Geographic and phylogenetic evidence for dispersed nuclear introgression in a daphniid with sexual propagules

The role of among-species gene flow in eukaryotic evolution remains controversial. Putative hybrid lineages are common in water fleas, but their ecological success is often associated with polyploidy and the production of asexual propagules. Advanced hybrid lineages with sexual propagules are expected to be geographically restricted because their successful dispersal is contingent on overcoming fertility complications, assimilation by parent taxa, and competition with parent taxa. Here we provide evidence that a diploid lineage of Daphnia has been formed by introgression between distantly related species and attained a broad distribution (Nearctic) despite its requirement for sexual propagules. The evidence is based on geographical discordance, phylogenetic discordance, recombinant genotypes and additive genotypes of the nuclear internal transcribed spacer regions (ITS) and mitochondrial DNA. Additive genotypes also provided evidence of hybridization between introduced European Daphnia and North American Daphnia. We argue that the unique biology of Holarctic lacustrine water fleas and the spatial separation of lineages during Pleistocene glaciation have promoted hybridization and its evolutionary consequences.     

Historical biogeography, divergence times, and diversification patterns of bumble bees (Hymenoptera: Apidae: Bombus)

Bumble bees (Bombus) are a cold-adapted, largely alpine group that can elucidate patterns of Holarctic historical biogeography, particularly in comparison to the alpine plants with which they likely coevolved. A recently published molecular phylogeny of bumble bees provides uniquely comprehensive species sampling for exploring historical patterns of distribution and diversification. Using this phylogeny and detailed data on extant distributions, I reconstruct the historical distribution of bumble bees in a temporal framework, estimating divergence times using fossil data and molecular rates derived from the literature. The nearly comprehensive phylogeny allows assessment of the tempo of diversification within the bumble bees using lineage-through-time plots and diversification statistics, which have been performed with special consideration to confidence intervals. These analyses reveal movements of Bombus concordant with geographic and climatic events of the late Cenozoic. The initial diversification of extant bumble bee lineages was estimated at around 25 to 40 Ma, near the Eocene-Oligocene boundary 34 Ma, a period of dramatic global cooling. Dispersal-vicariance analysis (DIVA) predicted an Old World Bombus ancestor, with early diversification events largely restricted to the eastern Old World. The numerous intercontinental dispersal events occurred mostly in the direction of Old World to New World and North America to South America. Early movements from the Palearctic into the Nearctic most likely took place after 20 Ma and may have coincided with a period of Miocene cooling that gave rise to taiga habitat across Beringia. Subsequent dispersal between these regions is estimated to have occurred among boreal and tundra-adapted species mostly in the last 5 million years. Radiations are estimated in both Nearctic and Neotropical regions at approximately 6 to 8 Ma and after 3.5 Ma, concordant with the opening of land corridors between the continents.     

Genetic signatures of intermediate divergence: population history of Old and New World Holarctic ravens (Corvus corax)

Many studies of phylogeography, speciation, and species limits restrict their focus to a narrow issue: gene tree monophyly. However, reciprocal monophyly does not provide an ideal touchstone criterion of any aspect of evolutionary divergence. There is a continuum of divergence stages as isolated populations go from initial allele frequency differences to well-differentiated species. Studying intermediate stages of divergence will increase our understanding of geographical speciation, species limits, and conservation priorities. We develop a conceptual framework and terminology for thinking about the stages of 'intermediate polyphyly'. The Holarctic clade of common ravens (Corvus corax), found throughout much of Eurasia and North America, provides a case study of these stages of intermediate divergence. We used coalescent, phylogenetic, and population genetic methods to investigate the history and current status of this Old World-New World distribution using 107 mitochondrial control region sequences. Phylogenetically, New World and Old World samples are intermixed. However, most samples are grouped into small subclades that are restricted to either the New World or the Old World, and only one haplotype is shared between the hemispheres. Analysis of moleculalr variance (amova) results reflect this low haplotype sharing between hemispheres (Phi(ST) = 0.13, P < 0.01). Isolation with Migration (im) coalescent results suggest a sustained period of divergence between the hemispheres and low levels of maternal gene flow. Although there has not been sufficient time to evolve reciprocal monophyly and some gene flow may occur, New World and Old World ravens are genetically quite distinct. We use this example to demonstrate these early stages of divergence as populations go from sharing only internal haplotypes, to sharing no haplotypes, to having population specific subclades. Studies of phylogeography, speciation and systematics will benefit from increased attention to these stages of intermediate polyphyly.     

