Evolutionary relationships among narrow-headed rats (genus Stenocephalemys, Muridae, Rodentia) inferred from complete cytochrome b gene sequences

Using the data on complete sequences of cytochrome b gene, phylogenetic relationships were studied among the Stenocephalemys s. lat. (Stenocephalemys ssp. + Praomys albipes) murine rodents, inhabiting adjacent altitudinal belts of the isolated Ethiopian mountain massifs, and among the related Praomys s. lat. species. Extremely low resolution of the relationships among the main Praomys s. lat. lineages hampered identification of the nearest sister group for the Stenocephalemys s. lat. "Ethiopian" clade, monophyly of which was strongly supported. Sister relationships between P. albipes and S. griseicauda (implying "accelerated" morphological and chromosomal evolution upon the formation of the former species), as well as between S. albocaudata and the recently described novel chromosomal form of Stenocephalemus sp. A (2n = 50; NFa = 56) were demonstrated. Definite discordance between the rates of their molecular, chromosomal, and morphological evolution was revealed. Based on phylogenetic reconstructions and the estimates of the divergence time, obtained by use of molecular clock method, an attempt to draw a phylogenetic scenario for the group examined was made. The obtained data were compared to those for analogous Sigmodontinae species complexes, distributed across a marked altitudinal gradient on the Andean slopes. It was shown that molecular genetic data on the rodents from mountain tropics did not support the gradient model of diversification, based on the possibility of morphological diversification prior to their achievement of the species status (without interruption of the gene flow between the forms) due to differently directed selection across a strong environmental gradient.     

Thaptomys Thomas 1915 (Rodentia, Sigmodontinae, Akodontini) with karyotypes 2n = 50, FN = 48, and 2n = 52, FN = 52: Two monophyletic lineages recovered by molecular phylogeny

A novel karyotype with 2n = 50, FN = 48, was described for specimens of Thaptomys collected at Una, State of Bahia, Brazil, which are morphologically indistinguishable from Thaptomys nigrita, 2n = 52, FN = 52, found in other localities. It was hence proposed that the 2n = 50 karyotype could belong to a distinct species, cryptic of Thaptomys nigrita, once chromosomal rearrangements observed, along with the geographic distance, might represent a reproductive barrier between both forms. Phylogenetic analyses using maximum parsimony and maximum likelihood based on partial cytochrome b sequences with 1077 bp were performed, attempting to establish the relationships among the individuals with distinct karyotypes along the geographic distribution of the genus; the sample comprised 18 karyotyped specimens of Thaptomys, encompassing 15 haplotypes, from eight different localities of the Atlantic Rainforest. The intra-generic relationships corroborated the distinct diploid numbers, once both phylogenetic reconstructions recovered two monophyletic lineages, a northeastern clade grouping the 2n = 50 and a southeastern clade with three subclades, grouping the 2n = 52 karyotype. The sequence divergence observed between their individuals ranged from 1.9% to 3.5%.     

Karyotype differentiation in Chromaphyosemion killifishes (Cyprinodontiformes, Nothobranchiidae). III: extensive karyotypic variability associated with low mitochondrial haplotype differentiation in C. bivittatum

We investigated chromosomal evolution in the African killifish species Chromaphyosemion bivittatum using a combination of cytogenetic and phylogenetic methods. Specimens from five populations were examined by conventional Giemsa staining as well as sequential chromosome banding with 4',6-diamidino-2-phenylindole (DAPI), chromomycin A(3) (CMA(3)), AgNO(3)-staining and C-banding. The cytogenetic analysis revealed variability in 2n ranging from 2n = 29 to 2n = 36 and in NF ranging from NF = 38 to NF = 44. Two populations showed an extensive chromosomal polymorphism (2n = 29-34, NF = 44 and 2n = 32-34, NF = 38-42, respectively). Karyotypic variability within and among populations was mainly due to Robertsonian translocations and heterochromatin additions, and chromosome banding patterns suggested that both types of chromosomal rearrangements were related to the presence of AT-rich heterochromatin. A phylogenetic analysis of the partial mitochondrial (mt) cytochrome b gene, using specimens from eleven populations, revealed a low degree of haplotype differentiation, which suggested a relatively recent divergence of the populations examined. This finding conformed to the low degree of morphological differentiation observed among C. bivittatum populations and might indicate fast chromosomal evolution. The high karyotypic variability may be caused by an elevated chromosomal mutation rate as well as certain aspects of the mating system and population dynamics of C. bivittatum facilitating the fixation of new chromosomal variants.     

