Subterranean termite phylogeography reveals multiple postglacial colonization events in southwestern Europe

Phylogenetic relationship of subterranean termite Coptotermes gestroi (Blattodea: Rhinotermitidae) inhabiting urban and natural habitats

Coptotermes termites were collected from forestry habitats at University Sains Malaysia, Penang, while urban samples were collected from residentials from Penang and Kedah, Malaysia. Mitochondrial DNA markers, Cytochrome Oxidase 1 (CO1), and 16S ribosomal RNA (16S rRNA) genes were amplified and sequenced to confirm the species of the termite samples as Coptotermes gestroi. Through Blastn, all 25 CO1 and 16S rRNA sequences, respectively from urban and natural habitats were found to be 99.54-100.00 % similar to C. gestroi reference sequences from previous studies in Peninsular Malaysia. The phylogenetic trees constructed using Neighboring-joining (NJ) and Maximum Likelihood (ML) methods resulted in CO1 sequences clustering in two clades and 16S rRNA sequences clustering in a single clade. The overall mean distance was low for the C. gestroi populations from natural habitats and urban settings (FST = 0.004). Analysis of natural habitat populations using CO1 sequences revealed two haplotypes within the population, with a haplotype diversity (Hd) of 0.045 ± 0.005, while the urban population shared a common haplotype with the natural habitat populations and there was no haplotype diversity recorded between the populations. Urban and natural habitats included only one haplotype for 16S rRNA sequences, indicating a lack of nucleotide diversity. Based on the findings, a non-significant difference between the natural habitat and urban population suggests C. gestroi inhabiting both regions likely originated from a similar source and underwent population homogeneity in different settings facilitated by anthropogenic dispersal.

Global termite methane emissions have been affected by climate and land-use changes

Termites with symbiotic methanogens are a known source of atmospheric methane (CH4), but large uncertainties remain regarding the flux magnitude. This study estimated global termite CH4 emissions using a framework similar to previous studies but with contemporary datasets and a biogeochemical model. The global termite emission in 2020 was estimated as 14.8 ± 6.7 Tg CH4 year-1, mainly from tropical and subtropical ecosystems, indicating a major natural source from upland regions. Uncertainties associated with estimation methods were assessed. The emission during the historical period 1901-2021 was estimated to have increased gradually (+ 0.7 Tg CH4 year-1) as a result of combined influences of elevated CO2 (via vegetation productivity), climatic warming, and land-use change. Future projections using climate and land-use scenarios (shared socioeconomic pathways [ssp] 126 and 585) also showed increasing trends (+ 0.5 to 5.9 Tg CH4 year-1 by 2100). These results suggest the importance of termite emissions in the global CH4 budget and, thus, in climatic prediction and mitigation.

Proof-of-Principle That Cellular Automata Can Be Used to Predict Infestation Risk by Reticulitermes grassei (Blattodea: Isoptera)

Over the past few decades, species distribution modelling has been increasingly used to monitor invasive species. Studies herein propose to use Cellular Automata (CA), not only to model the distribution of a potentially invasive species but also to infer the potential of the method in risk prediction of Reticulitermes grassei infestation. The test area was mainland Portugal, for which an available presence-only dataset was used. This is a typical dataset type, resulting from either distribution studies or infestation reports. Subterranean termite urban distributions in Portugal from 1970 to 2001 were simulated, and the results were compared with known records from both 2001 (the publication date of the distribution models for R. grassei in Portugal) and 2020. The reported model was able to predict the widespread presence of R. grassei, showing its potential as a viable prediction tool for R. grassei infestation risk in wooden structures, providing the collection of appropriate variables. Such a robust simulation tool can prove to be highly valuable in the decision-making process concerning pest management.

Hybridization and invasiveness in social insects - The good, the bad and the hybrid

Hybridization may help drive biological invasions by reducing Allee effects, increasing genetic variation, and generating novel adaptive genotypes/phenotypes. Social insects (ants, bees, wasps, and termites) are among the world's worst invasive species. In this review, we study the relationship between hybridization and invasiveness in social insects. We examine three types of hybridization based on the reproductive characteristics of first-generation hybrids. We discuss several examples of the association between hybridization and invasiveness, which are predominantly found in bees and termites. However, hybridization also occurs in several non-invasive species, and highly invasive species are not consistently associated with hybridization events, indicating that hybridization is not a main driver of invasiveness in social insects. We discuss why hybridization is not more commonly seen in invasive social insects.

