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Brigitte Fiala - One of the best experts on this subject based on the ideXlab platform.

  • taxonomy of coccids hemiptera coccidae coccus l associated with crematogaster ants hymenoptera formicidae in the stems of Macaranga plants euphorbiaceae in southeast asia
    Zootaxa, 2018
    Co-Authors: Penny J Gullan, Takumasa Kondo, Brigitte Fiala, Sweepeck Quek
    Abstract:

    The Southeast Asian soft scale insects (Hemiptera: Coccomorpha: Coccidae) associated with ants of the Crematogaster borneensis -group (Hymenoptera: Formicidae) and living in the hollow stems of Macaranga plants (Euphorbiaceae) are revised taxonomically. Ten species of the genus Coccus L. are recognised: seven were described previously and three new species are described herein. The species are: Coccus caviramicolus Morrison, C. circularis Morrison, C. heckrothi Gullan & Kondo sp. n., C. lambirensis Gullan & Kondo sp. n., C. macarangicolus Takahashi, C. Macarangae Morrison, C. penangensis Morrison, C. pseudotumuliferus Gullan & Kondo sp. n., C. secretus Morrison and C. tumuliferus Morrison. All of these species are described or redescribed and newly illustrated based on the adult females, and a key to distinguish the species is provided. We designate a lectotype for C. macarangicolus . The first-instar nymphs of all species are morphologically extremely similar and therefore only the first-instar nymph of C. Macarangae is described and illustrated. Seven of these species currently are known only from Macaranga , but C. Macarangae, C. secretus and perhaps C. pseudotumuliferus have been recorded from the hollow stems of several other ant-plants and a few non-myrmecophytes. The Coccus species from Macaranga are closely related to C. hesperidum L., the type species of the genus, and therefore are retained in the genus Coccus even though the adult females exhibit a few morphological differences from C. hesperidum . The species of Coccus from Macaranga appear to be parthenogenetic because no male nymphs or adults have been found, despite extensive collecting.

  • Taxonomic Revision of the Obligate Plant-Ants of the Genus Crematogaster Lund (Hymenoptera: Formicidae: Myrmicinae), Associated with Macaranga Thouars (Euphorbiaceae) on Borneo and the Malay Peninsula
    Sociobiology, 2016
    Co-Authors: Heike Feldhaar, Ulrich Maschwitz, Brigitte Fiala
    Abstract:

    The taxonomy and natural history of ants of the genus Crematogaster Lund, 1831 ( Crematogaster borneensis -group of the former subgenus Decacrema ) obligately associated with myrmecophytic host-plants of the euphorb genus Macaranga are reviewed. Within this group of ants Crematogaster borneensis Andre, 1896 (with five subspecies and four varieties), Crematogaster captiosa Forel, 1910 as well as Crematogaster decamera Forel, 1910 have previously been described from SE Asia. Here we synonymise C. borneensis subsp. capax Forel, 1911 , C. borneensis subsp. hosei Forel, 1911 , C. borneensis subsp. sembilana Forel, 1911 , and C. borneensis var. Macarangae Viehmeyer, 1916 with C. borneensis Andre, 1896. Crematogaster borneensis var. harpyia Forel, 1911, C. borneensis var. insulsa Forel, 1911, C. borneensis subsp. symbia Forel, 1911, and C. borneensis subsp. novem Forel, 1911 are synonymised with C. captiosa Forel, 1910. In addition we describe five new species: C. claudiae sp. nov., C. hullettii sp. nov., C. linsenmairi sp. nov., C. maryatii sp. nov., and C. roslihashimi sp. nov.. Seven of these eight species are placed into two informal species subgroups based on queen morphology, life-history characters and a formerly published molecular phylogeny. Keys are provided for the identification of queens and workers, as well as natural history information on the eight ant species. The morphology of these Macaranga -associated Crematogaster (formerly Decacrema ) species is compared to the only other three species described for this former subgenus in SE Asia, i.e. C. angulosa Andre, 1896, C. biformis Andre, 1892 and C. cephalotes Smith, 1857.

  • Monophyletic clades of Macaranga-pollinating thrips show high specificity to taxonomic sections of host plants
    Biological Journal of the Linnean Society, 2015
    Co-Authors: Brigitte Fiala, Rosli Hashim, Konstans Wells, Julia Haubenreisser, Andreas Pittroff, Sinan Kaya‐zeeb, Arthur Y. C. Chung, Alexander Keller
    Abstract:

    Thrips (Thysanoptera) have been recorded as pollinators of various plant species, but they are mostly regarded to be of low ecological relevance. In Southeast Asia, thrips were recently discovered to pollinate flowers of several taxonomic sections of the pioneer tree genus Macaranga (Euphorbiaceae), which is particularly well known as an ant-plant, and for its importance in early forest succession. The lack of taxonomic treatment and of knowledge about systematic relationships among extant thrips, however, has prevented firm conclusions on the specificity of this plant–pollinator interaction. Here, results from sequencing of the mitochondrial cytochrome oxidase subunit support our previous morphospecies concept of Macaranga flower thrips, and confirm the genetic identity of five recently described species. They were remarkably all assigned to the genus Dolichothrips (Phlaeothripidae), which typically consists of phytophagous species. In addition, the molecular data revealed one cryptic species. A first phylogenetic tree of the Dolichothrips associated with Macaranga provides insights into their systematic position. In particular, we identify monophyly of all important Macaranga pollinator species, all species being largely specific to particular taxonomic host plant sections. Our results suggest a closely matched diversification of pollinating thrips with Macaranga trees. This adds a novel type of association to thrips pollinator–plant interactions, which have been so far documented as single-species interactions or generalist thrips species visiting multiple plant taxa.