A retroposon analysis of Afrotherian phylogeny

Recent comprehensive studies of DNA sequences support the monophyly of Afrotheria, comprising elephants, sirenians (dugongs and manatees), hyraxes, tenrecs, golden moles, aardvarks, and elephant shrews, as well as that of Paenungulata, comprising elephants, sirenians, and hyraxes. However, phylogenetic relationships among paenungulates, as well as among nonpaenungulates, have remained ambiguous. Here we applied an extensive retroposon analysis to these problems to support the monophyly of aardvarks, tenrecs, and golden moles, with elephant shrews as their sister group. Regarding phylogenetic relationships in Paenungulata, we could characterize only one informative locus, although we could isolate many insertions specific to each of three lineages, namely, Proboscidea, Sirenia, and Hyracoidea. These data prompted us to reexamine phylogenetic relationships among Paenungulata using 19 nuclear gene sequences resulting in three different analyses, namely, short interspersed element (SINE) insertions, nuclear sequence analyses, and morphological cladistics, supporting different respective phylogenies. We concluded that these three lineages diverged very rapidly in a very short evolutionary period, with the consequence that ancestral polymorphism present in the last common ancestor of Paenungulata results in such incongruence. Our results suggest the rapid fixation of many large-scale morphological synapomorphies for Tethytheria; implications of this in relation to the morphological evolution in Paenungulata are discussed.     

Evolutionary relationships among narrow-headed rats (genus Stenocephalemys, muridae, rodentia) inferred from complete cytochrome b gene sequences

Using the data on complete sequences of cytochrome b gene, phylogenetic relationships were studied among the Stenocephalemys s. lat. (Stenocephalemys spp. + Praomys albipes) murine rodents, inhabiting adjacent altitudinal belts of the isolated Ethiopian mountain massifs, and among the related Praomys s. lat. species. Extremely low resolution of the relationships among the main Praomys s. lat. lineages hampered identification of the nearest sister group for the Stenocephalemys s. lat. “Ethiopian” clade, monophyly of which was strongly supported. Sister relationships between P. albipes and S. griseicauda (implying “accelerated” morphological and chromosomal evolution upon the formation of the former species), as well as between S. albocaudata and the recently described novel chromosomal form of Stenocephalemus sp. A (2n = 50; NFa = 56) were demonstrated. Definite discordance between the rates of their molecular, chromosomal, and morphological evolution was revealed. Based on phylogenetic reconstructions and the estimates of the divergence time, obtained by use of molecular clock method, an attempt to draw an evolutionary scenario for the group examined was made. The obtained data were compared to those for Sigmodontinae species complexes, distributed across a marked altitudinal gradient on the Andean slopes. It was shown that molecular genetic data on the rodents from mountain tropics did not support the gradient model of diversification, based on the possibility of diversification of the forms up to their achievement of the species rank (without interruption of the gene flow between them) due to differently directed selection across a strong environmental gradient.     

Phylogenetic relationships between spiny, slipper and coral lobsters (Crustacea, Decapoda, Achelata)

Molecular data can aid in the resolution of conflicting hypotheses generated through difficulties in the interpretation of morphological data and/or an incomplete fossil record. Moreover, the reconstruction of phylogenetic relationships using molecular data may help to trace back the origin of morphological innovations which had a major impact on the radiation of a taxonomical group. In this work, different nuclear (18S, 28S, and H3) and mitochondrial (16S and COI) gene regions were sequenced in a total of 35 Achelatan species to test conflicting hypotheses of evolutionary relationships within the Achelata infraorder and solve the taxonomic disagreements in the group. The combined molecular dataset strongly supports the hypothesis that Achelata is a monophyletic group composed of two main families: Palinuridae and Scyllaridae. Synaxidae is found to be a polyphyletic group, which should be included within Palinuridae. Consequently, our results indicate that the origin of the stridulating organ occurred only once during Achelata evolution. Finally, the two main clades found within the Scyllaridae are in agreement with previous inferences based on adult morphological data. The dating of divergence of Achelata obtained with a relaxed-clock model is compatible with previous hypotheses of a Triassic origin of the Achelata.     

