Evolution in the High Andes: The Phylogenetics of Muscisaxicola Ground-Tyrants

Phylogenetic relationships within the genus Muscisaxicola, a primarily Andean group of tyrant-flycatchers, were studied using complete sequences of the mitochondrial genes COII and ND3. Relationships among Muscisaxicola species were found to differ substantially from those of previous views, suggesting convergence in traditional avian taxonomic characters within the genus. The 11 species of large, gray, “typical” Muscisaxicola flycatchers (including M. grisea, newly restored to species status) formed a distinct clade, consisting of two major groups: a clade of 6 species breeding primarily in the central Andes and a clade of 5 species breeding primarily in the southern Andes. The other 2 species traditionally placed in this genus, M. fluviatilis, an Amazonian species, and M. maculirostris, were both rather divergent genetically from the typical species, although M. maculirostris may be the sister taxon to the typical clade. The patterns of sympatry exhibited by Muscisaxicola species in the high Andes appear to be the consequence of speciation and secondary contact within regions of the Andes, rather than a result of dispersal between regions. Diversification of the typical Muscisaxicola species appears to have occurred during the middle and late Pleistocene, suggesting generally that taxa of the high Andes and Patagonia may have been greatly influenced by mid-to-late Pleistocene events. There were likely several independent developments of migration within this genus, but migration is probably ancestral in the southern clade, with subsequent loss of migration in two taxa.     

Molecular phylogenetics and biogeography of the Neotropical redstarts (Myioborus; Aves, Parulinae)

Montane areas in the Neotropics are characterized by high diversity and endemism of birds and other groups. The avian genus Myioborus (Parulinae) is a group of insectivorous warblers, characteristic of cloud forests, that represents one of the few Parulinae genera (New World warblers) that has radiated substantially in South America. The genus is distributed throughout most montane regions from the southwestern United States to northern Argentina. Here, I use mitochondrial sequences from the cytochrome b, ND2, and ND3 genes to present the first hypothesis of phylogenetic relationship among all Myioborus species level taxa. Phylogenetic reconstructions based on maximum parsimony, maximum likelihood, and Bayesian methods produced similar results and suggest a northern origin for the genus Myioborus with subsequent colonization of the Neotropical Montane Region. The lower-montane species, M. miniatus, is the sister taxon to a clade in which all taxa occupy upper-montane habitats. These "highland" taxa diverged early in the history of the genus and produced two well-defined monophyletic lineages, a Central-northern Andean clade formed by M. albifrons, M. ornatus, and M. melanocephalus, and a Pantepui (table-mountains of southern Venezuela, northern Brazil, and western Guyana) clade consisting of M. castaneocapillus, M. albifacies, and M. cardonai, and probably M. pariae. M. brunniceps, M. flavivertex, and M. torquatus were included in this upper-montane clade but without clear relationships to other taxa. Lack of resolution of nodes defining the upper-montane species clade is likely to result from a period of rapid diversification mediated by geological and climatic events during the Late Pliocene. These results suggest that an interplay of dispersal and vicariance has shaped the current biogeographic patterns of Myioborus.     

Phylogeny and diversification of Valerianaceae (Dipsacales) in the southern Andes

The southern Andean clade of Valeriana provides an excellent model for the study of biogeography. Here we provide new data to help clarify phylogenetic relationships among the South American valerians, with special focus on taxa found in the southern Andes. We found that the southern Andean taxa formed a clade in maximum likelihood and maximum parsimony analyses, and used a Bayesian relaxed clock method to estimate divergence times within Valerianaceae. Our temporal results were similar to other studies, but we found greater variance in our estimates, suggesting that the species of Valeriana have been on the South American continent for some time, and have been successful at exploiting new niche opportunities that reflects the contemporary radiation. Regardless of the time frame for the radiation of the clade, the uptick in the rate of diversification in Valerianaceae appears correlated with a dispersal event from Central to South America. The appearance of Valeriana in the southern Andes (13.7 Ma) corresponds with the transition from closed forest on the western side of the Andes in central Chile to a more open Mediterranean woodland environment. This would suggest that the high species richness of Valerianaceae in South America is the result of multiple, smaller radiations such as the one in the southern Andes, that may or may not be geographically isolated. These smaller radiations may also be driven by species moving into new biomes (migration from a temperate to a more Mediterranean-type climate and into alpine). The degree to which different ecological and geological factors interact to drive diversification is difficult to ascertain. Likewise, without a better-resolved phylogeny it is impossible to determine the directionality of dispersal in this group; did they colonize the southern Andes first, then move northward as the central Andean alpine habitat became more widely available or vice versa?     

