the five gynes produced belonged to a single paternal lineage.
-
habitat related microgeographic variation of worker size and colony size in the ant Cataglyphis Cursor
Oecologia, 2007Co-Authors: Johanna Clemencet, Claudie DoumsAbstract:In social insects, colony size is a crucial life-history trait thought to have major implications for the evolution of social complexity, especially in relation to worker size polymorphism. Yet, little is known about how ecological factors can affect and constrain colony. Here, we explored the pattern of colony-size and worker-size variation in the Mediterranean ant Cataglyphis Cursor, in relation to the type of habitats colonized (seaside vs. vineyard). The high level of the water table in the seaside habitat could constrain the depth of C. Cursor underground nests and directly constrain its colony size. If worker size increases with colony size, as observed in other ant species, larger colony size and larger workers should be found in the vineyard populations. By comparing worker size among 16 populations, we verified that workers were significantly larger in the vineyard populations. We further determined that the morphological similarities detected among populations from the same habitat type were not due to geographic or genetic proximity. In two populations from each habitat type, the depth of nests was positively correlated with colony size and colony size with worker size. Using a type II regression approach, we further showed that the difference between the two populations in the depth of nest was sufficient to explain the difference in colony size, and similarly, variation in colony size was sufficient to explain variation in worker size. Our results suggest that a single proximate ecological factor could lead to significant variation in major life-history parameters.
Thibaud Monnin - One of the best experts on this subject based on the ideXlab platform.
-
Chemical Characterization of Young Virgin Queens and Mated Egg-Laying Queens in the Ant Cataglyphis Cursor: Random Forest Classification Analysis for Multivariate Datasets
Journal of Chemical Ecology, 2018Co-Authors: Thibaud Monnin, Florence Helft, Chloé Leroy, Patrizia D’ettorre, Claudie DoumsAbstract:Social insects are well known for their extremely rich chemical communication, yet their sex pheromones remain poorly studied. In the thermophilic and thelytokous ant, Cataglyphis Cursor, we analyzed the cuticular hydrocarbon profiles and Dufour’s gland contents of queens of different age and reproductive status (sexually immature gynes, sexually mature gynes, mated and egg-laying queens) and of workers. Random forest classification analyses showed that the four groups of individuals were well separated for both chemical sources, except mature gynes that clustered with queens for cuticular hydrocarbons and with immature gynes for Dufour’s gland secretions. Analyses carried out with two groups of females only allowed identification of candidate chemicals for queen signal and for sexual attractant. In particular, gynes produced more undecane in the Dufour’s gland. This chemical is both the sex pheromone and the alarm pheromone of the ant Formica lugubris . It may therefore act as sex pheromone in C. Cursor , and/or be involved in the restoration of monogyny that occurs rapidly following colony fission. Indeed, new colonies often start with several gynes and all but one are rapidly culled by workers, and this process likely involves chemical signals between gynes and workers. These findings open novel opportunities for experimental studies of inclusive mate choice and queen choice in C. Cursor .
-
worker thelytoky allows requeening of orphaned colonies but increases susceptibility to reproductive cheating in an ant
Animal Behaviour, 2018Co-Authors: Claudie Doums, Pierre Federici, Pascaline Chiffletbelle, Thibaud MonninAbstract:In some social insects, workers can produce females asexually through thelytokous parthenogenesis. This allows them to produce replacement queens (i.e. requeening) if the queen has died, but also to compete with the queen to produce females (i.e. reproductive cheating). For the first time, we experimentally tested the role of worker thelytoky under quasinatural conditions in the ant Cataglyphis Cursor, where the queen uses both sexual and thelytokous reproduction. We reared pairs of orphaned and queenright colonies in enclosures for almost 3 months, during which they competed for resources. Orphaned colonies lost more workers than queenright colonies over the course of the experiment, presumably because of the costs of reproductive conflicts between workers. Nevertheless, they produced new queens through worker thelytoky and new colonies through colony fission. This is the first unambiguous demonstration that worker thelytoky allows requeening under natural conditions in this species. We further showed that worker thelytoky results in reproductive cheating in the form of a few workers reproducing in the presence of the queen (in queenright colonies) and a few worker lineages producing more new queens than other lineages (in orphaned colonies). In addition, it also results in rare instances of social parasitism, that is, workers entering and reproducing in foreign colonies. These benefits to workers seem too occasional and too low to drive the evolution of thelytoky in this species. We argue that thelytoky probably evolved in the queen caste, where it allows the production of young queens and confers frequent and large benefits by increasing gene transmission, but is also expressed in workers because of genetic correlations between the two castes.
