Phylogeography of an Australian termite, Amitermes laurensis (Isoptera, Termitidae), with special reference to the variety of mound shapes

Evolutionary history of Nasutitermes kemneri (Termitidae, Nasutitermitinae), a termite from the South American diagonal of open formations

Little is known about the phylogeography of termites in the Neotropical region. Here, we explored the genetic patterns and phylogeographical processes in the evolutionary history of Nasutitermes kemneri, an endemic termite of the South American diagonal of open formations (DOF) formed by the Chaco, Cerrado, and Caatinga phytogeographic domains. We sampled 60 individuals across the three domains of the DOF, and using the mitochondrial genes 16S, COI, and COII, as well as the nuclear gene ITS, evaluated the genetic diversity and divergence time of the populations, along with their genetic structure. The results show a strong genetic and spatial structure within the samples, evidencing the existence of two well-differentiated genetic groups: the Northeastern and the Southwestern populations, which diverged about 2.5 Mya, during the Pliocene-Pleistocene boundary. The Northeastern population, which encompasses Caatinga and northern portions of Cerrado, has an intricate structure and seems to have suffered repetitive retraction-expansion events due to climactic fluctuations during the Quaternary. The Southwestern population, which ranges from central-south Cerrado to the northeast peripherical portions of the Chaco, displays a star-shaped haplotype structure, indicating that this region may have acted as a refugia during interglacial periods.

Historical and future climate change fosters expansion of Australian harvester termites, Drepanotermes

Past evolutionary adaptations to Australia's aridification can help us to understand the potential responses of species in the face of global climate change. Here, we focus on the Australian-endemic genus Drepanotermes, also known as Australian harvester termites, which are mainly found in semiarid and arid regions of Australia. We used species delineation, phylogenetic inference, and ancestral state reconstruction to investigate the evolution of mound-building in Drepanotermes and in relation to reconstructed past climatic conditions. Our findings suggest that mound-building evolved several times independently in Drepanotermes, apparently facilitating expansions into tropical and mesic regions of Australia. The phylogenetic signal of bioclimatic variables, especially limiting environmental factors (e.g., precipitation of the warmest quarter), suggests that the climate exerts a strong selective pressure. Finally, we used environmental niche modeling to predict the present and future habitat suitability for eight Drepanotermes species. Abiotic factors such as annual temperature contributed disproportionately to calibrations, while the inclusion of biotic factors such as predators and vegetation cover improved ecological niche models in some species. A comparison between present and future habitat suitability under two different emission scenarios revealed continued suitability of current ranges as well as substantial habitat gains for most studied species. Human-mediated climate change occurs more quickly than these termites can disperse into newly suitable habitat; however, their role in stabilizing arid ecosystems may allow them to mitigate effects on some other organisms at a local level.

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.

The origins and radiation of Australian Coptotermes termites: from rainforest to desert dwellers

The termite genus Coptotermes (Rhinotermitidae) is found in Asia, Africa, Central/South America and Australia, with greatest diversity in Asia. Some Coptotermes species are amongst the world's most damaging invasive termites, but the genus is also significant for containing the most sophisticated mound-building termites outside the family Termitidae. These mound-building Coptotermes occur only in Australia. Despite its economic and evolutionary significance, the biogeographic history of the genus has not been well investigated, nor has the evolution of the Australian mound-building species. We present here the first phylogeny of the Australian Coptotermes to include representatives from all described species. We combined our new data with previously generated data to estimate the first phylogeny to include representatives from all continents where the genus is found. We also present the first estimation of divergence dates during the evolution of the genus. We found the Australian Coptotermes to be monophyletic and most closely related to the Asian Coptotermes, with considerable genetic diversity in some Australian taxa possibly representing undescribed species. The Australian mound-building species did not form a monophyletic clade. Our ancestral state reconstruction analysis indicated that the ancestral Australian Coptotermes was likely to have been a tree nester, and that mound-building behaviour has arisen multiple times. The Australian Coptotermes were found to have diversified ∼13million years ago, which plausibly matches with the narrowing of the Arafura Sea allowing Asian taxa to cross into Australia. The first diverging Coptotermes group was found to be African, casting doubt on the previously raised hypothesis that the genus has an Asian origin.

Evolution of apolar sporocytes in marchantialean liverworts: implications from molecular phylogeny

In meiosis of basal land plants, meiotic division planes are typically predicted by quadri-lobing of the cytoplasm and/or quadri-partitioning of plastids prior to nuclear divisions. However, sporocytes of several marchantialean liverworts display no indication of premeiotic establishment of quadripolarity, as is observed in flowering plants. In these cases, the shape of sporocytes remains spherical or elliptical and numerous plastids are distributed randomly in the cytoplasm during meiosis. Through a survey of sporocyte morphology in marchantialean liverworts, we newly report the occurrence of apolar sporocytes in Sauteria japonica and Athalamia nana (Cleveaceae; Marchantiales). Molecular phylogenetic analyses revealed that the quadri-lobing of cytoplasm and quadri-partitioning of plastids were lost independently several times during the evolution of marchantialean liverworts. In addition, our phylogenetic analyses indicate that the simplified sporophytes of several marchantialean liverworts are not a primitive condition but rather represent the result of reductive evolution. The loss of the quadripolarity of sporocytes appears to correlate with the evolutionary trend of the sporophyte towards reductions. Through the evolution of the simplified sporophytes, suppression of mitotic divisions of sporogenous cells might had caused not only the modification of sporophyte ontogeny but also the drastic cytological change of sporocyte.

