mtDNA phylogeny of Japanese ant crickets (Orthoptera : Myrmecophilidae): Diversification in host specificity and habitat use

Ant crickets (Myrmecophilidae, Orthoptera) are typical ant guests. Although ten species (all belonging to genus Myrmecophilus) have recently been described from Japan, their phylogeny and the extent of host specificity are not known. Here, we reconstruct mtDNA phylogeny of 48 individuals from six species to examine their host specificity, habitat use, and congruence of mtDNA lineages with the morphological species. The cytb phylogeny reveals seven well-supported lineages that in part do not corroborate morphological taxonomy. M. kubotai was split into two distinct mtDNA lineages which differ in their host specificity: one (lineage F) mainly parasitizes Tetramorium tsushimae (Myrmicinae) and the other (lineage E) parasitizes several species of Formicine ants. Five out of the seven Myrmecophilus lineages did not have significant host-specificity, although lineages C and the above mentioned F both preferably parasitized T tsushimae. Preference for light environment was significant for three cricket lineages. Although ant crickets arc not diverse in their morphology, these results demonstrate that they have diversified in host specificity and habitat use.ArticleSOCIOBIOLOGY. 52(3):553-565 (2008)journal articl

How Do Scale Insects Settle into the Nests of Plant-Ants on Macaranga Myrmecophytes? Dispersal by Wind and Selection by Plant-Ants

This report elucidates the process of settlement by Coccus scale insects into Crematogaster plant-ant nests formed inside the hollow stems of a myrmecophytic species, Macaranga bancana, in a tropical rain forest. We collected wafting scale insect nymphs from the canopy using sticky traps and characterized the DNA sequence of the trapped nymphs. In addition, we experimentally introduced first-instar nymphs of both symbiotic and nonsymbiotic scale insects to M. bancana seedlings with newly formed plant-ant colonies. Nymphs of symbiotic species were generally carried by ants into their nests within a few minutes of introduction. Most nymphs of nonsymbiotic species were thrown to the ground by ants. Our results suggest that in Crematogaster-Macaranga myrmecophytism, symbiotic coccids disperse by wind onto host plant seedlings at the nymphal stage, and plant-ants actively carry the nymphs landing on seedlings into their nests in discrimination from nonsymbiotic scale insects.ArticleSOCIOBIOLOGY. 59(2):435-446 (2012)journal articl

Phylogeography of the Coccus scale insects inhabiting myrmecophytic Macaranga plants in Southeast Asia

Comparative historical biogeography of multiple symbionts occurring on a common host taxa can shed light on the processes of symbiont diversification. Myrmecophytic Macaranga plants are associated with the obligate mutualistic symbionts: Crematogaster (subgenus Decacrema) ants and Coccus scale insects. We conduct phylogeographic analyses based on mitochondrial cytochrome oxidase I (COI) from 253 scale insects collected from 15 locations in Borneo, Malaya and Sumatra, to investigate the historical biogeography of the scales, and then to draw comparisons with that of the symbiotic, but independently dispersing, Decacrema ants which are not specific to different Coccus lineages. Despite the different mode of ancient diversification, reconstruction of ancestral area and age estimation on the Coccus phylogeny showed that the scales repeatedly migrated between Borneo and Malaya from Pliocene to Pleistocene, which is consistent with the Decacrema ants. Just as with the ants, the highest number of lineages in the scale insects was found in northern northwest Borneo, suggesting that these regions were rainforest refugia during cool dry phases of the Pleistocene. Overall, general congruence between the Plio-Pleistocene diversification histories of the symbiotic scales and ants suggests that they experienced a common history of extinction/migration despite their independent mode of dispersal and host-colonization.ArticlePopulation ecology. 52(1):137-146 (2010)journal articl

