Phylogenetic investigation and divergence dating of Poa (Poaceae,tribe Poeae) in the Australasian region

The Australasian region contains a significant proportion of worldwide Poa diversity, but the evolutionary relationships of taxa from this region are incompletely understood. Most Australasian species have been placed in a monophyletic Poa subgenus, Poa supersection Homalopoa section Brizoides clade, but with limited resolution of relationships. In this study, phylogenetic relationships were reconstructed for Australasian Poa, using three plastid (rbcL and matK genes and the rpl32‐trnL intergenic spacer) and two nuclear [internal/external transcribed spacer (ITS/ETS)] markers. Seventy‐five Poa spp. were represented (including 42 Australian, nine New Guinean, nine New Zealand and three Australian/New Zealand species). Maximum parsimony, maximum likelihood and Bayesian inference criteria were applied for phylogenetic reconstruction. Divergence dates were estimated using Bayesian inference, with a relaxed clock applied and rates sampled from an uncorrelated log‐normal distribution. Australasian Poa spp. are placed in three lineages (section Brizoides, section Parodiochloa and the ‘X clade’), each of which is closely related to non‐Australasian taxa or clades. Section Brizoides subsection Australopoa is polyphyletic as currently circumscribed. In Australasia, Poa has diversified within the last 4.3 Mya, with divergence dating results broadly congruent with fossil data that record the appearance of vegetation with a prominent grassland understorey or shrubland/grassland mosaic vegetation dating from the mid‐Pliocene. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175 , 523–552.     

Genetic and morphological divergence in theAndrocymbium gramineum complex (Colchicaceae)

Narrow endemism is a poor predictor of genetic potential in the six taxa that conform theAndrocymbium gramineum complex, as shown by the unexpectedly high values of variability associated with ten allozymic loci and 13 biometrical variables. Although both levels are shown not to be correlated, variability is always concentrated within populations. This result, together with environmental, reproductive and historical data strongly suggests differentiation in local isolates, where changes can be quickly assimilated by stochastic processes. A key implication for conservation is that sampling within the largest population will save effort while neglecting only very low frequency alleles.     

Genetic divergence in the Chorthippus parallelus species group (Orthoptera: Acrididae)

Specimens of Chorthippus parallelus parallelus, C. p. erythropus, C. montanus, C. curtipennis and C. dorsatus were examined electrophoretically. This analysis indicates that C. curtipennis is very closely related to C. p. parallelus and C.p. erythropus (Nei's I = 0.97) while C. montanus is more distantly related ( I = 0.88). The values are consistent with divergence of C. p. erythropus from C. p. parallelus since its separation by the Pyrenean ice sheet during the Pleistocene and of C. curtipennis since invasion of North America by C. parallelus at the same time. A much earlier divergence of C. montanus is implied.     

Trophodynamics of Protomyctophum (Myctophidae) in the Scotia Sea (Southern Ocean)

This study investigated spatial and temporal patterns in distribution, population structure and diet of Bolin's lanternfish Protomyctophum bolini, Tenison's lanternfish Protomyctophum tenisoni and gaptooth lanternfish Protomyctophum choriodon in the Scotia Sea using data collected by midwater trawl during spring, summer and autumn. Protomyctophum bolini was the most abundant species of the genus encountered throughout the Scotia Sea with the greatest concentrations occurring around the Antarctic Polar Front (APF). This species had a life cycle of 2+ years, but spatial differences in population structure were apparent as the I‐group was absent from all regions south of the APF, suggesting that the species does not recruit in the Scotia Sea. Protomyctophum tenisoni occurred mostly in waters characteristic of the APF and was absent from the southern Scotia Sea. It had a limited size range, but there was clear size‐related sexual dimorphism with males significantly larger than females. The species had a life cycle of c. 2 years, but the I‐group (c. 1 year old, 1 November to 31 October the next year) occurred only in regions close to the APF suggesting that recruitment is restricted to these waters. A seasonal southward migration for P. choriodon is likely as the species occurred mostly to the south‐west of South Georgia in summer, but extended to the sea‐ice sectors in autumn. Protomyctophum choriodon had a life cycle of 4+ years in the Scotia Sea and the population was dominated by age classes >3 years old. Larval stages were absent during the surveys for all species. Diurnal variations in vertical distribution were apparent for all three species. Interspecific variations in diet were evident, but all species were primarily copepod feeders, with Metridia spp., Rhincalanus gigas and Calanus simillimus generally dominating their diet. Small euphausiids, principally Thysanoessa spp., were also an important component of their diets, particularly for P. choriodon which had the largest body size. The spatial and temporal variations in diet for both P. bolini and P. tenisoni were broadly consistent with underlying abundance patterns within the mesozooplankton community.     

