Hybridization between subspecies of waterbuck (Kobus ellipsiprymnus) in zones of overlap with limited introgression

Two subspecies of waterbuck (Kobus ellipsiprymnus), common (Kobus ellipsiprymnus ellipsiprymnus) and defassa (Kobus ellipsiprymnus defassa), are recognized based on differences in rump pattern, coat colour and geographical distribution. These forms are parapatrically distributed with an area of range overlap in East Africa, where phenotypically intermediate populations occur. Variation in 478 bp of the mitochondrial DNA control region and 14 polymorphic microsatellite loci were used to describe the genetic structure and phylogeographical pattern of the species, and to assess if the intermediate populations are the results of hybridization. In total, 186 individuals from 11 localities were analysed. A high degree of genetic differentiation was found between subspecies, although this was most evident from the microsatellite data. Hybridization was suggested in the phenotypically and geographically intermediate Nairobi NP population in Kenya. A neighbour-joining (NJ) tree based on microsatellite population genetic distances grouped Nairobi between the common and defassa populations, and a Bayesian analysis clearly showed introgression. Individuals sampled in Samburu NP, Kenya, had a common waterbuck phenotype, but introgression was suggested by both markers. Although a high degree of maternal defassa input was indicated from the sequence data, the Samburu population grouped with the common waterbuck in the microsatellite population genetic distance tree, with high support. Analyses of linkage disequilibrium and maximum-likelihood estimates of genetic drift suggested that admixture between subspecies is a recent event. The fact that introgression is limited between subspecies could be caused by chromosomal differences, hindering gene flow between common and defassa waterbuck.     

Differences in ribosomal DNA distribution on A and B chromosomes between eastern and western populations of the grasshopper Eyprepocnemis plorans plorans

Distribution of ribosomal DNA (rDNA) on standard (A) and supernumerary (B) chromosomes of the grasshopper Eyprepocnemis plorans was analysed in specimens collected in Turkey and Armenia, belonging to the E. p. plorans subspecies, and in South Africa, belonging to the E. p. meridionalis subspecies. The latter individuals showed rDNA loci in chromosomes 9 and 11 only, whereas those from Armenia carried it in chromosomes 9 and 11 or else in chromosomes 9-11, depending on the population. The specimens from Turkey carried it in chromosomes 1, 9-11 and X. A comparison of this pattern with those previously observed in populations from Spain, Morocco, and Greece (belonging to E. p. plorans) suggests the existence of two evolutionary patterns in rDNA chromosome location in A chromosomes of this subspecies: eastern populations showing rDNA restricted to the small (9-11) chromosomes (as in E. p. meridionalis and other closely related taxa within the Eyprepocneminae subfamily) and western populations carrying rDNA in most A chromosomes (Spain) or all of them (Morocco). The intermediate pattern discerned in geographically intermediate populations (in Greece and Turkey), with rDNA also being located on the X chromosome, suggests a possible east-west cline. Additional support for east-west differentiation in the rDNA location pattern comes from the analysis of B chromosomes. In eastern populations, including Daghestan, Armenia, Turkey, and Greece, B chromosomes are composed mostly of rDNA, whereas in western populations (Spain and Morocco) they contain roughly similar amounts of rDNA and a 180-bp tandem repeat (satDNA), the latter being scarce in eastern Bs.     

Heterochromatin and chromosome evolution: a FISH probe of Cebus apella paraguayanus (Primate: Platyrrhini) developed by chromosome microdissection

Neotropical Primate karyotypes are highly variable, particularly in the heterochromatic regions, not only regarding the amount of heterochromatin, but also the composition. G and C banding and FISH techniques provide useful information to characterize interspecific relationships. We used chromosome microdissection to develop a FISH probe of the chromosome 11 heterochromatic block (11qHe+) of Cebus apella paraguayanus (CAPp). Fragments of the 11qHe+ microdissected from fibroblast cell culture were collected in a PCR tube, amplified by degenerate oligonucleotide primer-PCR and subsequently labeled. The specificity of the FISH probe was confirmed in metaphases of some Ceboidea species. Signals were located in the He+ of chromosomes 4, 11, 12, 13, and 19 of CAPp and in the He+ of chromosomes 4, 12 and 13 of C. a. nigritus (CAPn); no signals were observed when other Ceboidea species were analyzed. We propose that the heterochromatin observed in CAPp and CAPn is specific for these species. We consider this C. apella heterochromatin identity as a possible key for the interpretation of chromosomal evolution in these Ceboidea.     

