Ecotypes and genetic structure of Rhinanthus alectorolophus (Orobanchaceae) in southwestern Germany

European annual species of the genus Rhinanthus often exhibit seasonal ecotypic variation, a phenomenon also known from related genera of hemiparasitic Orobanchaceae. Populations with different flowering times exist, correlated with differences in a number of morphological characters. The present study evaluates the correlation of morphological characters and genetic differentiation of populations of Rhinanthus alectorolophus. Thirty-nine populations of three different subspecies from southwestern Germany were sampled. A total of 798 individuals were used for morphological analyses and 187 of these for AFLP analyses. Principal component analysis showed that morphological variation is mostly continuous. In a discriminant analysis based on morphological characters, only 89.7 % of all individuals were correctly assigned to their previously determined subspecies, indicating that subspecies identification is ambiguous for some populations. Using AFLP data and Bayesian assignment analysis, the sampled individuals could be grouped in three genetic clusters which do not correspond to the three subspecies. Instead, the clustering shows a clear geographic pattern and a Mantel test likewise revealed a significant correlation between genetic and geographic distances. Correlations of genetic distances with differences in morphological characters were weak and mostly insignificant. The results indicate that the subspecies of R. alectorolophus do not form discrete entities and that the character combinations distinguishing them are homoplastic.     

基于细胞色素b基因的中国岩羊不同地理种群遗传差异分析

为了揭示中国岩羊不同地理种群的遗传差异,探讨岩羊亚种分化的分子机制,采用中国岩羊不同地理种群的细胞色素b(Cyt b)基因的全序列,分析了碱基变异情况、遗传距离以及核苷酸序列差异。用最大似然法和贝叶斯法构建分子系统树并对获得的拓扑结构进行分析。结果发现,西藏亚种与四川亚种Cyt b基因平均序列差异为4.2%(±0.007),处于偶蹄目亚种的序列差异范围内,支持了目前对岩羊西藏亚种的分类地位。四川亚种内部各地理种群之间的遗传距离(0.033±0.0 111)与它们分别到西藏种群的遗传距离(0.042±0.007)差异不显著(t=1.824,P=0.084),说明四川亚种内部各地理种群间已经发生较显著的遗传分化。其中,四川、甘肃和青海种群亲缘关系较近,并与四川亚种内部的其它种群已产生了显著的遗传分化。因此认为四川亚种内部各地理种群的种下分化需要深入研究。     

Morphometric analysis of floral variation in the Pyrola picta species complex (Ericaceae): interpretation and implications for ecological and phylogenetic differentiation

The Pyrola picta species complex of western North America comprises four species (P. picta, P. dentata, P. aphylla and P. crypta) that grow sympatrically in some parts of their collective ranges, have remarkably similar flowers and share pollinators. These species do not exhibit the genetic signatures typical of random or heterospecific mating, but instead show genetic divergence patterns indicating that they maintain surprising levels of reproductive isolation. To better understand how species boundaries are maintained, the current study uses statistical ordination analyses to determine whether species isolation across shared geographical ranges might be achieved through subtle differences in floral characters among species. The possible contribution of differences in flowering phenology (e.g. temporal reproductive isolation) to reproductive isolation was also evaluated for the small subset of populations in which two or more species occur in direct sympatry. Among species in the P. picta complex, there are both phylogenetic and geographical trends in some floral characteristics, whereas other characters do not covary with either geography or species identity. In several sympatric populations, differences in flowering phenology among species suggest that timing plays a major role in non‐random (i.e. mainly conspecific) mating. The conclusions of this study are that reproductive isolation in the P. picta species complex is reinforced by differences in the timing of floral maturation and the morphologies of androecium and floral display characters. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 00 , 000–000.     