Phylogenetic assessment of molecular and morphological data for eutherian mammals

The interordinal relationships of eutherian (placental) mammals were evaluated by a phylogenetic analysis of four published data sets (three sequences and one morphological). The nature and degree of support and conflict for particular groups were assessed by separate bootstrap and homogeneity tests, which were followed by combined analyses of the sequence and morphological data. Between orders, strong support (i.e., > or = 95% bootstrap scores) was found for a paraphyletic Artiodactyla (relative to Cetacea) and a monophyletic Cetartiodactyla (Artiodactyla and Cetacea) and Paenungulata (Hyracoidea, Proboscidea, and Sirenia). In turn, some reasonable to strong evidence (> or = 85%) was obtained for Hyracoidea with Sirenia, Dermoptera with Scandentia, Glires (Lagomorpha with Rodentia), and Afrotheria (Amblysomus, Macroscelidea, Paenungulata, and Tubulidentata). Otherwise, no other interordinal clades were supported at these reasonable to strong levels. This overall lack of resolution for eutherian interordinal clusters agrees with other studies that suggest further progress will continue to be slow and difficult. Further resolution will require the integration of more recently published data, the continued sampling of taxa and characters, and the use of more powerful methods of data analysis.     

Maximum-Likelihood Analysis of the Tethythere Hypothesis Based on a Multigene Data Set and a Comparison of Different Models of Sequence Evolution

Hyracoids have been allied with either perissodactyls or tethytheres (i.e., Proboscidea + Sirenia) based on morphological data. The latter hypothesis, termed Paenungulata, is corroborated by numerous molecular studies. However, molecular studies have failed to support Tethytheria, a group that is supported by morphological data. We examined relationships among living paenungulate orders using a multigene data set that included sequences from four mitochondrial genes (12S rRNA, tRNA valine, 16S rRNA, cytochrome b) and four nuclear genes (aquaporin, A2AB, IRBP, vWF). Nineteen maximum-likelihood models were employed, including models with process partitions for base composition and substitution parameterizations. With the inclusion of partitions with a heterogeneous base composition, 18 of 19 models favored Hyracoidea + Sirenia. All 19 models favored Hyracoidea + Sirenia after excluding heterogeneous base composition partitions. Most of the support for Hyracoidea + Sirenia derived from the mitochondrial genes (bootstrap support ranged from 51 to 99%); Tethytheria, in turn, received 0 to 19% support in different analyses. Bootstrap support deriving from the nuclear genes was more evenly split among the competing hypotheses (3 to 45% for Tethytheria; 17.5 to 62% for Hyracoidea + Sirenia). Lineage-specific rate variation among both mitochondrial and nuclear genes may contribute to the different results that were obtained with mitochondrial versus nuclear data. Whether Tethytheria or a competing hypothesis is correct, short internodes on the molecular phylogenies suggest that paenungulate orders diverged from each other over a 5- to 8-million-year time window extending from the late Paleocene into the early Eocene. We also used likelihood-ratio tests to compare different models of sequence evolution. A gamma distribution of rates results in a greater improvement in likelihood scores than does an allowance for invariant sites. Twenty-one rate partitions corresponding to stems, loops, and codon positions of different genes result in higher likelihood scores than a gamma distribution of rates and/or an allowance for invariant sites. Process partitions of the data that incorporate base composition and substitution parameterizations result in significant improvements in likelihood scores in comparison to models that allow only for relative rate differences among partitions.     