Shennongjia-Wushan Mountains-One cryptic glacial refugium introduced by the phylogeographical study of the Geometridae moth Ourapteryx szechuana Wehrli

The origin and evolution of biodiversity in the Shennongjia and Wushan Mountains, located in central China, are little known. In this study, we used Ourapteryx szechuana, which is widely distributed in China and northern Nepal, to explore whether these mountains acted as glacial refugia during climate oscillations of the Quaternary. In total, 192 samples of O. szechuana were collected throughout much of the distribution range. Phylogenetic analysis, molecular dating, demographic history reconstructions, and MAXENT were used to investigate the evolutionary history and differentiation mechanisms and predict the potential species distributions during four different periods. The phylogenetic tree and the star-like median-joining network strongly supported two reciprocally monophyletic and allopatric lineages. Lineage I was restricted to the Shennongjia and Wushan Mountains. The divergence time of O. szechuana from its sister species O. thibetaria was approximately 1.94 Ma. The differentiation processes of the two intraspecific lineages occurred at approximately 0.47 Ma. The demographic history reconstruction and the ecological niche model suggested that Lineage II experienced an expansion after the LGM (Last Glacial Maximum), whereas Lineage I did not experience any expansion. Our results suggested the Naynayxungla glaciation promoted the divergence of the two lineages by restricting them to different refugia. The valleys of the Shennongjia-Wushan Mountains may have kept stable and warm (thus ice-free) environments during Quaternary glaciations, allowing this region to act as a glacial refugia. Our studies show that the Shennongjia and Wushan Mountains are likely to be important but little studied glacial refugia for the insect and thus worthy of more attention.

Molecular systematics, biogeography, and colony fusion in the European dry-wood termites Kalotermes spp. (Blattodea, Termitoidae, Kalotermitidae)

European dry-wood termites belong to the genus Kalotermes (Kalotermitidae), one of the two termite genera in Europe. Until the recent description of two new species, Kalotermes italicus in Italy and Kalotermes phoenicae in the eastern Mediterranean area, Kalotermes flavicollis was the only taxon known in this region. The presence of additional entities, suggested by morphological and physiological variation observed in K. flavicollis, was supported by molecular studies revealing four distinct genetic lineages: lineage A, K. flavicollis sensu strictu, from the Aegean area to Italy; lineage B, in Tuscany; lineage SC, in Sardinia and Corsica; lineage SF, in southern France. Lineages A and B may form mixed colonies, suggesting hybridization. To draw a more detailed picture of Kalotermes evolution and biogeography in Europe, we analyzed samples from previously unsampled areas, such as Spain and southern Italy, by means of the highly informative cox1/trnL/cox2 mitochondrial DNA marker. Overall, phylogenetic analyses confirmed previously identified lineages and taxa, but widened the distribution of the lineage SC to the mainland and of the lineage SF to Spain and Portugal. Results further provided evidence for the synonymy between lineage B and K. italicus. Species delimitation analysis suggested that the three K. flavicollis lineages, as well as K. italicus, can be separate taxa. Data also suggest a possible interspecific hybridization between K. italicus and both K. flavicollis lineages A and SC.

Phylogeography of Nasutitermes corniger (Isoptera: Termitidae) in the Neotropical Region

BACKGROUND

The Neotropical Region is known for its biodiversity and ranks third in number of known termite species. However, biogeographic and phylogeographic information of termites of this region is limited compared to other world geographic regions. Nasutitermes corniger is widely distributed in the region and is of considerable economic importance. The goal of this study was to describe the phylogeography of N. corniger in the Neotropical Region, to better understand its evolutionary processes.

RESULTS

The sampled populations of N. corniger showed high genetic variation. Results indicated strong geographic structure among N. corniger populations, with most haplotypes not broadly shared among separated locations. Phylogeographic analyses showed a dispersal route for N. corniger from Central America into South America via the Isthmus of Panama, with subsequent dispersal through the highlands east of the Andes and into eastern regions of the continent. The majority of haplotypes were limited in distribution to proximal regions, corresponding to particular biomes (Atlantic Forest, Amazonia, Chaco, Cerrado and Caatinga).

CONCLUSIONS

Nasutitermes corniger is suggested to be a good model for biogeographic and phylogeographic studies in the Neotropical Region. This study clarified the phylogeographic history of N. corniger and can contribute to the understanding of biogeographic dispersion processes in the Neotropical Region.

Closing the gap: Avian lineage splits at a young, narrow seaway imply a protracted history of mixed population response

The evolutionary significance of spatial habitat gaps has been well recognized since Alfred Russel Wallace compared the faunas of Bali and Lombok. Gaps between islands influence population structuring of some species, and flightless birds are expected to show strong partitioning even where habitat gaps are narrow. We examined the population structure of the most numerous living flightless land bird in New Zealand, Weka (Gallirallus australis). We surveyed Weka and their feather lice in native and introduced populations using genetic data gathered from DNA sequences of mitochondrial genes and nuclear β-fibrinogen and five microsatellite loci. We found low genetic diversity among extant Weka population samples. Two genetic clusters were evident in the mtDNA from Weka and their lice, but partitioning at nuclear loci was less abrupt. Many formerly recognized subspecies/species were not supported; instead, we infer one subspecies for each of the two main New Zealand islands. Although currently range restricted, North Island Weka have higher mtDNA diversity than the more wide-ranging southern Weka. Mismatch and neutrality statistics indicate North Island Weka experienced rapid and recent population reduction, while South Island Weka display the signature of recent expansion. Similar haplotype data from a widespread flying relative of Weka and other New Zealand birds revealed instances of North Island-South Island partitioning associated with a narrow habitat gap (Cook Strait). However, contrasting patterns indicate priority effects and other ecological factors have a strong influence on spatial exchange at this scale.