Local environment rather than past climate determines community composition of mountain stream macroinvertebrates across Europe

Community assembly is determined by a combination of historical events and contemporary processes that are difficult to disentangle, but eco‐evolutionary mechanisms may be uncovered by the joint analysis of species and genetic diversity across multiple sites. Mountain streams across Europe harbour highly diverse macroinvertebrate communities whose composition and turnover (replacement of taxa) among sites and regions remain poorly known. We studied whole‐community biodiversity within and among six mountain regions along a latitudinal transect from Morocco to Scandinavia at three levels of taxonomic hierarchy: genus, species and haplotypes. Using DNA barcoding of four insect families (>3100 individuals, 118 species) across 62 streams, we found that measures of local and regional diversity and intraregional turnover generally declined slightly towards northern latitudes. However, at all hierarchical levels we found complete (haplotype) or high (species, genus) turnover among regions (and even among sites within regions), which counters the expectations of Pleistocene postglacial northward expansion from southern refugia. Species distributions were mostly correlated with environmental conditions, suggesting a strong role of lineage‐ or species‐specific traits in determining local and latitudinal community composition, lineage diversification and phylogenetic community structure (e.g., loss of Coleoptera, but not Ephemeroptera, at northern sites). High intraspecific genetic structure within regions, even in northernmost sites, reflects species‐specific dispersal and demographic histories and indicates postglacial migration from geographically scattered refugia, rather than from only southern areas. Overall, patterns were not strongly concordant across hierarchical levels, but consistent with the overriding influence of environmental factors determining community composition at the species and genus levels.     

Mitochondrial DNA phylogeography and population history of Meladema diving beetles on the Atlantic Islands and in the Mediterranean basin (Coleoptera,Dytiscidae)

The phylogeny and population history of Meladema diving beetles (Coleoptera, Dytiscidae) were examined using mitochondrial DNA sequence from 16S ribosomal RNA and cytochrome oxidase I genes in 51 individuals from 22 populations of the three extant species (M. imbricata endemic to the western Canary Islands, M. lanio endemic to Madeira and M. coriacea widespread in the Western Mediterranean and on the western Canaries), using a combination of phylogenetic and nested clade analyses. Four main lineages are observed within Meladema, representing the three recognized species plus Corsican populations of M. coriacea. Phylogenetic analyses demonstrate the sister relationship of the two Atlantic Island taxa, and suggest the possible paraphyly of M. coriacea. A molecular clock approach reveals that speciation within the genus occurred in the Early Pleistocene, indicating that the Atlantic Island endemics are not Tertiary relict taxa as had been proposed previously. Our results point to past population bottlenecks in all four lineages, with recent (Late-Middle Pleistocene) range expansion in non-Corsican M. coriacea and M. imbricata. Within the Canary Islands, M. imbricata seems to have independently colonized La Gomera and La Palma from Tenerife (although a colonization of La Palma from La Gomera cannot be discarded), and M. coriacea has independently colonized Tenerife and Gran Canaria from separate mainland lineages. In the Mediterranean basin this species apparently colonized Corsica on a single occasion, relatively early in its evolutionary history (Early Pleistocene), and has colonized Mallorca recently on multiple occasions. On the only island where M. coriacea and M. imbricata are broadly sympatric (Tenerife), we report evidence of bidirectional hybridization between the two species.     

