Organisms Diversity & Evolution最新文献

The family Lutjanidae, commonly called “Snappers,” is a large, commercially important, and highly diverse clade of bony fishes with 17 genera and 113 species of order Perciformes. They primarily inhabit the shallow coastal waters of tropical oceans, including rocky and coral reefs, and are characterized by their colorful body patterns, which place them in the aquarium trade category. The diversity of snapper species in the Bay of Bengal is profoundly influenced mainly due to overfishing for high commercial trade. The phylogenetic relationship among snapper species is poorly understood, especially from the Bay of Bengal, and remains a topic of intense interest with conflicting morphological topologies and predominantly molecular data. In this study, we integrate two mitochondrial markers (COI and 16S rRNA) and morphological characteristics to explore the phylogenetic relationships, species diversification, and biogeographical history of the family Lutjanidae at the generic level. We collected 12 species among two genera: Lutjanus Bloch, 1790 and Pinjalo Bleeker, 1873 from the Odisha coast, Bay of Bengal, India. Phylogenetic analyses by both neighbor-joining (NJ) and maximum likelihood (ML) produce high congruence trees defining well-supported clades. In addition to phylogenetic analyses, the divergence time was based on RelTime-ML and Bayesian phylogeography approaches. Our results suggest that the studied snapper species were diversified from the common ancestor in the middle Paleogene period (42 Mya). Biogeographical reconstruction resulted in successive dispersal events from an ancestral range from the Indo-Pacific region to the eastern Pacific and to the Bay of Bengal. We believe that our results critically explain the origin of snapper species, their diversification, and their local distribution.

Charopidae is a family of mostly minute land snails whose diversity is centered in the southern hemisphere. This family is represented on Australia’s Lord Howe Island in the Tasman Sea with 13 currently accepted species in seven genera, including Australia’s largest charopid species. We comprehensively revise the taxonomy of all endemic Lord Howe Island charopids using comparative morpho-anatomy and phylogenetic analyses of mitochondrial (COI, 16S) and nuclear (ITS2, ELAVI8) markers and demonstrate that these species represent two independent island radiations. We recognise these radiations as two distinct genera, Goweroconcha and Pseudocharopa, containing six and five species respectively. The two genera have distinct biogeographic affinities. Whereas the sister clade of Goweroconcha comprises several Australian genera, indicating its evolutionary origin likely being in Australia, the sister group of Pseudocharopa predominantly contains species endemic to New Zealand. Both genera have diversified on Lord Howe Island into flocks of species that differ most notably in shell size and, in the case of Pseudocharopa, to some extent, also in the degree of shell reduction. Hence, we demonstrate that while both charopid radiations include unusually large species, there is no evidence of the island effect, which tends to produce a narrower range of body sizes than observed in both groups.

Within the hyper-diverse group of the amphipods, little is known about deep-sea benthic species that still represent an unknown reservoir of species to be discovered, particularly in remote regions of the southwestern Pacific. Herein, we are describing three new deep-sea species of Rhachotropis from Papua New Guinea, Solomon archipelago, and Vanuatu using an integrative taxonomy approach, combining morphological and molecular characters with biological and ecological information. Nomenclatural comments and a key to Rhachotropis species occurring in the bathyal provinces from the southwestern Pacific are also provided. Comments on the sex ratio and fecundity of the genus are also discussed. The biogeography and distribution of the newly described species as well as congeneric species occurring in the area are discussed, and new DNA data are shedding new light on the global phylogenetic relationships (geography, depth range) of the deep-sea genus Rhachotropis.

Lutrinae, which contains 13 otter species, is a semi-aquatic subfamily. They reclaimed semi-aquatic environments as their habitat. As aquatic environments can lead high energy loss, otters require a highly efficient energy generating style. Mitochondria play key roles in energy production and supply. Thus, we hypothesized that different selective constraints might influence the mitochondrial genomic DNA (mtDNA) of otters compared to that of other terrestrial Mustelidae. To verify the conjecture, we compared the evolutionary rate of the mitochondrial genomes of 12 otter species (including those we previously assembled from five otter species) with those of 18 terrestrial Mustelidae. The results showed that four of the 13 protein-coding genes (PCGs) (COX2, ND1, ND4 and ND6) in the mitochondrial genomes of semi-aquatic otters possessed higher rate of non-synonymous nucleotide substitutions (d_N) to synonymous substitutions (d_S) (ω values, d_N/d_S), than those in terrestrial Mustelidae. For two genes, ND1 and ND4, this difference remained significant after controlling for evolutionary relationships using phylogenetic independent contrasts (PIC) analysis. Furthermore, ND1 and ND4 are rapidly evolving genes (REG). Overall, these results demonstrate that ND1 and ND4 have undergone divergent evolutionary patterns between otters and terrestrial Mustelidae, along with their niche differentiation. The unique evolutionary pattern of mtDNA in Lutrinae may thus play an important role in their semi-aquatic habitat adaptation.