  • Pollination systems in pioneer trees of the genus Macaranga (Euphorbiaceae) in Malaysian rainforests
    Biological Journal of the Linnean Society, 2011
    Co-Authors: Brigitte Fiala, Rosli Hashim, Ute Meyer, Ulrich Maschwitz
    Abstract:

    Many species of Macaranga (Euphorbiacae) are fast-growing pioneer trees with an important role in early succession in south-east Asian rainforests. Within the genus, diverse types of ant–plant associations exist and it has therefore been a model system for studying mutualistic interactions. Little information existed up to now, however, on its reproductive biology. Our comparative study in the genus Macaranga in Sundaland revealed specific flower characteristics and uncommon brood-site pollination systems: enclosed inflorescence morphologies with narrow entrances strongly restrict the set of flower visitors in many species. Thysanoptera were the most abundant insects in 20 of the 26 investigated Macaranga species and, in three species, heteropteran adults and larvae were dominant. Both insect groups used the flower chambers as breeding sites and fed on nectar-producing trichomes inside the bracteoles. Thrips as well as heteropterans are assumed to contribute to pollination. Different Macaranga sections were associated with different flower visitors, suggesting isolation by different pollinators. Thrips pollination and myrmecophyty often occurred in the same sections. The development of enclosed flowers might have facilitated tight ant–plant interactions and prevent ant–pollinator conflicts. However, the complex ecosystems in which the mutualistic systems evolved are rapidly changed with unknown consequences for these specific interactions. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103, 935–953. ADDITIONAL KEYWORDS: brood-site – flower traits – flowering phenology – heteroptera – mutualism – myrmecophytes – south-east Asia – Sundaland – thrips – thysanoptera.

  • Comparative chloroplast DNA phylogeography of two tropical pioneer trees, Macaranga gigantea and Macaranga pearsonii (Euphorbiaceae)
    Tree Genetics & Genomes, 2011
    Co-Authors: Daniela Guicking, Brigitte Fiala, Maryati Mohamed, Frank R. Blattner, Ferry Slik, Kurt Weising
    Abstract:

    Macaranga (Euphorbiaceae) has received much ecological and evolutionary research attention as a genus that includes some of the most conspicuous pioneer trees of Southeast Asian tropical rainforests and because of its manifold associations with ants, including about 30 species that are obligate ant-plants (myrmecophytes). We used sequence data from three chloroplast DNA loci (ccmp5, ccmp6, atpB-rbcL) to assess phylogeographical patterns in species of Macaranga, section Pruinosae, sampled from various regions of Borneo and the Malay Peninsula. Forty-nine chloroplast DNA haplotypes (HT) were identified among 768 specimens from five species, Macaranga gigantea (N = 329; 23 HT), Macaranga pearsonii (N = 347; 21 HT), Macaranga puberula (N = 24; 4 HT), Macaranga hosei (N = 48; 6 HT), and Macaranga pruinosa (N = 20; 5 HT). Forty-one haplotypes were species-specific, whereas eight haplotypes were shared by two, three, or four species and occupied internal positions in a parsimony network. Population genetic parameters based on haplotype frequencies proved to be in a similar range in the non-myrmecophytic M. gigantea and in the ant-associated M. pearsonii, which have overlapping distributions in northern and eastern Borneo. A comparison of G (ST) and N (ST) values revealed a strong phylogeographic structure in both species, whereas colonization pathways suggested by the network topology were different. Both species exhibited similar levels of haplotypic diversity and moderate to high levels of population differentiation. There were no obvious indications for an influence of the symbiotic ant partners on the population structure of their host plants

Ulrich Maschwitz - One of the best experts on this subject based on the ideXlab platform.

  • integration of scale insects hemiptera coccidae in the south east asian ant plant crematogaster formicidae Macaranga euphorbiaceae system
    Entomologica, 2016
    Co-Authors: Hanspeter Heckroth, B Fiala, Ulrich Maschwitz
    Abstract:

    INTEGRATION OF SCALE INSECTS (HEMIPTERA: COCCIDAE) IN THE SOUTH-EAST ASIAN ANT-PLANT (CREMATOGASTER (FORMICIDAE)-Macaranga (EUPHORBIACEAE)) SYSTEM. The coccid colonisers of myrmecophytic Macaranga were tested for their trophic integration into the mutualistic Crematogaster-Macaranga ant-plant system. Honeydew secretion by these mostly endophytic scale insects was observed in Coccus caviramicolus Morrison, C. penangensis Morrison, C. secretus Morrison, C. tumuliferus Morrison, C. tumuliferus var. C.84 and in two other Macaranga coccid species. However, the use of coccids as protein-rich food by ants under normal and starvation conditions was not observed. Key words: trophobiosis, ant nutrition, Myzolecaniinae, survival, dumping areas, C. Macarangae, food-bodies, Pseudococcidae, Malaysia, Macaranga bancana, M. hypoleuca, M. hullettii, M. winkleri, M. triloba.