Genetic divergence and reproductive isolation in the Ochthebius (Calobius) complex (Coleoptera: Hydraenidae)

The reproductive isolation in hydrenid beetles of the Ochthebius complex was studied by analysing gene exchange in natural populations of O. quadricollis, Ochthebius sp. A and O. brevicollis steinbuehleri collected along the Mediterranean coasts. The ranges of these three species are largely allopatric, but sympatric areas were detected between contiguous taxa, ie, O. quadricollis and Ochthebius sp. A; Ochthebius sp. A and O. b. steinbuehleri. Three levels of reproductive isolation and genetic divergence were observed. One level involves extensive intraspecific genetic divergence within the biological species O. quadricollis, Ochthebius sp. A and O. brevicollis, associated with both physical barriers (eg, sea and sand stretches) and the low dispersal capacity of larvae and adults. The finding of transitional samples between the most differentiated population groups should indicate, however, that there is still some gene flow between the populations of the three taxa. Another level is found between Ochthebius sp. A and O. b. steinbuehleri, whose gene pools appear to be fairly distinct in spite of the fact that reproductive isolation is still incomplete: in their few syntopic sites, some F1 hybrids appeared indeed to have lower fitness, since backcrosses or recombinant genotypes were never observed. The final level in the evolution of reproductive isolation (full reproductive isolation) has been achieved by the species O. quadricollis and Ochthebius sp. A. No F1 or F(n) hybrids, nor backcrosses were found in their sympatric areas. The relative importance of ecological factors and evolutionary forces in the prevention of gene exchange between taxa are discussed.     

A duplication of gcyc predates divergence within tribe Coronanthereae (Gesneriaceae): Phylogenetic analysis and evolution

Recent investigations in Gesneriaceae have indicated that the cycloidea homolog, gcyc, remains functional at the DNA level and rates of sequence divergence in this gene are not statistically different across all taxa regardless of floral symmetry. A duplication of gcyc has been detected within Coronanthereae, a tribe that has phylogenetic affinities to subfamily Gesnerioideae and includes two genera with radially symmetrical corollas. Duplication of gcyc has been detected in all Coronanthereae except Sarmienta. All paralogs appear functional at the DNA level. Likewise, there is no increased sequence divergence between the two copies, nor between species with radially symmetrical flowers to those with bilateral symmetry. The duplication of gcyc in Coronanthereae is most likely a result of polyploidy since Coronanthereae have the highest chromosome counts of all Gesneriaceae.     

Genetic divergence among morphotypes of Lake Tana (Ethiopia) barbs

The genus Barbus is a paraphyletic assemblage that includes three different ploidy levels: diploid, tetraploid and hexaploid. 'B.' intermedins , which inhabits Lake Tana (Ethiopia), is a hexaploid taxon that forms a 'species flock' consisting of at least 14 morphotypes. Thirty-one presumptive allozymic loci were analysed in a large sample of 'B.' intermedius. No diagnostic loci were observed between the morphotypes, but substantial differences in allele frequencies were found. One morphotype, Acute, differs significantly from the others. The presence of this genetic differentiation within the lake strongly suggests that the morphotypes are diverging lineages. Because of some parallel characteristics with cichlid species flocks, we put forward the hypothesis that the morphotypes of barbs in Lake Tana represent a species flock that originated via sympatric speciation with more rapid morphological than molecular differentiation. If the differentiation and the reproductive isolation are real, it is probable that the morphotypes already are or will soon reach the status of species.     

Genetic divergence among species of the section Strombocarpa,genusProsopis (Leguminosae)

We studied degree of variability and relationships among populations belonging to five species of the section Strombocarpa of the family Leguminosae, namelyProsopis ferox, P. torquata, P. pubescens, P. strombulifera andP. reptans, by isozyme electrophoresis. The genetic similarity betweenP. reptans andP. strombulifera is high enough for the two to be considered subspecies or geographic races ofP. strombulifera instead of good taxonomic species. As expected these species cluster withP. pubescens, all belonging to series Strombocarpae. This group is different isoenzymatically from the remaining species,P. torquata andP. ferox. Comparison of our results with those obtained earlier for species of the section Algarobia showed that genetic variability in the section Strombocarpa is lower than in the section Algarobia, while the species divergence is much higher. These results suggest different adaptive strategies between these sections.     