Pollen dispersal and breeding structure in a hawkmoth-pollinated Pampa grasslands species Petunia axillaris (Solanaceae)

Background and Aims The evolution of selfing is one of the most common transitions in flowering plants, and this change in mating pattern has important systematic and ecological consequences because it often initiates reproductive isolation and speciation. Petunia axillaris (Solanaceae) includes three allopatric subspecies widely distributed in temperate South America that present different degrees of self-compatibity and incompatibility. One of these subspecies is co-distributed with P. exserta in a restricted area and presents a complex, not well-understood mating system. Artificial crossing experiments suggest a complex system of mating in this sympatric area. The main aims of this study were to estimate the pollen dispersal distance and to evaluate the breeding structure of P. axillaris subsp. axillaris, a hawkmoth-pollinated taxon from this sympatric zone.Methods Pollen dispersal distance was compared with nearest-neighbours distance, and the differentiation in the pollen pool among mother plants was estimated. In addition, the correlation between genetic differentiation and spatial distance among plants was tested. All adult individuals (252) within a space of 2800 m² and 15 open-pollinated progeny (285 seedlings) were analysed. Genetic analyses were based on 12 polymorphic microsatellite loci.Key Results A high proportion of self-pollination was found, indicating a mixed-mating system. The maximum pollen dispersal distance was 1013 m, but most pollination events (96 %) occurred at a distance of 0 m, predominantly in an inbreeding system. Both parents among sampled individuals could be identifed in 60–85 % of the progeny.Conclusions The results show that most pollen dispersal in the hawkmoth-pollinated P. axillaris subsp. axillaris occurs within populations and there is a high proportion of inbreeding. This mating system appears to favour species integrity in a secondary contact zone with the congener species P. exserta.     

Floral and vegetative morphometrics of five Pleurothallis (Orchidaceae) species: correlation with taxonomy,phylogeny, genetic variability and pollination systems

Morphometric analyses of vegetative and floral characters were conducted in 21 populations of five Pleurothallis (Orchidaceae) species occurring in Brazilian 'campo rupestre' vegetation. A phylogenetic analysis of this species group was also carried out using nuclear ribosomal DNA internal transcribed spacers (ITS1 and ITS2). Results of the ordination and cluster analyses agree with species' delimitation revealed by taxonomic and allozyme studies. The groups formed in ordination analysis correspond to the pollinator groups determined in a previous pollination study. Relationships among the species in the cluster analysis using only vegetative characters are similar to those found in a previous allozyme study, but those indicated by cluster analysis using only floral characters differ. These results support the hypothesis that floral similarities are due to convergence driven by similar pollination mechanisms, and therefore floral traits may not be good indicators of phylogenetic relationships in this group. The results of the phylogenetic analysis support this conclusion to some extent. There is no correlation between genetic (allozyme) and morphological variability in the populations nor in the way this variability is distributed among conspecific populations. We describe a new subspecies of Pleurothallis ochreata based on differences in vegetative and chemical characters as well as geographic distribution. Absence of differentiation in floral characters, attraction of the same pollinator species, interfertility and genetic similarity support the argument for subspecific rather than specific status.     

High congruence of intraspecific variability in floral scent and genetic patterns in Gentianella bohemica Skalický (Gentianaceae)

Gentianella bohemica Skalický (Gentianaceae) is a critically endangered species endemic to the Bohemian Massif in the border region of Germany, Czechia and Austria. It consists of a restricted number of extremely scattered populations which are known to form distinct genetic groups. The objective of this work was to test for differences in the floral scent between Gentianella bohemica and Gentianella germanica and within these two species among populations, and to test for a correlation of scent and genetic similarity among the populations of G. bohemica. Floral scent was collected from the inflorescences/plants of eight flowering populations of G. bohemica and three populations of G. germanica using dynamic headspace methods, followed by GC/MS analyses. Both species emitted several aromatic and terpenoid compounds and multivariate analyses revealed differences in scent between the two species and within species among G. bohemica populations. Volatile components overlapped as expected for closely related species but floral scent was taxon-specific. Floral scent differentiation among G. bohemica populations was in high congruence with the genetic differentiation suggesting that scent differences among populations have a genetic basis and showing that scent is a suitable chemotaxonomic marker in this species.     