  • Taxonomic Revision of the Obligate Plant-Ants of the Genus Crematogaster Lund (Hymenoptera: Formicidae: Myrmicinae), Associated with Macaranga Thouars (Euphorbiaceae) on Borneo and the Malay Peninsula
    Sociobiology, 2016
    Co-Authors: Heike Feldhaar, Ulrich Maschwitz, Brigitte Fiala
    Abstract:

    The taxonomy and natural history of ants of the genus Crematogaster Lund, 1831 ( Crematogaster borneensis -group of the former subgenus Decacrema ) obligately associated with myrmecophytic host-plants of the euphorb genus Macaranga are reviewed. Within this group of ants Crematogaster borneensis Andre, 1896 (with five subspecies and four varieties), Crematogaster captiosa Forel, 1910 as well as Crematogaster decamera Forel, 1910 have previously been described from SE Asia. Here we synonymise C. borneensis subsp. capax Forel, 1911 , C. borneensis subsp. hosei Forel, 1911 , C. borneensis subsp. sembilana Forel, 1911 , and C. borneensis var. Macarangae Viehmeyer, 1916 with C. borneensis Andre, 1896. Crematogaster borneensis var. harpyia Forel, 1911, C. borneensis var. insulsa Forel, 1911, C. borneensis subsp. symbia Forel, 1911, and C. borneensis subsp. novem Forel, 1911 are synonymised with C. captiosa Forel, 1910. In addition we describe five new species: C. claudiae sp. nov., C. hullettii sp. nov., C. linsenmairi sp. nov., C. maryatii sp. nov., and C. roslihashimi sp. nov.. Seven of these eight species are placed into two informal species subgroups based on queen morphology, life-history characters and a formerly published molecular phylogeny. Keys are provided for the identification of queens and workers, as well as natural history information on the eight ant species. The morphology of these Macaranga -associated Crematogaster (formerly Decacrema ) species is compared to the only other three species described for this former subgenus in SE Asia, i.e. C. angulosa Andre, 1896, C. biformis Andre, 1892 and C. cephalotes Smith, 1857.

  • Pollination systems in pioneer trees of the genus Macaranga (Euphorbiaceae) in Malaysian rainforests
    Biological Journal of the Linnean Society, 2011
    Co-Authors: Brigitte Fiala, Rosli Hashim, Ute Meyer, Ulrich Maschwitz
    Abstract:

    Many species of Macaranga (Euphorbiacae) are fast-growing pioneer trees with an important role in early succession in south-east Asian rainforests. Within the genus, diverse types of ant–plant associations exist and it has therefore been a model system for studying mutualistic interactions. Little information existed up to now, however, on its reproductive biology. Our comparative study in the genus Macaranga in Sundaland revealed specific flower characteristics and uncommon brood-site pollination systems: enclosed inflorescence morphologies with narrow entrances strongly restrict the set of flower visitors in many species. Thysanoptera were the most abundant insects in 20 of the 26 investigated Macaranga species and, in three species, heteropteran adults and larvae were dominant. Both insect groups used the flower chambers as breeding sites and fed on nectar-producing trichomes inside the bracteoles. Thrips as well as heteropterans are assumed to contribute to pollination. Different Macaranga sections were associated with different flower visitors, suggesting isolation by different pollinators. Thrips pollination and myrmecophyty often occurred in the same sections. The development of enclosed flowers might have facilitated tight ant–plant interactions and prevent ant–pollinator conflicts. However, the complex ecosystems in which the mutualistic systems evolved are rapidly changed with unknown consequences for these specific interactions. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103, 935–953. ADDITIONAL KEYWORDS: brood-site – flower traits – flowering phenology – heteroptera – mutualism – myrmecophytes – south-east Asia – Sundaland – thrips – thysanoptera.

  • AN UNUSUAL MYRMECOPHYTIC Macaranga ASSOCIATION, OCCURRING IN A DISJUNCT AREA IN THE MONSOON ZONE OF SOUTH-EAST ASIA: PHENOLOGY AND THE DESCRIPTION OF A NEW ANT SPECIES
    2004
    Co-Authors: Ulrich Maschwitz, Brigitte Fiala, Klaus Dumpert
    Abstract:

