Evolutionary history of the reef fish Anisotremus interruptus (Perciformes: Haemulidae) throughout the Tropical Eastern Pacific

The Tropical Eastern Pacific (TEP) is a dynamic coastal environment characterized by a complex system of oceanic processes and discontinuous rocky habitats. These features, in conjunction with the ecological and physiological characteristics of Anisotremus interruptus, might limit gene flow and shape the evolutionary history of the species. In this study, we investigate the evolutionary history of the reef fish A. interruptus (and its Atlantic sister species A. surinamensis) throughout its range in the TEP, using two mitochondrial (cox1 and cytb) and two nuclear markers (S7 and RAG1). We found three genetic groups of A. interruptus with recent divergence times from the Galapagos Archipelago, Revillagigedo Archipelago, the continental TEP, and A. surinamensis the sister specie from the Atlantic. The haplotype mtDNA networks show A. surinamensis in a central position with respect to Pacific genetic haplogroups, whereas nDNA networks show mixed haplotypes between the four genetic groups. In the species tree, A. surinamensis appears as the sister species of all the Pacific samples and the Galapagos Archipelago population emerges as a genetically distinctive group. The samples from the Revillagigedo Archipelago also constitute a genetic distinctive group, closely related to the continental samples. Continental individuals do not show significant genetic structure and exhibit a population expansion during the Pleistocene. The sandy gaps of the TEP not appear to act as barriers isolating populations of A. interruptus, whereas the open sea gap between the oceanic islands and the continental coast do.     

Aquatic adaptations in a Neotropical coral snake: A study of morphological convergence

Micrurus surinamensis is an aquatic member of the genus Micrurus. This species is known for its highly specialized venom and distinctive diet, mostly made of aquatic vertebrates. Here, we explore both external (head and body) and skull shape morphologies in M. surinamensis, comparing it with two terrestrial species of the genus (M. lemniscatus and M. spixii) and to aquatic and terrestrial species of distantly related groups. We use both traditional and geometric morphometrics to determine whether the presence of similar traits in head shape morphology is rather the result of adaptive convergences between M. surinamensis and other aquatic species, or whether it is the product of phylogenetic conservatism within the genus. Results from both traditional and geometric morphometrics show that M. surinamensis can be considered convergent with aquatic species, mainly in the skull shape. Micrurus surinamensis differs from the two terrestrial species of Micrurus by having a wider head, smaller distance between nostrils, and a long tail. Geometric morphometric analysis shows that despite having an extremely conserved skull and mandible shape, M. surinamensis shows a longer supratemporal and quadrate bones than in terrestrial Micrurus, indicating a larger gape for this species. A more kinetic skull combined with a larger gape would allow M. surinamensis to feed on fish, which represent larger and wider prey that contrast with the elongate prey, which compose the main diet of species in the genus Micrurus. Our results illustrate the importance of both phylogenetic conservatism and adaptation in shaping species morphology.     

A new record for Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) species complex of Turkey

In this study, species complex of Turkish Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) populations was determined by PCR‐based DNA analysis. According to phylogenetic analyses, the B. tabaci samples have been identified within three generic groups. A major part of the samples belonged to two invasive species, either Middle East–Asia Minor 1 (MEAM1) or Mediterranean (MED). In addition to these two invasive species, several samples collected from greenhouses and cotton fields have been found to be related to Middle East–Asia Minor 2 (MEAM2), which is the first record of Turkish B. tabaci species complex.     