Actinobacteria isolated from termite guts as a source of novel oxidative enzymes

A multi-faceted screening programme was designed to search for the oxidases, laccase, peroxidase and tyrosinase. Actinobacteria were selectively isolated from the paunch and colon region of the hindguts of the higher termite, Amitermes hastatus. The isolates were subjected to solid media assays (dye decolourization, melanin production and the utilization of indulin AT as sole carbon source) and liquid media assays. Eleven of the 39 strains had the ability to decolourize the dye RBBR, an indicator for the production of peroxidases in actinobacteria. Melanin production on ISP6 and ISP7 agar plates served as a good indicator for laccase and/or tyrosinase production and the ability of the strains to grow in the presence of indulin AT as a sole carbon source served as a good indicator of lignin peroxidase and/or general peroxidase production. Enzyme-producing strains were cultivated in liquid media and extracellular enzyme activities measured. Strains with the ability to produce oxidative enzymes under the conditions tested were identified to genus level by 16S rRNA gene analysis and compared to known oxidase producers. A strong relationship was observed between the environment sampled (termite guts where lignocellulose degradation occurs) and the dominant type of oxidative enzyme activity detected (laccases and peroxidases), which suggests the possibility of future targeted screening protocols linking the physical properties of the target enzymes with specific operational conditions required, such as lignocellulosic degradation in the preparation of biofuel feedstocks.

Insect biodiversity and conservation in Australasia

Australasia, which consists of Australia and the adjacent islands of the southwestern Pacific Ocean, has an insect diversity approximately proportional to the land mass. This diversity is distinctive, with some major groups missing and others having radiated. Iconic species are familiar to most people living in Australia and New Zealand, and a range of insects once contributed to Aboriginal Australian culture and diet. Conservation of Australasian entomological biodiversity is an increasing challenge for contemporary scientists. Examples are provided of insect conservation schemes from New Guinea, New Zealand, and Australia. Funding for insect biodiversity studies beyond flagship species is needed.

Biogeography of butterflies in the Australian monsoon tropics

The biogeography of butterflies within the monsoon tropical biome of northern Australia is reviewed in terms of patterns of species richness, endemism and area relationships. Available data indicate that the region supports a relatively rich fauna, comprising 265 species (~62% of the total Australian fauna), but endemism is low (6%). No genera are endemic to the monsoon tropics, but two (Neohesperilla, Nesolycaena) are characteristic components, embracing a total of seven species in the region, of which five are endemic. Three ecological specialists (Neohesperilla senta, Elodina walkeri, Candalides delospila), each associated with different vegetation types, appear to be characteristic elements of the monsoon tropics. Of 67 range-restricted species in the monsoon tropics, 15 (mostly associated with savanna) are endemic to the region, while 52 (mostly associated with rainforest) are non-endemic, occurring also in south-east Asia and/or mainland New Guinea. A pronounced attenuation in species richness from Cape York Peninsula across the Top End to the Kimberley is evident. Within the monsoon tropics, Cape York Peninsula stands out as an area of exceptional biodiversity, with 95% of the butterflies (251 species; 7 endemic species, 31 endemic subspecies/geographical forms) recorded from the entire region, compared with the Top End (123 species; 3 endemic species, 17 endemic subspecies/geographical forms). In contrast, the Kimberley has a comparatively depauperate fauna (85 species; 1 endemic species, 0 endemic subspecies) without strong Indonesian affinities, and contains only two range-restricted species. A sister-area relationship between Cape York Peninsula and the Top End–Kimberley is evident in one clade, Acrodipsas hirtipes (northern Cape York Peninsula) + A. decima (Top End), with a pairwise divergence of ~1% based on mtDNA, and is suspected in another, Nesolycaena medicea (southern Cape York Peninsula) and N. urumelia (Top End) + N. caesia (Kimberley); a further five species show similar sister-area relationships across the Carpentarian Gap but at the level of subspecies or geographical form. Three general and complementary hypotheses are proposed to explain patterns of geographical differentiation of butterflies in the monsoon tropics: (1) the Carpentarian Gap is a biogeographical filter, functioning as a barrier for some species but as a bridge for others; (2) divergence among taxa between Cape York Peninsula and the Top End–Kimberley has occurred fairly recently (Quaternary), probably through vicariance; and (3) the Bonaparte Gap, with the exception of Nesolycaena, is not a vicariant barrier for butterflies in the Top End and Kimberley.

Karyology, mitochondrial DNA and the phylogeny of Australian termites

A comprehensive karyological characterization of 20 Australian and three European species of Isoptera, together with a mitochondrial gene analysis is presented. Higher termites appear karyotypically very uniform, while lower termites are highly variable. The differences in chromosome number are explained through Robertsonian changes or multiple translocation events. An ancestral acrocentric karyotype can be suggested as the most primitive one. In Kalotermitidae chromosomal repatterning has repeatedly arisen with the X0-male type possibly representing a XY-derived condition. This argues against a simple origin of termites from cockroaches. The fixed chromosome number of Rhinotermitidae and Termitidae (2n=42, XY/XX) may be explained with the non-random nature of chromosomal evolution. A sex-linked multivalent, either with a ring or a chain structure, is found in the majority of species. Phylogenetic analyses on COII sequences recognize Mastotermitidae as the basal lineage and define the Rhinotermitidae+Termitidae cluster with a good bootstrap support. Kalotermitidae fail to be joined in a single cluster in agreement with the detected chromosomal variability. On the other hand, the karyotypic conservation of the Termitidae family contrasts with the polytomy evidenced at the subfamily level.