Molecular phylogeny, recent radiation and evolution of gross morphology of the rhubarb genus Rheum (Polygonaceae) inferred from chloroplast DNA trnL-F sequences

BACKGROUND AND AIMS: Rheum, a highly diversified genus with about 60 species, is mainly confined to the mountainous and desert regions of the Qinghai-Tibetan plateau and adjacent areas. This genus represents a good example of the extensive diversification of the temperate genera in the Qinghai-Tibetan plateau, in which the forces to drive diversification remain unknown. To date, the infrageneric classification of Rheum has been mainly based on morphological characters. However, it may have been subject to convergent evolution under habitat pressure, and the systematic position of some sections are unclear, especially Sect. Globulosa, which has globular inflorescences, and Sect. Nobilia, which has semi-translucent bracts. Recent palynological research has found substantial contradictions between exine patterns and the current classification of Rheum. Two specific objectives of this research were (1) to evaluate possible relationships of some ambiguous sections with a unique morphology, and (2) to examine possible occurrence of the radiative speciation with low genetic divergence across the total genus and the correlation between the extensive diversification time of Rheum and past geographical events, especially the recent large-scale uplifts of the Qinghai-Tibetan Plateau. METHODS: The chloroplast DNA trnL-F region of 29 individuals representing 26 species of Rheum, belonging to seven out of eight sections, was sequenced and compared. The phylogenetic relationships were further constructed based on the sequences obtained. KEY RESULTS: Despite the highly diversified morphology, the genetic variation in this DNA fragment is relatively low. The molecular phylogeny is highly inconsistent with gross morphology, pollen exine patterns and traditional classifications, except for identifying all samples of Sect. Palmata, three species of Sect. Spiciformia and a few species of Sect. Rheum as corresponding monophyletic groups. The monotypic Sect. Globulosa showed a tentative position within the clade comprising five species of Sect. Rheum. All of the analyses revealed the paraphyly of R. nobile and R. alexandrae, the only two species of Sect. Nobilia circumscribed by the possession of large bracts. The crude calibration of lineages based on trnL-F sequence differentiation implied an extensive diversification of Rheum within approx. 7 million years. CONCLUSIONS: Based on these results, it is suggested that the rich geological and ecological diversity caused by the recent large-scale uplifts of the Qinghai-Tibetan Plateau since the late Tertiary, coupled with the oscillating climate of the Quaternary stage, might have promoted rapid speciation in small and isolated populations, as well as allowing the fixation of unique or rare morphological characters in Rheum. Such a rapid radiation, combined with introgressive hybridization and reticulate evolution, may have caused the transfer of cpDNA haplotypes between morphologically dissimilar species, and might account for the inconsistency between morphological classification and molecular phylogeny reported here.     

Confrontation of morphological and molecular data: the Praomys group (Rodentia, Murinae) as a case of adaptive convergences and morphological stasis

Phylogenetic relationships in a group of 21 African rodent species designated as the Praomys group (Murinae) were investigated using morphological characters and sequence data from the complete mitochondrial cytochrome b gene and nuclear IRBP gene fragment (840bp). The molecular results confirm the monophyly of the Praomys group, including the species Malacomys verschureni, while the other Malacomys species appear very divergent. The basal relationships within the Praomys group are poorly resolved, suggesting a rapid radiation at about 7-9 million years ago based on genetic divergence rates calibrated from the fossil record. Discrepancies between molecular and morphological results probably reflect of numerous convergences as well as variations in the rates of morphological evolution among lineages. Reconstructions of the ancestral character states suggest a savannah origin for the Praomys group, along with some morphological traits conserved by stasis in savannah taxa. At the same time, forest taxa seem to be characterized by an accelerated morphological evolution, with acquisition of convergent adaptive characters.     

Leaf morphology shift linked to climate change

Climate change is driving adaptive shifts within species, but research on plants has been focused on phenology. Leaf morphology has demonstrated links with climate and varies within species along climate gradients. We predicted that, given within-species variation along a climate gradient, a morphological shift should have occurred over time due to climate change. We tested this prediction, taking advantage of latitudinal and altitudinal variations within the Adelaide Geosyncline region, South Australia, historical herbarium specimens (n = 255) and field sampling (n = 274). Leaf width in the study taxon, Dodonaea viscosa subsp. angustissima, was negatively correlated with latitude regionally, and leaf area was negatively correlated with altitude locally. Analysis of herbarium specimens revealed a 2 mm decrease in leaf width (total range 1-9 mm) over 127 years across the region. The results are consistent with a morphological response to contemporary climate change. We conclude that leaf width is linked to maximum temperature regionally (latitude gradient) and leaf area to minimum temperature locally (altitude gradient). These data indicate a morphological shift consistent with a direct response to climate change and could inform provenance selection for restoration with further investigation of the genetic basis and adaptive significance of observed variation.     