Disintegrating over space and time: Paraphyly and species delimitation in the Wehrle's Salamander complex

Accurate species delimitation is critical for biodiversity studies. However, species complexes characterized by introgression, high levels of population structure and subtle phenotypic differentiation can be challenging to delimit. Here, we report on a molecular systematic investigation of the woodland salamanders Plethodon wehrlei and Plethodon punctatus, which traditionally have been placed in the Plethodon wehrlei species group. To quantify patterns of genetic variation, we collected genetic samples from throughout the range of both species, including 22 individuals from nine populations of P. punctatus, and 60 individuals from 26 populations of P. wehrlei. From these samples, we sequenced three mtDNA loci (5596 base pairs) and five nuclear loci (3377 base pairs). We inferred time‐calibrated gene trees and species trees using BEAST 2.4.6, and we delimited putative species using a Bayesian implementation of the general mixed Yule‐coalescent model (bGMYC) and STRUCTURE. Finally, we validated putative species using the multispecies coalescent as implemented in Bayesian Phylogenetics and Phylogeography (BPP). We found substantial phylogeographic diversity in P. wehrlei, including multiple geographically cohesive clades and an inferred mitochondrial common ancestor at 11.5 myr (95% HPD: 9.6–13.6 myr) that separated populations formerly assigned to P. dixi from all other populations. We also found that P. punctatus is deeply nested within P. wehrlei, rendering the latter paraphyletic. After discussing the challenges faced by modern species delimitation methods, we recommend retaining P. punctatus because it is ecologically and phenotypically distinct. We further recommend that P. dixi be recognized as a valid species.     

The impact of genetic diversity on the accuracy of DNA barcoding to identify species: A study on the genus Phellodendron

DNA barcoding is widely used in species identification, but there is considerable controversy regarding the extent of sampling in research methods. Some scholars have proposed that this small sample size underestimates the intraspecific genetic diversity, which would impact on the accuracy of DNA barcoding to identify species. In study, we selected all Phellodendron species (including P. amurense Rupr., P. chinense Schneid., and P. chinense var. glabriusculum Schneid.) as the materials, collected 59 P. amurense samples from 35 populations greatly to represent the genetic diversity, and analyzed the haplotype, genetic distance, barcoding gap, and Neighbor‐Joining (NJ) trees based on psbA‐trnH and internal transcribed spacer gene sequences. Additionally, a sampling simulation was conducted to assess the correlation between genetic diversity and the number of populations. Finally, analysis of critical geographical populations was performed. Based on analysis of haplotype, genetic distance, barcoding gap, and NJ trees, we found that eight P. amurense samples impacted on the effectiveness of DNA barcoding, which genetic information were very important to identify Phellodendron species. Moreover, the result of the NJ tree analysis performed the small‐scale P. amurense sample size did not completely match the objective phylogenetic relationship in Phellodendron. In simulation sampling analysis, the data showed the genetic diversity indexes at the same population level gradually decreased and stabilized as the number of simulation sampling populations increased. We found that 1–2 samples from over 24 populations based on uniform geographical distribution could represent 80% of the genetic diversity of P. amurense and ensure authenticity and reliability of DNA barcoding. Thus, we proposed it is particularly important adequately samples to cover infraspecific genetic diversity in order to ensure identification accuracy of DNA barcoding.     

Broad infectivity of Leidynema appendiculatum (Nematoda: Oxyurida: Thelastomatidae) parasite of the smokybrown cockroach Periplaneta fuliginosa (Blattodea: Blattidae)

Host specificity of parasites is important for the understanding of evolutionary strategies of parasitism that would be a basis of predictions of the disease expansion when parasitized hosts invade new environments. The nematode order Oxyurida is an interesting parasite group for studying the evolution of parasitism as it includes parasites of both invertebrates and vertebrates. In our survey, we found that the smokybrown cockroach Periplaneta fuliginosa was primarily infected with only one nematode species Leidynema appendiculatum. In two cases, L. appendiculatum was isolated from two additional cockroach species Pycnoscelus surinamensis, sold in Japan as a reptile food, and Blatta lateralis, captured in the field and cultured in the laboratory. Inoculation of L. appendiculatum into three additional cockroach species P. japonica, Blattella nipponica, and P. surinamensis also resulted in parasitism. Infection prevalence was high, and timing of postembryonic development from hatched nematode larva to mature adult in these hosts was identical with that in P. fuliginosa. While ecological interactions strongly determine the host range, such broad infectivity is still possible in this parasitic nematode.     