Genetic divergence in the superspecies Manacus

The bearded manakins in the genus Manacus are lekking, neotropical passerines. Male plumage colour varies with geographical location and classification is based solely on these plumage patterns. It has recently been suggested that in this group of birds, plumage patterns may be a misleading taxonomic character. In this study we used microsatellite variation in a collection of museum samples to establish the amount of genetic divergence between the previously described bearded manakin species/subspecies. We found substantial genetic substructuring between species/subspecies and that plumage patterns indeed may be a misleading taxonomic character because the presence of yellow in male nuptial plumage is found in most divergent forms. We did not detect a significant isolation by distance relationship although the P -value was close to significance. Physical barriers such as rivers and mountains may affect gene flow and play a role in shaping genetic structure of the genus Manacus . Accordingly, boundaries between species/subspecies often coincide with large rivers, mountains and seas.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 81 , 439–447.     

Nutlet morphology in the tribe Elsholtzieae (Lamiaceae)

A comprehensive study on nutlet morphology on 46 taxa from the tribe Elsholtzieae was conducted using stereomicroscopy, light microscopy and scanning electron microscopy. The objectives were to evaluate the nutlet characteristics in a systematics context and to provide additional evidence for taxon delimitation. The nutlet shape varied from elliptical, widely elliptical, spheroidal and ovate to pyriform. The size ranged from 0.50 to 2.70 mm in length and 0.34 to 2.65 mm in width. The three types of trichomes included simple non-glandular trichomes (Collinsonia punctata), clavate non-glandular trichomes (Elsholtzia cephalantha) and peltate glandular trichomes (Mosla grosseserrata and M. chinensis). We also report the presence of a mucilaginous reaction in nine species of the genus Elsholtzia in Elsholtzieae for the first time. Four types (undulate, papillae-like projection, thorn-like pattern and reticulate) and three subtypes (reticulate, reticulate-cellular and supra-reticulate) of nutlet surface patterns in the mid-ventral region were recognized in Elsholtzieae based on the differences in cell outline, outer periclinal walls and dentations of the anticlinal walls. These nutlet micromorphological results may serve as a reference for future hypotheses on the classification of the tribe Elsholtzieae.     

Genetic divergence is not the same as phenotypic divergence

Far too often, phenotypic divergence has been misinterpreted as genetic divergence, and based on phenotypic divergence, genetic divergence has been indicated. We have attempted to disprove this statement and call for the differentiation of phenotypic and genotypic variation.     

Genetic divergence of Platycerus hongwonpyoi (Coleoptera: Lucanidae) in South Korea

We examined the genetic divergence of Platycerus hongwonpyoi Imura & Choe, 1989 in South Korea using the nuclear wingless (Wg) gene, internal transcribed spacer (ITS) region and mitochondrial cytochrome oxidase subunit I (COI) gene. We found no variation in Wg or ITS. Based on COI, P. hongwonpyoi was split into four well defined and one weakly supported clades, which were inferred to have diverged 2.11–1.33 Ma. The Platycerus hongwonpyoi population size seems to have decreased during the past several tens of thousands of years. The divergence times of major clades of P. hongwonpyoi were comparable with those involved in the speciation of certain Japanese species. Frequent overlapping of different clades at the same sites suggests the occurrence of secondary gene flow following differentiation in South Korea. In conclusion, the genus Platycerus underwent strikingly different divergence patterns in South Korea compared with Japan according to the disparate topographies of these two geographical areas.     