Phylogenetic analysis of Pinguicula (Lentibulariaceae): chloroplast DNA sequences and morphology support several geographically distinct radiations

The genus Pinguicula is one of the three genera of the carnivorous Lentibulariaceae, comprising approximately 80 species. Phylogeny inference using nucleotide sequences of the chloroplast gene matK and the trnK group II intron, as well as a set of 32 morphological characters revealed five well-supported, major lineages within the genus. These lineages largely reflect radiations in clearly defined geographic regions, whereas most previously recognized sections of the genus are shown to be para- or polyphyletic. A species-rich Mexican-Central American-Caribbean clade has the Eurasian P. alpina and an East Asian clade as successive sisters. All three are characterized by a production of flower buds on winter-resting plants, a specific corolla hair structure and a very large corolla lower central lobe. Another diverse clade is composed of species with primarily European distribution including the widespread type species P. vulgaris. For this clade, vegetative reproduction during dormancy is synapomorphic. Species native to SE North America and the South American Andes and a group of Mediterranean and NE Atlantic coast species together appear in a fifth well-supported clade, that is characterized by a tropical-type growth habit. It is the only clade that has reached temperate zones of the southern hemisphere.     

Phylogenetic relationships and evolution in Chrysosplenium (Saxifragaceae) based on matK sequence data

Chrysosplenium (Saxifragaceae) consists of 57 species widely distributed in temperate and arctic regions of the Northern Hemisphere, with two species restricted to the southern part of South America. Species relationships within the genus are highly problematic. The genus has traditionally been divided into two groups, sometimes recognized as sections (Oppositifolia and Alternifolia), based on leaf arrangement, or, alternatively, into 17 series. Based on morphological features, Hara suggested that the genus originated in South America and then subsequently migrated to the Northern Hemisphere. We conducted phylogenetic analyses of DNA sequences of the chloroplast gene matK for species of Chrysosplenium to elucidate relationships, test Hara's biogeographic hypothesis for the genus, and examine chromosomal and gynoecial diversification. These analyses revealed that both sections Oppositifolia and Alternifolia are monophyletic and form two large sister clades. Hence, leaf arrangement is a good indicator of relationships within this genus. Hara's series Pilosa and Macrostemon are each also monophyletic; however, series Oppositifolia, Alternifolia, and Nepalensia are clearly not monophyletic. MacClade reconstructions suggest that the genus arose in Eastern Asia, rather than in South America, with several independent migration events from Asia to the New World. In one well-defined subclade, species from eastern and western North America form a discrete clade, with Old World species as their sister group, suggesting that the eastern and western North American taxa diverged following migration to that continent. The South American species forms a clade with species from eastern Asia; this disjunction may be the result of ancient long-distance dispersal. Character mapping demonstrated that gynoecial diversification is dynamic, with reversals from inferior to half-inferior ovaries, as well as to ovaries that appear superior. Chromosomal evolution also appears to be labile with several independent origins of n = 12 (from an original number of n = 11) and multiple episodes of aneuploidy.     

Global chloroplast phylogeny and biogeography of bracken (Pteridium; Dennstaedtiaceae)

Bracken ferns (genus Pteridium) represent an ancient species complex with a natural worldwide distribution. Pteridium has historically been treated as comprising a single species, but recent treatments have recognized several related species. Phenotypic plasticity, geographically structured morphological variation, and geographically biased sampling have all contributed to taxonomic confusion in the genus. We sampled bracken specimens worldwide and used variable regions of the chloroplast genome to investigate phylogeography and reticulate evolution within the genus. Our results distinguish two major clades within Pteridium, a primarily northern hemisphere Laurasian/African clade, which includes all taxa currently assigned to P. aquilinum, and a primarily southern hemisphere Austral/South American clade, which includes P. esculentum and P. arachnoideum. All European accessions of P. aquilinum subsp. aquilinum appear in a monophyletic group and are nested within a clade containing the African P. aquilinum taxa (P. aquilinum subsp. capense and P. aquilinum subsp. centrali-africanum). Our results allow us to hypothesize the maternal progenitors of two allotetraploid bracken species, P. caudatum and P. semihastatum. We also discuss the biogeography of bracken in the context of the chloroplast phylogeny. Our study is one of the first to take a worldwide perspective in addressing variation in a broadly distributed species complex.     

