Phylogenetic relationships of the callitrichinae (Platyrrhini,Primates) based on β2‐microglobulin DNA sequences

The phylogenetic relationships of callitrichine primates have been determined by DNA sequence analyses of exons 1, 2, and 3 of the β₂‐microglobulin gene. Parsimony, distance, and maximum likelihood analyses of ca. 900 base pairs of 21 taxa, representing all callitrichine genera, indicated that Saguinus was the most basal offshoot. Within Saguinus, S. fuscicollis appeared as the first divergent lineage followed by an unresolved trichotomy formed by S. mystax/S. imperator, S. midas/S. bicolor, and S. oedipus. A second callitrichine lineage was formed by Leontopithecus; each of the three species studied showed identical nucleotide sequences. Callimico appeared as the sister taxon of Callithrix/Cebuella. Genetic distances within this latter group were very small, although a stronger association between Cebuella and species of the Callithrix argentata group was observed. The inclusion of Cebuella in the genus Callithrix is suggested. These studies indicated that tamarins are more plesiomorphic than marmosets in agreement with the phyletic dwarfism hypothesis. Am. J. Primatol. 48:225–236, 1999. © 1999 Wiley‐Liss, Inc.     

Phylogenetic relationships in theCampanulales based onrbcL sequences

Phylogenetic relationships within the angiosperm orderCampanulales were investigated by comparative sequencing of the chloroplast generbcL. CompleterbcL sequences were obtained for ten species in six families within the order. These data were analyzed along with previously publishedrbcL sequences from other taxa (for a total of 117 species) within the subclassAsteridae and outgroups, producing 32 equally parsimonious trees. A subset consisting of 44 of these taxa was then chosen and more rigorous analyses performed, resulting in four equally parsimonious trees. Results indicate that two major clades roughly corresponding to traditionally circumscribedAsterales andCampanulales exist as sister taxa. In particular, therbcL trees indicate thatSphenoclea is not a member ofCampanulales orAsterales, thatPentaphragma is more closely allied toAsterales thanCampanulales, that theCyphiaceae are not monophyletic, thatCampanulaceae andLobeliaceae are not sister taxa, and thatStylidiaceae are correctly placed withinCampanulales.     

Gypsy homologous sequences inDrosophila subobscura (gypsyDS)

Summary Characterization of sequences homologous to theDrosophila melanogaster gypsy transposable element was carried out inDrosophila subobscura (gypsyDS). They were found to be widely distributed among natural populations of this species. From Southern blot and in situ analyses, these sequences appear to be mobile in this species.GypsyDS sequences are located in both euchromatic and heterochromatic regions. A completegypsyDS sequence was isolated from aD. subobscura genomic library, and a 1.3-kb fragment which aligns with the ORF2 of theD. melanogaster gypsy element was sequenced. Comparisons of this sequence in three species (D. subobscura, D. melanogaster, and D. virilis) indicate that there is greater similarity between theD. subobscura-D. virilis sequences than betweenD. subobscura andD. melanogaster. Molecular divergence ofgypsy sequences betweenD. virilis andD. subobscura is estimated at 16 MY, whereas the most likely divergence time of these two species is more than 60 MY. These data strongly suggest thatgypsy sequences have been horizontally transferred between these species.Offprint requests to: T.M. Alberola     

A molecular systematic study ofCathaya, a relic genus of thePinaceae in China

The systematic position ofCathaya, a relic genus of thePinaceae, was discussed based on therbcL gene sequence. The sequence data were analysed with PAUP and MEGA programs. The great genetic distance value betweenCathaya and any other genus of thePinaceae showed thatCathaya was a distinct and isolated genus. The most parsimonious Fitch tree and neighbor-joining tree showed thatCathaya was distantly related to the clade comprisingAbies, Keteleeria, Pseudolarix andTsuga, and a sister group relationship betweenCathaya andPinus was weakly supported.Pseudotsuga is closely related toLarix. In theAbies-Keteleeria-Pseudolarix-Tsuga clade,Abies has a close relationship toKeteleeria whilePseudolarix is relatively closely related toTsuga.     

