The Experts below are selected from a list of 3084 Experts worldwide ranked by ideXlab platform

Serge Aron - One of the best experts on this subject based on the ideXlab platform.

  • The Interplay between Incipient Species and Social Polymorphism in the Desert Ant Cataglyphis.
    Scientific reports, 2019
    Co-Authors: Tali Reiner Brodetzki, Serge Aron, Shani Inbar, Pnina Cohen, Eyal Privman, Abraham Hefetz
    Abstract:

    In social insects, due to considerable polyphenism as well as high level of hybridization, the delimitation of species can be challenging. The genus Cataglyphis presents a high level of diversification, making it an excellent model with which to study evolutionary paths. Israel appears to be a "hot spot" for recent speciation in this genus. Although previous studies have described multiple species of Cataglyphis in Israel, a recent genetic study has questioned the existence of some of these historically described species. The present study focuses on an apparent species complex, the C. niger species complex which includes C. niger, C. savigyi, and C. drusus that are distinguishable by their mitochondrial DNA (and therefore named mitotypes) but not by their nuclear DNA. Using a multi-method approach (genetics, chemistry and behavior), we show that these mitotypes also differ in their social structures and are readily distinguishable by their cuticular hydrocarbons profiles. While most populations of the different mitotypes are allopatric, at our study site they are sympatric, but nonetheless maintain the observed differences between them. This raises the evolutionary question: Are these incipient species that have diverged with gene flow, or is this a case of social and chemical polymorphism that is maintained within a single species? Unveiling the interplay between social polyphenism and species segregation is at the core of evolutionary biology.

  • Evolution of hybridogenetic lineages in Cataglyphis ants
    Molecular ecology, 2019
    Co-Authors: Hugo Darras, Alexandre Kuhn, Serge Aron
    Abstract:

    In most social Hymenoptera, a diploid egg develops into either a queen or a worker depending on environmental conditions. Hybridogenetic Cataglyphis ants display a bizarre genetic system, where queen-worker caste determination is primarily determined by genetic factors. In hybridogenetic populations, all workers are F1 hybrids of two distinct lineages, whereas new queens are nearly always pure-lineage individuals produced by clonal reproduction. The distribution and evolutionary history of these hybridogenetic populations have not yet been thoroughly analysed. Here, we studied the phylogeographic distribution of hybridogenetic populations in two closely related Spanish species: Cataglyphis humeya and Cataglyphis velox. Hybridogenesis has been previously documented in a locality of C. velox, but whether this system occurs elsewhere within the range of the two species was yet unknown. Queens and workers from 66 localities sampled across the range of the species were genotyped at 18 microsatellite markers to determine whether queens were produced by parthenogenesis and whether workers were hybrids of divergent lineages. Populations with F1 hybrid workers were identified by combining genetic, geographical and mating assortments data. In most populations of C. velox, workers were found to be hybrids of two divergent lineages. Workers were however produced via random mating in two marginal populations of C. velox, and in all populations studied of its sister species C. humeya. High-throughput sequencing data were obtained to confirm inferences based on microsatellites and to characterize relationships between populations. Our results revealed a complicated history of reticulate evolution that may account for the origin of hybridogenetic lineages in Cataglyphis.

  • Incipient species or social polymorphism? Diversity in the desert ant Cataglyphis
    2018
    Co-Authors: Tali Reiner Brodetzki, Serge Aron, Shani Inbar, Pnina Cohen, Eyal Privman, Abraham Hefetz
    Abstract:

    Abstract Species are the fundamental units upon which evolutionary research is based. In insects, due to the high level of hybridization, the delimitation of such species can be challenging. The genus Cataglyphis presents a high level of diversification, making it an excellent model with which to study evolutionary paths. Israel appears to be a “hot spot” for recent speciation in this genus. Although previous studies have described multiple species of Cataglyphis in Israel, a recent genetic study has questioned the existence of some of these historically described species. The present study focuses on an apparent species complex that is distinguishable by its mitochondrial DNA (and therefore named mitotypes) but not by its nuclear DNA. Using a multi-method approach (genetics, chemistry and behavior), we show that these mitotypes also differ in their social structures and are readily distinguishable by their cuticular hydrocarbons profiles. While the different mitotypes are in general allopatric, at our study site they all coexist but nonetheless maintain the observed differences between them. This raises many evolutionary questions: Are these incipient species that have diverged with gene flow, or is this a case of social and chemical polymorphism that is maintained within a single species.