Morphological and genetic differentiation of two loliginid squids, Uroteuthis (Photololigo) chinensis and Uroteuthis (Photololigo) edulis (Cephalopoda: Loliginidae), in Asia

The squids Uroteuthis (Photololigo) edulis and Uroteuthis (Photololigo) chinensis (family Loliginidae) are commercially important fishery species in many coastal regions of Asia. The morphologies of these two squids are very similar, and identification based on morphology has been inadequate. The occurrence of cryptic species in the family Loliginidae has been reported. The widely distributed U. (P.) chinensis and U. (P.) edulis are believed to comprise several cryptic species. In this study, the taxonomic status of the two species in East Asia was elucidated by morphological and genetic analyses. Analysis of U. (P.) chinensis from Hong Kong and Xiamen (China) and U. (P.) edulis from Yamaguchi (Japan) and Shanghai (China) was performed in order to determine the effectiveness of different morphometric variables in discriminating between the two species. Multivariate analysis of 27 morphometric indices revealed no new morphological characters for the taxonomic identification of the two taxa, which can be distinguished by the teeth shape and number on arm sucker rings, and the percentage of hectocotylized part of left arm IV of males. The morphometric differences between U. (P.) edulis individuals from the two localities is most probably due to differences in the maturity stages of the sampled individuals between the two localities. Genetic analysis based on the mitochondrial COI and 16S rRNA genes revealed a high divergence of 15.5% and 7.5% respectively, indicating that U. (P.) edulis and U. (P.) chinensis are distinct species.     

Subspecies of the Central American Squirrel Monkey (Saimiri oerstedii) as Units for Conservation

The accurate diagnosis of conservation units now typically includes recognition of genetic diversity and unique evolutionary lineages and is necessary to inform the conservation management of endangered species. We evaluated whether the two currently recognized subspecies of the endangered Central American squirrel monkey (Saimiri oerstedii) in Costa Rica are evolutionarily significant units (ESUs) that should be managed separately in conservation efforts. We used previously published sequences of 50 individuals of Saimiri oerstedii for 880 bp of the mtDNA d-loop and genotypes of 244 individuals for 16 microsatellites and conducted novel analyses to characterize genetic differentiation between subspecies of Saimiri oerstedii. We measured sequence differentiation and inferred an intraspecific molecular phylogeny and a haplotype network, and found consistent results supporting statistically significant divergence and reciprocal monophyly between subspecies. A population aggregation analysis also supported Saimiri oerstedii citrinellus and S. o. oerstedii as diagnosably distinct units. These results confirm previous genetic studies with smaller sample sizes and are consistent with other factors including differences in pelage and morphology and divergence at nuclear markers. Conservation managers should manage these subspecies separately to prevent the loss of genetic diversity via artificially induced outbreeding. High levels of genetic diversity may buffer populations against outside extinction pressures, to which Saimiri oerstedii are vulnerable because of their dwindling habitat and small population size.     

The role of genetic constraints on the diversification of Iberian taxa of the genus Aquilegia (Ranunculaceae)

The microevolutionary process of adaptive phenotypic differentiation of quantitative traits between populations or closely‐related taxa depends on the response of populations to the action of natural selection. However, this response can be constrained by the structure of the matrix of additive genetic variance and covariance between traits in each population ( G matrix). In the present study, we obtained additive genetic variance and narrow sense heritability for 25 floral and vegetative traits of three subspecies of Aquilegia vulgaris, and one subspecies of Aquilegia pyrenaica through a common garden crossing experiment. For two vegetative and one floral trait, we also obtained the G matrix and genetic correlations between traits in each subspecies. The amount of genetic variation available in wild populations is not responsible for the larger differentiation of vegetative than floral traits found in this group of columbines. However, the low heritability of some traits constrained their evolution because phenotypic variability among taxa was larger for traits with larger heritability. We confirmed that the process of diversification of the studied taxa involved shifts in the G matrix, mainly determined by changes in the genetic covariance between floral and vegetative traits, probably caused by linkage disequilibrium in narrow endemic taxa. © 2013 The Linnean Society of London, Biological Journal of the Linnean Society, 2014, 111 , 252–261.     