Biogeography of Old World emballonurine bats (Chiroptera: Emballonuridae) inferred with mitochondrial and nuclear DNA

Extant bats of the genus Emballonura have a trans-Indian Ocean distribution, with two endemic species restricted to Madagascar, and eight species occurring in mainland southeast Asia and islands in the western Pacific Ocean. Ancestral Emballonura may have been more widespread on continental areas, but no fossil identified to this genus is known from the Old World. Emballonura belongs to the subfamily Emballonurinae, which occurs in the New and Old World. Relationships of all Old World genera of this subfamily, including Emballonura and members of the genera Coleura from Africa and western Indian Ocean islands and Mosia nigrescens from the western Pacific region, are previously unresolved. Using 1833 bp of nuclear and mitochondrial genes, we reconstructed the phylogenetic history of Old World emballonurine bats. We estimated that these lineages diverged around 30 million years ago into two monophyletic sister groups, one represented by the two taxa of Malagasy Emballonura, Coleura and possibly Mosia, and the other by a radiation of Indo-Pacific Emballonura, hence, rendering the genus Emballonura paraphyletic. The fossil record combined with these phylogenetic relationships suggest at least one long-distance dispersal event across the Indian Ocean, presumably of African origin, giving rise to all Indo-Pacific Emballonura species (and possibly Mosia). Cladogenesis of the extant Malagasy taxa took place during the Quaternary giving rise to two vicariant species, E. atrata in the humid east and E. tiavato in the dry west.     

Dynamic colonization exchanges between continents and islands drive diversification in paradise‐flycatchers (Terpsiphone,Monarchidae)

Aim We use parametric biogeographical reconstruction based on an extensive DNA sequence dataset to characterize the spatio‐temporal pattern of colonization of the Old World monarch flycatchers (Monarchidae). We then use this framework to examine the role of dispersal and colonization in their evolutionary diversification and to compare plumages between island and continental Terpsiphone species. Location Africa, Asia and the Indian Ocean. Methods We generate a DNA sequence dataset of 2300 bp comprising one nuclear and three mitochondrial markers for 89% (17/19) of the Old World Monarchidae species and 70% of the Terpsiphone subspecies. By applying maximum likelihood and Bayesian phylogenetic methods and implementing a Bayesian molecular clock to provide a temporal framework, we reveal the evolutionary history of the group. Furthermore, we employ both Lagrange and Bayes‐ Lagrange analyses to assess ancestral areas at each node of the phylogeny. By combining the ancestral area reconstruction with information on plumage traits we are able to compare patterns of plumage evolution on islands and continents. Results We provide the first comprehensive molecular phylogenetic reconstruction for the Old World Monarchidae. Our phylogenetic results reveal a relatively recent diversification associated with several dispersal events within this group. Moreover, ancestral area analyses reveal an Asian origin of the Indian Ocean and African clades. Ancestral state reconstruction analyses of plumage characters provide an interpretation of the plumage differentiation on islands and continents. Ancestral plumage traits are inferred to be close to those of the Asian paradise‐flycatcher (Terpsiphone paradisi), and island species display a high degree of plumage autapomorphy compared with continental species. Main conclusions Terpsiphone paradisi is polyphyletic and comprises populations that have retained the ancestral plumage of the widespread Terpsiphone genus. The genus appears to have colonized south‐west Asia, the Indian Ocean and Africa from eastern Asia. The phylogeny and divergence time estimates indicate multiple simultaneous colonizations of the western Old World by Terpsiphone. These results reinforce a hypothesis of range expansions of a Terpsiphone paradisi‐like ancestor into eastern Asia and the western Old World.     