Stilbonematinae are nematodes commonly found in shallow marine sands. They are overgrown by a genus- and species-specific coat of chemoautotrophic sulphur-oxidizing ectosymbiotic bacteria which profit from the vertical migration of their hosts through the chemocline by alternately gaining access to oxidizing and reducing chemical species, while in return, the host feeds on its symbionts. The subfamily exhibits a large morphological variability; e.g. the anterior pharynx is cylindrical in genera possessing a voluminous coat, but species with a bacterial monolayer possess a distinctly swollen corpus and therefore a tripartite pharynx. Since 18S-based phylogenetic analyses do not show close relationships between corpus-bearing species, we investigated the pharynx morphology using phalloidin staining in combination with confocal laser scanning microscopy, transmission electron microscopy and light microscopy in order to assess an independent evolution. The class-wide stable position of the subventral pharynx ampullae was used as a morphological marker. Ampullae are positioned at the anterior-most end of the isthmus in Cyathorobbea, further posterior in Catanema and Robbea and inside the corpus in Laxus oneistus. We therefore conclude an independent evolution of corpus enlargements within Stilbonematinae. This further suggests that pharynx morphology is driven by the volume of the symbiotic bacterial coat rather than phylogeny. Based on an existing mathematical model, an enlarged corpus should enable its bearer to ingest food in smaller quantities, in gourmet style, whereas a cylindrical pharynx would restrict its bearer to ancestral gourmand feeding. A review of pharynx types of Nematoda showed that the Stilbonematinae pharynx is substantially different compared to other tripartite pharynges. The lack of pharyngeal tubes and valves, the undivided corpus and evenly distributed nuclei in the isthmus warrant the definition of the “stilbonematoid” three-part pharynx.

Around the world, the spread of pheretimoid earthworm species from Southeast Asia has raised ecological, environmental, and conservation concerns in urban-suburban settings and forest habitats. There is currently a global discourse surrounding the taxonomic status of pheretimoid earthworms. Therefore, a comparative molecular systematics study was conducted on pheretimoid, utilizing an integrative taxonomy approach that relied on morpho-anatomical characterization and the COI gene. The study generated and compared the 51 COI barcodes of pheretimoid with existing 156 COI sequences of pheretimoid earthworms worldwide, with the primary goal of testing various analytical methods for species delimitation and examining phylogenetic reconstruction. Seven different methods of species delineation were applied, viz., Automatic Barcode Gap Discovery (ABGD), Assemble Species by Automatic Partitioning (ASAP), General Mixed Yule Coalescence (GMYC), Poisson Tree Processes (PTP), Bayesian Poisson Tree Processes (bPTP), Multiple Poisson Tree Processes (mPTP), and Refined Single Linkage (RESL). Additionally, trees using Bayesian Inference (BI) and Maximum Likelihood (ML) were created for phylogenetic studies. The results unveiled 10 species belonging to 3 genera, viz., Amynthas, Metaphire, and Polypheretima. Furthermore, the study reported one new record from India, Amynthas andersoni choprai, and range expansion of Amynthas alexandri, Metaphire posthuma, and Polypheretima elongata to Manipur, the north-eastern region of India. Further, the peregrine species Amynthas corticis was reported for the first time in Madhya Pradesh in the central part of India. The study concluded that the genera Amynthas, Metaphire, and Pheretima do not exhibit monophyletic lineages which corroborates with previous studies. The study aligns with earlier studies that recommended reassessing the numerical revision of the genus Pheretima auct. (Sims & Easton, 1972). In addition, a comprehensive analysis of the evolutionary relationships between multiple pheretimoid earthworms in India has been provided, laying the foundation for understanding their origins.

The burrowing scorpions of the genus Scorpio Linnaeus, 1758 were considered to be a single polymorphic species, Scorpio maurus Linnaeus, 1758, distributed from West Africa across the Sahel and the Saharan highlands through the Maghreb and the Middle East, to Iran. After various revisions, the complex was treated as including 18 species and seven subspecies. Five additional new Scorpio species were recently described. However, doubts remain regarding the validity of these taxa due to the lack of reliable characters and the lack of genetic data for many species. The aim of the present study was to analyze the phylogenetic relationships and the evolutionary events that promoted diversification within the genus. Phylogenetic analyses were performed using 633 base pairs of the mitochondrial COI gene from 51 individuals collected in Tunisia, Morocco, and Egypt, combined with 74 previously published sequence data. Phylogenetic analyses revealed twenty distinct lineages forming two geographically separate clades, a Maghrebian clade and a Middle Eastern clade. Although most named species formed distinct lineages, various additional lineages were identified, highlighting potential unnamed species. Divergence time estimates indicate that the division within the genus Scorpio began during the Mid-Miocene, a period characterized by tectonic events coupled with climatic oscillations. Further differentiation occurred during the Miocene-Pliocene transition when climatic fluctuations resumed and the Mediterranean became increasingly arid. Speciation within the genus Scorpio may have been driven by the expansion of the savannas and Sahara Desert, the associated reduction of a once widespread rainforest into numerous micro-refugia in the mountains of the Mediterranean region, and by adaptation to these new habitats.

