Molecular ecology and phylogeography of the bent-wing bat complex (Miniopterus schreibersii) (Chiroptera: Vespertilionidae) in Asia Minor and adjacent regions

In this study we investigate population genetic structure and phylogeography of the bent-wing bat complex ( Miniopterus schreibersii ) in Asia Minor and adjacent regions. PCR amplification and sequencing of the first hypervariable domain of the mitochondrial control region were used to obtain the genetic data. Morphometric differentiation between lineages was analysed by comparing forearm lengths. We found two reciprocally monophyletic lineages within the M . schreibersii complex, identified as M.   s. schreibersii and M. s . pallidus . Distributions of the lineages were allopatric with a U-shaped suture zone passing through Central Anatolia. The suture zone separated coastal regions occupied by M.   s. schreibersii from inland, higher altitude regions occupied by M.   s. pallidus . The lineages showed a considerable sequence divergence of c . 9%, accompanied by a corresponding difference in forearm length. The presence of the genetically distinct lineages, with allopatric distribution and corresponding morphometric differences, probably reflects their long isolation during the ice-age in the Balkans and the Caspian/Caucasus refugia, followed subsequently by expansion into different habitats. Based on the present data, the lineages can be recognized as evolutionary significant units.     

On the occurence of a short period of delayed implantation in Schreibers'long-fingered bat (Miniopterus schreibersii) from a tropical latitude in Zimbabwe

Mating in Schrcibers'long-fingered bat ( Miniopterus schreibersii ) from central Zimbabwe (18°S) occurred between mid-April and mid-May, after a five-month period of spermatogenesis. Implantation was delayed until early July and parturition occurred between late October and mid-November, about four months after implantation and six to seven months after fertilization. The timing and length of gestation at 18°S are similar to that described for M. schreibersii from Zaire (11σS) and when these date are compared with those for the same species from higher latitudes in Africa, it is apparent that there is a small, but distinct, increase in the total length of pregnancy and the length of delayed implantation with increasing latitude. The reproductive bilogy of Miniopterus schreibersii from Africa and France differs fundamentally from that of the same species from Australia and Japan, and it is suggested that studies of the relationship between latitude and duration of delayed implantation should be based on comparisons within single species from different latitudes on the same continent, and that comparisons between species and between continents should be avoided.     

Molecular taxonomy and phylogeography of Miniopterus schreibersii (Kuhl, 1817) (Chiroptera: Vespertilionidae), in the Eurasian transition

Miniopterus schreibersii is a polytypic bat species, with one of the widest distribution ranges among the mammals. We studied the genetic differentiation and taxonomy of this species in the transition zone between south-eastern Europe and Anatolia (in Asia), where two subspecies have been described. The results indicated a sharp genetic break between the samples from western Anatolia and south-eastern Europe and those of eastern Anatolia. In addition, the samples from western Anatolia and south-eastern Europe were seen to be reciprocally monophyletic, although the differentiation was less drastic. These patterns of genetic differentiation suggest the presence of two distinct groups within the M. schreibersii complex in the region, concordant with previous subspecific recognition. The cause of this genetic break is most likely differentiation in separate glacial refugia followed by secondary contact. However, more samples are needed to assess whether these represent different species, as well as to understand more clearly the causes of this differentiation.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 87 , 577–582.     

Phylogeography of the freshwater crayfish Cherax destructor Clark (Parastacidae) in inland Australia: historical fragmentation and recent range expansion

