Genetic differences among subspecies of the saddle-back tamarin (Saguinus fuscicollis):evidence from hybrids

The subspecies of saddle-back tamarins (Saguinus fuscicollis) are known to be chromatically and morphologically diverse but little is known of the genetic basis for the observed morphological variation. The morphology of first generation subspecific hybrids can be compared to that of the parental subspecies to provide information on the extent and nature of genetic differences in morphology between subspecies. We compare two groups of saddle-back tamarin hybrids (S. f. illigeri × S. f. lagonotus and S. f. illigeri × S. f. leucogenys) to pure-bred members of their parental subspecies. These crosses were examined for heterosis, caused by allele frequency differences between the subspecies in combination with directional dominance. Thirty-nine craniofacial measurements were derived from three-dimensional coordinates of landmarks on 355 adult tamarin skulls. These measurements were corrected for sex differences and differences due to environment (wild-derived vs. laboratory-born) prior to analysis of hybridity. Sex differences were minimal for these traits. Environment had a more significant effect on craniofacial morphology. Laboratory environments produce larger faces but smaller orbits, anterior cranial vaults, and cranial bases. Significant heterosis was found for many individual traits and for the first principal component representing size and size-related shape measurements in the S. f. illigeri × S. f. lagonotus cross. The smaller samples involved in the S. f. illigeri× S. f. leucogenys cross led to a much lower number of statistically significant results, although most traits did display heterosis. Heterosis for craniofacial size was nearly statistically significant. These results suggest that there are large differences in allele frequencies among these subspecies of saddle-back tamarin for genes affecting craniofacial morphology. Based on these data we suggest that these subspecies are likely to be independent, largely isolated, evolutionary units. © 1993 Wiley-Liss, Inc.     

Breeding biology and seasonal abundance of Lappet-faced Vultures Torgos tracheliotus in western Saudi Arabia

Lappet-faced Vultures Torgos tracheliotus utilizing a 2200-km², fenced, protected area in western Saudi Arabia were studied over 4 years. Numbers fluctuated seasonally from minima of c. 30 individuals in the spring to maxima of 160 birds in the autumn. All birds foraged predominantly on domestic livestock carrion outside the Reserve. In each year, up to 17 pairs attempted to breed, with 81% of pairs laying eggs, typically in large Maerua crassifolia trees. In all, 81% of the eggs hatched and 85% of nestlings fledged. Most eggs were laid in December, when mean daily air temperatures were lowest, and young usually fledged c. 180 days later. Overall, 56% of nesting attempts fledged young. Juvenile mortality over the first 3 months after fledging was at least 17%. The numbers and proportion of breeders appeared to be stable, but it is not known whether the establishment of the Reserve concentrated the nesting and roosting of vultures in the area or has attracted birds from elsewhere. Breeding success was higher than in most well-studied African populations and probably those nesting elsewhere in Arabia. Four pairs reared 52% of the fledglings observed in the Reserve over 4 years. The Saudi Arabian Lappet-faced Vultures probably belong to the subspecies negevensis and, because of the extinction of this subspecies in the wild in Israel, the well-being of the Saudi Arabian population is critical to the subspecies' conservation.     

赤狐华南亚种与东北亚种上毛髓质指数的比较研究

选取赤狐华南亚种和东北亚种8个部位上毛,用测试格测定上毛的髓质指数。结果表明,赤狐华南亚种和东北亚种上毛髓质指数在同一亚种的不同部位及亚种间差异极显著（P〈0．01）。无论在总体平均值上,还是在不同亚种个体同一部位上,赤狐东北亚种上毛的髓质指数均大于华南亚种。两亚种躯干部上毛髓质指数的平均值均明显大于前肢。这种差异性表现为从前肢末端到动物体躯干部呈梯度递增,其递增梯度在两个亚种的个体中表现有同步变化的趋势。     

Use of RAPD-PCR-analysis of cellular DNA for the evaluation of genetic polymorphism and subspecies diagnostics of the Far Eastern leopard Panthera pardus orientalis]

Genetic polymorphism in the Far-Eastern leopard subspecies Panthera pardus orientalis was examined by RAPD-PCR analysis of total cellular DNA. Primers diagnostic for the leopard subspecies were detected. These primers can be used for differentiating wild-living animals from those kept in captivity and distinguishing different breeding lines. Genetic diversity was shown to be lower in animals from the zoo (D = 0.058) and higher in a natural population (D = 0.137). Two lines of the Persian subspecies were genetically closest (D = 0.042), and the Persian and Far-Eastern subspecies represented by wild animals, genetically most remote (D = 0.274). The level of genetic divergence of the Persian subspecies and Far-Eastern subspecies (zoo animals) was lower (D = 0.108) than between representatives of the Persian subspecies from the captive and natural population (D = 0.220). On the basis of analysis of relatedness, performed using NTSYS and PHYLIP software packages, the possibility cannot be excluded that some P. p. orientalis animals from the zoo have a hybrid origin and may be assigned to another Far-Eastern subspecies.     