Meiosis and chromosome painting of sex chromosome systems in Ceboidea

The identity of the chromosomes involved in the multiple sex system of Alouatta caraya (Aca) and the possible distribution of this system among other Ceboidea were investigated by chromosome painting of mitotic cells from five species and by analysis of meiosis at pachytene in two species. The identity of the autosome #7 (X2) involved in the multiple system of Aca and its breakage points were demonstrated by both meiosis and chromosome painting. These features are identical to those described by Consigliere et al. [1996] in Alouatta seniculus sara (Assa) and Alouatta seniculus arctoidea (Asar). This multiple system was absent in the other four Ceboidea species studied here. However, data from the literature strongly suggest the presence of this multiple in other members of this genus. The presence of this multiple system among several species and subspecies that show high levels of chromosome rearrangements may suggest a special selective value of this multiple. The meiotic features of the sex systems of Aca and Cebus apella paraguayanus (Cap) are strikingly different at pachytene, as the latter system is similar to the sex pair of man and other primates. The relatively large genetic distances between species presently showing this multiple system suggest that its origin is not recent. Other members of the same genus should be investigated at meiosis and by chromosome painting in order to know the extent and distribution of this complex sex-chromosome system.     

Geographic Variation in Nonmetric Dental Traits of the Deciduous Molars of Pan and Gorilla

Physical anthropologists often use nonmetric dental traits to trace the movement of human populations, but similar analysis of the teeth of nonhuman primates or the deciduous teeth is rare. Because nonmetric dental characteristics are manifestations of genetic differences among groups, they vary among geographically distant members of the same species and subspecies. We use 28 nonmetric dental traits in the deciduous molars to compare genetically and geographically distinct groups of extant African apes (Gorilla and Pan). Previous researchers have studied these traits in the adult or juvenile teeth of great apes and humans, and we score our observations according to established standards for hominins. We observe marked differences in trait frequencies between Gorilla and Pan, Pan troglodytes and P. paniscus, and two P. troglodytes subspecies but we find no significant differences between geographically isolated groups within the subspecies. Trait frequencies differ from those found in previous studies that contained fewer individuals. We find that the deciduous molars show similar variation to adult premolars and molars within Pan and Gorilla. This suggests that the deciduous dentition of these and other apes may contain diagnostic traits that are not currently in use.     

Intraspecific chromosome variation in Cebus apella (cebidae,platyrrhini): The chromosomes of the yellow breasted capuchin Cebus apella xanthosternos wied, 1820

Chromosome studies in six wild-caught specimens of Cebus apella xanthosternos showed a distinctive chromosome pair number 11 that made it possible to distinguish this subspecies from other Cebus apella. The characteristic chromosome pair had intercalar heterochromatin unlike the “standard” chromosome type of Cebus apella and other species of the same genus, in which this chromosome pair shows a large, terminal, heterochromatic block. A comparison at the chromosomal level between different Cebus apella populations suggests that chromosome 11 in Cebus apella xanthosternos is a derived chromosome that has probably become fixed in this subspecies, either by selection or by drift in a small isolated population.     

Geometric morphometric and phylogenetic analyses of Arizona Sky Island populations of Scaphinotus petersi Roeschke (Coleoptera: Carabidae)

Scaphinotus petersi Roeschke, 1907 (Carabidae) is a ground beetle endemic to Sky Islands in south‐eastern Arizona. Previous taxonomic studies described several subspecies with morphological differences inhabiting geographically isolated mountain ranges. We combined molecular sequence data and morphometric data, especially head and pronotum shape analyses, to examine the variation and divergence in subspecies and isolated montane populations. In this study, we employ a combination of distance morphometrics as well as geometric morphometrics to quantify the level of morphological variation, and to test the hypothesis that geographically distinct populations of S. petersi are phenotypically distinct. Results suggest that these isolated populations have diverged morphologically and genetically. Phylogenetic analyses identified two monophyletic lineages within the species that correspond generally to pronotum shape. We observed significant morphological variation among most montane populations in of S. petersi, with the pronotum shape as the clearest delimiting trait. © 2015 The Linnean Society of London     

The relationship between locomotor behavior and limb morphology in brown (Cebus apella) and weeper (Cebus olivaceus) capuchins

This study is a comparison of locomotor behavior and postcranial form in two species of capuchin monkey, the brown capuchin (Cebus apella), and the weeper capuchin (Cebus olivaceus). Behavioral data from groups of wild C. apella and C. olivaceus in Guyana were collected during the period of December 1999 through November 2000. Postcranial variables including 40 measurements and three indices were taken from 43 adult and subadult specimens of C. apella and 14 adult and subadult specimens of C. olivaceus housed in American museums, as well as two wild-caught adult specimens of C. olivaceus from the Georgetown Zoo in Guyana. The results of this study indicate that these two capuchins exhibit similar patterns of locomotor behavior, but that there are important differences in how they move through their homerange, particularly with respect to quadrupedalism. These differences in behavior are reflected in their postcranial morphology and can be related to differences in foraging strategies. This study provides an example of the importance of using more exclusive categories of quadrupedal behaviors when comparing closely related arboreal quadrupeds, as well as an alternative explanation for some of the postcranial features of C. apella that may relate to foraging postures and foraging strategy rather than traditionally categorized patterns of locomotor behavior.     