Discrepancies between genetic and ecological divergence patterns suggest a complex biogeographic history in a Neotropical genus

Phylogenetic patterns and the underlying speciation processes can be deduced from morphological, functional, and ecological patterns of species similarity and divergence. In some cases, though, species retain multiple similarities and remain almost indistinguishable; in other cases, evolutionary convergence can make such patterns misleading; very often in such cases, the “true” picture only emerges from carefully built molecular phylogenies, which may come with major surprises. In addition, closely related species may experience gene flow after divergence, thus potentially blurring species delimitation. By means of advanced inferential methods, we studied molecular divergence between species of the Virola genus (Myristicaceae): widespread Virola michelii and recently described, endemic V. kwatae, using widespread V. surinamensis as a more distantly related outgroup with different ecology and morphology—although with overlapping range. Contrary to expectations, we found that the latter, and not V. michelii, was sister to V. kwatae. Therefore, V. kwatae probably diverged from V. surinamensis through a recent morphological and ecological shift, which brought it close to distantly related V. michelii. Through the modeling of the divergence process, we inferred that gene flow between V. surinamensis and V. kwatae stopped soon after their divergence and resumed later, in a classical secondary contact event which did not erase their ecological and morphological differences. While we cannot exclude that initial divergence occurred in allopatry, current species distribution and the absence of geographical barriers make complete isolation during speciation unlikely. We tentatively conclude that (a) it is possible that divergence occurred in allopatry/parapatry and (b) secondary contact did not suppress divergence.     

GENETIC DIVERSITY AND INTROGRESSION IN TWO CULTIVATED SPECIES (PORPHYRA YEZOENSIS AND PORPHYRA TENERA) AND CLOSELY RELATED WILD SPECIES OF PORPHYRA (BANGIALES,RHODOPHYTA)1

We investigated the genetic variations of the samples that were tentatively identified as two cultivated Porphyra species (Porphyra yezoensis Ueda and Porphyra tenera Kjellm.) from various natural populations in Japan using molecular analyses of plastid and nuclear DNA. From PCR‐RFLP analyses using nuclear internal transcribed spacer (ITS) rDNA and plastid RUBISCO spacer regions and phylogenetic analyses using plastid rbcL and nuclear ITS‐1 rDNA sequences, our samples from natural populations of P. yezoensis and P. tenera showed remarkably higher genetic variations than found in strains that are currently used for cultivation. In addition, it is inferred that our samples contain four wild Porphyra species, and that three of the four species, containing Porphyra kinositae, are closely related to cultivated Porphyra species. Furthermore, our PCR‐RFLP and molecular phylogenetic analyses using both the nuclear and plastid DNA demonstrated the occurrence of plastid introgression from P. yezoensis to P. tenera and suggested the possibility of plastid introgression from cultivated P. yezoensis to wild P. yezoensis. These results imply the importance of collecting and establishing more strains of cultivated Porphyra species and related wild species from natural populations as genetic resources for further improvement of cultivated Porphyra strains.     

Patterns of genetic diversity of the cryptogenic red alga Polysiphonia morrowii (Ceramiales,Rhodophyta) suggest multiple origins of the Atlantic populations

The red alga Polysiphonia morrowii, native to the North Pacific (Northeast Asia), has recently been reported worldwide. To determine the origin of the French and Argentine populations of this introduced species, we compared samples from these two areas with samples collected in Korea and at Hakodate, Japan, the type locality of the species. Combined analyses of chloroplastic (rbcL) and mitochondrial (cox1) DNA revealed that the French and Argentine populations are closely related and differ substantially from the Korean and Japanese populations. The genetic structure of P. morrowii populations from South Atlantic and North Atlantic, which showed high haplotype diversity compared with populations from the North Pacific, suggested the occurrence of multiple introduction events from areas outside of the so‐called native regions. Although similar, the French and Argentine populations are not genetically identical. Thus, the genetic structure of these two introduced areas may have been modified by cryptic and recurrent introduction events directly from Asia or from other introduced areas that act as introduction relays. In addition, the large number of private cytoplasmic types identified in the two introduced regions strongly suggests that local populations of P. morrowii existed before the recent detection of these invasions. Our results suggest that the most likely scenario is that the source population(s) of the French and Argentine populations was not located only in the North Pacific and/or that P. morrowii is a cryptogenic species.     

