Sexual conflict in Gerris gillettei (Insecta: Hemiptera): intraspecific intersexual correlated morphology and experimental assessment of behaviour and fitness

The contemporary dynamics of sexually antagonistic coevolution caused by sexual conflicts have seldom been investigated at the intraspecific level. We characterized natural populations of Gerris gillettei and documented significant intersexual correlations for morphological traits previously related to sexual conflict in water striders. These results strongly indicate that sexually antagonistic coevolution contributed to population differentiation and resulted in different balances of armaments between the sexes within natural populations of this species. No-choice mating experiments further revealed that both male and male-female relative arms levels influence copulation duration. However, there were no asymmetries in reproductive behaviour and fitness between sympatric and allopatric mating pairs, suggesting that differentiation by sexual conflict was not sufficient to influence the outcome of mating interactions. Altogether, these results question the relative importance of female connexival spines vs. genitalia traits in mediating pre- and post-copulatory conflict in Gerris.     

Norwegian house mice (Mus musculus musculus/domesticus): distributions, routes of colonization and patterns of hybridization

We investigated the distributions and routes of colonization of two commensal subspecies of house mouse in Norway: Mus musculus domesticus and M. m. musculus. Five nuclear markers (Abpa, D11 cenB2, Btk, SMCY and Zfy2) and a morphological feature (tail length) were used to differentiate the two subspecies and assess their distributions, and mitochondrial (mt) D‐loop sequences helped to elucidate their colonization history. M. m. domesticus is the more widespread of the two subspecies, occupying the western and southern coast of Norway, while M. m. musculus is found along Norway’s southeastern coast and east from there to Sweden. Two sections of the hybrid zone between the two subspecies were localized in Norway. However, hybrid forms also occur well away from that hybrid zone, the most prevalent of which are mice with a M. m. musculus‐type Y chromosome and an otherwise M. m. domesticus genome. MtDNA D‐loop sequences of the mice revealed a complex phylogeography within M. m. domesticus, reflecting passive human transport to Norway, probably during the Viking period. M. m. musculus may have colonized earlier. If so, that leaves open the possibility that M. m. domesticus replaced M. m. musculus from much of Norway, with the widely distributed hybrids a relict of this process. Overall, the effects of hybridization are evident in house mice throughout Norway.     

Anthropocene invasion of an ecosystem engineer: resolving the history of Corophium volutator (Amphipoda: Corophiidae) in the North Atlantic

Resolving the natural histories of species is important for the interpretation of ecological patterns, as it provides evolutionary context for the interactions between organisms and their environment. Despite playing an integral role on the intertidal mudflats of the North Atlantic as an abundant food source for predators and as an ecosystem engineer that alters the soft sediment environment, no previous studies have provided empirical evidence to determine the biogeographical origin of the amphipod Corophium volutator. To resolve its status as introduced or indigenous in Europe and North America, we analyzed sequence data for two mitochondrial loci and two nuclear markers, aiming to determine whether the present range of C. volutator is the result of unresolved taxonomy, persistence in glacial refugia, natural trans‐Atlantic dispersal, or human‐mediated introduction. Our results demonstrate a reduced genetic diversity in North American populations that is a subsample of diversity in European populations, with coalescent analyses of mitochondrial and nuclear DNA supporting different models of multiple introductions from Europe to the Bay of Fundy and Gulf of Maine in North America. These results suggest that C. volutator was introduced to North America prior to the first surveys of local biota in the 20th Century, which has broad implications for interpretations of community and ecosystem interactions in the North Atlantic intertidal. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 115 , 288–304.     

Hybridization and low genetic diversity in the endangered Alabama red‐bellied turtle (Pseudemys alabamensis)

Pseudemys alabamensis is one of the most endangered freshwater turtle species in the United States due to its restricted geographic distribution in coastal Alabama and Mississippi. Populations of P. alabamensis are geographically isolated from one another by land and saltwater, which could act as barriers to gene flow. It is currently unknown how differentiated these populations are from one another and whether they have experienced reductions in population size. Previous work found morphological differences between Alabama and Mississippi populations, suggesting that they may be evolutionarily distinct. Other Pseudemys turtles such as P. concinna and P. floridana occur naturally within the same geographic area as P. alabamensis and are known to hybridize with each other. These more abundant species could threaten the unique genetic identity of P. alabamensis through introgression. In order to evaluate the endangered status of P. alabamensis and the level of hybridization with other species, we used mitochondrial and nuclear microsatellite markers to assess genetic variation within and among populations of P. alabamensis throughout its range and estimate admixture with co‐occurring Pseudemys species. In P. alabamensis, we found no variation in mitochondrial DNA and an excess of homozygosity in microsatellite data. Our results show genetic differentiation between Alabama and Mississippi populations of P. alabamensis, and low estimated breeding sizes and signs of inbreeding for two populations (Fowl River, Alabama and Biloxi, Mississippi). We also found evidence of admixture between P. alabamensis and P. concinna/P. floridana. Based on our results, P. alabamensis is highly endangered throughout its range and threatened by both low population sizes and hybridization. In order to improve the species’ chances of survival, focus should be placed on habitat preservation, maintenance of genetic diversity within both the Mississippi and Alabama populations, and routine population‐monitoring activities such as nest surveillance and estimates of recruitment.     