中国西南横断山区的野生鸭茅资源

中国西南横断山区广泛分布野生鸭茅资源,包括鸭茅亚种和喜马拉雅鸭茅亚种。二者的分布范围相近,但在形态及物候发育等方面存在明显差异,鸭茅亚种的主要农艺性状优于喜马拉雅鸭茅亚种。两个亚种在人工控制条件下可以杂交形成三倍体后代,但自然状态下尚未发现二者杂交的确切证据。近年来,中国加强了对两个鸭茅亚种的基础研究,但从保护和利用研究角度出发,开展的工作较少。从来源角度分析,喜马拉雅鸭茅亚种为当地起源类型,鸭茅亚种为外来归化种的可能性较大。由于喜马拉雅鸭茅面临鸭茅亚种的竞争威胁,因此应加强中国喜马拉雅鸭茅亚种野生资源的保护和开发利用研究。     

An evaluation of the species and subspecies of the genus Salmonella with whole genome sequence data: Proposal of type strains and epithets for novel S. enterica subspecies VII,VIII, IX,X and XI

Species and subspecies within the Salmonella genus have been defined for public health purposes by biochemical properties; however, reference laboratories have increasingly adopted sequence-based, and especially whole genome sequence (WGS), methods for surveillance and routine identification. This leads to potential disparities in subspecies definitions, routine typing, and the ability to detect novel subspecies. A large-scale analysis of WGS data from the routine sequencing of clinical isolates was employed to define and characterise Salmonella subspecies population structure, demonstrating that the Salmonella species and subspecies were genetically distinct, including those previously identified through phylogenetic approaches, namely: S. enterica subspecies londinensis (VII), subspecies brasiliensis (VIII), subspecies hibernicus (IX) and subspecies essexiensis (X). The analysis also identified an additional novel subspecies, reptilium (XI). Further, these analyses indicated that S. enterica subspecies arizonae (IIIa) isolates were divergent from the other S. enterica subspecies, which clustered together and, on the basis of ANI analysis, subspecies IIIa was sufficiently distinct to be classified as a separate species, S. arizonae. Multiple phylogenetic and statistical approaches generated congruent results, suggesting that the proposed species and subspecies structure was sufficiently biologically robust for routine application. Biochemical analyses demonstrated that not all subspecies were distinguishable by these means and that biochemical approaches did not capture the genomic diversity of the genus. We recommend the adoption of standardised genomic definitions of species and subspecies and a genome sequence-based approach to routine typing for the identification and definition of novel subspecies.     

Responses to playback of different subspecies songs in the Reed Bunting Emberiza schoeniclus

Populations of Reed Buntings Emberiza schoeniclus in the western Palearctic are classified in two major subspecies groups according to morphology: northern migratory schoeniclus and Mediterranean resident intermedia . Songs of the two groups differ mainly in complexity and syllable structure, with intermedia songs being more complex. We explored the possibilities of song as a subspecies isolating mechanism by testing if male schoeniclus Reed Buntings reacted differently to field playbacks of songs from their own subspecies group, from the foreign subspecies group and from a control species, the Yellowhammer Emberiza citrinella . We tested 30 different males, each with a different song belonging to one of the three categories: own, foreign and Yellowhammer. Unlike songs of the two subspecies groups, Yellowhammer song elicited no response. Differences between reactions to own and foreign subspecies group songs were not significant, even though differences in response type (singing vs approaching) suggested some degree of uncertainty in classification of foreign song. We conclude from these results that the subspecies may be only in the first stages of the isolation process.     

Bacillus thuringiensis subsp. toguchini--a new subspecies of crystal-forming bacteria

A new subspecies of B. thuringiensis subsp. toguchini has been isolated from soil in Novosibirsk region. New subspecies forms elliptic crystals. Biologically and serologically it is different from other known subspecies.     