Geographic variation and molecular evidence of the Blackish Deer Mouse complex (Peromyscus furvus,Rodentia: Muridae)

Several authors have discussed whether Peromyscus furvus is a monotypic species rather than a polytypic entity, that it includes more than one species. Here, we analyze these questions by means of traditional morphometrics and by genetic analyses using ND3-ND4 mtDNA genes as markers. In spite of a generalized overlap of the measurable characters among populations, our analyses show that the northernmost populations, which was assignable to P. latirostris, consistently show larger dimensions overall. The amount of genetic differentiation revealed by our molecular data, support conclusive evidence to suggest this taxon is a valid species. Our results also disclose that morphometric and molecular segregation between P. furvus and P. angustirostris is still incomplete. Finally, the two populations from the state of Oaxaca showed more morphometric affinity with those attributable to P. furvus and revealed a discrete degree of genetic differentiation. Nevertheless, their systematic position is not clear yet.     

Genetic consequences of anagenetic speciation in Acer okamotoanum (Sapindaceae) on Ullung Island, Korea

Background and Aim

Anagenesis (also known as phyletic speciation) is an important process of speciation in endemic species of oceanic islands. We investigated genetic variation in Acer okamotoanum, an anagenetically derived species endemic to Ullung Island, South Korea, to infer genetic consequences of anagenesis in comparison with other groups that have undergone cladogenesis (and adaptive radiation).

Methods

We examined genetic variation based on eight polymorphic microsatellite markers from 145 individuals of A. okamotoanum and 134 individuals of its putative progenitor A. mono. We employed standard population genetic analyses, clustering analyses, Bayesian clustering analyses in STRUCTURE and bottleneck analyses.

Key Results

Based on both the Neighbor–Joining tree and Bayesian clustering analyses, clear genetic distinctions were found between the two species. Genetic diversity in terms of allelic richness and heterozygosity shows slightly lower levels in A. okamotoanum in comparison with A. mono. Bayesian clustering analyses showed a relatively high F-value in the cluster of A. okamotoanum, suggesting a strong episode of genetic drift during colonization and speciation. There was no clear evidence of a bottleneck based on allelic frequency distribution and excess of observed heterozygotes, but the M-ratio indicated a historical bottleneck in several populations of A. okamotoanum. No geographical genetic structure within the island was found, and the genetic variation among populations of A. okamotoanum was quite low.

Conclusions

We hypothesized that genetic consequences of oceanic-endemic plants derived via anagenesis would be quite different from those derived via cladogenesis. Populations of A. okamotoanum form a cluster and are clearly differentiated from A. mono, which suggests a single origin for the anagenetically derived island endemic. No pattern of geographical differentiation of populations occurs in A. okamotoanum, which supports the concept of initial founder populations diverging through time by accumulation of mutations in a relatively uniform environment without further specific differentiation.     

Discrimination of Iranian honeybee populations (Apis mellifera meda) from commercial subspecies of Apis mellifera L. using morphometric and genetic methods