Phylogenetic relationships of African killifishes in the genera Aphyosemion and Fundulopanchax inferred from mitochondrial DNA sequences

We have analyzed the phylogenetic relationships of 52 species representing all defined species groups (J. J. Scheel, 1990, Atlas of Killifishes of the Old World, 448 pp.) of the African aplocheiloid fish genera Aphyosemion and Fundulopanchax in order to examine their interrelationships and to reveal trends of karyotypic evolution. The data set comprised 785 total nucleotides from the mitochondrial 12S rRNA and cytochrome b genes. The molecular-based topologies analyzed by both maximum parsimony and neighbor-joining support the monophyly of most previously defined species groups within these two killifish genera. The genus Aphyosemion is monophyletic except for the nested position of Fundulopanchax kunzi (batesi group; subgenus Raddaella) within this clade, suggesting that this taxon was improperly assigned to Fundulopanchax. The remaining Fundulopanchax species sampled were supported as being monophyletic in most analyses. Relationships among the species groups in both genera were not as strongly supported, suggesting that further data will be required to resolve these relationships. Additional sampling from the 16S rRNA gene allowed further resolution of relationships within Fundulopanchax, more specifically identifying the nonannual scheeli group as the basal lineage of this otherwise annual genus. Chromosomal evolution within Aphyosemion has been episodic, with the evolution of a reduced n = 9-10 metacentric complement having occurred in multiple, independent lineages. Polarity of chromosomal reductions within the elegans species group appears to support previous hypotheses concerning mechanisms of karyotypic change within the genus Aphyosemion.     

Speciation and adaptive radiation of subterranean mole rats, Spalax ehrenbergi superspecies, in Jordan

The major initial mechanism of speciation in subterranean blind mole rats, Spalacidae, is chromosomal, primarily through Robertsonian rearrangements. Here we highlight another scenario of chromosomal rearrangement leading to ecological speciation and adaptive radiation apparently initiated by pericentric inversions and genie divergence to different ecologies in mole rats in Jordan. We analysed karyotype, allozyme, size and ecological diversity across the range of mole rats in Jordan from mesic Irbid in the north to xeric Wadi Musa (Petra region) in the south, a transect of 250 km. We examined mole rats for chromosome ( N =71), size ( N =76), and allozyme ( N =67) diversities, encoded by 32 loci, in 12 populations of the Spalax ehrenbetgi superspecies in Jordan. By a combination of chromosome morphology, genetic distance, body size and ecogeography, we identified four new putative biological species. All species (except two animals in Madaba) share 2 n = 60 but vary in chromosome morphology, caused by pericentric inversions and/or centromeric shifts. The 'north Moav' species is karyotypically polymorphic for 2 n (2 n = 60; including locally also two animals with 2 n = 62). The distribution of the four species is associated with ecogeographical different domains and climatic diversity. Genetic diversity indices were low, but like chromosome arms (NFa) were positively correlated with aridity stress. Discriminant analysis correctly classified 91% of the individuals into the four species utilizing combinatorially chromosome, allozyme and size diversities. It is hypothesized that mole rat evolution underground is intimately associated with climatic diversity stress above ground.     

Reproductive isolation in a nascent species pair is associated with aneuploidy in hybrid offspring