Molecular phylogenetics and biogeography of Neotropical tanagers in the genus Tangara

Species in the genus Tangara are distributed throughout the New World tropics and vary in their morphology, behavior, and ecology. We used data from the cytochrome b and ND 2 genes to provide the first phylogenetic perspective on the evolution of this diversity. Reconstructions based on parsimony, maximum likelihood, and Bayesian approaches were largely congruent. The genus is monophyletic and consists of two main clades. Within these clades, DNA sequence data confirm the monophyly of most previously recognized species groups within Tangara, indicating general concordance between molecular data and impressions based on geographic distribution, morphology, and behavior. Within some currently recognized species, levels of DNA sequence variation are larger than expected, suggesting multiple taxa may be involved. In contrast, some currently recognized species are only weakly differentiated from their sister species. Biogeographic analyses indicate that many early speciation events occurred in the Andes. More recently, dispersal events followed by subsequent speciation have occurred in other geographic areas of the Neotropics. Assuming a molecular clock, most speciation events occurred well before Pleistocene climatic cycles. The time frame of Tangara speciation corresponds more closely to a period of continued uplift in the Andes during the late Miocene and Pliocene.     

Patterns and timing of diversification in a tropical montane butterfly genus,Lymanopoda (Nymphalidae,Satyrinae)

Species distributions are a product of contemporary and historical forces. Using phylogenetic and geographic data, we explore the timing of and barriers to the diversification of the Andean butterfly genus Lymanopoda (Nymphalidae, Satyrinae). Clade and species level diversification is coincident with Andean orogeny and Pleistocene glaciation cycles. Lymanopoda has primarily diversified within elevational bands, radiating horizontally throughout the Andes with occasional speciation across elevational boundaries, often associated with ecotones. Narrow elevational ranges and infrequent speciation into adjacent elevational strata suggest that expansion across elevational gradients is relatively difficult. These results are similar to those found in studies of other Andean taxa.     

Out of Amazonia again and again: episodic crossing of the Andes promotes diversification in a lowland forest flycatcher

Most Neotropical lowland forest taxa occur exclusively on one side of the Andes despite the availability of appropriate habitat on both sides. Almost all molecular phylogenies and phylogenetic analyses of species assemblages (i.e. area cladograms) have supported the hypothesis that Andean uplift during the Late Pliocene created a vicariant barrier affecting lowland lineages in the region. However, a few widespread plant and animal species occurring in lowland forests on both sides of the Andes challenge the generality of this hypothesis. To understand the role of the Andes in the history of such organisms, we reconstructed the phylogeographic history of a widespread Neotropical flycatcher (Mionectes oleagineus) in the context of the other four species in the genus. A molecular phylogeny based on nuclear and mitochondrial sequences unambiguously showed an early basal split between montane and lowland Mionectes. The phylogeographic reconstruction of lowland taxa revealed a complex history, with multiple cases in which geographically proximate populations do not represent sister lineages. Specifically, three populations of M. oleagineus west of the Andes do not comprise a monophyletic clade; instead, each represents an independent lineage with origins east of the Andes. Divergence time estimates suggest that at least two cross-Andean dispersal events post-date Andean uplift.     

Molecular systematics of a speciose, cosmopolitan songbird genus: defining the limits of, and relationships among, the Turdus thrushes

The avian genus Turdus is one of the most speciose and widespread of passerine genera. We investigated phylogenetic relationships within this genus using mitochondrial DNA sequence data from the ND3, ND2 and cytochrome b genes. Our sampling of Turdus included 60 of the 65 extant species currently recognized, as well as all four species from three genera previously shown to fall inside Turdus (Platycichla, Nesocichla, and Cichlherminia). Phylogenetic trees based on maximum likelihood and maximum parsimony algorithms were congruent. Most of the Turdus taxa sampled fall into one of four clades: an African clade, a Central American-Caribbean clade, a largely South American clade, and a Eurasian clade. Still other taxa are placed either at the base of Turdus, or as links between clades. In no instance is any continent reciprocally monophyletic for the species distributed on it. A general lack of nodal support near the base of the phylogeny seems related to a rapid intercontinental establishment of the major clades within Turdus very early in the history of the genus. The monotypic genus Psophocichla is distantly related to, but clearly the sister of, Turdus rather than a constituent member of it.     