    The phytogeographic boundary Pattani-Kangar on the Malay Peninsula near the Malay-Thai boundary, between the evergreen rainforest and the Thai semi-evergreen rainforest, is the northern distribution limit of most myrmecophytic Macaranga associations. Only three myrmecophytic Macaranga species were found to occur along the northern distribution boundary of perhumid conditions: M. bancana, M. hypoleuca and M. griffithiana. We found no uninhabited plants there, suggesting that the distribution ranges of myrmecophytic Macaranga species and their associated Decacrema ants are largely concordant. Macaranga griffithiana was additionally found much further north in a disjunct area in continental eastern Thailand near Cambodia. It is the only myrmecophytic Macaranga species known to occur in the seasonally dry monsoon zone, which is possible because of exceptionally high rainfall in the so-called Chantaburi pocket. Here it is associated with a Camponotus (Colobopsis) species (Formicinae) instead of the typical southern Crematogaster (Decacrema) (Myrmicinae) partner ants. Also the endophytic trophobiotic scale insect partner differs from the species found in the southern populations. A new ant is described in this paper as Camponotus markli, belonging to the Colobopsis vitreus species group. This species, which is different from other known Camponotus plant-ant partners of Macaranga, is a specific partner of its plant, colonizing polydomously several trees and probably defending them against herbivores and climbers. The evolutionary implications of the disjunct distribution of Macaranga griffithiana and its partners are discussed. They are hypothesized to be relicts of larger former distribution ranges and of differing ancestor associations in former times. Accepted 28 April 2004.

  • Molecular phylogeny of Crematogaster subgenus Decacrema ants (Hymenoptera: Formicidae) and the colonization of Macaranga (Euphorbiaceae) trees.
    Molecular phylogenetics and evolution, 2003
    Co-Authors: Heike Feldhaar, Brigitte Fiala, Jurgen Gadau, Maryati Mohamed, Ulrich Maschwitz
    Abstract:

    To elucidate the evolution of one of the most species-rich ant-plant symbiotic systems, the association between Crematogaster (Myrmicinae) and Macaranga (Euphorbiaceae) in South-East Asia, we conducted a phylogenetic analysis of the ant partners. For the phylogenetic analysis partial mitochondrial cytochrome oxidase I and II were sequenced and Maximum Parsimony analysis was performed. The analyzed Crematogaster of the subgenus Decacrema fell into three distinct clades which are also characterized by specific morphological and ecological traits (queen morphology, host-plants, and colony structure). Our results supported the validity of our currently used morphospecies concept for Peninsula Malaysia. However, on a wider geographic range (including North and North-East Borneo) some morphospecies turned out to be species complexes with genetically quite distinct taxa. Our phylogenetic analysis and host association studies do not indicate strict cocladogenesis between the subgenus Decacrema and their Macaranga host-plants because multiple ant taxa occur on quite distinct host-plants belonging to different clades within in the genus Macaranga. These results support the view that host-shifting or host-expansion is common in the ants colonizing Macaranga. Additionally, the considerable geographic substructuring found in the phylogenetic trees of the ants suggests that allopatric speciation has also played a role in the diversification and the current distribution of the Decacrema ants.

Bert Hölldobler - One of the best experts on this subject based on the ideXlab platform.

  • Pruning of host plant neighbours as defence against enemy ant invasions: Crematogaster ant partners of Macaranga protected by "wax barriers" prune less than their congeners
    Oecologia, 2002
    Co-Authors: Walter Federle, Ulrich Maschwitz, Bert Hölldobler
    Abstract:

    Many ant partners of tropical ant-plants prune the leaves and shoot tips of other plants growing around their hosts. According to the hypothesis proposed by Davidson et al. (Ecology 69:801–808), this specialized behaviour not only protects the host plants against overgrowth, but it also conveys a direct benefit to the ant colony as it removes contact points to the neighbouring vegetation where invasions of enemy ants could occur. Here we test this hypothesis by comparing pruning intensity in five closely related Crematogaster (subgenus Decacrema) plant-ant species (and one species of Technomyrmex) that differ in their exposure to competition by other ants. Pruning intensity was quantified by measuring the area loss of paper tape pieces wrapped around the stems of Macaranga host plants. All Crematogaster (Decacrema) ants tested but not Technomyrmex sp. pruned, but the intensity of the behaviour varied strongly between and within species. Pruning was significantly weaker in the three tested Crematogaster species inhabiting Macaranga host plants with a slippery, waxy stem surface, which functions as a mechanical barrier protecting the specific ant partners against generalist competitors. Pruning was generally stronger on more densely ant-populated trees. Even though the number of ants per twig length was lower in associations of ants with glaucous Macaranga hosts, only part of the variation of pruning activity could be explained by "ant density". When corrected for ant density, "wax-running" Crematogaster (Decacrema) ants still pruned more weakly than their congeners inhabiting non-glaucous Macaranga hosts. Pruning is obviously most important when an ant-plant is potentially accessible to intruders, but less necessary when the ant colony is isolated by a protective wax barrier. Our results support the hypothesis that "selfish" defence against invasions is the major selective pressure that has led to the development and maintenance of pruning behaviour in weakly competitive plant-ants.