Speciation may occur when the genomes of two populations accumulate genetic incompatibilities and/or chromosomal rearrangements that prevent inter-breeding in nature. Chromosome stability is critical for survival and faithful transmission of the genome, and hybridization can compromise this. However, the role of chromosomal stability on hybrid incompatibilities has rarely been tested in recently diverged populations. Here, we test for chromosomal instability in hybrids between nascent species, the ‘dwarf’ and ‘normal’ lake whitefish (Coregonus clupeaformis). We examined chromosomes in pure embryos, and healthy and malformed backcross embryos. While pure individuals displayed chromosome numbers corresponding to the expected diploid number (2n = 80), healthy backcrosses showed evidence of mitotic instability through an increased variance of chromosome numbers within an individual. In malformed backcrosses, extensive aneuploidy corresponding to multiples of the haploid number (1n = 40, 2n = 80, 3n = 120) was found, suggesting meiotic breakdown in their F₁ parent. However, no detectable chromosome rearrangements between parental forms were identified. Genomic instability through aneuploidy thus appears to contribute to reproductive isolation between dwarf and normal lake whitefish, despite their very recent divergence (approx. 15–20 000 generations). Our data suggest that genetic incompatibilities may accumulate early during speciation and limit hybridization between nascent species.     

Evolution of a Neotropical marine fish lineage (Subfamily Chaenopsinae, Suborder Blennioidei) based on phylogenetic analysis of combined molecular and morphological data

Phylogenetic relationships within tube blennies (Chaenopsinae) were reconstructed using Bayesian, maximum parsimony and likelihood analyses of multiple molecular markers (mitochondrial DNA: COI; nuclear DNA: TMO-4C4, RAG1, Rhodopsin, and Histone H3) and 148 morphological characters. This total-evidence based topology is well-resolved and congruent across analytical methods with strong support for the monophyly of the Chaenopsinae, all included genera and several internal nodes. A rapid radiation in the early evolution of chaenopsins is inferred from the relatively poor support values for relationships among basal lineages and their divergence into different habitats (rocky reefs, coral reefs and the reef/sand interface). Rates of molecular evolution in chaenopsins, as inferred by divergence among four putative transisthmian geminate species pairs, are rapid compared to other fishes. Conflicts among genetic markers and morphology are especially evident within the genus Coralliozetus, with different species relationships supported by morphology, TMO-4C4, and RAG1 plus Rhodopsin. This study hypothesizes a novel sistergroup relationship between Ekemblemaria and Hemiemblemaria, consistent with morphological, molecular and habitat use data. Our total evidence phylogenetic hypothesis indicates that previously hypothesized morphological characters supporting a close relationship between Hemiemblemaria and Chaenopsis plus Lucayablennius resulted from convergent evolution in these relatively free-swimming blennies.     

CHROMOSOME CYTOLOGY OF EUCHARIS,CALIPHRURIA, AND URCEOLINA (AMARYLLIDACEAE)

Karyotypes are presented for 19 taxa of Eucharis, Caliphruria, and Urceolina, a monophyletic group of Andean Amaryllidaceae within “infrafamily” Pancratioidinae Traub. All three genera are characterized by 2n = 46, the most common somatic number occurring in the “infrafamily.” Incidences of polyploidy are low. Only two tetraploid (2n = 92) species of Eucharis are so far known, E. bouchei and E. bonplandii, the northernmost species of E. subg. Eucharis. The 2n = 68 karyotype of E. amazonica is interpreted as triploid-derived (3x – 1). Chromosomal heteromorphism is reported for C. subedentata. Karyotype data is analyzed with principal component analysis and unweighted pairgroup cluster analysis. In a number of cases, phenetic relationships among the karyotypes correlate with phenetic and cladistic relationships based on morphological data. Karyotype evolution among the three genera is discussed in the context of classical theories of karyotypic symmetry. Stability of chromosome number in Eucharis and related genera suggests that chromosomal evolution has proceeded via nonreciprocal interchanges between chromosomes and infrachromosomal structural change. In at least one case (E. bakeriana), rapid sympatric speciation may have been vectored by chromosomal change.     