The morphological characters of honeybees have an important role for discriminating honeybee subspecies. In the present research, Iranian populations of honeybee (Apis mellifera) were collected from 19 areas in Iran. The samples were collected from stationary beekeeping sites. Moreover, pictures of honeybee forewings held in the Bee Data Bank in Oberursel were compared with Iranian honeybee populations. 19 morphological characters were measured for each forewing of worker honeybee to evaluate differentiation of Iranian honeybee populations from the commercial honeybee subspecies A. m. mellifera, A. m. carnica, A. m. caucasica and A. m. ligustica. Additionally, part of the tRNA^leu gene, an intergenic region and part of COII was used to confirm differentiation of the commercial subspecies from Iranian honeybee populations. Results of the cluster analyses showed that 19 morphological characters of forewings differentiated Iranian populations from the commercial subspecies. Moreover, the phylogenetic tree of part of the tRNA^leu gene, an intergenic region and part of COII differentiated the commercial subspecies from Iranian honeybee populations. Results of the discriminant function analyses (DFA) indicated that the references samples of A. m. meda overlapped with Iranian populations.     

Microsatellite variation and microevolution in the critically endangered San Clemente Island loggerhead shrike (Lanius ludovicianus mearnsi)

Polymorphic nuclear microsatellite loci were used to characterize genetic variation in contemporary and historic populations of the San Clemente Island loggerhead shrike (Lanius ludovicianus mearnsi), an endangered bird with a current population of 30 individuals that is endemic to to one of the California Channel Islands. We also compared the population of the shrike with two contemporary populations of the still abundant subspecies, L. l. gambeli, which live 120 km away on the adjacent mainland. The current population of L. l. mearnsi has 60 per cent of the genetic variation of the mainland shrike populations and is strongly differentiated from them. Comparison of living birds with 19 birds collected in 1915 shows that most of the variation within the island population was lost before the recent 90 per cent decline in population size, and the 20 per cent decrease in variation this century is probably attributable to genetic drift. Mitochondrial DNA control region sequence data from 80 year old specimens show that there may have been limited introgression to L. l. mearnsi, this century, from another island subspecies, L. l. anthonyi, found in the northern Channel Islands. Today, gene flow between L. l. mearnsi and mainland L. l. gambel is very low, even though a few mainland birds visit the island annually. The island subspecies population has evolved sufficient genetic independence to justify ongoing conservation efforts to counter demographic collapse and genetic erosion; the course of genetic erosion can now be monitored non-invasively, as demonstrated by this study, based on DNA amplified from feathers.     

Morphological variability in rupicolous species of the Acianthera prolifera complex (Orchidaceae) occurring in southeastern Brazil

We carried out multivariate morphometric analysis of 23 floral characters in seven populations of a complex of four species of Acianthera (Orchidaceae) occurring in Brazilian campo rupestre (rocky field) vegetation (A.?hamosa, A.?limae, A.?modestissima, and A.?prolifera) that flower synchronously and are partially intercompatible, and one putative hybrid population between A.?limae and A.?prolifera. We also carried out cluster analysis involving these eight populations plus 21 populations of a previously published study belonging to another species complex of Acianthera occurring in campo rupestre, including 12 floral characters in the analysis. Allopatric species pollinated by the same group of Diptera showed higher floral similarity among themselves than to a sympatric species pollinated by another group of Diptera. Such patterns indicate the existence of floral convergence in allopatric species and/or radiation in sympatric species. The analysis also indicated that there is more floral similarity between species of different complexes but that share the same group of pollinators. Large overlap was observed between A.?limae and the putative sympatric hybrids, indicating the occurrence of later generations of hybrids and/or individuals of A.?limae with introgression. The results do not support A.?hamosa and A.?modestissima as distinct species. These taxa are geographically isolated, occurring in different environments, are recognized only by vegetative characters that show high phenotypic plasticity, and share the same pollinators, being interfertile.     

Recombinational and mutational analyses of subspecific differentiation in Oryza sativa L.

Recombinational and mutational analyses were performed in an attempt to elucidate the nature of the genic differences and the ancestral relationship between the indica and japonica subspecies of Oryza sativa L. by taking representative varieties from each group. The absence of cytological aberrations at meiosis in indica×japonica hybrids suggest that genetic differences are predominantly genic rather than chromosomal. The pattern of variation induced in the key characters, and the frequency and spectra of mutations obtained in each group, failed to support the hypothesis that indica has given rise to japonica, and suggested that the two subspecies have originated from a common ancestor.     