The yabby, Cherax destructor Clark, is the most widespread species in the most widespread genus of Australian freshwater crayfish. It has a distribution that spans several distinct drainage basins and biogeographical regions within semiarid and arid inland Australia. Here we report a study designed to investigate patterns of genetic variation within the species and hypotheses put forward to account for its extensive distribution using DNA sequences from the mitochondrial 16S rRNA gene region. Results of phylogenetic analyses contradicted previous allozyme data and revealed relatively deep phylogenetic structure in the form of three geographically correlated clades. The degree of genetic divergences between clades (8–15 bp) contrasted with the relatively limited haplotype diversity within clades (1–3 bp). Network-based analyses confirmed these results and revealed genetic structure on both larger and more restricted geographical scales. Nevertheless some haplotypes and 1-step clades had large distributions, some of which crossed boundaries between river basins and aquatic biogeographical regions. Thus both older and more recent historical processes, including fragmentation on a larger geographical scale and more recent range expansion on a local scale, appear to be responsible for the observed pattern of genetic variation within C. destructor . These results support elements of alternative hypotheses previously put forward to account for the evolutionary history of C. destructor and the origin of its large distribution.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 539–550.     

The biology and evolution of the reproductive cycle of Miniopterus schreibersii and M. australis (Chiroptera: Vespertilionidae)

The reproductive biology of Miniopterus schreibersii and M. australis was studied at latitude 28·5°S, in eastern Australia. Comparison was made with material from 23·5°S to 37°S.
Both species are monoestrous and monotocous. Ovulation is from the left ovary and implantation is in the right cornu. At latitude 28·5°S, a "silent heat" precedes behavioural oestrus and fertilization by two months in M. schreibersii and three months in M. australis. In M. schreibersii copulation and fertilization occur in late May and early June, immediately after a relatively short period of spermatogenesis and about one month after the release of sperm to the epididymides. During winter, implantation of the blastocyst stage is delayed. The male accessory glands involute but a store of epididymal sperm is retained. Implantation occurs in August and birth is in December.
M. australis conceives in mid-August, after an extended period of spermatogenesis which ceases four to six weeks prior to copulation. An epididymal sperm store is present some 21/2 months prior to insemination. Implantation has occurred by mid-September and parturition takes place in December.
Comparative data from other latitudes in eastern Australia show no differences in the timing of a reproductive events of M. australis between 23·5°S and 31°S. In M. schreibersii in South Australia (37°S) mating occurs in April and May. Plasticity in the timing of parturition (October to December) and other anomalies of this population are discussed.
The data suggest that evolutionary hypotheses involving extrapolation from one species to the other are questionable and that a more complex and varied adaptive response to climate may exist than has hitherto been supposed.     

The cardiac innervation of a marsupial heterotherm,the fat-tailed dunnart (Sminthopsis crassicaudata)

This study investigated the pattern of autonomic innervation of the heart of the fat-tailed dunnart (Sminthopsis crassicaudata) using isolated cardiac preparations. While the pattern of autonomic innervation of the atria was consistent with that found in other mammals, the ventricles displayed an unusual pattern of mammalian cardiac innervation. Transmural stimulation of the intramural nerves of isolated right ventricular preparations caused a decrease in the force of contraction of 46.8+/-3.2% followed by a rebound increase in the force of contraction beyond basal levels of 40.9+/-6.9%. These responses could be blocked independently by the application of the muscarinic receptor antagonist hyoscine and beta-adrenoreceptor antagonist propranolol respectively and could also be mimicked by the application of the agonists acetylcholine (Ach) and noradrenaline (NA). These findings indicated the presence of a functional cholinergic innervation of the ventricles that was capable of reducing the force of contraction below basal levels. This pattern of innervation has only been found previously in one other mammal, the bent-winged bat (Miniopterus schreibersii). Given that both of these species are heterotherms, it is possible that such a pattern of innervation may relate to the control of cardiac output during torpor. These findings are the first that demonstrate the homogeneity of a physiological control mechanism in a so-called 'shallow, daily torpidator' (S. crassicaudata) and a 'deep hibernator' (M. schreibersii) that is absent in mammalian homeotherms. These findings are consistent with recent work suggesting that there may be little difference between these types of heterothermy.     