Systematics, conservation and morphology of the spider genus Tayshaneta (Araneae, Leptonetidae) in Central Texas Caves

The spider genus Tayshaneta is revised based on results from a three gene phylogenetic analysis (Ledford et al. 2011) and a comprehensive morphological survey using scanning electron (SEM) and compound light microscopy. The morphology and relationships within Tayshaneta are discussed and five species-groups are supported by phylogenetic analyses: the anopica group, the coeca group, the myopica group, the microps group and the sandersi group. Short branch lengths within Tayshaneta contrast sharply with the remaining North American genera and are viewed as evidence for a relatively recent radiation of species. Variation in troglomorphic morphology is discussed and compared to patterns found in other Texas cave invertebrates. Several species previously known as single cave endemics have wider ranges than expected, suggesting that some caves are not isolated habitats but instead form part of interconnected karst networks. Distribution maps are compared with karst faunal regions (KFR's) in Central Texas and the implications for the conservation and recovery of Tayshaneta species are discussed. Ten new species are described: Tayshaneta archambaultisp. n., Tayshaneta emeraldaesp. n., Tayshaneta fawcettisp. n., Tayshaneta grubbsisp. n., Tayshaneta madlasp. n., Tayshaneta oconnoraesp. n., Tayshaneta sandersisp. n., Tayshaneta sprouseisp. n., Tayshaneta vidriosp. n. and Tayshaneta whiteisp. n. The males for three species, Tayshaneta anopica (Gertsch, 1974), Tayshaneta devia (Gertsch, 1974) and Tayshaneta microps (Gertsch, 1974) are described for the first time. Tayshaneta furtiva (Gertsch, 1974) and Tayshaneta uvaldea (Gertsch, 1974) are declared nomina dubia as the female holotypes are not diagnosable and efforts to locate specimens at the type localities were unsuccessful. All Tayshaneta species are thoroughly illustrated, diagnosed and keyed. Distribution maps are also provided highlighting areas of taxonomic ambiguity in need of additional sampling.     

A molecular approach to the tangled intrageneric relationships underlying phylogeny in Euplotes (Ciliophora, Spirotrichea).

The cosmopolitan genus Euplotes is remarkable among ciliates for its species richness. To understand the still tangled taxonomy and phylogenetic relationships within the genus, small subunit rRNA sequences of 11 morphologically defined species colonizing different habitats were determined. Euplotes 18S rRNA is unique among ciliates for its anomalous length and high evolutionary rate. Phylogenetic reconstruction pointed to a high divergence between this genus and the other Spirotrichea, together with a high variability within the genus. Some of the relationships within the Euplotes group were also resolved. Data from the literature, based on morphological features, habitat, and symbiotic relationships, have been compared with our results and are critically discussed. In many cases, the molecular phylogenetic analysis disagreed with species relatedness established on morphological and ecological grounds. The occurrence of a radiation phenomenon in the evolution of the genus is postulated.     

A new species of Paramunida Baba, 1988 from the Central Pacific Ocean and a new genus to accommodate P. granulata (Henderson, 1885)

The genus Paramunida belongs to the most diverse family of galatheoids and it is commonly reported from the continental slope across the Indian and Pacific Oceans. Examination of material collected by the NOAA RV Townsend Cromwell Cruise near Christmas (Kiritimati) Island, Kiribati, revealed the existence of a new species of Paramunida (P. haigae), which represents the fourth record of the genus for the Central Pacific. Furthermore, recent efforts to unravel phylogenetic relationships and diversification patterns in Paramunida revealed P. granulata (Henderson, 1885) to be the most basally diverging taxon within the genus. This species is clearly distinguished from other species of Paramunida by the spinulation of the carapace and the length of the distomesial spine of the second antennal peduncle article, which in combination with a high level of genetic divergence suggest that this species represents a separate monotypic lineage. A new genus, Hendersonida gen. n., is proposed to accommodate this species based on morphological and molecular evidence. An updated dichotomous identification key for all species of Paramunida is presented.     

A rhesus macaque radiation hybrid map and comparative analysis with the human genome

The genomes of nonhuman primates are powerful references for better understanding the recent evolution of the human genome. Here we compare the order of 802 genomic markers mapped in a rhesus macaque (Macaca mulatta) radiation hybrid panel with the human genome, allowing for nearly complete cross-reference to the human genome at an average resolution of 3.5 Mb. At least 23 large-scale chromosomal rearrangements, mostly inversions, are needed to explain the changes in marker order between human and macaque. Analysis of the breakpoints flanking inverted chromosomal segments and estimation of their duplication divergence dates provide additional evidence implicating segmental duplications as a major mechanism of chromosomal rearrangement in recent primate evolution.