  • Proteome stability, heat hardening and heat-shock protein expression profiles in Cataglyphis desert ants.
    The Journal of Experimental Biology, 2017
    Co-Authors: Quentin Willot, Cyril Gueydan, Serge Aron
    Abstract:

    ABSTRACT In ectotherms, high temperatures impose physical limits, impeding activity. Exposure to high heat levels causes various deleterious and lethal effects, including protein misfolding and denaturation. Thermophilic ectotherms have evolved various ways to increase macromolecular stability and cope with elevated body temperatures; these include the high constitutive expression of molecular chaperones. In this study, we investigated the effect of moderate to severe heat shock (37–45°C) on survival, heat hardening, protein damage and the expression of five heat tolerance-related genes ( hsc70-4 h1 , hsc70-4 h2 , hsp83 , hsc70-5 and hsf1) in two closely related Cataglyphis ants that occur in distinct habitats. Our results show that the highly thermophilic Sahara ant Cataglyphis bombycina constitutively expresses HSC70 at higher levels, but has lower induced expression of heat tolerance-related genes in response to heat shock, as compared with the more mesophilic Cataglyphis mauritanica found in the Atlas Mountains. As a result, C. bombycina demonstrates increased protein stability when exposed to acute heat stress but is less disposed to acquiring induced thermotolerance via heat hardening. These results provide further insight into the evolutionary plasticity of the hsp gene expression system and subsequent physiological adaptations in thermophilous desert insects to adapt to harsh environmental conditions.

  • Social Life in Arid Environments: The Case Study of Cataglyphis Ants
    Annual review of entomology, 2016
    Co-Authors: Raphaël Boulay, Serge Aron, Xim Cerdá, Claudie Doums, Paul Graham, Abraham Hefetz, Thibaud Monnin
    Abstract:

    Unlike most desert-dwelling animals, Cataglyphis ants do not attempt to escape the heat; rather, they apply their impressive heat tolerance to avoid competitors and predators. This thermally defined niche has promoted a range of adaptations both at the individual and colony levels. We have also recently discovered that within the genus Cataglyphis there are incredibly diverse social systems, modes of reproduction, and dispersal, prompting the tantalizing question of whether social diversity may also be a consequence of the harsh environment within which we find these charismatic ants. Here we review recent advances regarding the physiological, behavioral, life-history, colony, and ecological characteristics of Cataglyphis and consider perspectives on future research that will build our understanding of organic adaptive responses to desertification.

Rüdiger Wehner - One of the best experts on this subject based on the ideXlab platform.

  • Long-leggedness in cataglyphoid Baltic amber ants
    Palaeobiodiversity and Palaeoenvironments, 2020
    Co-Authors: Rüdiger Wehner, Renate Rabenstein, Jörg Habersetzer
    Abstract:

    All truly thermophilic ants inhabiting the subtropical belts of our planet— Cataglyphis (Formicinae) in the southern Palearctic region, Ocymyrmex (Myrmicinae) in southern Africa and Melophorus (Formicinae) in Australia—are characterised by extremely long legs and remarkable locomotor agility including extremely high running speeds (relative to body size). In the classic surveys of the rich assemblages of Eocene Baltic amber ants, Gustav Mayr ( 1868 ) and William Morton Wheeler ( 1915 ) described a few specimens that exhibited some Cataglyphis -like traits. They assigned them to the genera Camponotus and Formica , respectively, but more recently Gennady Dlussky ( 2008 ) considered these traits sufficient enough to establish a new genus— Cataglyphoides —for them. Using micro-computed tomographic 3D reconstructions, we show that the relative lengths of the Cataglyphoides legs and the relative contributions of different leg segments (femur, tibia, basitarsus) to the lengths of the legs, fully fit the allometric functions determined for extant Cataglyphis species. Moreover, fossil Formica flori specimens taken from the same Baltic amber deposits have highly significantly shorter legs, and in this respect coincide with extant Formica species. It is also the cuneiform to nodiform petiole characterising the most agile extant Cataglyphis species and promoting their agility and the slit-like shape of the propodeal spiracle found in all truly thermophilic ants that we observe in Cataglyphoides . We discuss the occurrence of a cataglyphoid ant in Eocene northern Europe in the light of hypotheses about the phylogeography of extant Cataglyphis species and surmise that Cataglyphoides has evolved in parallel to, and in this context has acquired a set of traits characteristic for, the most highly advanced Cataglyphis species.