Effects of mode of reproduction on genetic divergence over large spatial and temporal scales in intertidal snails of the genus Bembicium Philippi (Gastropoda: Littorinidae)

The littorine genus Bembicium , restricted to Australia and Lord Howe and Norfolk Islands, provides special opportunities to examine the effects of contrasting modes of development on genetic divergence over large spatial and temporal scales. Two species, Bembicium auratum and Bembicium nanum , have planktotrophic larvae, and large, overlapping geographical distributions, whereas the three direct developers, Bembicium vittatum , Bembicium melanostoma , and Bembicium flavescens , are geographical replacements. Phylogenetic analysis of genetic distances at 28 allozyme loci supported the current taxonomic treatment of the genus and monophyly of the direct developers. Both individually and as a clade, the direct developers showed substantially greater divergence than the species with planktotrophic larvae. Controlling for geographical distance and for particular sections of coastline, genetic subdivision within the direct developers was shown to be much higher than in the planktotrophs. Low levels of subdivision in B. auratum and B. nanum over distances of 4000–6800 km indicate maintenance of substantial genetic connectivity, independent of habitat and biogeographical history. By contrast, the direct developers show clear genetic impacts of their geographical histories. Despite extreme genetic subdivision within species, the direct developers B. vittatum and B. melanostoma have geographically coherent and complementary distributions, associated with biogeographical provinces. Thus, speciation appears to be driven by special biogeographical circumstances, rather than simply by genetic divergence of locally isolated populations.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 689–704.     

Evolutionary history of the fish genus <Emphasis Type="Italic">Astyanax</Emphasis> Baird &; Girard (1854) (Actinopterygii,Characidae) in Mesoamerica reveals multiple morphological homoplasies

Background  

Mesoamerica is one of the world's most complex biogeographical regions, mostly due to its complex geological history. This complexity has led to interesting biogeographical processes that have resulted in the current diversity and distribution of fauna in the region. The fish genus Astyanax represents a useful model to assess biogeographical hypotheses due to it being one of the most diverse and widely distributed freshwater fish species in the New World. We used mitochondrial and nuclear DNA to evaluate phylogenetic relationships within the genus in Mesoamerica, and to develop historical biogeographical hypotheses to explain its current distribution.     

The vestigial teeth of Miniopterus schreibersii natalensis (Mammalia: Chiroptera)

Miniopterus schreibersii nufalensis has a vestigial tooth on both sides of the upper jaw between the canine and following premolar. This tooth is regarded as permanent premolar P² in vestigial form.     

Phylogenomics,biogeography, and evolution of morphology and ecological niche of the eastern Asian–eastern North American Nyssa (Nyssaceae)

Nyssa (Nyssaceae, Cornales) represents a classical example of the well‐known eastern Asian–eastern North American floristic disjunction. The genus consists of three species in eastern Asia, four species in eastern North America, and one species in Central America. Species of the genus are ecologically important trees in eastern North American and eastern Asian forests. The distribution of living species and a rich fossil record of the genus make it an excellent model for understanding the origin and evolution of the eastern Asian–eastern North American floristic disjunction. However, despite the small number of species, relationships within the genus have remained unclear and have not been elucidated using a molecular approach. Here, we integrate data from 48 nuclear genes, fossils, morphology, and ecological niche to resolve species relationships, elucidate its biogeographical history, and investigate the evolution of morphology and ecological niches, aiming at a better understanding of the well‐known EA–ENA floristic disjunction. Results showed that the Central American (CAM) Nyssa talamancana was sister to the remaining species, which were divided among three, rapidly diversified subclades. Estimated divergence times and biogeographical history suggested that Nyssa had an ancestral range in Eurasia and western North America in the late Paleocene. The rapid diversification occurred in the early Eocene, followed by multiple dispersals between and within the Erasian and North American continents. The genus experienced two major episodes of extinction in the early Oligocene and end of Neogene, respectively. The Central American N. talamancana represents a relic lineage of the boreotropical flora in the Paleocene/Eocene boundary that once diversified in western North America. The results supported the importance of both the North Atlantic land bridge and the Bering land bridge (BLB) for the Paleogene dispersals of Nyssa and the Neogene dispersals, respectively, as well as the role of Central America as refugia of the Paleogene flora. The total‐evidence‐based dated phylogeny suggested that the pattern of macroevolution of Nyssa coincided with paleoclimatic changes. We found a number of evolutionary changes in morphology (including wood anatomy and leaf traits) and ecological niches (precipitation and temperature) between the EA–ENA disjunct, supporting the ecological selection driving trait evolutions after geographic isolation. We also demonstrated challenges in phylogenomic studies of lineages with rapid diversification histories. The concatenation of gene data can lead to inference of strongly supported relationships incongruent with the species tree. However, conflicts in gene genealogies did not seem to impose a strong effect on divergence time dating in our case. Furthermore, we demonstrated that rapid diversification events may not be recovered in the divergence time dating analysis using BEAST if critical fossil constraints of the relevant nodes are not available. Our study provides an example of complex bidirectional exchanges of plants between Eurasia and North America in the Paleogene, but “out of Asia” migrations in the Neogene, to explain the present disjunct distribution of Nyssa in EA and ENA.     