The trophodynamics of Southern Ocean Electrona (Myctophidae) in the Scotia Sea

The Scotia Sea is one of the most productive regions of the Southern Ocean, but its surface waters are experiencing a rapid increase in temperature, which may be changing the behaviour and distribution of many myctophids and their prey species. Electrona antarctica and Electrona carlsbergi are two of the most abundant myctophids in the region, but their ecology is poorly understood and their response to ongoing environmental change is difficult to determine. This study investigated spatial and temporal patterns in their abundance, population structure and diets using mid-water trawl nets deployed across the Scotia Sea during spring, summer and autumn. E. antarctica was the most numerically abundant species (0.09–0.21 ind. 1,000 m^?3), with greatest concentrations occurring in the sea-ice sectors. E. carlsbergi occurred in more northern regions, comprising densities of 0.02–0.11 ind. 1,000 m^?3. There was evidence of seasonal variation in depth distribution, size-related sexual dimorphism and size-specific vertical stratification for both species. Latitudinal trends in sex ratio and female body size were apparent for E. antarctica. Its diet varied between regions, seasons and size classes, but overall, Euphausia superba, Metridia spp. and Themisto gaudichaudii were the dominant prey items. E. carlsbergi appeared not to recruit in the Scotia Sea. Its diet was dominated by copepods, particularly Rhincalanus gigas and Metridia spp., but regional, seasonal and ontogenetic variations were evident. This study contributes to our understanding of how mid-water food webs are structured in the Southern Ocean and their sensitivity to ongoing environmental change.     

石荠苎属的遗传分化与种间关系分析

杂交实验结果表明,石荠苎属(唇形科)中国产的7个种,即小花荠苎Mosla cavaleriei、石香薷M． chinensis、小鱼仙草M．dianthera、杭州石荠苎M．hangchouensis、疏花荠苎M．pauciflora、石荠苎M． scabra和苏州石荠苎M．soochouensis,彼此之间生殖隔离。这7个种中,疏花荠苎是四倍体,由杂交伴随多倍化产生。根据21个代表居群在15个酶系统的28个位点的等位酶资料分析,其余6个二倍体种组成3个亲缘关系密切的种对。杭州石荠苎和石香薷的亲缘关系最近,石香薷可能由于涉及繁育系统类型的大突变而与杭州石荠苎分化开来。小花荠苎与小鱼仙草比较接近,但它们的遗传分化很显著,除了突变之外,染色体结构也有大的变异,最明显的表现是随体的位置不同,小花荠苎的随体位于长臂上,而小鱼仙草与其它种一样,随体位于短臂上。石荠苎和苏州石荠苎在酶基因位点上的分化不大,但生境隔离、花期隔离和繁育系统的差别等能有效地保持种的独立性。不同的生境要求、不同的花期、花的形态结构的分化、繁育系统类型的不同、杂种F_l代高度不育、染色体数目和核型的差异等均为石荠苎属下种间有效的隔离机制,而且近缘种间常是多种机制共同起作用。     

Genetic and morphological divergence within the Sebastes pachycephalus complex (Scorpaeniformes: Scorpaenidae)

Genetic and morphological divergence among the four subspecies in the Sebastes pachycephalus complex (S. pachycephalus pachycephalus, S. p. nigricans, S. p. nudus and S. p. chalcogrammus) was clarified. Principal coordinate analysis (PCoA) based on AFLP clearly divided 55 specimens of the complex into two groups, the S. p. pachycephalus?CS. p. nigricans group (P-Ni group) and the S. p. nudus?CS. p. chalcogrammus group (Nu-C group), although three specimens occupied intermediate positions. The minimum spanning network (MSN) based on partial sequences of the mitochondrial control region (mtCR) failed to separate either the P-Ni and Nu-C groups or the four subspecies into distinct clades, although restricted gene flow and genetic differentiation between the former were indicated by the F _ST estimation. Differences in morphological characters, including counts of pectoral fin rays and counts of dorsal fin spines lacking basal scales, were also evident between the two groups. However, little or no genetic or morphological difference was found between the two subspecies within each group. It was concluded that the P-Ni and Nu-C groups of the S. pachycephalus complex actually represent two different species, which is further supported by their sympatric distribution. Differences in dorsal body coloration and the presence or absence of brown spots on the ventral surface, which were formerly used to discriminate between four ??subspecies,?? may simply represent intraspecific variation. The three specimens occupying intermediate positions in the AFLP PCoA also occupied equivocal positions between the two species in the principal component analysis (PCA) based on morphometric characters, suggesting that they were hybrids between the two species. The star-shaped MSN of mtCR, which lacks distinct clades representing the two species, may be due to not only interspecific hybridization but also the sharing of ancestral haplotypes.     

Myctophid (Myctophidae) Abundance and Ecology in the Gulf of Alaska in Winter

Russian Journal of Marine Biology - The distribution and abundance of four common myctophid fish species in the upper epipelagic layer of the northeastern North Pacific in winter were analyzed...     