  • Cataglyphis meets Drosophila.
    Journal of neurogenetics, 2020
    Co-Authors: Rüdiger Wehner
    Abstract:

    In Cataglyphis and Drosophila - in desert ants and fruit flies - research on visually guided behavior took different paths. While work in Cataglyphis started in the field and covered the animal's wide navigational repertoire, in Drosophila the initial focus was on a particular kind of visual control behavior scrutinized within the confines of the laboratory arena, before research concentrated on more advanced behaviors. In recent times, these multi-pronged approaches in flies and ants increasingly converge, both conceptually and methodologically, and thus lay the ground for combined neuroethological efforts. In spite of the obvious differences in the behavioral repertoire of these two groups of insects, likely commonalities in the navigational processes and underlying neuronal circuitries are increasingly coming to the fore.

  • The Cataglyphis Mahrèsienne: 50 years of Cataglyphis research at Mahrès
    Journal of Comparative Physiology A, 2019
    Co-Authors: Rüdiger Wehner
    Abstract:

    Every year since 1969, research groups from Zürich have spent the summer months in the barren sandy areas around the Tunisian village Mahrès to study the navigational behaviour of Cataglyphis desert ants, its sensory underpinnings, and ecophysiological settings. From the 1990s onwards, researchers from other countries were invited to join the Zürich group, so that Cataglyphis increasingly advanced to become a model organism for the study of animal navigation. Its cockpit became the focus of a dynamic research system, an ‘epistemic thing’, as modern parlance in the philosophy of science has it. Investigations aimed at the ants’ compasses and odometers, at path integration, view-based landmark guidance, and how information from these various navigational routines is combined in computing the courses to steer. In this multifaceted work, the researchers’ familiarity with the site, with Mahrès, and its local geographical and historical conditions, has been essential. The essay briefly retraces the historical development of this research system. After the system had been firmly established at the North African Mahrès site, it was extended to the ecological equivalents of Cataglyphis in other true deserts of the world, to Ocymyrmex in the Namib Desert of southern Africa, and to Melophorus in central Australia.

  • The Cataglyphis Mahrèsienne: 50 years of Cataglyphis research at Mahrès.
    Journal of comparative physiology. A Neuroethology sensory neural and behavioral physiology, 2019
    Co-Authors: Rüdiger Wehner
    Abstract:

    Every year since 1969, research groups from Zurich have spent the summer months in the barren sandy areas around the Tunisian village Mahres to study the navigational behaviour of Cataglyphis desert ants, its sensory underpinnings, and ecophysiological settings. From the 1990s onwards, researchers from other countries were invited to join the Zurich group, so that Cataglyphis increasingly advanced to become a model organism for the study of animal navigation. Its cockpit became the focus of a dynamic research system, an ‘epistemic thing’, as modern parlance in the philosophy of science has it. Investigations aimed at the ants’ compasses and odometers, at path integration, view-based landmark guidance, and how information from these various navigational routines is combined in computing the courses to steer. In this multifaceted work, the researchers’ familiarity with the site, with Mahres, and its local geographical and historical conditions, has been essential. The essay briefly retraces the historical development of this research system. After the system had been firmly established at the North African Mahres site, it was extended to the ecological equivalents of Cataglyphis in other true deserts of the world, to Ocymyrmex in the Namib Desert of southern Africa, and to Melophorus in central Australia.

  • Species-specific differences in the fine structure of learning walk elements in Cataglyphis ants.
    The Journal of experimental biology, 2017
    Co-Authors: Pauline N Fleischmann, Rüdiger Wehner, Robin Grob, Wolfgang Rössler
    Abstract:

    Cataglyphis desert ants are famous navigators. Like all central place foragers, they are confronted with the challenge to return home, i.e. relocate an inconspicuous nest entrance in the ground, after their extensive foraging trips. When leaving the underground nest for the first time, desert ants perform a striking behavior, so-called learning walks that are well structured. However, it is still unclear how the ants initially acquire the information needed for sky- and landmark-based navigation, in particular how they calibrate their compass system at the beginning of their foraging careers. Using high-speed video analyses, we show that different Cataglyphis species include different types of characteristic turns in their learning walks. Pirouettes are full or partial rotations (tight turns about the vertical body axis) during which the ants frequently stop and gaze back in the direction of the nest entrance during the longest stopping phases. In contrast, voltes are small walked circles without directed stopping phases. Interestingly, only Cataglyphis ant species living in a cluttered, and therefore visually rich, environment (i.e. C. noda and C. aenescens in southern Greece) perform both voltes and pirouettes. They look back to the nest entrance during pirouettes, most probably to take snapshots of the surroundings. In contrast, C. fortis inhabiting featureless saltpans in Tunisia perform only voltes and do not stop during these turns to gaze back at the nest - even if a set of artificial landmarks surrounds the nest entrance.

Harald Wolf - One of the best experts on this subject based on the ideXlab platform.

  • Accuracy and spread of nest search behaviour in the Saharan silver ant, Cataglyphis bombycina, and in the salt pan species, Cataglyphis fortis
    Animal Cognition, 2020
    Co-Authors: Sarah Pfeffer, Verena Wahl, Harald Wolf
    Abstract:

    Desert ants of the genus Cataglyphis are renowned for their navigation abilities, especially for their beeline homing after meandering foraging excursions reaching several hundreds of meters in length. A spiralling nest search is performed when an ant misses the nest entrance upon completing its homebound travel. We examined the nest search behaviours of two desert ant species dwelling in different habitats— Cataglyphis bombycina living in the dunes of the Sahara and Cataglyphis fortis found in the salt pans of North Africa. The two species show distinct differences in walking behaviour. C. bombycina performs a strict tripod gait with pronounced aerial phases, high stride frequencies, and extremely brief ground contact times. In view of these peculiarities and the yielding sand dune substrate, we hypothesised that homing accuracy, and namely distance measurement by stride integration, should be lower in C. bombycina , compared to the well-studied C. fortis with less specialised walking behaviour. We tested this hypothesis in ants’ homebound runs from a feeding site in a linear channel setup. Surprisingly, the accuracies of nest searches were similar in the two ant species, and search accuracy was also independent of the walking substrate, soft dune sand or a hard floor. The spread of the nest search, by contrast, differed significantly between the two species, C. bombycina exhibiting a larger search spread. This may be interpreted as an increased path integration uncertainty due to the above locomotor specialisations, or as a compensation strategy accounting for the silver ants’ particular environmental and behavioural situation.

  • High-speed locomotion in the Saharan silver ant, Cataglyphis bombycina.
    The Journal of Experimental Biology, 2019
    Co-Authors: Sarah E. Pfeffer, Verena L. Wahl, Matthias Wittlinger, Harald Wolf
    Abstract:

    ABSTRACT The diurnal thermophilic Saharan silver ant, Cataglyphis bombycina, is the fastest of the North African Cataglyphis desert ant species. These highly mobile ants endure the extreme temperatures of their sand dune environment with outstanding behavioural, physiological and morphological adaptations. Surprisingly, C. bombycina has comparatively shorter legs than its well-studied sister species Cataglyphis fortis from salt pan habitats. This holds despite the somewhat hotter surface temperatures and the more yielding sand substrate. Here, we report that C. bombycina employs a different strategy in reaching high running speeds, outperforming the fastest known runs of the longer-legged C. fortis ants. Video analysis across a broad range of locomotor speeds revealed several differences to C. fortis. Shorter leg lengths are compensated for by high stride frequencies, ranging beyond 40 Hz. This is mainly achieved by a combination of short stance phases (down to 7 ms) and fast leg swing movements (up to 1400 mm s−1). The legs of one tripod group exhibit almost perfect synchrony in the timings of their lift-offs and touch-downs, and good tripod coordination is present over the entire walking speed range (tripod coordination strength values around 0.8). This near synchrony in leg movement may facilitate locomotion across the yielding sand dune substrate.