中国圈养梅花鹿的遗传多样性和遗传结构

东北梅花鹿(Cervus nippon hortulorum)的野生种群已濒临灭绝,但其圈养种群遍布全国各地,是我国圈养梅花鹿的主要品种(亚种)。为了探讨圈养梅花鹿种群作为东北梅花鹿野外放归项目资源种群的可行性,测定了来自9个圈养种群45只梅花鹿个体的线粒体DNA控制区的部分序列,以此分析我国圈养梅花鹿种群的遗传多样性和遗传结构。结果表明,我国圈养梅花鹿种群的遗传多样性并不贫乏,种群之间并没有发生显著的遗传分化。因此,东北地区的圈养梅花鹿种群可以作为野外放归项目的资源种群,而野外放归项目的建群者应来源于东北地区的多个圈养种群。     

Geometric morphometrics and ecological niche modelling for delimitation of near-sibling triatomine species

Identifying morphologically similar triatomine species is key to Chagas' disease vector control and surveillance, but remains challenging when only qualitative phenotypic data are available. We investigated whether morphometric and ecological variation can provide additional criteria for species delimitation by combining geometric morphometrics and ecological niche modelling to characterize two near-sibling triatomine species, Triatoma sordida and Triatoma garciabesi (Reduviidae: Triatominae). We analysed size and shape variation in 231 wings and 123 heads from one T. garciabesi and three T. sordida populations. Predicted distribution maps (21 climatic variables, 324 vector occurrence points) were produced using the Maxent method. Multivariate analyses summarized morphological and ecological variation. Wings and heads of T. sordida were significantly larger and more elongated than those of T. garciabesi. Discriminant analyses separated the species, with a partial overlap between Argentinean populations. The predicted distribution of T. garciabesi included northwest Argentina (mainly arid Chaco), whereas that of T. sordida included northeast Argentina (humid Chaco) and the Brazilian Cerrado and Caatinga ecoregions. Clear ecological niche differences were observed, with T. garciabesi occupying colder and drier areas than T. sordida. Our results show how morphometric variation and niche divergence can be used to enhance operational criteria for the delimitation of phenotypically similar triatomine species.     

Genetic structure of two populations of the Namibian giraffe,Giraffa camelopardalis angolensis

Two geographically distinct populations of giraffe (Giraffa camelopardalis) were sampled for this study, the northern Namib Desert and Etosha National Park. Population genetic parameters and relationships within subpopulations were estimated to better understand the genetic architecture of this isolated subspecies. Gene flow between the geographically separated populations can be attributed to recent translocation of giraffe between the two populations. Inbreeding estimates in the six subpopulations studied were low though we found evidence that genetic drift may be affecting the genetic diversity of the isolated populations in northern Namibia. Population dynamics of the sampling locations was inferred with relationship coefficient analyses. Recent molecular systematics of the Namibian giraffe populations indicates that they are distinct from the subspecies Giraffa camelopardalis giraffa and classified as G. c. angolensis. Based on genetic analyses, these giraffe populations of northern Namibia, the desert‐dwelling giraffe and those protected in Etosha National Park, are a distinct subspecies from that previously assumed; thus we add data on G. c. angolensis to our scientific knowledge of this giraffe of southern Africa.     

Taxonomy and distribution of Nonnapsylla Wagner, 1938 (Siphonaptera: Stephanocircidae: Craneopsyllinae)

The genus Nonnapsylla Wagner, 1938 (Craneopsyllinae) includes only 1 species, Nonnapsylla rothschildi Wagner, 1938 . Two subspecies are recognized by the shape of the dorsal margin of the helmet, apical shape of the spines in helmet and genal combs, length of first and fourth segments of the maxillary palpus, and shape of the hilla of the spermatheca. The validity of the characters used to separate the 2 subspecies of Nonnapsylla rothschildi Wagner, 1938 is discussed based on information from the literature, as well as from direct observation of type specimens and specimens collected in northwestern Argentina. We conclude that Nonnapsylla rothschildi wagneri Johnson, 1957 should be considered as a synonym of the nominal subspecies. We also extend the southern limits of the distribution of the species and report its presence in Argentina.     