Diversification of subgenus Calathus (Coleoptera: Carabidae) in the Mediterranean region – glacial refugia and taxon pulses

Aim To investigate the effects of Pleistocene climatic variations on the diversification rate of the subgenus Calathus (Coleoptera: Carabidae), and to estimate the role of vicariance and dispersal for explaining current distributional patterns. Location Western Palaearctic Region, particularly the Mediterranean Basin. Methods Fragments of the mitochondrial cox1–cox2 and the nuclear 28S and EF1α genes were analysed by Bayesian inference. Lineage divergence times were estimated using a Bayesian relaxed molecular clock. Three diversification rate analyses were conducted, namely gamma (γ)‐statistic, birth–death likelihood (BDL) test and survival analyses, in order to test departures from a constant rate model of diversification. A Bayesian approach to dispersal–vicariance analysis was developed to reconstruct the most probable ancestral area of subgenus Calathus and subsequent events of dispersal and colonization. Results A constant rate of speciation events from the late Miocene onwards was found for the subgenus Calathus, whereas recent Pleistocene climatic oscillations played an important role only in shaping intraspecific diversity. Overall diversification patterns for the subgenus are best explained by at least four westward dispersal events from the eastern Mediterranean Basin. Three distinct phylogroups were found for the widely distributed Calathus fuscipes. Incongruence between mitochondrial and nuclear loci was found for a number of species. Main conclusions Diversification analyses suggest either a constant rate of diversification (BDL analysis) or a decrease in diversification rates for the subgenus (survival or γ‐statistics analyses), but not an increase related to the effects of glaciation cycles. Diversification patterns in the subgenus Calathus agree with predictions of the taxon pulse model. From the middle Miocene onwards the Anatolian Peninsula was possibly the main centre of diversification, with successive dispersal events towards the western Mediterranean Basin. Range expansion and secondary contact zones are postulated between members of different phylogroups in C. fuscipes.     

Phylogenetics and Evolution of theDaphnia longispinaGroup (Crustacea) Based on 12S rDNA Sequence and Allozyme Variation

Although members of the crustacean genusDaphniahave been the target of much research, there is little understanding of the group's evolutionary history. We addressed this gap by inferring a phylogeny for one of the major species groups (longispina) using nucleotide sequence variation of a 525-bp segment of the mitochondrial 12S rDNA and allozyme variation at 21 loci. We identified the major lineages and their relationships, assessed the phylogenetic utility of the few morphological characters in the group, and examinedDaphniaphylogeography. Nuclear and mtDNA phylogenies were generally concordant in recognizing the same four species complexes. An exception was the position ofDaphnia galeata mendotae.The allozyme tree paired this species with theDaphnia rosealineage, whereas the mtDNA trees groupedD. g. mendotaewithDaphnia galeata galeata.This discordance was consistent with the reticulate evolution of nuclear genes supporting the hypothesis thatD. g. mendotaerepresents a case of homoploid hybrid speciation. Striking morphological stasis in thelongispinagroup was evidenced by its very limited morphological divergence over an estimated 100 MY, and by the unusual transitional saturation of the conservative 12S rRNA gene within a species group. Phylogenetic inference also provided evidence that similarities in cephalic crest shape likely resulted from convergent or parallel evolution among species. Endemism at the continental level was indicated for previously cosmopolitan species, but the estimated times of these divisions were inconsistent with vicariance events suggesting recent dispersal among continents. A significant role for divergent selection in new habitats during speciation was suggested by the neighboringly sympatric distributions of four sister species pairs over broad geographic areas.     

Molecular genetic diagnostics of some Daphnia species (Crustacea,Cladocera) from the Volga river

Population genetic structure of the widespread Daphnia species from Kuibyshev and Saratov reservoirs was examined by use of RAPD-PCR technique with four mitochondrial DNA (16S rRNA) specific primers. One of the examined Daphnia clones from the Volga region appeared to be conspecific to the North American Daphnia galeata, while another clone was most likely a hybrid between D. galeata and D. cucullata.     

Inverse dispersal patterns in a group of ant parasitoids (Hymenoptera: Eucharitidae: Oraseminae) and their ant hosts