  • Two distance memories in desert ants—Modes of interaction
    2018
    Co-Authors: Harald Wolf, Matthias Wittlinger, Sarah E. Pfeffer
    Abstract:

    Navigation plays an essential role for many animals leading a mobile mode of life, and for central place foragers in particular. One important prerequisite for navigation is the ability to estimate distances covered during locomotion. It has been shown that Cataglyphis desert ants, well-established model organisms in insect navigation, use two odometer mechanisms, namely, stride and optic flow integration. Although both mechanisms are well established, their mode of interaction to build one odometer output remains enigmatic. We tackle this problem by selectively covering the ventral eye parts in Cataglyphis fortis foragers, the eye regions responsible for optic flow input in odometry. Exclusion of optic flow cues was implemented during different sections of outbound and inbound travel. This demonstrated that the two odometers have separate distance memories that interact in determining homing distance. Possible interpretations posit that the two odometer memories (i) take on different relative weights according to context or (ii) compete in a winner-take-all mode. Explanatory values and implications of such interpretations are discussed. We are able to provide a rough quantitative assessment of odometer cue interaction. An understanding of the interaction of different odometer mechanisms appears valuable not only for animal navigation research but may inform discussions on sensor fusion in both behavioural contexts and potential technical applications.

  • Food searches and guiding structures in North African desert ants, Cataglyphis.
    Journal of comparative physiology. A Neuroethology sensory neural and behavioral physiology, 2015
    Co-Authors: Siegfried Bolek, Harald Wolf
    Abstract:

    North African desert ants, Cataglyphis fortis, use path integration as their primary means of navigation. The ants also use landmarks when these are available to improve navigation accuracy. Extended landmarks, such as walls and channels, may serve further functions, for example, local guidance or triggering of local vectors. The roles of such structures were usually examined in homing animals but not during food searches. When searching for familiar feeding sites, Cataglyphis may show intriguing deviations from expected search performances. These may result from the presence of extended landmarks, namely experimental channels. Here we scrutinise this hypothesis of landmark guidance in food searches. We prevented the ants from seeing the channel walls by covering their eyes, except the dorsal rim area. This experiment was repeated in the open test field with an alley of black cylinders to extend our findings to a more normal foraging environment. Ants with covered eyes did not deviate from expected search performances, whereas ants with normal eyes extended their searches along the axis of the leading structures by 15–20 %, in both channels and landmark alleys. This demonstrates that Cataglyphis orients along extended landmarks when searching for familiar food sources and alters its search pattern accordingly.

  • Hair plate mechanoreceptors associated with body segments are not necessary for three-dimensional path integration in desert ants, Cataglyphis fortis.
    Journal of Experimental Biology, 2007
    Co-Authors: Matthias Wittlinger, Harald Wolf, Rüdiger Wehner
    Abstract:

    In formicine ants, the hair fields associated with the neck and the petiole (alitrunk–petiole and petiole–gaster joints) have long been established to function in graviception. Here, we examine a possible role of these hair receptors in three-dimensional (3-D) path integration of the (formicine) desert ant, Cataglyphis fortis . Cataglyphis judge the ground distance when travelling over hills, allowing correct homing even in (unpredictably) uneven terrain. We eliminated the function of these hair sensors in graviception either by shaving the hairs or by immobilising the joints monitored by the hair plates. With that major component of their sense of graviception eliminated, one would expect the ants to disregard, or at least misgauge, the ascents and descents performed across hills during outbound journey. The ants should thus consider the (much longer) actual walking trajectory, instead of the base distance, when calculating their homing distance. Surprisingly, neither shaving nor immobilisation of the hair sensillae affected correct path integration, across both uneven terrain (3-D) and level surface. If anything, the ants underestimated homing distance, which may reflect a general, safety-oriented navigation strategy. Animals that had performed the outbound journey with their gaster fixed in a horizontal position underestimated their homing so dramatically that this latter explanation cannot hold.

Abraham Hefetz - One of the best experts on this subject based on the ideXlab platform.

  • The Interplay between Incipient Species and Social Polymorphism in the Desert Ant Cataglyphis.
    Scientific reports, 2019
    Co-Authors: Tali Reiner Brodetzki, Serge Aron, Shani Inbar, Pnina Cohen, Eyal Privman, Abraham Hefetz
    Abstract:

    In social insects, due to considerable polyphenism as well as high level of hybridization, the delimitation of species can be challenging. The genus Cataglyphis presents a high level of diversification, making it an excellent model with which to study evolutionary paths. Israel appears to be a "hot spot" for recent speciation in this genus. Although previous studies have described multiple species of Cataglyphis in Israel, a recent genetic study has questioned the existence of some of these historically described species. The present study focuses on an apparent species complex, the C. niger species complex which includes C. niger, C. savigyi, and C. drusus that are distinguishable by their mitochondrial DNA (and therefore named mitotypes) but not by their nuclear DNA. Using a multi-method approach (genetics, chemistry and behavior), we show that these mitotypes also differ in their social structures and are readily distinguishable by their cuticular hydrocarbons profiles. While most populations of the different mitotypes are allopatric, at our study site they are sympatric, but nonetheless maintain the observed differences between them. This raises the evolutionary question: Are these incipient species that have diverged with gene flow, or is this a case of social and chemical polymorphism that is maintained within a single species? Unveiling the interplay between social polyphenism and species segregation is at the core of evolutionary biology.

  • Incipient species or social polymorphism? Diversity in the desert ant Cataglyphis
    2018
    Co-Authors: Tali Reiner Brodetzki, Serge Aron, Shani Inbar, Pnina Cohen, Eyal Privman, Abraham Hefetz
    Abstract:

    Abstract Species are the fundamental units upon which evolutionary research is based. In insects, due to the high level of hybridization, the delimitation of such species can be challenging. The genus Cataglyphis presents a high level of diversification, making it an excellent model with which to study evolutionary paths. Israel appears to be a “hot spot” for recent speciation in this genus. Although previous studies have described multiple species of Cataglyphis in Israel, a recent genetic study has questioned the existence of some of these historically described species. The present study focuses on an apparent species complex that is distinguishable by its mitochondrial DNA (and therefore named mitotypes) but not by its nuclear DNA. Using a multi-method approach (genetics, chemistry and behavior), we show that these mitotypes also differ in their social structures and are readily distinguishable by their cuticular hydrocarbons profiles. While the different mitotypes are in general allopatric, at our study site they all coexist but nonetheless maintain the observed differences between them. This raises many evolutionary questions: Are these incipient species that have diverged with gene flow, or is this a case of social and chemical polymorphism that is maintained within a single species.

  • Social Life in Arid Environments: The Case Study of Cataglyphis Ants
    Annual review of entomology, 2016
    Co-Authors: Raphaël Boulay, Serge Aron, Xim Cerdá, Claudie Doums, Paul Graham, Abraham Hefetz, Thibaud Monnin
    Abstract:

    Unlike most desert-dwelling animals, Cataglyphis ants do not attempt to escape the heat; rather, they apply their impressive heat tolerance to avoid competitors and predators. This thermally defined niche has promoted a range of adaptations both at the individual and colony levels. We have also recently discovered that within the genus Cataglyphis there are incredibly diverse social systems, modes of reproduction, and dispersal, prompting the tantalizing question of whether social diversity may also be a consequence of the harsh environment within which we find these charismatic ants. Here we review recent advances regarding the physiological, behavioral, life-history, colony, and ecological characteristics of Cataglyphis and consider perspectives on future research that will build our understanding of organic adaptive responses to desertification.

  • Chemical integration of Thorictus myrmecophilous beetles into Cataglyphis ant nests
    Biochemical Systematics and Ecology, 2013
    Co-Authors: Alain Lenoir, Abraham Hefetz, Jiri Hava, Xim Cedra, Raphaël Boulay
    Abstract:

    Thorictus beetles of the Dermestidae are obligatemyrmecophiles. To understand how these beetles are integrated into and tolerated by their host colonies, the cuticular hydrocarbon profiles of different species of the Thorictus castaneus group that are generally associated with Cataglyphis were examined. The beetles are characterized by small amounts of cuticular hydrocarbons, which render them partly chemically "insignificant". They also have the same cuticular hydrocarbon profiles as their hosts and thus likely use chemical mimicry to evade worker hostility but, like slaves in slave-maker species, they maintain some partial chemical identity. Thorictus martinezi from Burkina Faso were immediately adopted by conspecific colonies of their host, Cataglyphis sp. aff. bicolor, but were never adopted by colonies of other species (i.e. Cataglyphis viatica and Formica selysi). Thorictus buigasi from Morocco also mimicked the chemical profile of its host, C. viatica, but, in contrast to T. martinezi, individuals were adopted by colonies of Cataglyphis velox from Spain. This result can be explained by the similarity between the hydrocarbon profiles of C. viatica and C. velox, which may facilitate adoptions. T. buigasi beetles remained in Formica selysi colonies for some time but were ultimately rejected, probably due to their very different hydrocarbon profiles. In contrast, they were sometimes adopted by Camponotus herculeanus colonies and eventually chemically matched their new hosts, probably by passive camouflage. These data suggest that Thorictus of castaneus group myrmecophily is the result of coevolution with Cataglyphis hosts and that the mimicry is plastic, such that beetles can live with different hosts if the hosts show very limited CHC differences.