Genetic divergence between Melipona quadrifasciata Lepeletier (Hymenoptera,Apidae) populations

Melipona quadrifasciata is a stingless bee widely found throughout the Brazilian territory, with two recognized subspecies, M. quadrifasciata anthidioides, that exhibits interrupted metasomal stripes, and M. quadrifasciata quadrifasciata, with continuous metasomal stripes. This study aimed to estimate the genetic variability of these subspecies. For this purpose, 127 colonies from 15 Brazilian localities were analyzed, using nine species-specific microsatellite primers. At these loci, the number of alleles ranged from three to 15 (mean: 7.2), and the observed heterozygosity (H_o) ranged from 0.03–0.21, while the expected heterozygosity (H_e) ranged from 0.23–0.47. The genetic distances among populations ranged from 0.03–0.45. The F_ST multilocus value (0.23) indicated that the populations sampled were structured, and the clustering analysis showed the formation of two subgroups and two more distant populations. The first group contained the subspecies M. quadrifasciata quadrifasciata, and the other, the subspecies M. quadrifasciata anthidioides and the two M. quadrifasciata populations with continuous metasomal stripes from northern Minas Gerais. These results confirmed that the yellow metasomal stripes alone are not a good means for correctly identifying the different subspecies of M. quadrifasciata.     

Genetic divergence and analysis of the relationships between species of Mosla (Labiatae)

Seven species were recognized in Mosla in China. M. pauciflora (C. Y. Wu) C. Y. Wu et H. W. Li is an allotetraploid (2n=36 ), while the other six species are diploids (2n=18). Cluster analysis based on allozyme data from 28 loci of 15 enzyme systems reveals that the six diploid species formed three species pairs. M. cavaleriei Lévl.is closely related to M. dianthera (Buch.-Ham. ex Roxb. ) Maxim., M. chinensis and M. hangchouensis Matsuda are sibling species, and M. scabra (Thunb.) C. Y. Wu et H. W. Li is allied to M. soochouensis. Although M. cavaleriei and M. dianthera are close relatives, considerable genetic divergence has been detected between them. One third of alleles are unique to either of them, and 28.6 % of their loci have different alleles fixed. The average genetic identity ( 1 ) between populations of these two species is 0.770, and the average genetic distance (D) is 0.261. M. scabra and M. soochouensis are the least divergent species pair (I =0.979, D＝0.025). No completely divergent locus was detected, and the percentages of unique alleles are 11.1% to M. scabra and 16.7 % to M. soochouensis. This finding indicates that a high level of genetic differentiation is unnecessarily a prerequisite of speciation. A moderate divergence is detected between M. chinensis and M. hangchouensis (I＝0.899, D=0.107, and 7.1% of completely diverged loci) yet the latter harbors four times as many unique alleles (45.1% ) as the former does(11.8 % ). Compared to the genetic divergence between M. scabra and M. soochouensis, M. dianthera and M. hangchouensis and may well been undergoing active speciation have the high genetic distance betweenpopulations (0.034 and 0.026 respectively).     

Genetic divergence and larval dispersal in two spider crabs (Crustacea: Decapoda)

The spider crabs Inachus dorsettensis (Pennant) and Hyas coarctatus Leach are widespread in subtidal areas of muddy sand or gravel around western Europe. Both species have a life cycle with an obligatory planktonic larval phase of several weeks, which might be expected to cause widespread larval dispersal and consequent genetic homogeneity over considerable distances. However, earlier work on both taxa has indicated differences in growth pattern between populations separated by tens of kilometres. This study was undertaken to determine whether these differences were purely environmental or whether, despite the short distances involved, differences may have a genetic basis. A study of gene frequencies, as indicated by allozymes in samples of adults collected off the Isle of Man (northern Irish Sea), indicates significant genetic differentiation between populations over a geographical distance of only about 40 km in both Inachus dorsettensis ( = 0.086 ± 0.048) and Hyas coarctatus ( = 0.023 ± 0.017). Variability measures differed between species, showing I. dorsettensis to have a mean number of alleles per locus of 2.5–2.6 and a range of gene diversity of 0.216–0.241, while H. coarctatus showed lower values of mean number of alleles (1.9–2.0) and a range of gene diversity from 0.122 to 0.124. Given the high expected larval mobility of the two species the results are most surprising. Possible explanations are discussed in relation to population discontinuities and patterns of larval drift.