  • chemical composition of the slippery epicuticular wax blooms on Macaranga euphorbiaceae ant plants
    Chemoecology, 2000
    Co-Authors: Claus Markstadter, Walter Federle, Markus Riederer, Reinhard Jetter, Bert Hölldobler
    Abstract:

    The stems of many Macaranga ant-plants (Euphorbiaceae) are covered by epicuticular wax crystals rendering the surface very slippery for most insects. These wax blooms act as selective barriers protecting the symbiotic ant partners, which are specialized “wax-runners”, against the competition of other ants. Glaucous stems occur almost exclusively among the ant-plants of the genus Macaranga (). We analyzed the cuticular lipids of 16 Macaranga species by GC-MS and investigated the wax crystal morphology using SEM. Presence of crystalline wax blooms was strongly correlated with high concentrations (52%–88%) of triterpenoids. In contrast epicuticular waxes of glossy Macaranga surfaces contained only 0% to 36% of these dominant components. Therefore we conclude that triterpenoids are responsible for the formation of the thread-like Macaranga wax crystals. In all Macaranga ant-plants investigated, the principal components were epitaraxerol and taraxerone accompanied by smaller portions of taraxerol, β-amyrin and friedelin. Only in the case of the non-myrmecophytic M. tanarius did β-amyrin predominate. Moreover, we found that only in M. tanarius, the dense wax crystal lacework is torn into large mosaic-like pieces in the course of secondary stem diameter growth. Both chemical and macroscopic differences may contribute to a reduced slipperiness of M. tanarius stems and appear to be functionally important. The distribution of wax crystals and their composition amongst different sections of the genus suggests that glaucousness is a polyphyletic character within Macaranga.

  • slippery ant plants and skilful climbers selection and protection of specific ant partners by epicuticular wax blooms in Macaranga euphorbiaceae
    Oecologia, 1997
    Co-Authors: Walter Federle, Brigitte Fiala, Ulrich Maschwitz, Markus Riederer, Bert Hölldobler
    Abstract:

    In many ant-plant species of the genus Macaranga in South-East Asia, conspicuous blooms of epicuticular wax crystals cover the stem surface. We found that many ant species were unable to walk on these surfaces. Only the specific ant partners of glaucous Macaranga host plants were capable of moving on the slippery stems without difficulty. Therefore, the epicuticular coatings of Macaranga myrmecophytes appear to have a selective function and protect the associated ants against competitors. The epicuticular aggregates function as a physical barrier; no evidence of chemical repellence was found. The extent to which ”foreign” ant species are excluded from a tree strongly depends on inclination, diameter and length of the glaucous stem sections. The particular growth form of some glaucous Macaranga ant-plants enhances the influence of the wax barriers. The ant associates of glaucous and glossy Macaranga ant-plants (genera Crematogaster and Camponotus) differ strongly in their capacity to adhere to the glaucous stems. For this reason, the wax blooms in Macaranga can act as an ecological isolation mechanism for the sympiotic ants. Within the genus Macaranga, we find a high correspondence between the occurrence of glaucousness and obligatory ant association (50% in ant-plants; 6.7% in non-myrmecophytes). The genus Macaranga thus represents one of the few cases known so far where epicuticular wax crystals are likely to have evolved in relation to insects.

Walter Federle - One of the best experts on this subject based on the ideXlab platform.

  • Macaranga ant‐plants hide food from intruders: correlation of food presentation and presence of wax barriers analysed using phylogenetically independent contrasts
    Biological Journal of the Linnean Society, 2005
    Co-Authors: Walter Federle, Frank E. Rheindt
    Abstract:

    Many tropical ant-plants provide specialized ant partners with food, which may attract foreign ants parasitizing the mutualism. We present evidence for the ant-plant genus Macaranga, showing that ant competition has forced host plants to hide food resources and restrict access to the mutualists. In Macaranga myrmecophytes, the influence of ant competition strongly depends on the presence of slippery ‘wax barriers’. Of all Macaranga ant-plant species, 50% have waxy stems that can be climbed only by the specific ant partners and not by other ant species. We compared the presentation of food (food bodies and extrafloral nectar) between waxy and non-waxy Macaranga host plants using traditional and phylogenetic comparative methods. Consistent with the hypothesized effect of ant competition, wax-free Macaranga host species had fewer extrafloral nectaries and more often produced food bodies under recurved or tubular stipules inaccessible to other ants; closed stipules were less persistent in waxy hosts. Several traits showed phylogenetic signal, but our finding of a more promiscuous food presentation in waxy Macaranga hosts was still supported by phylogenetic comparative analyses. We conclude that competition among ants is an important factor in the evolution of myrmecophytism, and that it has given rise to traits acting as protective filter mechanisms. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 84, 177–193.