  • Mating system and population structure in the desert ant Cataglyphis livida
    Insectes Sociaux, 2009
    Co-Authors: Iris Timmermans, Abraham Hefetz, Laurent Grumiau, Serge Aron
    Abstract:

    We investigated population genetic structure, mating system, worker reproduction and thelytokous parthenogenesis in the desert ant Cataglyphis livida. Pedigree analyses at polymorphic microsatellite loci show that colonies are headed by a single queen, and that queens are mated with two to eight males. No inbreeding was found in the population sampled. Colonies are genetically differentiated and exhibit no isolation-by-distance pattern, consistent with independent foundation of new colonies. Workers do reproduce and lay haploid (arrhenotokous) eggs in queenless colonies; conversely, we found no evidence of worker reproduction in queenright nests. In contrast with C. cursor, where new queens are produced by thelytokous parthenogenesis, female sexuals and workers of C. livida arise from classical sexual reproduction. We discuss the parallels and contrasts between the mating system and population structure in C. livida and the other Cataglyphis species studied so far.

Wolfgang Rössler - One of the best experts on this subject based on the ideXlab platform.

  • Magnetoreception in Hymenoptera: importance for navigation
    Animal Cognition, 2020
    Co-Authors: Pauline N Fleischmann, Robin Grob, Wolfgang Rössler
    Abstract:

    The use of information provided by the geomagnetic field (GMF) for navigation is widespread across the animal kingdom. At the same time, the magnetic sense is one of the least understood senses. Here, we review evidence for magnetoreception in Hymenoptera. We focus on experiments aiming to shed light on the role of the GMF for navigation. Both honeybees and desert ants are well-studied experimental models for navigation, and both use the GMF for specific navigational tasks under certain conditions. Cataglyphis desert ants use the GMF as a compass cue for path integration during their initial learning walks to align their gaze directions towards the nest entrance. This represents the first example for the use of the GMF in an insect species for a genuine navigational task under natural conditions and with all other navigational cues available. We argue that the recently described magnetic compass in Cataglyphis opens up a new integrative approach to understand the mechanisms underlying magnetoreception in Hymenoptera on different biological levels.

  • The brain of Cataglyphis ants: Neuronal organization and visual projections
    The Journal of comparative neurology, 2020
    Co-Authors: Jens Habenstein, Emad Amini, Kornelia Grübel, Basil El Jundi, Wolfgang Rössler
    Abstract:

    Cataglyphis ants are known for their outstanding navigational abilities. They return to their inconspicuous nest after far-reaching foraging trips using path integration, and whenever available, learn and memorize visual features of panoramic sceneries. To achieve this, the ants combine directional visual information from celestial cues and panoramic scenes with distance information from an intrinsic odometer. The largely vision-based navigation in Cataglyphis requires sophisticated neuronal networks to process the broad repertoire of visual stimuli. Although Cataglyphis ants have been subjected to many neuroethological studies, little is known about the general neuronal organization of their central brain and the visual pathways beyond major circuits. Here, we provide a comprehensive, three-dimensional neuronal map of synapse-rich neuropils in the brain of Cataglyphis nodus including major connecting fiber systems. In addition, we examined neuronal tracts underlying the processing of visual information in more detail. This study revealed a total of 33 brain neuropils and 30 neuronal fiber tracts including six distinct tracts between the optic lobes and the cerebrum. We also discuss the importance of comparative studies on insect brain architecture for a profound understanding of neuronal networks and their function.