Competition and overlap of Oryzaephilus surinamensis and Plodia interpunctella populations under condition of stored date fruits

Plodia interpunctella and Oryzaephilus surinamensis are found in food storehouses including dates and palm storages. The current study aimed to determine competition and overlap potentials of the two pests of date fruits. Time series models were used to study two species populations and logistic growth model to estimate the effect of density of the species. The results revealed the environmental capacities of O. surinamensis and P. interpunctella were 433 and 1610 (maximum number per 20 g), respectively, and the population growth rates (r) were 1.2 and 1.3, respectively. Ecological balances of the two species were close to each other from the first to the third week. The population of O. surinamensis decreased in the fourth week of the competition. The highest population balance of the two species was in the 14th week. The potential of exploitable ecological niches (e_ij) and the amount of non-exploited ecological niches by any species (z_ij) for O. surinamensis was higher than for P. interpunctella from the 8th week untill the end of sampling period. The overlap of ecological niches in the two species (D) ranged from 0.94 to 1, indicating a complete overlap of temporal activity in the two populations on date palm. The current results of this study can be used by integrated pest management specialists. Information over the effects of species competition on population dynamics and their coexistence can be used to predict population status and to adopt simple pest control methods.     

The diet and distribution of Pentacoelum kazukolinda (Kawakatsu & Mitchell, 1984), a maricolan planarian with a freshwater ecology

Among the marine triclads or Maricola, the genus Pentacoelum represents one of the few exceptions in that species occur in brackish water or in freshwater. We examined specimens of a maricolan triclad that externally looked remarkably similar to the continental Spanish representatives of freshwater Pentacoelum hispaniense, albeit that these new samples came from habitats in Germany, the Netherlands, Mallorca and Japan. Comprehensive comparative morphological studies revealed that the animals from these populations are identical to a species described earlier from Hawaii, viz. Oahuhawaiiana kazukolinda Kawakatsu & Mitchell, 1984. It is argued that the species now should be called Pentacoelum kazukolinda (Kawakatsu & Mitchell, 1984) comb. nov. Remarkably, Dutch and German specimens of P. kazukolinda almost completely lack any signs of the presence of the lateral gonopore system, being the defining feature of their taxonomic family, the Bdellouridae. The reason for this reduction or even complete absence of this structure remains obscure. Nonetheless, morphological similarities and 18S rDNA sequences strongly suggest that all animals belong to the same species. Analyses of the mitochondrial gene sequences Cox1 and 16SrDNA of the gut content of P. kazukolinda revealed that the flatworm has a preference for different species of gastropods, while in one population annelids were detected. Our study suggests that gastropods may form the food refuge of P. kazukolinda. Circumstantial evidence suggests that the worldwide distribution of P. kazukolinda may result from human‐mediated transport of the aroid Colocasia esculenta and/or the introduced snail Potamopyrgus antipodarum. The use of P. antipodarum as a food resource may have facilitated the spread and establishment of new populations of P. kazukolinda.     