Phylogeographical patterns of genetic divergence and speciation in African mole-rats (Family: Bathyergidae)

African mole-rats are subterranean Hystricomorph rodents, distributed widely throughout sub-Saharan Africa, and displaying a range of social and reproductive strategies from solitary dwelling to the 'insect-like' sociality of the naked mole-rat, Heterocephalus glaber. Both molecular systematic studies of Rodentia and the fossil record of bathyergids indicate an ancient origin for the family. This study uses an extensive molecular phylogeny and mitochondrial cytochrome b and 12s rRNA molecular clocks to examine in detail the divergence times, and patterns of speciation of the five extant genera in the context of rift valley formation in Africa. Based on a value of 40-48 million years ago (Myr) for the basal divergence of the family (Heterocephalus), we estimate divergence times of 32-40 Myr for Heliophobius, 20-26 Myr for Georychus/Bathyergus and 12-17 Myr for Cryptomys, the most speciose genus. While early divergences may have been independent of rifting, patterns of distribution of later lineages may have been influenced directly by physical barriers imposed by the formation of the Kenya and Western Rift, and indirectly by accompanying climatic and vegetative changes. Rates of chromosomal evolution and speciation appear to vary markedly within the family. In particular, the genus Cryptomys appears to have undergone an extensive radiation and shows the widest geographical distribution. Of the two distinct clades within this genus, one exhibits considerable karyotypic variation while the other does not, despite comparatively high levels of sequence divergence between some taxa. These different patterns of speciation observed both within the family and within the genus Cryptomys may have been a result of environmental changes associated with rifting.     

Historical demography and genetic structure of sister species: deermice (Peromyscus) in the North American temperate rain forest

To investigate the evolutionary and biogeographical history of Peromyscus keeni and P. maniculatus within the coastal forest ecosystem of the Pacific Northwest of North America, we sampled 128 individuals from 43 localities from southeastern Alaska through Oregon. We analysed mitochondrial DNA variation using DNA sequence data from the mitochondrial cytochrome-b (cyt-b) gene and control region, and we found two distinct clades consistent with the morphological designation of the two species. The sequence divergence between the two clades was 0.0484 substitutions per site for cyt-b and 0.0396 for the control region, suggesting that divergence of the two clades occurred during the middle to late Pleistocene. We also examined the historical demography of the two clades using stepwise and exponential expansion models, both of which indicated recent rapid population growth. Furthermore, using the program migrate we found evidence of migration from populations north of the Fraser River (British Columbia) to the south in both clades. This study demonstrates the utility of these model-based demographic methods in illuminating the evolutionary and biogegographic history of natural systems.     

Distribution,body size,genetic structure and conservation of Siphlaenigma janae (Insecta: Ephemeroptera)

Distribution, body size and genetic structure of the poorly known New Zealand mayfly Siphlaenigma janae were investigated to improve understanding of its conservation status. It has now been recorded from 42 locations, 22 of which are reported for the first time. The distribution of S. janae extends from Northland to the central North Island, and also into the northwestern South Island. Population structure consisted of three distinct haplotype networks; two in the North Island and one in the South Island. Maximum uncorrected genetic distance was 6.1% but no strong evidence for the presence of sibling species was found. The specialist nymphs predominantly live in low-gradient first- and second-order forested streams, a habitat that is increasingly being threatened by land-use modification. We recommend S. janae remain classified as Nationally Vulnerable due to its unique taxonomic position, regionally distinct genetic structure and fragmented population that is likely experiencing ongoing decline.     

Comparing salinity tolerance in embryonic and larval development of two species of water strider,Aquarius paludum and Gerris latiabdominis (Hemiptera: Gerridae)

Water strider Aquarius paludum (Fabricius) is a cosmopolitan species colonizes mainly freshwater but occasionally brackish habitats throughout the Palearctic and Oriental regions. Water strider Gerris latiabdominis (Miyamoto) is a common species in Japan lives in temporary habitats as freshwater paddy fields. These two species often occur syntopically. We investigated differences in the developmental response to brackish water during embryonic and larval stages between the two species. Eggs were exposed to 0–1.8% NaCl solutions within 24 h of oviposition. Larvae of G. latiabdominis were exposed to salinities of 0, 0.5%, and 0.9% from the first instar until adult emergence. Limits of NaCl concentration for hatching were 1.3% and 1.0% for A. paludum and G. latiabdominis, respectively. The hatching rate of G. latiabdominis was lower than that of A. paludum at salinities ≥0.9%. The period of embryonic development of G. latiabdominis was more prolonged than that of A. paludum at a given salinity. Although the salinity tolerance of G. latiabdominis was lower than that of A. paludum, our results suggest G. latiabdominis has the physiological capacity to expand into brackish waters. High and low salinity tolerances of A. paludum and G. latiabdominis, respectively, reflect the relatively wide range of habitat salinities utilized by A. paludum and the relatively restricted habitats preferred by G. latiabdominis. The high salinity tolerance of A. paludum could be an important factor contributing to their cosmopolitan distribution because high tolerance to salinity means the possibility of them to be dispersed via ocean or sea to other continents and islands.     