Paranepheliinae亚族(菊科,Liabeae族)的系统发育和可能的属间杂交

The nuclear ribosomal ITS region and the chloroplast trnL-trnF (trnLF) intergenic region were sequenced for 45 accessions of Paranephelius and six accessions of Pseudonoseris, the two genera of the subtribe Paranepheliinae (Liabeae, Asteraceae) distributed in the alpine regions of the Andes. This data set was used to estimate relationships between these genera and within each genus to aid in evaluating morphological variation and classification. Our results with both ITS and trnLF markers support the monophyly of subtribe Paranepheliinae, and place Pseudonoseris discolor as the first diverged taxon sister to the clade containing Paranephelius. Pseudonoseris szyszylowiczii exhibited intraspecific divergence supporting intergeneric hybridization between Pseudonoseris and Paranephelius. Within Paranephelius, genetic divergence is low and not adequate to fully resolve phylogenetic relationships at the species level, but two genetically and morphologically recognizable groups were revealed by the ITS data. Several accessions possessing multiple ITS sequences represent putative hybrids between the two groups. These putative hybrids have caused some taxonomic confusion and difficulties in establishing species boundaries in Paranephelius. The divergence time estimates based on ITS sequences indicated that the stem of subtribe Paranepheliinae dates to 13 million years ago, but the diversification of the crown clade of the extant members began in the early Pleistocene or late Pliocene, perhaps associated with the uplift of the Andes and the climatic changes of global cooling.     

Divergent timing and patterns of species accumulation in lowland and highland neotropical birds

Late Pliocene and Pleistocene climatic instability has been invoked to explain the buildup of Neotropical biodiversity, although other theories date Neotropical diversification to earlier periods. If these climatic fluctuations drove Neotropical diversification, then a large proportion of species should date to this period and faunas should exhibit accelerated rates of speciation. However, the unique role of recent climatic fluctuations in promoting diversification could be rejected if late Pliocene and Pleistocene rates declined. To test these temporal predictions, dateable molecular phylogenies for 27 avian taxa were used to contrast the timing and rates of diversification in lowland and highland Neotropical faunas. Trends in diversification rates were analyzed in two ways. First, rates within taxa were analyzed for increasing or decreasing speciation rates through time. There was a significant trend within lowland taxa towards decreasing speciation rates, but no significant trend was observed within most highland taxa. Second, fauna wide diversification rates through time were estimated during one-million-year intervals by combining rates across taxa. In the lowlands, rates were highest during the late Miocene and then decreased towards the present. The decline in rates observed both within taxa and for the fauna as a whole probably resulted from density dependent cladogenesis. In the highlands, faunawide rates did not vary greatly before the Pleistocene but did increase significantly during the last one million years of the Pleistocene following the onset of severe glacial cycles in the Andes. These contrasting patterns of species accumulation suggest that lowland and highland regions were affected differently by recent climatic fluctuations. Evidently, habitat alterations associated with global climate change were not enough to promote an increase in the rate of diversification in lowland faunas. In contrast, direct fragmentation of habitats by glaciers and severe altitudinal migration of montane vegetation zones during climatic cycles may have resulted in the late Pleistocene increase in highland diversification rates. This increase resulted in a fauna with one third of its species dating to the last one million years.     