Early phenology and growth trait variation in closely related European pine species

Closely related taxa occupying different environments are valuable systems for studying evolution. In this study, we examined differences in early phenology (bud set, bud burst) and early growth in a common garden trial of closely related pine species: Pinus sylvestris, P. mugo, and P. uncinata. Seeds for the trial were sourced from populations across the ranges of each species in Europe. Over first 4 years of development, clear differences were observed between species, while the most significant intraspecific differentiation was observed among plants from P. sylvestris populations from continental European locations. Trait differences within P. sylvestris were highly correlated with altitude and latitude of the site of origin. Meanwhile, P. mugo populations from the Carpathians had the earliest bud set and bud flush compared to other populations of the species. Overall, populations from the P. mugo complex from heterogeneous mountain environments and P. sylvestris from the Scottish Highlands showed the highest within‐population variation for the focal traits. Although the three species have been shown to be genetically highly similar, this study reveals large differences in key adaptive traits both among and within species.     

Leaving the tropics: The successful colonization of cold temperate regions by Dolicheremaeus dorni (Acari,Oribatida)

Species diversity is generally higher in the tropics compared to the temperate zones. The phenomenon that one species of an almost exclusively tropical living genus was able to adapt successfully to the cold northern regions is rather rare. However, the oribatid mite Dolicheremaeus dorni represents such a species and is in the focus of this study. While 180 Dolicheremaeus species are confined to the tropics and subtropics, only five species are known to occur in temperate climates and D. dorni represents the only species with a wider distribution in this climatic region. This species is distributed in Central and Southern Europe and was now recorded for the first time in Austria. A morphological and molecular genetic investigation of specimens from Austria, Poland and Croatia confirmed this distribution pattern and revealed specific geographic clades and haplotypes for each population and hence indicate low gene flow between populations. A further molecular genetic analysis of the 18S rRNA gene sequence of D. dorni confirmed its phylogenetic position within Carabodoidea. Based on record information, this species is associated with trees or tree habitats and seems to be rather a generalist than a specialist for a specific substrate (e.g., tree species) or food source.     

Microsympatry in cryptic lowland salamanders (Caudata: Plethodontidae: Bolitoglossa subgenus Nanotriton) from north‐western Honduras: implications for taxonomy and regional biogeography

The taxonomy of the diminutive bolitoglossine salamanders of the subgenus Nanotriton has previously been a source of confusion among specialists. At various times, at least three different species of Nanotriton have been reported to occur in Honduras: Bolitoglossa nympha, B. occidentalis and B. rufescens. Phylogenetic analysis of 16S and cyt b from samples from three localities in Honduras (departments of Yoro, Copán and Cortés) confirms that most populations are assignable to B. nympha. Nine samples collected from a single locality on the northern slope of the Sierra de Omoa, between 120 and 190 m in elevation, were found to represent two distinct taxa: B. nympha and B. rufescens. Field examination of these nine specimens found them to be morphologically indistinguishable, including a lack of maxillary teeth in all specimens. As such, in situ identification of the two species in north‐western Honduras is problematic given the occurrence of the two taxa in microsympatry in at least one locality. The discovery of yet another divergent lineage of B. rufescens highlights the need for a taxonomic reassessment within this species complex.     

Witnessing extinction: Population genetics of the last European Rollers (Coracias garrulus) in Austria and a first phylogeographic analysis of the species across its distribution range

Due to broad‐scale habitat loss, European Rollers (Coracias garrulus) have been decreasing in numbers rapidly during the 20th century in parts of their European distribution range. In Austria, as of 2017, only a completely isolated relict population of two breeding pairs and a few non‐breeders remained in Styria compared to about 270 pairs in the 1950s. In 2018, no breeders have been recorded. Since 2002, all nestlings and adult birds in Austria have been ringed. Given the small census size, combined with lack of immigration from other populations, genetic depletion seems likely. In the present study, mitochondrial control region sequence and microsatellite data based on blood samples of nestlings from recent years were collected and compared with museum samples from historical times (when Rollers were more common and widespread in Austria) and with birds across the distribution range to arrive at a first preliminary phylogeographic dataset for the species. The mitochondrial DNA showed a decrease in variation over time in Austria, eventually reaching monomorphism, while genetic diversity of 10 microsatellite loci was higher than expected and a change in genetic structuring through time was observed. These results indicate drift effects in this relict European Roller population caused by the fast population breakdown and small population size. Our phylogeographic analysis indicates a division into a European and an Asian group, roughly (but not exactly) in accordance with the two subspecies C. garrulus garrulus (Europe) and Coracias garrulus semenowi (Asia). The lack of substructuring in the European group along with the results from nuclear DNA markers show the Austrian Rollers to be part of a formerly continuous population and opens the way to restocking the present relict population with birds from Eastern Europe (“genetic rescue”).     