The complete mitochondrial genome sequence analysis of Tibetan argali (Ovis ammon hodgsoni): Implications of Tibetan argali and Gansu argali as the same subspecies

The genus Ovis (Bovidae, Artiodactyla) includes six species, i.e. Ovis ammon, Ovis aries, Ovis canadensis, Ovis dalli, Ovis nivicola and Ovis vignei. Based on morphology, geographical location, habitat, etc., the species O. ammon is divided into nine subspecies. The near threatened Tibetan argali is distributed across the Tibetan Plateau and its peripheral mountains, and believed to be one of the O. ammon subspecies (O. a. hodgsoni). However, considering its morphological features and distributions, a question has been proposed by some researchers about the subspecies status of Tibetan argali. In this study, we employed complete mitochondrial DNA (mtDNA) to explore the phylogenetic relationship and population genetic structure of Tibetan argali. The results revealed that the nucleotide composition, gene arrangement and codon usage pattern of the mitochondrial genome of Tibetan argali are similar to those of other caprines. Phylogenetic analyses showed that Tibetan argali was clustered with O. ammon. Interestingly, five Tibetan argali individuals and one of the three Gansu argali (O. a. dalailamae) individuals were clustered in the same branch, which is a sister group to other two Gansu argali individuals. Together with morphological characteristics, our results suggested that Tibetan argali and Gansu argali may belong to the same subspecies (O. a. hodgsoni) of O. ammon, rather than two different subspecies.     

Phylogeography-Based Delimitation of Subspecies Boundaries in the Common Pheasant (Phasianus colchicus)

To test the validity of subspecies status within the common pheasant (Phasianus colchicus), we used genetic data to assess differences among five subspecies distributed across the Loess Plateau in central China. Samples were collected from 191 individuals representing subspecies P. c. strauchi, P. c. satscheuensis, P. c. kiangsuensis, P. c. suehschanensis, and P. c. edzinensis. Analysis of mitochondrial genetic variation suggested that there were no phylogenetically distinct subspecies clades, and we could not exclude that hybridization has occurred among subspecies. A potential explanation of the observed pattern is that an increase in common pheasant rearing farms may have led to enforcement of hybridization between different subspecies. Consistent with phenotypic data, our analysis suggests that a previously identified common pheasant subspecies (P. c. strauchi) represents an intermediate form between the subspecies P. c. satscheuensis and P. c. suehschanensis.     

Weak divergence among African, Malagasy and Seychellois hinged terrapins (Pelusios castanoides, P. subniger) and evidence for human-mediated oversea dispersal

Using phylogenetic and haplotype network analyses of 2036 bp of mitochondrial DNA, we compare samples of the two hinged terrapin species Pelusios castanoides and P. subniger from continental Africa, Madagascar and the Seychelles to infer their biogeography. Owing to the long independent history of Madagascar and the Seychelles, the populations from those islands should be deeply divergent from their African conspecifics. Seychellois populations of the two species are currently recognized as Critically Endangered endemic subspecies. However, even though we found within P. subniger evidence for a cryptic species from the Democratic Republic of the Congo, all other samples assigned to this species were undifferentiated. This suggests that Malagasy and Seychellois populations of P. subniger were introduced by humans and that the Seychellois subspecies P. s. parietalis is invalid. This has implications for current conservation strategies for the Critically Endangered Seychellois populations and suggests that measures should rather focus on endemic species. The situation of P. castanoides could be different. Samples from Madagascar and the Seychelles are weakly, but consistently, differentiated from continental African samples, and Malagasy and Seychellois samples are reciprocally monophyletic in maximum likelihood analyses. However, due to a lack of samples from central and northern Mozambique and Tanzania, we cannot exclude that identical continental haplotypes exist there.