Phylogeography of Nasutitermes ephratae (Termitidae: Nasutitermitinae) in Neotropical region

The neotropical region ranks third in the number of termites with five different families. Of these, Termitidae is the most diverse and includes the species Nasutitermes ephratae and is common in the neotropics. To date, only one study has been published about phylogeographic issues in neotropical termites (N. corniger). Here, we aimed to investigate and analyze the population genetic patterns of N. ephratae and then evaluated the phylogeographical processes involved in the evolutionary history of the species. We used the mitochondrial genes 16S rRNA and COII as molecular markers: These were sequenced for 128 samples of N. ephratae. We estimated the genetic diversity and divergence time as well as the demographic and genetic structure analyses. We also produced ancestral area reconstruction and a haplotype network. The results showed high genetic variability, recent demographic expansion, and strong genetic structure. We also inferred a dispersal route for the species that occurred in both directions between South and Central America. The results emphasize a temporary separation between the South and Central America population that affected the origin of the current Central America populations. These were formed form different phylogeographic histories.

Mitogenome of the Extinct Desert ‘Rat-Kangaroo’ Times the Adaptation to Aridity in Macropodoids

The evolution of Australia’s distinctive marsupial fauna has long been linked to the onset of continent-wide aridity. However, how this profound climate change event affected the diversification of extant lineages is still hotly debated. Here, we assemble a DNA sequence dataset of Macropodoidea — the clade comprising kangaroos and their relatives — that incorporates a complete mitogenome for the Desert ‘rat-kangaroo’, Caloprymnus campestris. This enigmatic species went extinct nearly 90 years ago and is known from a handful of museum specimens. Caloprymnus is significant because it was the only macropodoid restricted to extreme desert environments, and therefore calibrates the group’s specialisation for increasingly xeric conditions. Our robustly supported phylogenies nest Caloprymnus amongst the bettongs Aepyprymnus and Bettongia. Dated ancestral area optimisations further reveal that the Caloprymnus-Bettongia lineage originated in nascent arid zone settings from the later-middle to early-late Miocene, ~12 million years ago (Ma), but subsequently dispersed into mesic habitats during the Pliocene and Pleistocene. This coincides with ancestral divergences amongst kangaroos in disparate woodland-forest and shrubland settings, but predates their adaptive radiation into proliferating grasslands during the late Miocene to Pliocene, after ~7 Ma. We thus demonstrate that protracted changes in both climate and vegetation likely staged the emergence of modern arid zone macropodoids.

Diversification and distribution of gall crabs (Brachyura: Cryptochiridae: Opecarcinus) associated with Agariciidae corals

Coral reefs are home to the greatest diversity of marine life, and many species on reefs live in symbiotic associations. Studying the historical biogeography of symbiotic species is key to unravelling (potential) coevolutionary processes and explaining species richness patterns. Coral-dwelling gall crabs (Cryptochiridae) live in obligate symbiosis with a scleractinian host, and are ideally suited to study the evolutionary history between heterogeneous taxa involved in a symbiotic relationship. The genus Opecarcinus Kropp and Manning, 1987, like its host coral family Agariciidae, occurs in both Indo-Pacific and Caribbean seas, and is the only cryptochirid genus with a circumtropical distribution. Here, we use mitochondrial and nuclear DNA gene fragments of Opecarcinus specimens sampled from 21 Indo-Pacific localities and one Atlantic (Caribbean) locality. We applied several species delimitation tests to characterise species diversity, inferred a Bayesian molecular-clock time-calibrated phylogeny to estimate divergence times and performed an ancestral area reconstruction. Time to the most recent common ancestor (tMRCA) of Opecarcinus is estimated at 15−6 Mya (middle Miocene—late Miocene). The genus harbours ~ 15 undescribed species as well as several potential species complexes. There are indications of strict host-specificity patterns in certain Opecarcinus species in the Indo-Pacific and Atlantic, however, a robust phylogeny reconstruction of Agariciidae corals—needed to test this further—is currently lacking. The Indo-West Pacific was inferred to be the most probable ancestral area, from where the Opecarcinus lineage colonised the Western Atlantic and subsequently speciated into O. hypostegus. Opecarcinus likely invaded from the Indo-West Pacific across the East Pacific Barrier to the Atlantic, before the full closure of the Isthmus of Panama. The subsequent speciation of O. hypostegus, is possibly associated with newly available niches in the Caribbean, in combination with genetic isolation following the closure of the Panama Isthmus.