Detecting an elusive invasive species: a diagnostic PCR to detect Burmese python in Florida waters and an assessment of persistence of environmental DNA

Recent studies have demonstrated that detection of environmental DNA (eDNA) from aquatic vertebrates in water bodies is possible. The Burmese python, Python bivittatus, is a semi‐aquatic, invasive species in Florida where its elusive nature and cryptic coloration make its detection difficult. Our goal was to develop a diagnostic PCR to detect P. bivittatus from water‐borne eDNA, which could assist managers in monitoring this invasive species. First, we used captive P. bivittatus to determine whether reptilian DNA could be isolated and amplified from water samples. We also evaluated the efficacy of two DNA isolation methods and two DNA extraction kits commonly used in eDNA preparation. A fragment of the mitochondrial cytochrome b gene from P. bivittatus was detected in all water samples isolated with the sodium acetate precipitate and the QIAamp DNA Micro Kit. Next, we designed P. bivittatus‐specific primers and assessed the degradation rate of eDNA in water. Our primers did not amplify DNA from closely related species, and we found that P. bivittatus DNA was consistently detectable up to 96 h. Finally, we sampled water from six field sites in south Florida. Samples from five sites, where P. bivittatus has been observed, tested positive for eDNA. The final site was negative and had no prior documented evidence of P. bivittatus. This study shows P. bivittatus eDNA can be isolated from water samples; thus, this method is a new and promising technique for the management of invasive reptiles.     

Demography and speciation history of the homoploid hybrid pine Pinus densata on the Tibetan Plateau

Pinus densata is an ecologically successful homoploid hybrid that inhabits vast areas of heterogeneous terrain on the south‐eastern Tibetan Plateau as a result of multiple waves of colonization. Its region of origin, route of colonization onto the plateau and the directions of introgression with its parental species have previously been defined, but little is known about the isolation and divergence history of its populations. In this study, we surveyed nucleotide polymorphism over eight nuclear loci in 19 representative populations of P. densata and its parental species. Using this information and coalescence simulations, we assessed the historical changes in its population size, gene flow and divergence in time and space. The results indicate a late Miocene origin for P. densata associated with the recent uplift of south‐eastern Tibet. The subsequent differentiation between geographical regions of this species began in the late Pliocene and was induced by regional topographical changes and Pleistocene glaciations. The ancestral P. densata population had a large effective population size but the central and western populations were established by limited founders, suggesting that there were severe bottlenecks during the westward migration out of the ancestral hybrid zone. After separating from their ancestral populations, population expansion occurred in all geographical regions especially in the western range. Gene flow in P. densata was restricted to geographically neighbouring populations, resulting in significant differentiation between regional groups. The new information on the divergence and demographic history of P. densata reported herein enhances our understanding of its speciation process on the Tibetan Plateau.     

Ensuring effective restoration efforts with salt marsh grass populations by assessing genetic diversity