When postulating evolutionary hypotheses for diverse groups of taxa using molecular data, there is a tradeoff between sampling large numbers of taxa with a few Sanger-sequenced genes or sampling fewer taxa with hundreds to thousands of next-generation-sequenced genes. High taxon sampling enables the testing of evolutionary hypotheses that are sensitive to sampling bias (i.e. dating, biogeography and diversification analyses), whereas high character sampling improves resolution of critical nodes. In a group of ant parasitoids (Hymenoptera: Eucharitidae: Oraseminae), we analyse both of these types of datasets independently (203 taxa with five Sanger loci, 92 taxa with 348 anchored hybrid enrichment loci) and in combination (229 taxa, 353 loci) to explore divergence dating, biogeography, host relationships and differential rates of diversification. Oraseminae specialize as parasitoids of the immature stages of ants in the subfamily Myrmicinae (Hymenoptera: Formicidae), with ants in the genus Pheidole being their most common and presumed ancestral host. A general assumption is that the distribution of the parasite must be limited by any range contraction or expansion of its host. Recent studies support a single New World to Old World dispersal pattern for Pheidole at c. 11–27 Ma. Using multiple phylogenetic inference methods (parsimony, maximum likelihood, dated Bayesian and coalescent analyses), we provide a robust phylogeny showing that Oraseminae dispersed in the opposite direction, from Old World to New World, c. 24–33 Ma, which implies that they existed in the Old World before their presumed ancestral hosts. Their dispersal into the New World appears to have promoted an increased diversification rate. Both the host and parasitoid show single unidirectional dispersals in accordance with the presence of the Beringian Land Bridge during the Oligocene, a time when the changing northern climate probably limited the dispersal ability of such tropically adapted groups.     

Repeat intercontinental dispersal and Pleistocene speciation in disjunct Mediterranean and desert Senecio (Asteraceae)

To explore the biogeographic history of Mediterranean/arid plant disjunctions, Old and New World Senecio sect. Senecio were analyzed phylogenetically using nuclear ribosomal DNA sequences (ITS). A clade corresponding to sect. Senecio was strongly supported. Area optimization indicated this clade to be of southern African origin. The Mediterranean and southern African floras were not distinguishable as sources of the main New World lineage, estimated to have become established during the middle Pliocene. Another previously suspected recent dispersal to the New World from the Mediterranean was confirmed for the recently recognized disjunction in S. mohavensis. The loss of suitable land connections by the Miocene means that both New World lineages must represent long-distance dispersal, providing the first evidence of repeat intercontinental dispersal in a Mediterranean group. In contrast, migration within Africa may have utilized an East African arid corridor. Recent dispersal to northern Africa is supported for S. flavus, which formed part of a distinct southern African lineage. Novel pappus modifications in both disjunct species may have enabled dispersal by birds. An estimated early Pliocene origin of sect. Senecio coincides with the appearance of summer-dry climate. However, diversification from 1.6 BP highlights the importance of Pleistocene climate fluctuations for speciation.     

Ice age cloning--comparison of the Quaternary evolutionary histories of sexual and clonal forms of spiny loaches (Cobitis; Teleostei) using the analysis of mitochondrial DNA variation

Recent advances in population history reconstruction offered a powerful tool for comparisons of the abilities of sexual and clonal forms to respond to Quaternary climatic oscillations, ultimately leading to inferences about the advantages and disadvantages of a given mode of reproduction. We reconstructed the Quaternary historical biogeography of the sexual parental species and clonal hybrid lineages within the Europe-wide hybrid complex of Cobitis spiny loaches. Cobitis elongatoides and Cobitis taenia recolonizing Europe from separated refuges met in central Europe and the Pontic region giving rise to hybrid lineages during the Holocene. Cobitis elongatoides due to its long-term reproductive contact with the remaining parental species of the complex--C. tanaitica and C. spec.--gave rise to two clonal hybrid lineages probably during the last interglacial or even earlier, which survived the Würmian glaciation with C. elongatoides. These lineages followed C. elongatoides postglacial expansion and probably decreased its dispersal rate. Our data indicate the frequent origins of asexuality irrespective of the parental populations involved and the comparable dispersal potential of diploid and triploid lineages.     

The demographic history of the New Zealand short-tailed bat Mystacina tuberculata inferred from modified control region sequences

Short-tailed bats Mystacina tuberculata were widespread throughout the forest that dominated prehuman New Zealand, but extensive deforestation has restricted them to scattered populations in forest fragments. In a previous study, the species' intraspecific phylogeny was investigated using multiple mitochondrial gene sequences. Six phylogroups were identified with estimated divergences of 0.93-0.68 Ma. In the current study, the phylogeographical structure and demographic history of the phylogroups were investigated using control region sequences modified by removing homoplasic sites. Phylogeographical structure in the North Island was generally consistent with an isolation-by-distance dispersal model. Coalescent-based analyses (i.e. mismatch distributions, skyline plots, lineage dispersal analysis and nested clade analysis) indicated that the three phylogroups found in central and southern North Island expanded before the last glacial maximum, presumably during interstadials when Nothofagus forest was most extensive. Genetic structure within a central North Island hybrid zone was consistent with range expansion from separate refugia following reforestation after catastrophic volcanic eruptions. Phylogeographical structure in the South Island was consistent with southern populations originating during rapid southward range expansion from refugia in northern South Island following postglacial reforestation of the South Island 10-9 kya.     