Genomic variation patterns of subspecies defined by phenotypic criteria: Analyses of the mangrove species complex,Avicennia marina

Subspecies is used to designate taxa below species but above geographical populations. What patterns of genomic variation are expected if taxa are designated as subspecies? In this study, we carry out such a survey on the mangrove tree Avicennia marina (Forssk.) Vierh. of the Indo-West Pacific coasts. This species has three subspecies, distinguished by morphological traits and geographical distribution. We collected samples from 16 populations (577 individuals) covering all three subspecies and sequenced 94 nuclear genes. We reveal comprehensive genetic divergence among subspecies, generally higher than among geographical populations within subspecies. The level of genetic diversity differs among the three subspecies, possibly hinting at a degree of separation among their gene pools. We observed that divergence varies from locus to locus across the genome. A small portion of the genome is most informative about subspecies delineation, whereas the rest is undifferentiated or slightly differentiated, hinting at uneven gene flow and incomplete isolation. The three subspecies likely split simultaneously with gene flow among lineages. This reticulate evolution results in some discordance between morphology and genetics in areas of population contact. In short, A. marina subspecies show species-like patterns in some respects and population-like patterns in others. We propose that the subspecies designated in A. marina are informative in predicting genetic divergences and useful in making conservation decisions.     

Numerical analysis of the phenotypic properties and total genomic characteristics of strains of Yersinia pestis related to different subspecies

The numerical analysis of the phenotypical properties of Y. pestis strains, classified with 5 subspecies by 60 signs, was carried out. In comparing the properties of strains belonging to the main (nomenclature) subspecies with strains of other subspecies, the similarity index varied within the range 82-95%. A high degree of genetic affinity between 21 Y. pestis strains of five subspecies was demonstrated by the method of molecular DNA-DNA hybridization. The level of DNA homology with respect to the alpha-CTP.[3H] reference mark of Y. pestis P-1300 in strains belonging to different subspecies was found to be 84-97%. The plasmid spectrum of 25 examined strains of these three subspecies proved to be identical and consisted of plasmids similar in their electrophoretic motility to marker plasmids from Y. pestis strains EV from the Research Institute of Epidemiology and Hygiene and Otten.     

Discrete subspecies of human low density lipoproteins are heterogeneous in their interaction with the cellular LDL receptor.

The low density lipoproteins (LDL) of human plasma consist of a series of discrete particle subspecies of distinct physicochemical, immunological, and hydrodynamic properties. Such structural differences are intimately linked to the metabolic heterogeneity of circulating LDL in vivo. The current studies were designed to evaluate and compare the interaction of discrete LDL subspecies from normolipidemic subjects with the LDL receptor. Plasma LDL of d 1.019-1.063 g/ml from healthy males were fractionated into 15 subspecies of defined physicochemical characteristics by isopycnic density gradient ultracentrifugation as described earlier (Chapman et al., J. Lipid Res. 1988. 29: 442-458). The major LDL subspecies, LDL-5 to LDL-10, exhibited an overall range in density from 1.0244 to 1.0435 g/ml; individual subspecies increased in density by increments of 0.027 (LDL-5), 0.026 (LDL-6), 0.030 (LDL-7), 0.031 (LDL-8), 0.035 (LDL-9), and 0.042 g/ml (LDL-10), respectively. Taken together, these subspecies accounted for approximately 70% of the total mass of LDL of d 1.019-1.063 g/ml; their cholesterol: protein ratios decreased from 1.70 to 1.12 and particle size from 275 to 260 A with increase in density. ApoB-100 was the unique protein component in subspecies 5-8, with trace amounts (less than 0.2% of apoLDL) of both apoA-I and apoE in subspecies 9 and 10. The interaction of individual LDL subspecies with the LDL receptor on cultured human U-937 monocyte-like cells was compared by determining receptor binding affinities at 4 degrees C. Scatchard analysis of specific binding curves demonstrated a single class of binding site for each subspecies. The lowest dissociation constants were displayed by LDL subspecies 6 (Kd 5.71 nM), 7 (Kd 5.24 nM) and 8 (Kd 4.67 nM), while subspecies 5, 9, and 10 displayed significantly higher Kd values (8.35, 7.20, and 6.87 nM, respectively). Competitive displacement studies at 4 degrees C, in which unlabeled subspecies from the same gradient series competed for binding with 125I-labeled LDL subspecies, confirmed the relative binding affinities of these subspecies. As the hydrophobic lipid core of LDL undergoes a thermotropic transition at approximately 37 degrees C, which may in turn influence the surface structure of the particle, internalization and degradation studies were performed at 37 degrees C. No effect of temperature was detectable; again, LDL subspecies at each extreme of the density distribution (LDL-5 and LDL-10) displayed significantly lower binding affinities for the LDL receptor than that from the peak region (LDL-7).(ABSTRACT TRUNCATED AT 400 WORDS)     