  • Pruning of host plant neighbours as defence against enemy ant invasions: Crematogaster ant partners of Macaranga protected by "wax barriers" prune less than their congeners
    Oecologia, 2002
    Co-Authors: Walter Federle, Ulrich Maschwitz, Bert Hölldobler
    Abstract:

    Many ant partners of tropical ant-plants prune the leaves and shoot tips of other plants growing around their hosts. According to the hypothesis proposed by Davidson et al. (Ecology 69:801–808), this specialized behaviour not only protects the host plants against overgrowth, but it also conveys a direct benefit to the ant colony as it removes contact points to the neighbouring vegetation where invasions of enemy ants could occur. Here we test this hypothesis by comparing pruning intensity in five closely related Crematogaster (subgenus Decacrema) plant-ant species (and one species of Technomyrmex) that differ in their exposure to competition by other ants. Pruning intensity was quantified by measuring the area loss of paper tape pieces wrapped around the stems of Macaranga host plants. All Crematogaster (Decacrema) ants tested but not Technomyrmex sp. pruned, but the intensity of the behaviour varied strongly between and within species. Pruning was significantly weaker in the three tested Crematogaster species inhabiting Macaranga host plants with a slippery, waxy stem surface, which functions as a mechanical barrier protecting the specific ant partners against generalist competitors. Pruning was generally stronger on more densely ant-populated trees. Even though the number of ants per twig length was lower in associations of ants with glaucous Macaranga hosts, only part of the variation of pruning activity could be explained by "ant density". When corrected for ant density, "wax-running" Crematogaster (Decacrema) ants still pruned more weakly than their congeners inhabiting non-glaucous Macaranga hosts. Pruning is obviously most important when an ant-plant is potentially accessible to intruders, but less necessary when the ant colony is isolated by a protective wax barrier. Our results support the hypothesis that "selfish" defence against invasions is the major selective pressure that has led to the development and maintenance of pruning behaviour in weakly competitive plant-ants.

  • incident daylight as orientation cue for hole boring ants prostomata in Macaranga ant plants
    Insectes Sociaux, 2001
    Co-Authors: Walter Federle, Brigitte Fiala, Georg Zizka, Ulrich Maschwitz
    Abstract:

    A key adaptation of obligate plant-ants inhabiting tropical myrmecophytes is the capacity to chew entrance holes into domatium walls. Our study of the factors determining ant entrance hole location in the ant-plant genus Macaranga (Euphorbiaceae) revealed a complex pattern caused by adaptations of both the host plants and their ant partners.¶1. Many adult Macaranga ant-plants possess "prostomata", i.e. preformed, thin zones of the stem, where ants preferably chew their entrance holes. The prostoma has the form of a straight line running the entire length of the internode. In all species except M. kingii it is located above the leaf insertion. Histological examination showed that the prostoma is characterized by the absence of vascular bundles and latex vessels and by a delayed cambium formation.¶2. Crematogaster ant workers recognize the position of the prostoma from inside the domatia by using incident daylight as an orientation cue. Experimental darkening of the translucent prostoma forced the ants to change over to other positions. We were able to make the ants chew holes at predicted, unnatural positions.¶3. When ants enter the domatia from outside, they are unable to find the prostoma. As a rule, holes in prostoma position were chewed from inside.¶4. Many Macaranga ant-plants lack a prostoma. The ant inhabitants of these species chew holes from outside the stem, exclusively on the twig undersides and at positions that are not related to phyllotaxy. However, colonies of these ants transplanted to "prostoma" hosts were nevertheless capable of chewing from inside the stem at "correct" prostoma positions.¶5. The stems of most prostoma-free Macaranga hosts are covered by slippery epicuticular wax crystals and their domatium walls are mostly thinner than in non-glaucous hosts. These correlations suggest that the prostoma acts as an ecological filter favoring specialists over generalists.

  • chemical composition of the slippery epicuticular wax blooms on Macaranga euphorbiaceae ant plants
    Chemoecology, 2000
    Co-Authors: Claus Markstadter, Walter Federle, Markus Riederer, Reinhard Jetter, Bert Hölldobler
    Abstract:

    The stems of many Macaranga ant-plants (Euphorbiaceae) are covered by epicuticular wax crystals rendering the surface very slippery for most insects. These wax blooms act as selective barriers protecting the symbiotic ant partners, which are specialized “wax-runners”, against the competition of other ants. Glaucous stems occur almost exclusively among the ant-plants of the genus Macaranga (). We analyzed the cuticular lipids of 16 Macaranga species by GC-MS and investigated the wax crystal morphology using SEM. Presence of crystalline wax blooms was strongly correlated with high concentrations (52%–88%) of triterpenoids. In contrast epicuticular waxes of glossy Macaranga surfaces contained only 0% to 36% of these dominant components. Therefore we conclude that triterpenoids are responsible for the formation of the thread-like Macaranga wax crystals. In all Macaranga ant-plants investigated, the principal components were epitaraxerol and taraxerone accompanied by smaller portions of taraxerol, β-amyrin and friedelin. Only in the case of the non-myrmecophytic M. tanarius did β-amyrin predominate. Moreover, we found that only in M. tanarius, the dense wax crystal lacework is torn into large mosaic-like pieces in the course of secondary stem diameter growth. Both chemical and macroscopic differences may contribute to a reduced slipperiness of M. tanarius stems and appear to be functionally important. The distribution of wax crystals and their composition amongst different sections of the genus suggests that glaucousness is a polyphyletic character within Macaranga.