Evidence for Gondwanan vicariance in an ancient clade of gecko lizards

Aim Geckos (Reptilia: Squamata), due to their great age and global distribution, are excellent candidates to test hypotheses of Gondwanan vicariance against post‐Gondwanan dispersal. Our aims are: to generate a phylogeny of the sphaerodactyl geckos and their closest relatives; evaluate previous phylogenetic hypotheses of the sphaerodactyl geckos with regard to the other major gecko lineages; and to use divergence date estimates to inform a biogeographical scenario regarding Gondwanan relationships and assess the roles of vicariance and dispersal in shaping the current distributions of the New World sphaerodactyl geckos and their closest Old World relatives. Location Africa, Asia, Europe, South America, Atlantic Ocean. Methods We used parsimony and partitioned Bayesian methods to analyse data from five nuclear genes to generate a phylogeny for the New World sphaerodactyl geckos and their close Old World relatives. We used dispersal–vicariance analysis to determine ancestral area relationships among clades, and divergence times were estimated from the phylogeny using nonparametric rate smoothing. Results We recovered a monophyletic group containing the New World sphaerodactyl genera, Coleodactylus, Gonatodes, Lepidoblepharis, Pseudogonatodes and Sphaerodactylus, and the Old World Gekkotan genera Aristelliger, Euleptes, Quedenfeldtia, Pristurus, Saurodactylus and Teratoscincus. The dispersal–vicariance analysis indicated that the ancestral area for this clade was North Africa and surrounding regions. The divergence between the New World spaherodactyl geckos and their closest Old World relative was estimated to have occurred c. 96 Myr bp . Main conclusions Here we provide the first molecular genetic phylogenetic hypothesis of the New World sphaerodactyl geckos and their closest Old World relatives. A combination of divergence date estimates and dispersal–vicariance analysis informed a biogeographical scenario indicating that the split between the sphaerodactyl geckos and their African relatives coincided with the Africa/South America split and the opening of the Atlantic Ocean. We resurrect the family name Sphaerodactylidae to represent the expanded sphaerodactyl clade.     

Behaviour plasticity without learning: phenotypic and genetic variation of naïve Daphnia in an ecological trade-off

The swimming behaviour of adult Daphnia largely governs their depth, which has a direct effect on both individual foraging success and predation avoidance. We treated individual swimming behaviour as a threshold character and used directional changes in average clonal depth within experimental tubes as a test for character plasticity. We compared the swimming behaviours of two cohabiting, phenotypically similar Daphnia (Daphnia galeata and Daphnia galeata-Daphnia rosea hybrid) to determine (1) whether there is inherited variation (H(2)) for different traits (responses to hunger and predator cues); (2) whether changes in genetic parameters (norm of reaction and character state) across four environments could be simulated by combinations of the presence or absence of a predator cue and high or low hunger levels; and (3) whether these Daphnia would respond to directional selection, particularly in a trade-off environment (high hunger and predator cue treatments). Responses of both D. galeata and the D. galeata-rosea hybrid to hunger and a predator cue and the trade-off environment were plastic. Daphnia galeata expressed significant genetic variation within (H(2)) and between environments (heritability of plasticity). Both the character state and norm of reaction estimates of heritable variation in the hybrid were close to zero. Genetic correlations were positive and stable across six environmental pairs in Daphnia galeata. Most hybrid genetic correlations were not significant. The phenotypic distributions of both D. galeata and the hybrid were bimodal in the trade-off environment. The D. galeata distribution was partly due to between-clone variation and the hybrid distribution was almost entirely due to within-clone variation. Genetic variation expressed by D. galeata in the trade-off environment appears to depend on both clone by environment interactions and stable inherited differences. These results indicate that while plastic phenotypic responses cause a similar opportunity for selection in D. galeata and the hybrid, their responses to selection would be different in the trade-off and in related environments. Copyright 2000 The Association for the Study of Animal Behaviour.     