Molecular phylogenetics and diversification of the genus Sporophila (Aves: Passeriformes)

The evolutionary affinities within and among many groups of nine-primaried oscines remain unresolved. One such group is Sporophila, a large genus of New World tanager-finches. Our study focused particularly on clarifying the relationship between this genus and a closely related one, Oryzoborus, and on examining the phylogenetic affinities of the "capuchinos," a group of 11 Sporophila species that share a similar male plumage coloration pattern. Our phylogenetic analyses, based on 498 bp of mitochondrial DNA sequence, indicated that: (1) Oryzoborus is embedded within a well-supported clade containing all Sporophila species, which strongly suggests that both genera should be merged, (2) the species of capuchinos comprise a monophyletic group, implying that the plumage patterns common to all probably arose only once, and (3) the capuchinos clade is comprised of two sub-clades, one including two species that are distributed in northern South America and the other one containing eight species that are present south of the Amazon River. Mean sequence divergence among the southern capuchinos species was extremely low, suggesting a rapid radiation within the last half-million years that may be related to the high level of sexual selection present in the genus and might have been promoted by marine ingressions and egressions that occurred in some southern coastal regions of South America in the Late Pleistocene.     

A histological study of the early stages of pregnancy in the bent-winged bat (Miniopterus schreibersii) in north-eastern New South Wales, Australia (30° 27'S)

A histological study of Miniopterus schreibersii was carried out in north-eastern New South Wales from April to September 1975. Reproductive tracts were examined from a total of 43 females collected during autumn and winter from three bat colonies in the New England region, Australia.
Copulation, ovulation and fertilization appeared synchronized over a one to two week period amongst all females observed. The conceptus developed to a blastocyst stage prior to commencement of hibernation and remained unattached during at least part of the hibernation period. Unlike populations from the south of France, implantation occurred before hibernation was completed, prior to resumption of regular activity and was not accompanied by an increase in corpus luteum development. The disparity in corpus luteum morphology and activity, suggests that mechanisms of control of delayed implantation in Australian M. schreibersii may differ from those proposed for populations from the south of France.     

The evolutionary history of Melianthus (Melianthaceae)

The evolutionary origins of the morphological and taxonomic diversity of angiosperms is poorly known. We used the genus Melianthus to explore the diversification of the southern African flora. Melianthus comprises eight species, and a phylogeny based on one nuclear and two plastid genes, as well as a morphological data set, confirmed that the genus is monophyletic. The two earliest diverging lineages are found in relatively mesic habitats, whereas the two terminal clades (an eastern and a western clade), each with three species, favor more arid habitats. The eastern clade is largely restricted to the summer-rainfall parts of southern Africa, and the western clade is found in winter-rainfall region. Molecular dating indicates a mid-Tertiary origin of the genus, with diversification of the eastern and western clades coincident with the Late Miocene-Pliocene uplift of the Escarpment mountains and the establishment of summer aridity along the west coast. The remarkably complex flowers are indicative of sunbird pollination, but many smaller birds can also visit. Speciation may be the consequence of allopatric divergence into edaphic-climatic niches. Divergence in flower and inflorescence morphology might be in response to the divergent pressures for nectar conservation in arid regions coupled with the need for signaling to avian pollinators in generally shrubby vegetation.     