Smooth cordgrass (Spartina alterniflora) is a foundation species that naturally occurs along the Atlantic coast of North America and is often used in restoration due to its extensive rooting capacity and ability to halt erosion. Clonal species, such as S. alterniflora, are easy to rear for transplant, but using a predominantly asexual species for restoration may lead to genetically depauperate populations. We (1) identified if genetic diversity was maintained during restoration; (2) determined if genotypes from the native populations were genetically distinct from the restored populations; and (3) evaluated if current efforts limited the number of multiple copies of the same multilocus genotypes (MLG) within restoration sites along the shorelines of the Mosquito Lagoon (ML), Florida, United States. All objectives were addressed where only one representative of an identical MLG was retained within each population. We found that allelic richness (p = 0.618) and expected heterozygosity (p = 0.527) did not significantly differ between restored and natural populations. Furthermore, pairwise F_ST estimates between naturally occurring populations ranged from 0.021 to 0.178, while estimates ranged from approximately 0 to 0.084 among restored populations. When we evaluated differentiation between natural and restored populations, average F_ST was 0.087. Finally, we found that higher numbers of samples with multiple copies of the same MLG occurred in restored populations (31.4–55.9% of samples per population) compared to natural populations (0–11.8% of samples per population). Overall, we found that current restoration efforts in the ML are effective at maintaining natural levels of genetic diversity.     

Rapid song divergence leads to discordance between genetic distance and phenotypic characters important in reproductive isolation

The criteria for species delimitation in birds have long been debated, and several recent studies have proposed new methods for such delimitation. On one side, there is a large consensus of investigators who believe that the only evidence that can be used to delimit species is molecular phylogenetics, and with increasing numbers of markers to gain better support, whereas on the other, there are investigators adopting alternative approaches based largely on phenotypic differences, including in morphology and communication signals. Yet, these methods have little to say about rapid differentiation in specific traits shown to be important in reproductive isolation. Here, we examine variation in phenotypic (morphology, plumage, and song) and genotypic (mitochondrial and nuclear DNA) traits among populations of yellow‐rumped tinkerbird Pogoniulus bilineatus in East Africa. Strikingly, song divergence between the P. b. fischeri subspecies from Kenya and Zanzibar and P. b. bilineatus from Tanzania is discordant with genetic distance, having occurred over a short time frame, and playback experiments show that adjacent populations of P. b. bilineatus and P. b. fischeri do not recognize one another's songs. While such rapid divergence might suggest a founder effect following invasion of Zanzibar, molecular evidence suggests otherwise, with insular P. b. fischeri nested within mainland P. b. fischeri. Populations from the Eastern Arc Mountains are genetically more distant, yet share the same song with P. b. bilineatus from Coastal Tanzania and Southern Africa, suggesting they would interbreed. We believe investigators ought to examine potentially rapid divergence in traits important in species recognition and sexual selection when delimiting species, rather than relying entirely on arbitrary quantitative characters or molecular markers.     

Population genomics meet Lagrangian simulations: Oceanographic patterns and long larval duration ensure connectivity among Paracentrotus lividus populations in the Adriatic and Ionian seas

Connectivity between populations influences both their dynamics and the genetic structuring of species. In this study, we explored connectivity patterns of a marine species with long‐distance dispersal, the edible common sea urchin Paracentrotus lividus, focusing mainly on the Adriatic–Ionian basins (Central Mediterranean). We applied a multidisciplinary approach integrating population genomics, based on 1,122 single nucleotide polymorphisms (SNPs) obtained from 2b‐RAD in 275 samples, with Lagrangian simulations performed with a biophysical model of larval dispersal. We detected genetic homogeneity among eight population samples collected in the focal Adriatic–Ionian area, whereas weak but significant differentiation was found with respect to two samples from the Western Mediterranean (France and Tunisia). This result was not affected by the few putative outlier loci identified in our dataset. Lagrangian simulations found a significant potential for larval exchange among the eight Adriatic–Ionian locations, supporting the hypothesis of connectivity of P. lividus populations in this area. A peculiar pattern emerged from the comparison of our results with those obtained from published P. lividus cytochrome b (cytb) sequences, the latter revealing genetic differentiation in the same geographic area despite a smaller sample size and a lower power to detect differences. The comparison with studies conducted using nuclear markers on other species with similar pelagic larval durations in the same Adriatic–Ionian locations indicates species‐specific differences in genetic connectivity patterns and warns against generalizing single‐species results to the entire community of rocky shore habitats.