Fine structure of the dental enamel in the Family Callitrichidae (Ceboidea,primates)

The fine structure of the dental enamel was intensively examined in the Family Callitrichidae.Leontopithecus rosalia has the nonserial pattern, butCallimico goeldii andSaguinus midas appear more or less modified from the typical nonserial pattern asSaimiri sciureus has (see Figs. 1 & 5). On the other hand,Callithrix jacchus andCebuella pygmaea attain to the primitive stage of the multiserial pattern (see Figs. 4 & 6). So far as the structural patterns of the dental enamel are concerned, a serial trend is confirmed in the Callitrichidae; extending from the genusLeontopithecus through the generaCallimico andSaguinus to the generaCallithrix andCebuella. The genusSaguinus shows extremely wide interspecific variation in the fine structure of the dental enamel, ranging fromS. leucopus with the most primitive features toS. bicolor with the most advanced (see Figs. 2 & 3). The rows of enamel prisms are slightly twisted mesiodistally in the former species, but strongly folded in the latter. This reflects transitional stages from the nonserial pattern to the multiserial. As a whole, however, the genusSaguinus is still regarded as nonserial. Thus, there is a slight, but important gap between the genusSaguinus andCallithrix, as shown by the decussation of clusters (see Fig. 5), as well as by other characters.     

Comparative karyology and evolution of the Amazonian Callithrix (Platyrrhini,Primates)

Chromosomal studies in three species of Amazonian Callithrix (2n=44) and data in the literature show that this group is karyomonotypic. Moreover, it is characterized by the presence of abundant heterochromatic regions, unlike the situation in congeneric forms of Callithrix of the Atlantic coast with 2n=46, and by the presence of a highly repetitive, exclusive DNA component, with a basic repeat motif of 1528 bp. Karyotypic comparisons with other Callitrichids and an outgroup species showed that Callitrichids are karyologically conserved and explained several rearrangements that had presumably occurred during their phyletic radiation. Analyses of karyologic data enabled the construction of two alternative phylogenetic topologies. The lack of derived homoeologies, common to all members of the genus Callithrix grouped at present, and the fact that Amazonian species were more similar to Cebuella pygmaea (2n=44) than to their congeneric forms with 2n=46 suggested that species at present included in the Amazonian Callithrix should be grouped with C. pygmaea.     

Reduction index of the upper M2 in marmosets

Marmosets have reduced second molars of which size and shape are varied in different species. Mesiodistal and buccolingual diameter of the first and second upper molars in 16 species were measured, and molar area (molar rectangle) and M2 reduction index were calculated by the equation,R=(M2 area/M1 area) × 100. This index ranged from 36.1 inSaguinus oedipus geoffroyi to 70.6 which was the largest found inCebuella pygmaea. Species ofSaguinus showed relatively wide variation as well as a consistantly smaller index. The index forCallithrix registered around 60 andLeontopithecus rosalia was positioned within this genus. There was no relationship between this index and body size of each form. The sizes of the first molar and second molar may not significantly correlate either with body size across species, becauseLeontopithecus rosalia had exceptionally large molars for its body size and contrarily genusSaguinus had relatively small molars. When the shape of the mandible was expressed as length/width ratio, the reduction index significantly correlate with this ratio in genusSaguinus andCallithrix, indicating that longer jaw in shape had relatively large M2. The reduction indices of two possible subspecies,S. oedipus geoffroyi andS. o. oedipus, were 36.1 and 47.3, respectively. This difference suggested that there was a difference in diet or function of jaw apparatus beyond subspecies level.     

Karyotypic evolution,morphological variability and phylogeny inMedicago sect.Intertextae

Karyotype and external morphological analyses were conducted onMedicago ciliaris, M. intertexta, M. muricoleptis andM. granadensis which comprise theIntertextae section of the genusMedicago. All species were found to have 2n = 16 chromosomes (= 2 ×), including one pair of satellite chromosomes in each respective complement. Karyotypic evolution in theIntertextae involves changes in absolute chromosome size and in centromeric and relative size symmetry. Numerical taxonomic analyses were conducted independently on 17 karyotypic features and on 16 features of external morphology. The results of the two sets of analyses proved comparable, withM. ciliaris andM. intertexta forming a fairly close pair, and the remaining two species appearing to have more distant relationships to each other and to the first pair. These observations are consistent with the infertility relationships and chorologies of the species. It is suggested thatM. muricoleptis andM. granadensis are derived from theM. ciliaris/intertexta species complex withM. granadensis arising fromM. muricoleptis, or these two species independently evolving from a common species complex. Chromosomal and numerical analyses suggest thatM. ciliaris is the most primitive andM. granadensis the most derived species of theIntertextae.     