Immergentia is an endolithic genus of ctenostome bryozoans and the sole member of the Immergentiidae. Etchings of their typical spindled-shaped and sometimes enantiomorphic borehole aperture in calcium carbonate substrates are accomplished by chemical dissolution. The tentacle crown of the bryozoan is essentially the only body part that extends beyond the shell surface when protruded. Previously, species were mainly described using external colony and zooidal characteristics or whole mounts, with partial histological sections conducted on a single species in 1947. Modern approaches, however, are hitherto missing. We examined the soft body morphology of Immergentia from different locations with confocal laser scanning microscopy and the production of 3D reconstructions. In addition, zooidal characteristics such as tentacle number, size, tubulets, and interzooidal distances were used to distinguish and describe species. The combination of conventional and modern methods revealed the presence of a cardiac constrictor and intercalary kenozooids that can interpose between the cystid appendages, something not previously reported in immergentiids, thus necessitating an amendment of the family diagnosis. The polypide typically has eight to ten tentacles, and the anus is positioned in the low or mid-lophophoral area. In addition, sequence data, including the mitogenome and the nuclear ribosomal genes (18S and 28S) of four species from five locations, are presented for the first time. Based on molecular and morphological data, a novel intertidal immergentiid from France, Immergentia stephanieae sp. nov., and a subtidal species from New Zealand, I. pohowskii sp. nov., are described. This work supplements the rather sparse existing knowledge on Immergentiidae and proposes additional characteristics to complement existing descriptions in order to enhance future species identification.

Modern giraffids are nowadays represented by few species; however, this family was quite diverse during the Neogene. Several lineages radiated, showing high morphological disparity in metapodial shapes. During the last few years, not many scholars have focused on this subject. Furthermore, modern statistical approaches have been totally neglected. Herein, we present the first attempt to fill this gap of knowledge adopting a plethora of phylogenetic comparative approaches alongside multivariate statistics. Namely, we performed a series of traditional and geometric morphometric analyses for a total of 207 metapodial specimens of extant and fossil giraffid species. Our results recognized four different clusters, grouped in different morphospaces. Moreover, two of these clusters are clearly outliers in respect to an overall homogeneous distribution. The two outlying clusters include short and robust metapodials observed in Sivatherium, and long and slender metapodials observed in Giraffa and Bohlinia, respectively. Similarities between the modern Okapia and the extinct genus Decennatherium were also detected. This study explores the relations between the morphological adaptations and the ecological roles of different members of the Giraffidae. It also provides insights into how different environmental factors might have influenced the evolution of this group and the adaptation of their members to diverse environments. Furthermore, locomotory adaptations of the most hyper-specialized Giraffidae groups are briefly discussed and investigated.

The cuticle is the tardigrade exoskeleton that, limiting animal growth, needs to be periodically shed. New cuticles must be formed (within the old ones) before getting rid of the obsolete exoskeletons at the end of moulting process. After ecdysis (the release of the old cuticle), the exuvia has different destinies according to tardigrade evolutionary lines. In the marine tardigrades (Heterotardigrada), the exuvia is lost and useless, while in the other taxa, it acquires interesting uses to be considered exaptations, since the cuticle previously shaped by natural selection for a function (i.e. as exoskeleton) is coopted for new adaptive scopes. These are related to egg deposition, parental care, mating, and diapause. Egg deposition within the exuvia is one of the three different egg deposition strategies developed by tardigrades: smooth eggs can be laid freely or within the exuvia, while ornamented eggs are laid freely. A new scenario for the evolution of such egg deposition strategies is characterised by five schematic steps: smooth eggs laid freely (ancestral state), synchronization of egg maturation with moulting (developed in tardigrade ancestor in sea), use of the exuvia for oviposition (for enhanced mechanical and physiological egg protection), acquisition of egg ornamentation, and ornamented eggs laid freely (related to a risk-spreading strategy). An interesting thanatochresis case related to the release of free eggs in crustaceans exuviae, convergently developed in two distant taxa of eu- and heterotardigrades, is presented and discussed.