  • slippery ant plants and skilful climbers selection and protection of specific ant partners by epicuticular wax blooms in Macaranga euphorbiaceae
    Oecologia, 1997
    Co-Authors: Walter Federle, Brigitte Fiala, Ulrich Maschwitz, Markus Riederer, Bert Hölldobler
    Abstract:

    In many ant-plant species of the genus Macaranga in South-East Asia, conspicuous blooms of epicuticular wax crystals cover the stem surface. We found that many ant species were unable to walk on these surfaces. Only the specific ant partners of glaucous Macaranga host plants were capable of moving on the slippery stems without difficulty. Therefore, the epicuticular coatings of Macaranga myrmecophytes appear to have a selective function and protect the associated ants against competitors. The epicuticular aggregates function as a physical barrier; no evidence of chemical repellence was found. The extent to which ”foreign” ant species are excluded from a tree strongly depends on inclination, diameter and length of the glaucous stem sections. The particular growth form of some glaucous Macaranga ant-plants enhances the influence of the wax barriers. The ant associates of glaucous and glossy Macaranga ant-plants (genera Crematogaster and Camponotus) differ strongly in their capacity to adhere to the glaucous stems. For this reason, the wax blooms in Macaranga can act as an ecological isolation mechanism for the sympiotic ants. Within the genus Macaranga, we find a high correspondence between the occurrence of glaucousness and obligatory ant association (50% in ant-plants; 6.7% in non-myrmecophytes). The genus Macaranga thus represents one of the few cases known so far where epicuticular wax crystals are likely to have evolved in relation to insects.

Kurt Weising - One of the best experts on this subject based on the ideXlab platform.

  • Comparative chloroplast DNA phylogeography of two tropical pioneer trees, Macaranga gigantea and Macaranga pearsonii (Euphorbiaceae)
    Tree Genetics & Genomes, 2011
    Co-Authors: Daniela Guicking, Brigitte Fiala, Maryati Mohamed, Frank R. Blattner, Ferry Slik, Kurt Weising
    Abstract:

    Macaranga (Euphorbiaceae) has received much ecological and evolutionary research attention as a genus that includes some of the most conspicuous pioneer trees of Southeast Asian tropical rainforests and because of its manifold associations with ants, including about 30 species that are obligate ant-plants (myrmecophytes). We used sequence data from three chloroplast DNA loci (ccmp5, ccmp6, atpB-rbcL) to assess phylogeographical patterns in species of Macaranga, section Pruinosae, sampled from various regions of Borneo and the Malay Peninsula. Forty-nine chloroplast DNA haplotypes (HT) were identified among 768 specimens from five species, Macaranga gigantea (N = 329; 23 HT), Macaranga pearsonii (N = 347; 21 HT), Macaranga puberula (N = 24; 4 HT), Macaranga hosei (N = 48; 6 HT), and Macaranga pruinosa (N = 20; 5 HT). Forty-one haplotypes were species-specific, whereas eight haplotypes were shared by two, three, or four species and occupied internal positions in a parsimony network. Population genetic parameters based on haplotype frequencies proved to be in a similar range in the non-myrmecophytic M. gigantea and in the ant-associated M. pearsonii, which have overlapping distributions in northern and eastern Borneo. A comparison of G (ST) and N (ST) values revealed a strong phylogeographic structure in both species, whereas colonization pathways suggested by the network topology were different. Both species exhibited similar levels of haplotypic diversity and moderate to high levels of population differentiation. There were no obvious indications for an influence of the symbiotic ant partners on the population structure of their host plants

  • Mechanisms of Speciation in Southeast Asian Ant-Plants of the Genus Macaranga (Euphorbiaceae)
    Evolution in Action, 2010
    Co-Authors: Kurt Weising, Daniela Guicking, Christina Fey-wagner, Tim Kröger-kilian, Tina Wöhrmann, Wiebke Dorstewitz, Gudrun Bänfer, Ute Moog, Miriam Vogel, Christina Baier
    Abstract:

    The palaeotropic genus Macaranga (Euphorbiaceae) is an excellent model system to analyze co-evolutionary processes associated with myrmecophytism, a mutualistic interaction between plants and ants. Ant-plants like Macaranga provide nesting space and feed their partners, whereas the ants protect the plants from herbivores and competitors such as lianas. We used genome-based evidence to investigate speciation mechanisms in Macaranga ant-plants, and their co-evolution with ants from the genus Crematogaster. Our previous work had shown that myrmecophytic Macaranga species show little genetic differentiation, suggesting an adaptive radiation. We hypothesized that the obligatory symbiosis with ants may reduce gene flow among plant populations, eventually enhancing allopatric speciation. To test this hypothesis, we verified the monophyly of the investigated plant lineages by phylogenetic analyses, reconstructed parsimony networks based on chloroplast DNA (cpDNA) variation, and assessed population genetic parameters using nuclear microsatellites and cpDNA haplotypes. Our data provided evidence for vicariant events as well as for hybridization and cpDNA introgression among closely related Macaranga species. The extent of population differentiation within myrmecophytic versus non-myrmecophytic species proved to be in a similar range, indicating that our working hypothesis of enhanced allopatric speciation in myrmecophytes cannot be sustained by the present evidence. Nevertheless, the mutualistic interactions of Macaranga and associated ants may be a key innovation that opened an adaptive zone putatively exploited by the divergence of Macaranga.