Phylogenomic insights into biogeographic diversification and character evolution of the Sino-Japanese disjunctive Diabelia (Caprifoliaceae)

Disjunctive distribution patterns and drivers of the Sino-Japanese flora in East Asia have attracted much attention in the past decades, which is also served as an important glacial sanctuary during the quaternary glacial period. However, few studies have focused on the phylogeography, diversification and evolution of morphological character at the genus level with both nuclear and plastid data. Diabelia (Caprifoliaceae) is an East Asian genus, with a disjunctive distribution across China, Japan and Korea, serving as an ideal group to explore the mechanism of East Asian flora speciation and diversification. However, the phylogenetic relationships among Diabelia remain elusive and species delimitation within the genus (three species or four species) are still controversial. In this study, we reconstructed the phylogenetic relationships among Diabelia based on nuclear and cpDNA by using target enrichment and genome skimming approaches, respectively. We found that the main clades within Diabelia were discordant between nuclear and plastid genome trees. Both nuclear and plastid phylogenetic analyses supported five main clades: D. serrata, D. tetrasepala, D. spathulata var. sanguinea, D. spathulata var. stenophylla and D. spathulata var. spathulata. Diabelia tetrasepala was inferred to be the result of a hybridization event from the species network analyses. The result of divergence time estimation and ancestral area reconstruction showed that Diabelia originated in Japan during the early Miocene, with subsequent gene flow between China, Japan and Korea. Overall, our results support the division of Diabelia into five main clades and this research provides new insights for the speciation process and taxonomy within Diabelia.

Polyploidy Expands the Range of Centaurium (Gentianaceae)

The Mediterranean region is one of the most important worldwide hotspots in terms of number of species and endemism, and multiple hypotheses have been proposed to explain how diversification occurred in this area. The contribution of different traits to the diversification process has been evaluated in different groups of plants. In the case of Centaurium (Gentianaceae), a genus with a center of diversity placed in the Mediterranean region, polyploidy seems to have been an important driver of diversification as more than half of species are polyploids. Moreover, ploidy levels are strongly geographically structured across the range of the genus, with tetraploids distributed towards more temperate areas in the north and hexaploids in more arid areas towards the south. We hypothesize that the diversification processes and biodiversity patterns in Centaurium are explained by the coupled formation of polyploid lineages and the colonization of different areas. A MCC tree from BEAST2 based on three nuclear DNA regions of a total of 26 taxa (full sampling, of 18 species and 8 subspecies) was used to perform ancestral area reconstruction analysis in “BioGeoBEARS.” Chromosome evolution was analyzed in chromEvol and diversification in BAMM to estimate diversification rates. Our results suggest that two major clades diverged early from the common ancestor, one most likely in the western Mediterranean and the other in a widespread area including west and central Asia (but with high uncertainty in the exact composition of this widespread area). Most ancestral lineages in the western clade remained in or around the western Mediterranean, and dispersal to other areas (mainly northward and eastward), occurred at the tips. Contrarily, most ancestral lineages in the widespread clade had larger ancestral areas. Polyploidization events in the western clade occurred at the tips of the phylogeny (with one exception of a polyploidization event in a very shallow node) and were mainly tetraploid, while polyploidization events occurred in the widespread clade were at the tips and in an ancestral node of the phylogeny, and were mainly hexaploid. We show how ancestral diploid lineages remained in the area of origin, whereas recent and ancestral polyploidization could have facilitated colonization and establishment in other areas.

Age, Origin, and Biogeography: Unveiling the Factors Behind the Diversification of Dung Beetles

The remarkable diversity and global distribution of dung beetles has long attracted the interest of researchers. However, there is still an ongoing debate on their origin, the reasons behind their diversity, and their path to global distribution. The two most prominent hypotheses regarding their origin and biogeographic history involve either vicariance events after the breakup of Gondwana, or an African origin and subsequent dispersal. One of the key reasons why the question is still disputed is a dependence on knowing the age of the dung beetles – a Mesozoic origin would favor the scenario of Gondwanan vicariance, a Cenozoic origin would suggest the out-of-Africa scenario. To help settle this longstanding question, we provide a taxonomically expanded phylogeny, with divergence times estimated under two calibration schemes suggesting an older or younger origin respectively. Using model-based inference, we estimate the ancestral area of the group and test for the influence of ranges on diversification rates. Our results support the hypothesis of an old age for Scarabaeinae and Gondwanan origin but remain ambiguous about the exact relation of range on lineage diversification.

Explosive diversification following continental colonizations by canids

Colonization of a new environment may trigger an explosive radiation process, defined as an accelerated accumulation of species in a short period of time. However, how often colonization events trigger explosive radiations is still an open question. We studied the worldwide dispersal of the subfamily Caninae, to investigate whether the invasion of new continents resulted in explosive radiations. We used a combination of phylogenetic analyses and ancestral area reconstructions to estimate ancestral ranges of 56 extant and extinct species of Caninae, as well as variation in speciation and extinction rates through time and across clades. Our findings indicate that canids experienced an explosive radiation event when lineages were able to cross the Bering Strait and the Isthmus of Panama to reach Eurasia and South America, respectively, around 11 million years ago. This large number of species arising in a short period of time suggests that canids experienced ecological opportunity events within the new areas, implying that the differences in the ecological settings between continents may be responsible for the variation in clade dynamics. We argue that interaction with other carnivores probably also affected the diversification dynamics of canids.