Taxonomy of theAlouatta seniculus group: Biochemical and chromosome data

Wild populations ofAlouatta belzebul andA. seniculus from Brazil were surveyed in relation to 20 protein loci. Estimates of genetic variability demonstrated thatA. seniculus presents the highest level of heterozygosity among several New World monkey species studied for the same loci. Additional information from DNA and chromosomes suggest thatA. seniculus andA. belzebul are not the closest species in theHershkovitz’sAlouatta seniculus group.     

Systematic relationships of theLactoridaceae,an endemic family of the Juan Fernandez Islands,Chile

The systematic relationships ofLactoridaceae are problematical, with alternative assignments toMagnoliales, Laurales, andPiperales. Phenetic analyses suggest thatLactoridaceae are best accomodated withinMagnoliales and are most closely related toAnnonaceae. Cladistic analyses indicate that the family is a relatively derived member of theMagnoliales, with affinities toAnnonaceae, Eupomatiaceae, Himantandraceae, andMyristicaceae. These analyses together with fossil pollen data are used to interpret the phylogeny ofLactoridaceae and its relatives.     

Evolution and systematic relationships in theTriticeae (Poaceae)

The evolution and taxonomic relationships in theTriticeae are discussed with the view to highlight aspects of this agronomically important group of plants, which may be of interest to molecular biology. Some of these aspects are addressed in more detail in adjoining papers in which specific genomic loci have been examined at the DNA sequence or isozyme level. Aspects discussed include the systematics and geographic distribution of theTriticeae species, isozyme and chromosome pairing studies on some of the species as well as more recent developments in DNA analyses. A survey of the systematics of theTriticeae indicated that the genomic system ofLöve is probably the most useful starting point for interpreting molecular data even though the system has many problems from a taxonomic point of view. The geographical distribution ofTriticeae species, using both published and unpublished data, suggested that information of this type taken together with the theory of continental drift provides a broad time-span for considering data from DNA sequence studies. The significance, and modes of analyses, of isozyme studies were assessed because they often provide valuable characters in determining relationships between species. The main character underlyingLöve's andDewey's analyses of theTriticeae, namely chromosome pairing, is discussed with particular reference to isozyme studies to show that in some cases, such as species ofHordeum sensu lato, consistent relationships are obtained. Finally, new developments in understanding chromosome structure are considered in relation to the above variables in the taxonomy and evolution of theTriticeae.     

Implications ofrbcL sequence data for higher order relationships of theLoasaceae and the anomalous aquatic plantHydrostachys (Hydrostachyaceae)

Subclass and ordinal relationships ofLoasaceae, a small predominately New World family, are examined usingrbcL sequence data. Sequences were examined for eight of the fifteen genera of theLoasaceae and the morphologically anomalous aquatic genusHydrostachys (Hydrostachyaceae). Parsimony analyses of these sequences, combined with previously publishedrcbL data, indicate thatLoasaceae belong in theCornales, and are the sister group ofHydrangeaceae. This agrees with phylogenies based on chloroplast DNA inverted repeat restriction site, morphological and chemical data. TherbcL trees support the monophyly of theLoasaceae and most generic relationships correspond to current subfamily divisions. TherbcL phylogeny also provides the first suggestion thatHydrostachys is allied with theHydrangeaceae in theCornales.     

Evolution of thedec-1 eggshell locus inDrosophila. I. Restriction site mapping and limited sequence comparison in themelanogaster species subgroup

Summary We have analyzed 18 kb of DNA in and upstream of thedefective chorion-1 (dec-1) locus of the eight known species of themelanogaster species subgroup ofDrosophila. The restriction maps ofD. simulans, D. mauritiana, D. sechellia, D. erecta, andD. orena are shown to have basically the restriction map ofD. melanogaster, whereas the maps ofD. teissieri andD. yakuba were more difficult to align. However, the basic amount of DNA and sequence arrangement appear to have been conserved in these species. A small deletion of varying length (65–200 bp) is found in a repeated sequence of the central transcribed region ofD. melanogaster, D. simulans, andD. erecta. Restriction site mapping indicated that thedec-1 gene is highly conserved in themelanogaster species subgroup. However, sequence comparison revealed that the amount of nucleotide and amino acid substitution in the repeated region is much larger than in the 5 translated region. The 5 flanking region showed noticeable restriction site polymorphisms between species. Based on calculations from the restriction maps a dendrogram was derived that supports earlier published phylogenetic relationships within themelanogaster species subgroup except that theerecta-orena pair is placed closer to themelanogaster complex than toD. teissieri andD. yakuba.     