Phylogeny and diversification of the cloud forest Morpho sulkowskyi group (Lepidoptera,Nymphalidae) in the evolving Andes

The monophyletic Morpho sulkowskyi butterfly group, endemic of Andean cloud forests, was studied to test the respective contributions of Mio‐Pliocene intense uplift period and Pleistocene glacial cycles on Andean biodiversity. We sampled nine taxa covering the whole geographical range of the group. Two mitochondrial and two nuclear genes were analysed using a Bayesian method. We established a dated phylogeny of the group using a relaxed clock method and a wide‐outgroup approach. To discriminate between two hypotheses, we used a biogeographical probabilistic method. Results suggest that the ancestor of the M. sulkowskyi group originated during the Middle–Late Miocene uplift of the Eastern Cordillera in northern Peru. Biogeographical inference suggests that the M. sulkowskyi and Morpho lympharis clades diverged in the northern Peruvian Andes. The subsequent divergences, from the Late Miocene to the Late Pliocene, should have resulted from a dispersal towards the Northern Andes (M. sulkowskyi clade), after the closure of the West Andean Portal separating the Central and Northern Andes, and a southwards dispersal along the Peruvian and Bolivian Eastern Cordilleras (M. lympharis clade). Only a few divergences occurred at the very end of the Pliocene or during the Pleistocene, a period when the more recent uplifts interfered with Pleistocene glacial cycles.     

Pleistocene range expansions might explain striking disjunctions between eastern Brazil,Andes and Mesoamerica in Leandra s.str. (Melastomataceae)

Leandra s.str. clade has around 200 species nearly restricted to eastern Brazil. Most species in this group are narrow endemics, but a few present striking disjunct distributions between eastern Brazil and Andes or Mesoamerica. Given the predominantly “montane” distribution observed in most Leandra s.str., we hypothesized that cyclical range expansions during colder Pleistocene periods, followed by local extinctions during warmer interglacial periods, could have shaped the distribution of the disjunct species in this clade. In order to gather support for this biogeographical scenario in a phylogenetic framework, the species that occur outside eastern Brazil were identified, ages of the dispersal events estimated, climatic niche models for the disjuncts were generated, and the climatic envelope of these species compared. Our results place all dispersal events from eastern Brazil to Andes or Mesoamerica during the Pleistocene. Climatic niche modeling indicates a potential range expansion during the Pleistocene colder times for the disjunct species. Although the surpassing of the “dry diagonal” could have been facilitated during glacial periods, this open corridor is an effective barrier for Leandra, given the reduced number of species that dispersed beyond an eastern Brazilian origin. Additionally, the disjunct species do not present significant differences in their climatic envelopes to the non‐disjunct species. Our results provide support to a short‐dispersion/stepping‐stone migration scenario to account for the observed disjunctions in this clade. Range expansions during Pleistocene colder periods followed by local extinctions during interglacial periods could have shaped the distribution of Leandra s.str.     

Plumage based classification of the bowerbird genus Sericulus evaluated using a multi-gene, multi-genome analysis

Past classifications of taxa within the bowerbird genus Sericulus (family: Ptilonorhynchidae) conflict since the discovery of hybrids identified though male plumage characteristics. We use molecular data to help define species within this genus, and by estimating a phylogeny, test for lability in the evolution of male plumage patterns. Because this genus includes the most brightly colored bowerbird species, and is hypothesized to be the basal genus of the avenue building bowerbird clade, the organization of the four taxa within this genus is especially important in understanding how bowerbird plumage coloration evolved. Analyses of two mitochondrial and six nuclear gene regions confirm the basal placement of Sericulus in the avenue building bowerbirds and Sericulus monophyly, and suggests the Australian S. chrysocephalus is the basal Sericulus species. Our analysis additionally supports the existence of three New Guinea Sericulus species, contrary to some previous plumage based classifications, as they are genetically equidistant from each other. Molecular and geographic data of New Guinea are consistent suggesting a series of speciation events starting approximately 3.7-4.3MYA leading to four extant Sericulus species. The absence of resolution within the New Guinea species precludes any statements of trait lability, but does suggest that traits under high selection pressures may not accurately indicate species level distinctions within this genus.     