  • Isolation and characterization of 11 new microsatellite markers for Macaranga (Euphorbiaceae)
    Molecular ecology resources, 2009
    Co-Authors: Christina Baier, Kurt Weising, Daniela Guicking, Christina Fey-wagner, Tina Wöhrmann, Kathleen Prinz, Thomas Debener, Stephan Schie, Frank R. Blattner
    Abstract:

    We provide primer sequences for 11 new polymorphic microsatellite markers developed in the tropical ant-plant genus Macaranga (Euphorbiaceae), after enrichment cloning of Macaranga tanarius and Macaranga hypoleuca. Allele numbers per locus ranged from two to 16 among 20 accessions of M. tanarius, and from three to 10 among 22 accessions of M. hypoleuca. Observed and expected heterozygosities ranged from 0.150 to 0.900 and from 0.375 to 0.894 in M. tanarius, and from 0.545 to 1.000 and from 0.434 to 0.870 in M. hypoleuca, respectively. Six of the 11 primer pairs successfully cross-amplified polymorphic polymerase chain reaction products in Macaranga winkleri.

  • a chloroplast genealogy of myrmecophytic Macaranga species euphorbiaceae in southeast asia reveals hybridization vicariance and long distance dispersals
    Molecular Ecology, 2006
    Co-Authors: Gudrun Bänfer, Brigitte Fiala, Kurt Weising, Ute Moog, Maryati Mohamed, Frank R. Blattner
    Abstract:

    Macaranga (Euphorbiaceae) includes about 280 species with a palaeotropic distribution. The genus not only comprises some of the most prominent pioneer tree species in Southeast Asian lowland dipterocarp forests, it also exhibits a substantial radiation of ant-plants (myrmecophytes). Obligate ant-plant mutualisms are formed by about 30 Macaranga species and 13 ant species of the genera Crematogaster or Camponotus. To improve our understanding of the co-evolution of the ants and their host plants, we aim at reconstructing comparative organellar phylogeographies of both partners across their distributional range. Preliminary evidence indicated that chloroplast DNA introgression among closely related Macaranga species might occur. We therefore constructed a comprehensive chloroplast genealogy based on DNA sequence data from the noncoding ccmp2, ccmp6, and atpB-rbcL regions for 144 individuals from 41 Macaranga species, covering all major evolutionary lineages within the three sections that contain myrmecophytes. A total of 88 chloroplast haplotypes were identified, and grouped into a statistical parsimony network that clearly distinguished sections and well-defined subsectional groups. Within these groups, the arrangement of haplotypes followed geographical rather than taxonomical criteria. Thus, up to six chloroplast haplotypes were found within single species, and up to seven species shared a single haplotype. The spatial distribution of the chloroplast types revealed several dispersals between the Malay Peninsula and Borneo, and a deep split between Sabah and the remainder of Borneo. Our large-scale chloroplast genealogy highlights the complex history of migration, hybridization, and speciation in the myrmecophytes of the genus Macaranga. It will serve as a guideline for adequate sampling and data interpretation in phylogeographic studies of individual Macaranga species and species groups.

  • a chloroplast genealogy of myrmecophytic Macaranga species euphorbiaceae in southeast asia reveals hybridization vicariance and long distance dispersals
    Molecular Ecology, 2006
    Co-Authors: Gudrun Bänfer, Brigitte Fiala, Kurt Weising, Ute Moog, Maryati Mohamed, Frank R. Blattner
    Abstract:

    Macaranga (Euphorbiaceae) includes about 280 species with a palaeotropic distribution. The genus not only comprises some of the most prominent pioneer tree species in Southeast Asian lowland dipterocarp forests, it also exhibits a substantial radiation of ant-plants (myrmecophytes). Obligate ant-plant mutualisms are formed by about 30 Macaranga species and 13 ant species of the genera Crematogaster or Camponotus. To improve our understanding of the co-evolution of the ants and their host plants, we aim at reconstructing comparative organellar phylogeographies of both partners across their distributional range. Preliminary evidence indicated that chloroplast DNA introgression among closely related Macaranga species might occur. We therefore constructed a comprehensive chloroplast genealogy based on DNA sequence data from the noncoding ccmp2, ccmp6, and atpB-rbcL regions for 144 individuals from 41 Macaranga species, covering all major evolutionary lineages within the three sections that contain myrmecophytes. A total of 88 chloroplast haplotypes were identified, and grouped into a statistical parsimony network that clearly distinguished sections and well-defined subsectional groups. Within these groups, the arrangement of haplotypes followed geographical rather than taxonomical criteria. Thus, up to six chloroplast haplotypes were found within single species, and up to seven species shared a single haplotype. The spatial distribution of the chloroplast types revealed several dispersals between the Malay Peninsula and Borneo, and a deep split between Sabah and the remainder of Borneo. Our large-scale chloroplast genealogy highlights the complex history of migration, hybridization, and speciation in the myrmecophytes of the genus Macaranga. It will serve as a guideline for adequate sampling and data interpretation in phylogeographic studies of individual Macaranga species and species groups.