  • The brain of Cataglyphis ants: neuronal organization and visual projections
    2020
    Co-Authors: Jens Habenstein, Emad Amini, Kornelia Grübel, Basil El Jundi, Wolfgang Rössler
    Abstract:

    Cataglyphis ants are known for their outstanding navigational abilities. They return to their inconspicuous nest after far-reaching foraging trips using path integration, and whenever available, learn and memorize visual features of panoramic sceneries. To achieve this, the ants combine directional visual information from celestial cues and panoramic scenes with distance information from an intrinsic odometer. The largely vision-based navigation in Cataglyphis requires sophisticated neuronal networks to process the broad repertoire of visual stimuli. Although Cataglyphis ants have been subject to many neuroethological studies, little is known about the general neuronal organization of their central brain and the visual pathways beyond major circuits. Here, we provide a comprehensive, three-dimensional neuronal map of synapse-rich neuropils in the brain of Cataglyphis nodus including major connecting fiber systems. In addition, we examined neuronal tracts underlying the processing of visual information in more detail. This study revealed a total of 33 brain neuropils and 30 neuronal fiber tracts including six distinct tracts between the optic lobes and the cerebrum. We also discuss the importance of comparative studies on insect brain architecture for a profound understanding of neuronal networks and their function.

  • Species-specific differences in the fine structure of learning walk elements in Cataglyphis ants.
    The Journal of experimental biology, 2017
    Co-Authors: Pauline N Fleischmann, Rüdiger Wehner, Robin Grob, Wolfgang Rössler
    Abstract:

    Cataglyphis desert ants are famous navigators. Like all central place foragers, they are confronted with the challenge to return home, i.e. relocate an inconspicuous nest entrance in the ground, after their extensive foraging trips. When leaving the underground nest for the first time, desert ants perform a striking behavior, so-called learning walks that are well structured. However, it is still unclear how the ants initially acquire the information needed for sky- and landmark-based navigation, in particular how they calibrate their compass system at the beginning of their foraging careers. Using high-speed video analyses, we show that different Cataglyphis species include different types of characteristic turns in their learning walks. Pirouettes are full or partial rotations (tight turns about the vertical body axis) during which the ants frequently stop and gaze back in the direction of the nest entrance during the longest stopping phases. In contrast, voltes are small walked circles without directed stopping phases. Interestingly, only Cataglyphis ant species living in a cluttered, and therefore visually rich, environment (i.e. C. noda and C. aenescens in southern Greece) perform both voltes and pirouettes. They look back to the nest entrance during pirouettes, most probably to take snapshots of the surroundings. In contrast, C. fortis inhabiting featureless saltpans in Tunisia perform only voltes and do not stop during these turns to gaze back at the nest - even if a set of artificial landmarks surrounds the nest entrance.

  • Experience-related reorganization of giant synapses in the lateral complex: Potential role in plasticity of the sky-compass pathway in the desert ant Cataglyphis fortis.
    Developmental neurobiology, 2015
    Co-Authors: Franziska Schmitt, Rüdiger Wehner, Sara M. Stieb, Wolfgang Rössler
    Abstract:

    Cataglyphis desert ants undergo an age-related polyethism from interior workers to relatively short-lived foragers with remarkable visual navigation capabilities, predominantly achieved by path integration using a polarized skylight-based sun compass and a stride-integrating odometer. Behavioral and physiological experiments revealed that the polarization (POL) pattern is processed via specialized UV-photoreceptors in the dorsal rim area of the compound eye and POL sensitive optic lobe neurons. Further information about the neuronal substrate for processing of POL information in the ant brain has remained elusive. This work focuses on the lateral complex (LX), known as an important relay station in the insect sky-compass pathway. Neuroanatomical results in Cataglyphis fortis show that LX giant synapses (GS) connect large presynaptic terminals from anterior optic tubercle neurons with postsynaptic GABAergic profiles of tangential neurons innervating the ellipsoid body of the central complex. At the ultrastructural level, the cup-shaped presynaptic structures comprise many active zones contacting numerous small postsynaptic profiles. Three-dimensional quantification demonstrated a significantly higher number of GS (∼13%) in foragers compared with interior workers. Light exposure, as opposed to age, was necessary and sufficient to trigger a similar increase in GS numbers. Furthermore, the increase in GS numbers was sensitive to the exclusion of UV light. As previous experiments have demonstrated the importance of the UV spectrum for sky-compass navigation in Cataglyphis, we conclude that plasticity in LX GS may reflect processes involved in the initial calibration of sky-compass neuronal circuits during orientation walks preceding active foraging. © 2015 Wiley Periodicals, Inc. Develop Neurobiol, 2015