Quaternary Climate Change was Not an Engine of Diversification in New World Bats (Chiroptera)

Quaternary climate change has been hypothesized to have played a significant role in driving diversification rates in a variety of taxa. We test the hypothesis of increased rates of diversification during the Quaternary in nine groups of New World bats (Chiroptera). The fit of six models of diversification was determined for each group. None experienced an increase in net diversification, rejecting the Quaternary hypothesis. Instead, four groups experienced constant net diversification rates, suggesting no Quaternary climate change impact. Five groups are evolving under a density-dependent model of diversification, suggesting climate cycles may have reduced rates initiated during the Pliocene or late Miocene. The distribution of divergences between sister taxa is consistent with results obtained from avian lineages experiencing declining rates of Quaternary diversification, further discrediting this often invoked hypothesis. Our results suggest that Quaternary climate change did not increase diversification rates in New World bats.     

Modes and mechanisms of a Daphnia invasion

Whether exotic species invade new habitats successfully depends on (i) a change in the invaded habitat that makes it suitable for the invader and (ii) a genetic change in the invading taxon that enhances its fitness in the new habitat, or both. We dissect the causes of invasions of Swiss lakes, north of the Alps, by Daphnia galeata (a zooplankter typical of eutrophic lakes, e.g. those south of the Alps, which are also warmer) by comparing the fitness performance of eight geographically distributed clones that were fed algal-food typical of oligotrophic versus eutrophic conditions at two temperatures. Daphnia longispina, native to oligotrophic Swiss lakes, served as a reference. Daphnia galeata requires eutrophic food to persist, whereas D. longispina survives and grows on oligotrophic food but does even better on eutrophic food. Invasion by D. galeata is further explained because invading clones from the north perform better on eutrophic food and at cooler temperatures than native clones from the south, suggesting a local response to countergradient selection. Our data support the hypothesis that populations of the invader in northern lakes are dominated by well-adapted genotypes. Our results illustrate how environmental change (i.e. eutrophication) and local adaptation can act together to drive a successful invasion.     

Multilocus phylogeography of a holarctic duck: colonization of north america from eurasia by gadwall (Anas strepera)

More than 100 species of birds have Holarctic distributions extending across Eurasia and North America, and many of them likely achieved these distributions by recently colonizing one continent from the other. Mitochondrial DNA (mtDNA) and five nuclear introns were sequenced to test the direction and timing of colonization for a Holarctic duck, the gadwall (Anas strepera). Three lines of evidence suggest gadwalls colonized North America from Eurasia. First, New World (NW) gadwalls had fewer alleles at every locus and 61% of the allelic richness found in Old World (OW) gadwalls. Second, NW gadwalls had lower mtDNA allelic richness than other NW ducks. Third, coalescent analysis suggested that less than 5% of the ancestral population contributed to NW gadwalls at the time of divergence. Gadwalls likely colonized North America during the Late Pleistocene (approximately 81,000 years ago), but the confidence interval on that estimate was large (8500-450,000 years ago). Intercontinental gene flow and selection also likely contributed to genetic diversity in gadwalls. This study illustrates the use of multiple loci and coalescent analyses for critically testing a priori hypotheses regarding dispersal and colonization and provides an independent datapoint supporting an OW to NW bias in the direction of colonization.     

Canary Grasses (Phalaris,Poaceae): biogeography,molecular dating and the role of floret structure in dispersal