The historical biogeography of the southern group of the sucker genus Moxostoma (Teleostei: Catostomidae) and the colonization of central Mexico

The historical biogeography of the southern group of Moxostoma Rafinesque, 1820, a genus of Nearctic freshwater fishes belonging to the Catostomidae, along its entire distribution in North America was inferred to: (1) determine the biogeographical events responsible for its current pattern of diversity and distribution; (2) correlate the climatic and geologic history of the region with the biogeographical pattern observed; and (3) trace the colonization route into central Mexico and the western Pacific slope drainages. The sequences of mitochondrial cytochrome b and the third intron of the growth hormone were obtained for the members of the southern group and related species of the Catostomidae. Phylogenetic analyses and relaxed molecular clock analyses were performed to determine the relatedness of the species and to estimate divergence times. To uncover biogeographical patterns, a dispersal–extinction–cladogenesis (DEC) analysis was conducted. The phylogenetic analyses were consistent with the historical hydrographic scenario in the region. The divergence times show that the southern group evolved during the Pliocene–Pleistocene. The DEC analyses showed that vicariance and dispersal played an important role in the current distribution patterns of the lineages in central Mexico, and allow us to trace an independent route of colonization from the northern areas of North America into central Mexico.     

Spatial pattern of intraspecific mitochondrial diversity in the Northern Carpathian endemic spring snail, Bythinella pannonica (Frauenfeld, 1865) (Gastropoda: Hydrobiidae)

Bythinella is a species-rich genus of spring-snails, having a wide range in Europe and Asia Minor. The genus contains several endemic species with narrow ranges, creating interest from a conservation perspective as well as their use as a model for research into biogeographical patterns and evolutionary development. Most of the species of the genus Bythinella are difficult to distinguish by traditional methods due to their similar shell morphology. In previous studies, molecular approaches often came to conclusions that contradicted those from a morphology-based approach, hence the classification of species of Bythinella has been in dispute. Bythinella pannonica has clearly distinct shell morphological features, and consequently is one of the few species of undisputed taxonomic status within this genus. As an important step towards clarifying the systematics of this genus, we have attempted to describe the structure and spatial pattern of diversity of the mitochondrial COI marker within this species, in the hope of applying these findings generally to the whole genus. Molecular results support the monophyly of B. pannonica within the genus. The largest pairwise intraspecific COI sequence difference was almost 5 %, much larger than the value of 1.5 % previously proposed as a barcoding threshold for delimitation of Bythinella species. This finding suggests that incautious application of barcoding might lead to incorrect taxonomic conclusions. Within B. pannonica there are two deeply divergent intraspecific clades, the spatial distribution of which has been shaped by fragmentation, as well as by short and long distance dispersal events. These two clades have not been found syntopically but, as a peculiar feature of this taxon, they are able to persist in nearby habitats. We have demonstrated that the patchy distribution of suitable habitats and the restricted, but non-zero gene flow amongst the populations might play a key role in maintenance of the observed genetic structure of this species.     