Timing of butterfly parasitization of a plant-ant-scale symbiosis

In the Southeast Asian tropics, Arhopala lycaenid butterflies feed on Macaranga ant-plants inhabited by Crematogaster (subgenus Decacrema) ants tending Coccus-scale insects. A recent phylogenetic study showed that (1) the plants and ants have been codiversifying for the past 20-16 million years (Myr), and that (2) the tripartite symbiosis was formed 9-7 Myr ago, when the scale insects became involved in the plant-ant mutualism. To determine when the lycaenids first parasitized the Macaranga tripartite symbiosis, we constructed a molecular phylogeny of the lycaenids that feed on Macaranga by using mitochondrial and nuclear DNA sequence data and estimated their divergence times based on the cytochrome oxidase I molecular clock. The minimum age of the lycaenids was estimated by the time-calibrated phylogeny to be 2.05 Myr, about one-tenth the age of the plant-ant association, suggesting that the lycaenids are latecomers that associated themselves with the pre-existing symbiosis of plant, ant, and scale insects.ArticleECOLOGICAL RESEARCH. 27(2):437-443 (2012)journal articl

Phylogeny and Phylogeography of Myrmica rubra

We investigated the genetic diversification of the mountain ant, Myrmica kotokui, in the Japanese Alps by using molecular phylogenetic analyses. Myrmica kotokui is widely distributed in Japan, and in the central Japanese Alps it is found only between elevations of approximately 1000 to 2000 m. We hypothesized that genetically distinct clades of this ant species might inhabit different mountain ranges in central Japan. To test this hypothesis, we reconstructed a molecular phylogeny using the DNA sequences of the mitochondrial cytochrome oxidase I gene and the nuclear long-wavelength rhodopsin gene of M. kotokui specimens collected from six mountain ranges in the Japanese Alps. The phylogeny showed four highly differentiated clades. However, the correspondence between the clades and morphological species was a little confusing. Two clades were composed only of M. kotokui specimens, whereas the other two clades were composed of multispecies, suggesting the possibility of multispecies composition of putative M. kotokui. The distribution pattern of these clades did not support our hypothesis of geographical differentiation, because two were distributed across all ranges, and a third was distributed in five of the six ranges. On the other hand, we found a pattern in the altitudinal distribution of the clades: one clade was distributed only at higher elevations, and the others were distributed at lower elevations. Thus, the ant clades do not show geographical segregation by mountain range, but they do show altitudinal differences

<S2-2> Geographical variation of mutualistic relationships between Macaranga myrmecophytes and their ant partners: research plans in Sarawak

This proceeding is a compilation of findings and progress activities of research collaboration between the Forest Department Sarawak (FDS) and the Japan Research Consortium for Tropical Forests in Sarawak (JRCTS). To highlight the research findings, An International Symposium entitled "Frontier in Tropical Forest Research: Progress in Joint Projects between the Forest Department Sarawak and the Japan Research Consortium for Tropical Forests in Sarawak" was ii held in Kuching, Sarawak on 21-22 September 2015.Myrmecophytes have mutualistic associations with plant-inhabiting ants (so-called plant-ants). They provide plant-ants with nest space and sometimes foods, and in return, the plant-ants protect their host-plants against herbivores, pathogens and climbing plants. In the tree genus Macaranga (Euphorbiaceae), 26 species are myrmecophytic, among which 18 species are distributed in Sarawak. The relationships between Macaranga myrmecophytes and plant-ants are remarkable for their high species-specificity and strong interdependency. For 20 years, we have studied the myrmecophyte-plant-ant relationships and their effects on the herbivorous insect assemblage associated with Macaranga plants at Lambir Hills National Park (LHNP), where 17 Macaranga species, including 12 myrmecophytic species, are distributed. Here, we describe 1) some ecological characteristics of Macaranga myrmecophytes, 2) the main results of our studies on the character of the mutualisms and their ecological consequences, and 3) our new research plans in Sarawak to investigate the geographical variations in the mutualisms. In our future research, we will enhance collaboration with Sarawakian researchers