Canary grasses (Phalaris, Poaceae) include 21 species, widely spread throughout the temperate and subtropical regions of the world with two centres of diversity: the Mediterranean Basin and western North America. The genus contains annual and perennial, endemic, cosmopolitan, wild, and invasive species with diploid, tetraploid and hexaploid cytotypes. As such, Phalaris presents an ideal platform to study diversification via historic hybridization and polyploidy events, and geographical dispersal in grasses. We present the first empirical phylogeographic study for Phalaris testing current, intuitive hypotheses on the centres of origin, historic dispersal events and diversification within a geological timeframe. Bayesian methods (beast , version 1.6.2) were used to establish divergence dates, and dispersal–vicariance analyses (rasp , version 2.1b) were implemented for ancestral node reconstructions. Our phylogeographic results indicate that the genus emerged during the Miocene epoch [20.6–8.4 Ma (million years ago)] in the Mediterranean basin followed by dispersal and vicariance events to Africa, Asia and the Americas. We propose that a diploid ancestor of P. arundinacea migrated to western North America via the Bering Strait, where further diversification emerged in the New World. It appears that polyploidy played a major role in the evolution of the genus in the Old World, while diversification in the New World followed a primarily diploid pathway. Dispersal to various parts of the Americas followed different routes. Fertile florets with hairy protruding sterile lemmas showed significant correlation with wider geographical distribution.     

New phylogenetic perspectives on the Cervidae (Artiodactyla) are provided by the mitochondrial cytochrome b gene.

The entire mitochondrial cytochrome b (cyt b) gene was compared for 11 species of the artiodactyl family Cervidae, representing all living subfamilies, i.e., the antlered Cervinae (Cervus elaphus, C. nippon, Dama dama), Muntiacinae (Muntiacus reevesi), and Odocoileinae (Odocoileus hemionus, Mazama sp., Capreolus capreolus, C. pygargus, Rangifer tarandus, Alces alces); and the antlerless Hydropotinae (Hydropotes inermis). Phylogenetic analyses using Tragulidae, Antilocapridae, Giraffidae and Bovidae as outgroups provide evidence for three multifurcating principal clades within the monophyletic family Cervidae. First, Cervinae and Muntiacus are joined in a moderately-to-strongly supported clade of Eurasian species. Second, Old World Odocoileinae (Capreolus and Hydropotes) associate with the Holarctic Alces. Third, New World Odocoileinae (Mazama and Odocoileus) cluster with the Holarctic Rangifer. The combination of mitochondrial cyt b and nuclear k-casein sequences increases the robustness of these three clades. The Odocoileini + Rangiferini clade is unambiguously supported by a unique derived cranial feature, the expansion of the vomer which divides the choana. Contrasting with current taxonomy, Hydropotes is not the sister group of all the antlered deers, but it is nested within the Odocoileinae. Therefore, Hydropotes lost the antlers secondarily. Thus, the mitochondrial cyt b phylogeny splits Cervidae according to plesiometacarpal (Cervinae + Muntiacinae) versus telemetacarpal (Odocoileinae + Hydropotinae) conditions, and suggests paraphyly of antlered deer.     

A phylogeny of the "evil tribe" (Vernonieae: Compositae) reveals Old/New World long distance dispersal: support from separate and combined congruent datasets (trnL-F, ndhF, ITS)

The Vernonieae is one of the major tribes of the largest family of flowering plants, the sunflower family (Compositae or Asteraceae), with ca. 25,000 species. While the family's basal members (the Barnadesioideae) are found in South America, the tribe Vernonieae originated in the area of southern Africa/Madagascar. Its sister tribe, the Liabeae, is New World, however. This is the only such New/Old World sister tribe pairing anywhere in the family. The Vernonieae is now found on islands and continents worldwide and includes more than 1500 taxa. The Vernonieae has been called the "evil tribe" because overlapping character states make taxonomic delimitations difficult at all levels from the species to the subtribe for the majority of taxa. Juxtaposed with these difficult-to-separate entities are monotypic genera with highly distinctive morphologies and no obvious affinities to any other members of the tribe. The taxonomic frustration generated by these contrary circumstances has resulted in a lack of any phylogeny for the tribe until now. A combined approach using DNA sequence data from two chloroplast regions, the ndhF gene and the noncoding spacer trnL-F, and from the nuclear rDNA ITS region for 90 taxa from throughout the world was used to reconstruct the evolutionary history of the tribe. The data were analyzed separately and in combination using maximum parsimony (MP), minimum evolution neighbor-joining (NJ), and Bayesian analysis, the latter producing the best resolved and most strongly supported tree. In general, the phylogeny shows Old World taxa to be basal and New World taxa to be derived, but this is not always the case. Old and New World species are found together in two separate and only distantly related clades. This is best explained by long-distance dispersal with a minimum of two trans-oceanic exchanges. Meso/Central America has had an important role in ancient dispersals between the Old and New World and more recent movements from South to North America in the New World.