Molecular phylogeny of the genus Apatrobus (Coleoptera: Carabidae: Patrobinae) in western Japan

We performed a molecular phylogenetic analysis of the ground beetles Apatrobus (Carabidae), endemic to Japan, using the mitochondrial cytochrome c oxidase subunit I (COI) and the nuclear 28S rRNA (28S) genes. We focused on the species divergence in Kyushu, Shikoku and western Honshu and used 15 of 19 species and three populations with undetermined species in the DNA analysis. The gene trees showed that, of the Apatrobus species studied, A. hayachinensis Nakane from northern Honshu was not included in the monophyletic group of the other Apatrobus species and likely to be of a different genus. Divergence time estimation suggested that Apatrobus species excluding A. hayachinensis diverged 5.2 million years ago and the subsequent divergence of species occurred during the Pliocene and Pleistocene. In each of the main islands, Kyushu, Shikoku and Honshu, two or more distinct lineages occurred and all species had restricted distribution areas, suggesting that ancient dispersal and vicariance among the three main islands resulted in the nested biogeographical pattern of species distribution.     

Molecular evidence of a peripatric origin for two sympatric species of field crickets (Gryllus rubens and G. texensis) revealed from coalescent simulations and population genetic tests

Species pairs that differ primarily in characters involved in mating interactions and are largely sympatric raise intriguing questions about the mode of speciation. When species divergence is relatively recent, the footprint of the demographic history during speciation might be preserved and used to reconstruct the biogeography of species divergence. In this study, patterns of genetic variation were examined throughout the geographical range of two cryptic sister taxa of field crickets, Gryllus texensis and G. rubens; mitochondrial cytochrome oxidase I (COI) was sequenced in 365 individuals sampled from 48 localities. Despite significant molecular divergence between the species, they were not reciprocally monophyletic. We devised several analyses to statistically explore what historical processes might have given rise to this genealogical structure. The analyses indicated that the biogeographical pattern of genetic variation does not support a model of recent gene flow between species. Instead, coalescent simulations suggested that the genealogical structure within G. texensis, namely a deep split between two geographically overlapping clades, reflects historical substructure within G. texensis. Additional tests that consider the concentration of G. rubens haplotypes in one of the two G. texensis genetic clusters suggest a model of speciation in which G. rubens was derived from one lineage of a geographically subdivided ancestor. These results indicate that, despite the contemporary sympatry of G. texensis and G. rubens, the data are indicative of an peripatric origin in which G. rubens was derived from one of the two historical partitions in the species currently recognized as G. texensis. This proposed model of species divergence suggests how the interplay of geography and selection may give rise to new species, although this requires testing with multilocus data. Specifically, the model highlights how that geographical partitioning of ancestral variation in the past may augment the selectively driven divergence of characters involved in the reproductive isolation of the species today.     

Distribution pattern and radiation of the European subterranean genus Verhoeffiella (Collembola,Entomobryidae)

One of the most striking features of obligate subterranean species is their narrow distribution ranges. These prevail not only at specific, but often also at generic level. However, some subterranean genera have continental scale and disjunct distribution, which challenges their monophyly and questions the scenarios of their origin and colonization. In our study, we investigated the subterranean collembolan genus Verhoeffiella, currently known from five remote karst regions of Europe. Four nuclear and one mitochondrial genes were assembled to reveal the evolutionary history of the genus. We tested the monophyly of the genus, explored its relationship with putative surface relatives, and its temporal patterns of molecular diversification. The phylogeny revealed a complex relationship of Verhoeffiella with surface species Heteromurus nitidus and partially disentangled the biogeographical question of its disjunct distribution. Further on, several lineages of Verhoeffiella were recognized in the Dinarides, showing highly underestimated diversity and, compared with the number of described species, a sevenfold increase in the number of MOTUs. The radiation is relatively recent, with the events triggering the diversification linked to the Messinian salinity crisis and Pleistocene climatic shifts. The combination of this extensive subterranean radiation and close evolutionary links with epigean relatives makes Verhoeffiella an exceptional case within the subterranean fauna of temperate areas, which significantly contributes to our understanding of subterranean colonization and diversification patterns.     