Protein variation,taxonomy and differentiation in five species of marmosets (genusCallithrix Erxleben, 1777)

The electrophoretic patterns of 15 protein systems codified for 20 genetic loci were investigated using horizontal electrophoresis. A total of 150 blood samples, from five species of the genusCallithrix were analyzed. Polymorphic variation was observed in 10 out 20 loci analyzed. The genotypic distributions are in Hardy-Weinberg equilibrium. The average heterozygosity (H) varied from 1% to 5%, similar to those observed for other Neotropical primates. The genetic distance coefficients revealed a phylogenetic separation of these species into two groups: (1) “argentata” (C. humeralifer andC. emiliae); (2) “jacchus” (C. jacchus, C. penicillata, andC. geoffroyi). This arrangement is according to the taxonomic arrangement proposed byHershkovitz (1977),de Vivo (1988), andMittermeier et al. (1988). The results in each group are compatible with the subspecies values recorded for the Platyrrhini. These values showed that:C. humeralifer andC. emiliae are subspecies ofC. argentata;C. jacchus, C. penicillata, andC. geoffroyi are subspecies ofC. jacchus. These results also suggest thatC. j. geoffroyi is the “jacchus” group taxon, most similar genetically to the “argentata” group.     

Phylogenetic analysis ofEremosyne pectinata (Saxifragaceae s. l.) based onrbcL sequence data

Earlier analyses ofrbcL sequences clarified phylogenetic relationships of 16 of 17 subfamilies ofSaxifragaceae s. l. This study investigates the affinities of the monotypicEremosynoideae, the only subfamily ofSaxifragaceae s. l. not examined previously forrbcL sequence variation. Our analyses suggest thatEremosyne is only distantly related to core members ofSaxifragaceae s. l. (i.e.Saxifragoideae = Saxifragaceae s. str.); it is allied instead with members ofAsteridae. A particularly close relationship is indicated betweenEremosyne andEscallonia, another traditional member ofSaxifragaceae s. l. that also appears as part ofAsteridae. Inclusion ofEremosyne withinAsteridae is in agreement with embryology, as well as with 18S rDNA sequence data.     

Interspecific relationships ofCallithrix based on the dental characters

The dental structure of all species ofCallithrix, C. argentata, C. humeralifer, C. aurita, C. flaviceps, C. geoffroyi, C. penicillata, andC. jacchus is examined.Callithrix are divided intoC. jacchus group andC. argentata group, based on the analysis of dental characters.C. jacchus group consists ofC. jacchus, C. penicillata, C. geoffroyi, C. flaviceps, andC. aurita, whileC. argentata andC. humeralifer are assigned toC. argentata group. InC. jacchus group,C. aurita andC. flaviceps were differentiated from the original stock of their common ancestor, followed byC. geoffroyi, last byC. penicillata, and finallyC. jacchus. Based on the relationships among species ofCallithrix, it is possible to infer the relative age of the formation of the refuges which caused their speciation. First, the forests in southeastern Brazilian coast were split from Amazonia. In southeastern Brazilian coast, the Paulista center separated, followed by the Rio Doce center, the Bahia center, finally by the Pernambuco center.     

Recent developments inRhizobium taxonomy

Recent developments inRhizobium taxonomy are presented from a molecular and evolutionary point of view. Analyses of ribosomal RNA gene sequences provide a solid basis to infer phylogenies in the Rhizobiaceae family. These studies confirmed thatRhizobium andBradyrhizobium are only distantly related and showed thatRhizobium andBradyrhizobium are related to other groups of bacteria that are not plant symbionts.Rhizobium andAgrobacterium species are intermixed. Differences in plasmid content may explain to a good extent the different behavior ofRhizobium andAgrobacterium as symbionts or pathogens. Other approaches to identify and classify bacteria such as DNA-DNA hybridization, fatty acid analysis, RFLP and RPD-PCR techniques and phylogenies derived from other genes are in general agreement to the groupings derived by ribosomal sequences. Only a small proportion of nodulated legumes have been sampled for their symbionts and more knowledge is required on the systematics and taxonomy ofRhizobium andBradyrhizobium species.     