-
No evidence of pre-copulatory mate choice by gynes in the facultatively parthenogenetic ant Cataglyphis Cursor
Insectes Sociaux, 2015Co-Authors: Florence Helft, Claudie Doums, Thibaud MonninAbstract:Virgin queens (gynes) of the ant Cataglyphis Cursor mate on the ground at the nest entrance, where they benefit from the protection of nestmate workers. By carrying out mating tests in the laboratory, we show that gynes mate with the first males they encounter, suggesting the absence of pre-copulatory mate choice by gynes. This is in agreement with the recent finding that workers behave aggressively towards foreign males and could thereby exercise a form of inclusive mate choice, which could replace pre-copulatory mate choice by gynes.
-
first evidence of inclusive sexual selection in the ant Cataglyphis Cursor worker aggressions differentially affect male access to virgin queens
Ethology, 2015Co-Authors: Florence Helft, Claudie Doums, Thibaud MonninAbstract:Sexual selection typically shapes the traits of individuals capable of reproduction. However, in social species, it may also affect the behaviour of non-reproductive individuals if this increases their inclusive fitness. We examined the potential role of workers during mating in the polyandrous ant Cataglyphis Cursor. In this species, mating takes place on the ground near the nest entrance, and workers chase away foreign males trying to mate with young queens (gynes). We investigated the effects of worker aggression on male mating attempts by placing three or four males in the presence of one foreign gyne and 20 of her nestmate workers and contrasted this with a second group of 3–4 males in the presence of another gyne without nestmate workers (n = 8 paired replicates). Workers strongly attacked males (more than 20 aggressions per minute), although this did not affect the total number of mating attempts by the 3– 4m ales or the skew in the number of mating attempts among these males. However, there was an interaction between worker aggression and relative male weight, as relatively heavy males attempted to mate more often than lighter males in the absence of worker whereas the reverse occurred in the presence of workers. Our study is the first to experimentally test the potential role of non-reproductive individuals in sexual selection. It shows that workers could potentially change male mating success by disfavouring heavier males.
-
Facultative use of thelytokous parthenogenesis for queen production in the polyandrous ant Cataglyphis Cursor
Journal of Evolutionary Biology, 2013Co-Authors: Claudie Doums, Pierre Federici, Adam L. Cronin, Claudy Haussy, Claire Tirard, Camille Ruel, Thibaud MonninAbstract:The evolutionary paradox of sex remains one of the major debates in evolutionary biology. The study of species capable of both sexual and asexual reproduction can elucidate factors important in the evolution of sex. One such species is the ant Cataglyphis Cursor, where the queen maximizes the transmission of her genes by producing new queens (gynes) asexually while simultaneously maintaining a genetically diverse workforce via the sexual production of workers. We show that the queen can also produce gynes sexually and may do so to offset the costs of asexual reproduction. We genotyped 235 gynes from 18 colonies and found that half were sexually produced. A few colonies contained both sexually and asexually produced gynes. Although workers in this species can also use thelytoky, we found no evidence of worker production of gynes based on genotypes of 471 workers from the six colonies producing sexual gynes. Gynes are thus mainly, and potentially exclusively, produced by the queen. Simulations of gynes inbreeding level following one to ten generations of automictic thelytoky suggest that the queen switches between or combines thelytoky and sex, which may reduce the costs of inbreeding. This is supported by the relatively small size of inbred gynes in one colony, although we found no relationship between the level of inbreeding and immune parameters. Such facultative use of sex and thelytoky by individual queens contrasts with other known forms of parthenogenesis in ants, which are typically characterized by distinct lineages specializing in one strategy or the other.