A proposed core genome scheme for analyses of the Salmonella genus

The salmonellae are found in a wide range of animal hosts and many food products for human consumption. Most cases of human disease are caused by S. enterica subspecies I; however as opportunistic pathogens the other subspecies (II-VI) and S. bongori are capable of causing disease. Loci that were not consistently present in all of the species and subspecies were removed from a previously proposed core genome scheme (EBcgMLSTv2.0), the removal of these 252 loci resulted in a core genus scheme (SalmcgMLSTv1.0). SalmcgMLSTv1.0 clustered isolates from the same subspecies more rapidly and more accurately grouped isolates from different subspecies when compared with EBcgMLSTv2.0. All loci within the EBcgMLSTv2.0 scheme were present in over 98% of S. enterica subspecies I isolates and should, therefore, continue to be used for subspecies I analyses, while the SalmcgMLSTv1.0 scheme is more appropriate for cross genus investigations.     

Genetic and morphological divergence between populations of the flatfish Platichthys flesus (L.) (Pleuronectidae)

Populations of the flounder, Platichthys flesus , were screened for electrophoretically detectable protein variation at up to 37 loci. Atlantic and North Sea populations (subspecies flesus ) were genetically very similar to one another ( I >0.99) but different from Adriatic (subspecies italicus ) and Black Sea (subspecies luscus ) populations. The values for genetic identity between subspecies were around 0.9. Diagnostic loci enabled specimens of flesus, italicus and luscus to be differentiated from one another. Samples of flesus showed two to three times the heterozygosity levels of italicus or luscus , consistent with the greater population size of flesus . Morphological comparisons enabled populations to be categorized to subspecies. Platichthys flesus italicus and luscus are valid subspecies: the terms are not synonyms. The genetic distance data provide an estimate of divergence time of the three subspecies at about 2 My ago, an estimate that seems reasonable in the light of present knowledge concerning the recent geological histories of the Mediterranean and Black Sea basins.     

Comparison of three subspecies of Trichinella spiralis by scanning electron microscopy

The surface morphology of three subspecies of Trichinella spiralis was examined by SEM in an attempt to find characteristics useful for distinguishing the subspecies. The subspecies studied were T. spiralis spiralis, which had been maintained in swine and laboratory animals for about 50 yr; T. spiralis nativa collected from Ursus maritimus at 58 degrees N latitude and 95 degrees W longitude in 1976; and, T. spiralis pseudospiralis, which was derived from the original isolation of this subspecies from Procyon lotor at 43 degrees N latitude and 47 degrees 30'E longitude in 1972. All three subspecies were passed in CFW mice and adult worms were collected from the small intestine at 4, 5, 6, 7, 8, and 11 days PI. Characteristics examined included labial and cephalic papillae, cuticular ridges and folds, hypodermal gland cell pores, pseudobursal lobes, genital papillae, cloacal aperture, copulatory bell and vulval morphology. Previous reports of subspecies differences within Trichinella spiralis in the number and distribution of hypodermal gland cell pores, position of genital papillae, shape of the cloacal aperture and shape of pseudobursal lobes were not confirmed and are believed to have been in error resulting from artifacts of fixation and a lack of knowledge of variations within the subspecies caused by low numbers of samples. Differences in surface morphology were not found among the three subspecies. The available names of the recognized biological populations of Trichinella were used at the subspecies level rather than species level because this more clearly represents the state of our knowledge of the nematodes. The question of whether the epidemiology of trichinosis is complicated by the presence of more than one species has not been answered, and it is important that our nomenclature reflect this.     