Differentiation of <Emphasis Type="Italic">Harmonia axyridis</Emphasis> Pall. according to polymorphic morphological traits and variability of the mitochondrial COI gene

The geographic variability of Harmonia axyridis Pall. has been studied with regard to three morphological features. A study of the cytochrome C oxidase subunit I (COI) polymorphism was begun. Two geographically separated zones inside the Russian part of the geographic range of the species are recognized. Interpopulational differences, as judged using polymorphic traits, are very small within each zone. In contrast, the differences between the populations of the western and eastern zones reach the subspecies level of. A zone of clinal variability of morphological traits is noted in Transbaikalia. It obviously resulted from secondary contact between the western and eastern groups of populations, which were separated during the last glaciation and then rejoined.     

Chromosome polymorphism in populations of the grasshopper Trimerotropis pallidipennis from southern Argentina

Three populations of the grasshopper Trimerotropis pallidipennis from southern Argentina have been studied cytologically. A very characteristic B-chromosome was found in all three. They also showed geographical variability in respect of the presence of pericentric inversions, and the inversion system was found to influence chiasma frequency. The Laguna Blanca population, which is on the hypothetical pathway the species is believed to have followed during its migration from northern to southern latitudes, has the same karyotype composition as the N. American form, with fixed inversions in the 3 largest autosomes and the X-chromosome. Its members have a high total chiasma frequency and a great number of interstitial chiasmata. The Sierra de la Ventana population, situated at the absolute eastern border of the species distribution is highly polymorphic with respect to the presence of inversions in the medium chromosomes. Its members have the lowest total chiasma frequency and a greatly reduced number of interstitial chiasmata. Situated geographically between the other two, the Choele-Choel population has the highest frequency of inversions and many of them are homozygous. Its members have a higher total chiasma frequency than that observed in specimens from Sierra de la Ventana, and a greatly reduced number of interstitial chiasmata, similar to that observed in individuals from the latter population.     

Linkage Disequilibrium in Natural Populations of DROSOPHILA MELANOGASTER

Two large, stable populations (Texas and Japan) of Drosophila melanogaster were surveyed at 21 allozyme loci on the second and third chromosomes and for chromosomal gene arrangements on those two chromosomes. Over 220 independent gametes were sampled from each population. The types and frequencies of the surveyed genetic variation are similar to those observed previously and suggest only slight differentiation among geographically distant populations. Linkage disequilibrium among linked allozymes loci is only slightly, if at all, detectable with these sample sizes. Linkage disequilibrium between linked inversions and allozymes loci is common especially when located in the same arm. These disequilibria appear to be in the same direction for most comparisons in the two population samples. This result is interpreted as evidence of similar selective environments (ecological and genetic) in the two populations. It is also noted that the direction of these linkage disequilibria appears to be oriented with respect to the gene frequencies at the component loci.     

Phenotypic Variation in Mangrove Cuckoo (Coccyzus minor) across Its Geographic Range

Mangrove Cuckoo (Coccyzus minor) exhibits substantial phenotypic variation across its geographic range, but the significance of this variation for taxonomy remains unresolved. Using measurements of bill size and ventral color recorded from 274 museum specimens, I found that variation in these traits was clinal. No named subspecies was reciprocally diagnosable from all others, and none was distinguishable from the nominate form, such that previously recognized subspecific distinctions are invalid. Greatest differences in phenotype occurred between populations in Florida, the Bahamas, and the Greater Antilles–characteristically small-billed–and those in the Lesser Antilles, which had larger bills. Phenotypically intermediate individuals on the geographically intermediate islands of Barbuda and Antigua linked these two extremes. Individuals intermediate in bill size and color also characterized populations from throughout the remainder of the range in northern South America and Middle America. Mechanisms maintaining the fairly pronounced phenotypic differences between nearby populations of Greater and Lesser Antillean birds are unknown, yet the geographic proximity of these populations suggests that they probably persist despite occasional gene flow, and may be adaptive.     