Evidence for interspecific transfer of the transposable element mariner betweenDrosophila andZaprionus

Summary The transposable element mariner occurs widely in themelanogaster species group ofDrosophila. However, in drosophilids outside of themelanogaster species group, sequences showing strong DNA hybridization with mariner are found only in the genusZaprionus. the mariner sequence obtained fromZaprionus tuberculatus is 97% identical with that fromDrosophila mauritiana, a member of themelanogaster species subgroup, whereas a mariner sequence isolated fromDrosophila tsacasi is only 92% identical with that fromD. mauritiana. BecauseD. tsacasi is much more closely related toD. mauritiana than isZaprionus, the presence of mariner inZaprionus may result from horizontal transfer. In order to confirm lack of a close phylogenetic relationship between the genusZaprionus and themelanogaster species group, we compared the alcohol dehydrogenase (Adh) sequences among these species. The results show that the coding region of Adh is only 82% identical betweenZ. tuberculatus andD. mauritiana, as compared with 90% identical betweenD. tsacasi andD. mauritiana. Furthermore, the mariner gene phylogeny obtained by maximum likelihood and maximum parsimony analyses is discordant with the species phylogeny estimated by using the Adh genes. The only inconsistency in the mariner gene phylogeny is in the placement of theZaprionus mariner sequence, which clusters with mariner fromDrosophila teissieri andDrosophila yakuba in themelanogaster species subgroup. These results strongly suggest horizontal transfer.     

Update on the Phylogenetic Systematics of New World Monkeys: Further DNA Evidence for Placing the Pygmy Marmoset (Cebuella) within the Genus Callithrix

We determined DNA sequences spanning the 1.8-kb long intron 1 of the interstitial retinol-binding protein nuclear gene (IRBP) for Callithrix geoffroyi, Callithrix humeralifer, and Callithrix argentata. With the 22 previously determined IRBP intron 1 sequences—21 from the 16 currently recognized genera of New World monkeys—the enlarged IRBP data represent for the marmoset genus Callithrix both its argentata and its jacchus species groups. Maximum-parsimony and neighbor-joining trees, constructed for the 25 aligned IRBP intron 1 sequences, support a provisional phylogenetic classification with three families: Atelidae, containing subfamily Atelinae; Pitheciidae, containing subfamily Pitheciinae; and Cebidae, containing subfamilies Cebinae, Aotinae, and Callitrichinae. In order to have taxa at the same hierarchical rank at equivalent age, this classification has all living callitrichines in a single tribe, Callitrichini, with four subtribes: Saguinina (Saguinus), Callimiconina (Callimico), Leontopithecina (Leontopithecus), and Callitrichina (Callithrix with the pygmy marmoset, Cebuella pygmaea, merged into it). The DNA evidence shows not only that Callithrix must include C. pygmaea to be monophyletic but also that the times of separation of pygmaea and the argentata and jacchus species groups from one another are to be expected (<5 Ma—million years ago) for species in a single genus. On relating the time course of the ceboid radiation to biogeographic information, it appears that in mid-Miocene times (10–11 Ma) a basal callitrichin stock branched into the ancestral population of Saguinus in one clade and the ancestral population of Leontopithecus and Callimico–Callithrix (or Leontopithecus–Callimico and Callithrix) in another clade. The proto-lion tamarins migrated south and eastward, where they were isolated in refugia, becoming the genus Leontopithecus. The stock remaining in Amazonia gave rise to present-day Callimico and Callithrix. The latter genus occupied a vast geographic area, giving rise to the argentata and pygmaea groups in Amazonia and to the jacchus group in central and eastern Brazil.     

Craniometrical variations among eastern Brazilian marmosets and their systematic relationships

The craniometrical variations among marmosets on the eastern coast of Brazil or theCallithrix jacchus group (C. jacchus, C. penicillata, C. kuhli, C. geoffroyi, C. flaviceps, andC. aurita) were analyzed to test various hypotheses for the arrangement of the species and phylogenetic relationships ofC. kuhli andC. flaviceps. Q-mode correlation coefficients and principal component analysis were employed to extract important shape factors from the craniometrical data. On this basis, the shape distances among the eastern Brazilian marmosets were found to be larger than those between the marmosets which are recognized as distinct species. This evidence supports the hypothesis that the members of theC. jacchus group are distinct species.C. kuhli shows the strongest resemblance toC. geoffroyi within theC. jacchus group.C. flaviceps is the most similar toC. aurita in its cranial shape. These findings indicate thatC. kuhli is most closely related toC. geoffroyi, whileC. flaviceps is toC. aurita.