Phylogenetic systematics and biogeography of the poison frogs: evidence from mitochondrial DNA sequences

Regions of the mitochondrial genome were sequenced and analysed in representative species of poison frogs, in order to investigate phylogenetic relationships within the family Dendrobatidae. Mitochondrial DNA (mfDNA) fragments from three gene regions; cytochrome b, 16S ribosomal RNA (rRNA), and 12S rRNA, provided 1198 base pairs of DNA sequence and 589 informative sites. Phylogenetic analysis using parsimony was used to infer the evolutionary relationships among the species in the survey. Our analysis supported previous partitions of species into the genera Epipedobates, Phyllobates and Dendrobates , with two exceptions; Epipedobates (Allobates) femoralis was placed outside the clade containing the other toxic dendrobatids, and Minyobates minutus was placed within the genus Dendrobates. Genetic distances estimated between all pairs of taxa using the Kimura 2-parameter model indicated substantial genetic divergence between species, particularly those found in Amazonia. Time of divergence estimates were highly variable depending on gene region, but even the lowest estimates were inconsistent with the Pleistocene Refugia hypothesis.     

The Andean Hapalopsittaca parrots (Psittacidae,Aves): an example of montane‐tropical lowland vicariance

Quintero, E., Ribas, C. C. & Cracraft, J. (2012). The Andean Hapalopsittaca parrots (Psittacidae, Aves): an example of montane‐tropical lowland vicariance. —Zoologica Scripta, 42, 28–43. We describe a phylogenetic and biogeographical pattern connecting high montane biotas to those of the lowlands, as exemplified by the exclusively montane parrot genus Hapalopsittaca and its lowland sister genus Pyrilia, both nested within Tavares et al.’s “amazons and allies” clade. As Hapalopsittaca is the only genus within the “amazons and allies” clade that is exclusively distributed in the Andes, the optimization leads to the inference that the ancestral distribution of the branch leading to Pyrilia + Hapalopsittaca was lowland. Museum specimens were examined to determine basal diagnosably distinct taxonomic units. Based on this analysis, mitochondrial sequences (cyt b and ND2 genes) from 17 individuals, mostly from toe pads, and representing all basal taxa within Hapalopsittaca, were obtained. A divergence‐dating analysis using both nuclear (RAG‐1) and mitochondrial (cyt b) genes was conducted to explore whether the uplift of the Andes coincides temporarily with the origin of this montane group, and thus might be causally linked to its origin. Molecular dating estimates the split between Hapalopsittaca and Pyrilia to have occurred between 6.6 and 8.0 Myr; thus, the timing of this highland/lowland disjunction is consistent with that of the final uplift of the Central Andes, supporting a hypothesis of vicariance due to Andean uplift. These results suggest that the taxonomic assembly of montane biotas may be, at least in part, explained by events of Earth history rather than by long‐distance dispersal and colonization. Diversification within Hapalopsittaca and the origin of current species are more recent in time and probably are related to Pleistocene climatic oscillations, as has been shown in other montane groups.     

Molecular Phylogeny and Taxonomy of the Genus Minidiscus (Bacillariophyceae), with Description of Mediolabrus gen. nov

The genus Minidiscus comprises a group of ecologically-important and globally-distributed planktonic diatoms that are characterized by their small cell size, high mantle and processes more or less concentrated in the valve center. Monoclonal strains were established from collections along the Chinese coast. In the phylogenetic analyses inferred from a LSU and SSU dataset, six Minidiscus species clustered into two well-supported clades. The first clade was located within a larger clade formed mainly by Thalassiosira taxa, and the second clade appeared as sister to a clade comprising the genus Skeletonema. Hence, presently known Minidiscus do not form a monophyletic clade, but rather make up a phenotypic grouping. Based on the morphology of the type species, M. trioculatus, as well as morphological characters of all taxa in the clade with M. trioculatus, Minidiscus is characterized by having fultoportula(e) in the valve center or sub-centered close to a single rimoportula, and the cells are usually cylindrical. Mediolabrus gen. nov. is proposed to accommodate species in the second clade. The main difference between Minidiscus and Mediolabrus is the type of process found in the valve (sub-)center, with fultoportula(e) close to a rimoportula in the former, and only a single rimoportula in the latter. According to the above criteria, previously described Minidiscus taxa were re-examined, and either retained in Minidiscus or transferred to Mediolabrus.