Population genetic structure of the blue-fronted Amazon (Amazona aestiva, Psittacidae: Aves) based on nuclear microsatellite loci: implications for conservation

The blue-fronted Amazon (Amazona aestiva) is a widely distributed Neotropical parrot and one of the most captured parrots in nature to supply the illegal trade of wild animals. The objectives of the present study were to analyze the genetic structure of A. aestiva to identify management units and support conservation planning and to verified if A. aestiva populations have undergone a recent bottleneck due to habitat loss and capture for the pet trade. The genetic structure was accessed by analyzing six microsatellite loci in 74 individuals of A. aestiva, including samples from the two subspecies (A. a. aestiva and A. a. xanthopteryx), from five populations: four in Brazil and one in Argentina. A significant genetic differentiation (theta = 0.007, p = 0.005) could be detected only between the most distant populations, Tocantins and Argentina, localized at the northeast and southwest limits of the sample sites, respectively. There was no evidence of inbreeding within or between populations, suggesting random mating among individuals. These results suggest a clinal distribution of genetic variability, as observed for variation in plumage color of the two A. aestiva subspecies. Bottleneck analysis did not show a recent reduction in population size. Thus, for the management and conservation of the species, the populations from Argentina and Tocantins should be considered as different management units, and the other populations from the center of the geographical distribution as another management unit.     

Subspecies composition and founder contribution of the captive U.S. chimpanzee (Pan troglodytes) population

Chimpanzees are presently classified into three subspecies: Pan troglodytes verus from west Africa, P.t. troglodytes from central Africa, and P.t. schweinfurthii from east Africa. A fourth subspecies (P.t. vellerosus), from Cameroon and northern Nigeria, has been proposed. These taxonomic designations are based on geographical origins and are reflected in sequence variation in the first hypervariable region (HVR-I) of the mtDNA D-loop. Although advances have been made in our understanding of chimpanzee phylogenetics, little has been known regarding the subspecies composition of captive chimpanzees. We sequenced part of the mtDNA HVR-I region in 218 African-born population founders and performed a phylogenetic analysis with previously characterized African sequences of known provenance to infer subspecies affiliations. Most founders were P.t. verus (95.0%), distantly followed by the troglodytes schweinfurthii clade (4.6%), and a single P.t. vellerosus (0.4%). Pedigree-based estimates of genomic representation in the descendant population revealed that troglodytes schweinfurthii founder representation was reduced in captivity, vellerosus representation increased due to prolific breeding by a single male, and reproductive variance resulted in uneven representation among male P.t.verus founders. No increase in mortality was evident from between-subspecies interbreeding, indicating a lack of outbreeding depression. Knowledge of subspecies and their genomic representation can form the basis for phylogenetically informed genetic management of extant chimpanzees to preserve rare genetic variation for research, conservation, or possible future breeding.     

Divergent sexual signals reflect costs of local parasites*

Many closely related populations are distinguished by variation in sexual signals and this variation is hypothesized to play an important role in reproductive isolation and speciation. Within populations, there is considerable evidence that sexual signals provide information about the incidence and severity of parasite infections, but it remains unclear if variation in parasite communities across space could play a role in initiating or maintaining sexual trait divergence. To test for variation in parasite-associated selection, we compared three barn swallow subspecies with divergent sexual signals. We found that parasite community structure and host tolerance to ecologically similar parasites varied between subspecies. Across subspecies we also found that different parasites were costly in terms of male survival and reproductive success. For each subspecies, the preferred sexual signal(s) were associated with the most costly local parasite(s), indicating that divergent signals are providing relevant information to females about local parasite communities. Across subspecies, the same traits were often associated with different parasites, indicating that parasite-sexual signal links are quite flexible and may evolve relatively quickly. This study provides evidence for (1) variation in parasite communities and (2) different parasite-sexual signal links among three closely related subspecies with divergent sexual signal traits, suggesting that parasites may play an important role in initiating and/or maintaining the divergence of sexual signals among these closely related, yet geographically isolated populations.     

Spatial and temporal continuity of kangaroo rat populations shown by sequencing mitochondrial DNA from museum specimens

Summary The advent of direct sequencing via the polymerase chain reaction (PCR) has opened up the possibility of molecular studies on museum specimens. Here we analyze genetic variation in populations over time by applying PCR to DNA extracted from museum specimens sampled from populations of one species over the last 78 years. Included in this study were 43 museum specimens of the Panamint kangaroo ratDipodomys panamintinus from localities representing each of three geographically distinct subspecies. These specimens were originally collected and prepared as dried skins in 1911, 1917, or 1937. For each specimen, a 225-bp segment of the mitochondrial genome was sequenced. These mitochondrial DNA sequences were compared to those of 63 specimens collected at the same localities in 1988. The three subspecies were nearly completely distinct. Only 2 of the 106 individuals shared mitochondrial types between subspecies. For all three localities, the diversity levels were maintained between the two temporal samples. The concordance observed between the two temporally separate phylogenies supports the use of museum specimens for phylogenetic inference. This study demonstrates the accuracy and routine nature of the use of museum specimens in the analysis of mitochondrial sequence variation in natural populations and, importantly, that a temporal aspect can now be added to such studies.