Subspecific selectivity by a mammalian herbivore: Geographic differentiation of interactions between two taxa of Sciurus aberti and Pinus ponderosa

We compared host selection by two subspecies of Abert's squirrel, a highly specialized and selective herbivore. Both subspecies are restricted to stands of ponderosa pine, upon which they are ecologically dependent, but the two subspecies are geographically disjunct and each is closely associated with stands of trees that represent strongly differentiated chemical races. The criteria by which trees were selected as sources of phloem by each subspecies of squirrel included heritable features of xylem oleoresin and phloem. Trees that were potentially available to the subspecies of squirrel in Colorado differed substantially in biochemical features from trees that were available to the subspecies in Arizona; as a result, chemically mediated feeding patterns were distinct between the two squirrel subspecies. Based on multivariate analysis of chemical characteristics, trees utilized by the squirrels for feeding (target trees) differed significantly from control trees (non-target tre es) for each subspecies. However, the discriminant functions that separated target trees from non-target trees within a site generated different patterns of predicted classification when applied to trees at the other site. Vertebrate herbivores that are feeding specialists can exert selection pressures in populations of their host plants, and results suggest that geographically differentiated herbivore–host interactions can produce different sets of selection pressures, which may result in different evolutionary outcomes. Such geographic differentiation is a potentially important evolutionary aspect of chemically mediated mammal–plant interactions.     

Genetic diversity in Delphinium variegatum (Ranunculaceae): a comparison of two insular endemic subspecies and their widespread mainland relative

Delphinium variegatum is subdivided into three subspecies: D. v. variegatum is widespread in central and northern California, while D. v. kinkiense (an endangered taxon) and D. v. thornei are endemic to San Clemente Island off the coast of southern California. Electrophoretic data for 19 loci were collected from 7 populations of the mainland subspecies and all 24 known populations of the two insular endemic subspecies. Populations of the widespread mainland subspecies have more polymorphic loci (33.6% vs. 24.5%) and more alleles per polymorphic locus (2.61 vs. 2.15) than the insular endemic subspecies. However, observed heterozygosities are lower in the mainland subspecies (0.041 vs. 0.071), presumably due to lower levels of outcrossing (t = 0.464 vs. 0.895). Expected heterozygosities are similar (0.064 vs. 0.074) due to lower alternative allele frequencies in populations of the mainland subspecies (mean q = 0.075 vs. 0.190). Populations of the two insular subspecies are almost equivalent genetically (mean I = 0.997) regardless of taxonomic designation or geographic location. In contrast, one of the mainland populations is genetically well differentiated from the others. If this exceptional population is excluded, the mainland subspecies partitions genetic diversity similarly to the island subspecies, with most variation being found within populations (G(ST) = 0.073 vs. 0.030).     

A dental topographic analysis of chimpanzees

Molar tooth morphology is generally said to reflect a compromise between phylogenetic and functional influences. Chimpanzee subspecies have been reported to exhibit differences in molar dimensions and nonmetric traits, but these have not been related to differences in their diets. And in fact, observations to date of the diets of chimpanzees have not revealed consistent differences among subspecies. This study uses dental topographic analyses shown to reflect diet-related differences in occlusal morphology among primate species, to assess within-species variation among chimpanzee subspecies. High-resolution casts from museum collections were examined by laser scanning, and resulting data were analyzed using GIS algorithms and a two-factor ANOVA model. Although differences were noted between wear stages within subspecies in surface slope, relief, and angularity, none were found to distinguish the subspecies from one another in these attributes. This might reflect limitations in the ability of this method to detect diet-related differences, but is also consistent with a lack of differences in functionally relevant aspects of occlusal morphology among chimpanzee subspecies.     

Latitudinal variation in subspecific diversification of birds

Patterns of evolution are believed to vary latitudinally, but our understanding of this variation remains limited. Here we examine how patterns of subspecific diversification vary within species of birds, specifically addressing three questions: (1) Are subspecies more numerous at lower latitudes within species, consistent with greater phenotypic differentiation at lower latitudes? (2) If there are more subspecies at lower latitudes within species, can area of breeding range explain this relationship? and (3) how do latitudinal differences in subspecies within species vary geographically across the globe? Using all species with five or more subspecies from 12 of the most diverse families of birds in the world, we found consistently more subspecies at lower latitudes across all families, both hemispheres, and all continents examined. Despite the positive influence of area on the number of subspecies within species, area did not explain the greater number of subspecies at lower latitudes within species. Global patterns of subspecies support the idea that phenotypic differentiation of populations is greater at lower latitudes within species. If subspecies density provides an index of rates of incipient speciation, then our results support evolutionary hypotheses for the latitudinal diversity gradient that invoke higher tropical speciation rates.