Phylogeny and biogeography Eupholidoptera Mařan (Orthoptera,Tettigoniidae): morphological speciation in correlation with the geographical evolution of the eastern Mediterranean

Recently, the systematics and biogeography of the Mediterranean biota have received much attention. This paper deals with Eupholidoptera Ma?an, a Mediterranean lineage of Tettigoniidae. The genus is restricted to the northern and eastern basin of the Mediterranean, with a significant number of species found on the Aegean islands. To produce a phylogeny and use it to make assumptions about the historical biogeography of Eupholidoptera, material of 46 species from several collections was studied. A phylogenetic analysis based mainly on morphological characters suggested two lineages in the genus: the E. chabrieri and the E. prasina groups. Based on the consistency between historical geographical events and branching events on the phylogenetic tree, Eupholidoptera is assumed to have evolved from an ancestor present in the Aegeid plate in the Mid‐Miocene. The division of the Aegeid plate into Anatolia and Greece in the Tortonian, the reoccurrence of terrestrial corridors between these mainlands in the Messinian, the regression of the Aegean area in the Pliocene and sea level changes in the Pleistocene are assumed to have been the main palaeogeographical events directing speciation in Eupholidoptera. As most of the species are allopatric, vicariance is suggested to be the main pattern. By combining the nature of the characters used in the phylogenetic analysis, the phylogenetic tree produced and the biogeographical assumptions, four tentative conclusions can be made: (i) radiation in the genus is a result of divergence in morphology; (ii) because the main character source is male genitalia, there has possibly been intensive sexual selection, which leads to morphological speciation; (iii) as the difference in temporal parameters of the song is prominent in sympatric/parapatric species pairs only, co‐occurrence is suggested to be the main reason driving divergence in the song; (iv) there seems to be a negative correlation between the size of the distribution range and the evolutionary rate in speciation; this may be the reason why the E. prasina group (restricted to a small part of the range of the genus) is more diverse than the E. chabrieri group, which is distributed over the entire range.     

Molecular phylogenetics, historical biogeography, and chromosome number evolution of Portulaca (Portulacaceae)

Portulaca is the only genus in Portulacaceae and has ca. 100 species distributed worldwide, mainly in the tropics and subtropics. Molecular data place the genus as one of the closest relatives of Cactaceae, but phylogenetic relationships within Portulaca are barely known. This study samples 59 species of Portulaca, 10 infraspecific taxa, and three cultivars, including multiple samples of widespread species. The sampled taxa represent all subgenera in the classifications of von Poellnitz (1934), Legrand (1958), and Geesink (1969) and come from around the world. Nuclear ITS and chloroplast ndhF, trnT-psbD intergenic spacer, and ndhA intron DNA sequences were analyzed using maximum likelihood and Bayesian methods to produce a hypothesis of relationships within Portulaca. Divergence times were estimated using Hawaiian endemics for calibration, and biogeographical patterns were examined using a Bayes-DIVA approach. In addition, the evolution of chromosome numbers in the genus was investigated using probabilistic models. The analyses strongly support the monophyly of Portulaca, with an age of the most recent common ancestor (MRCA) of 23 Myr. Within Portulaca are two major lineages: the OL clade (comprising opposite-leaved species) distributed in Africa, Asia, and Australia, and the AL clade (comprising alternate to subopposite-leaved species), which is more widespread and originated in the New World. Sedopsis, a genus sometimes recognized as distinct from Portulaca based on a long corolla tube, is nested within the OL clade and does not merit taxonomic recognition. Samples of Portulaca grandiflora, Portulaca halimoides, and Portulaca oleracea were found to be non-monophyletic. It is hypothesized that the ancestral distribution area of Portulaca included southern hemisphere continents and Asia. The OL clade remained restricted to the Old World (except Portulaca quadrifida, a pantropical weed), while the AL clade, with a South American origin, was able to disperse multiple times to other continents. The base chromosome number for Portulaca is inferred to be x=9, although the analysis was primarily based on the available data for the AL clade. A number of chromosome number change events (polyploidization, demi-polyploidization, gain, and loss) were shown to have occurred in the genus, especially within the Oleracea clade.