Phylogeographic history of Patagonian lizards of the Liolaemus elongatus complex (Iguania: Liolaemini) based on mitochondrial and nuclear DNA sequences

In this study, we present a phylogeographic analysis of a group of lizards distributed in north‐western Patagonia, the Liolaemus elongatus complex. We sequenced 581 individuals for one mitochondrial gene (cytochrome‐b), and for a subset, we sequenced another mitochondrial gene (12S rRNA) and two nuclear genes: kinesin family member 24 (KIF24) and the anonymous nuclear locus LDAB1D. We estimated gene trees, mitochondrial and nuclear haploytpe networks, standard molecular diversity indices, genetic distances between lineages and Bayesian skyline plots. Our results provide evidence for recognition of seven species previously described within the L. elongatus complex: Liolaemus antumalguen, Liolaemus chillanensis, Liolaemus carlosgarini, Liolaemus burmeisteri, Liolaemus smaug, Liolaemus elongatus and Liolaemus crandalli, but we did not find sufficient evidence to support Liolaemus choique, Liolaemus shitan or Liolaemus sp. 6 as distinct species. We identified four candidate species (Liolaemus sp. 1, Liolaemus sp. 2, Liolaemus sp. 3 and Liolaemus sp. 7), and we discuss evolutionary processes that may have contributed to the origin of these lineages and their taxonomic and conservation implications.     

Phylogeographical patterns in Coenosia attenuata (Diptera: Muscidae): a widespread predator of insect species associated with greenhouse crops

The tiger‐fly Coenosia attenuata is a globally widespread predatory fly which is not only associated with greenhouse crops, but also occurs in open fields. It is a potential control agent against some of the more common pests in these crops. Assessing the genetic structure and gene flow patterns may be important for planning crop protection strategies and for understanding the historical processes that led to the present distribution of genetic lineages within this species. In the present study, the phylogeographical patterns of this species, based on mitochondrial cytochrome oxidase I and nuclear white and elongation factor‐1α genes, are described, revealing relatively low genetic diversity and weak genetic structure associated with a recent and sudden population expansion of the species. The geographical distribution of mitochondrial haplotypes indicates the Mediterranean as the most likely region of origin of the species. Some dispersal patterns of the species are also revaled, including at least three independent colonizations of North and South America: one from Middle East to North America with a strong bottleneck event, another from Europe to South America (Chile), with both likely to be a result of unintentional introduction, and a third one of still undetermined origin to South America (Ecuador). © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 308–326.     

Significant population structure and asymmetric gene flow patterns amidst expanding populations of Clinus cottoides (Perciformes,Clinidae): application of molecular data to marine conservation planning in South Africa

Clinus cottoides is a fish endemic to the coast of South Africa, predominantly inhabiting rock pools. All South African clinids are viviparous, but probably breed throughout the year; as such, their dispersal may be limited, unlike species with pelagic larval stages. We analysed 343 fish from 14 localities on the west, south and east coasts using two mitochondrial genes and the second intron of the S7 ribosomal gene. Mitochondrial DNA analyses recovered significant genetic differentiation between fish populations from the east coast and other sampling locations, with a second break found between Gansbaai and Cape Agulhas on the south coast. Nuclear DNA recovered shallower, but significant, levels of population structure. Coalescent analyses suggested remarkably asymmetrical gene flow between sampling locations, suggesting that the cold Atlantic Benguela Current and Indian Ocean Agulhas counter‐current play important roles in facilitating dispersal. There was no gene flow between the east coast and the other sites, suggesting that these populations are effectively isolated. Divergence times between them were estimated to at least 68 000 years. Neutrality tests and mismatch distributions suggest recent population expansions, with the exception of peripheral western and eastern populations (possibly a consequence of environmental extremes at the edge of the species distribution). Analyses of the current South African marine protected areas network show that it is not connected and that De Hoop, one of South Africa's largest marine reserves, appears to be an important source population of recruits to both the south and southwest coasts.     

Biogeographical patterns of genetic differentiation in dung beetles of the genus Trypocopris (Coleoptera, Geotrupidae) inferred from mtDNA and AFLP analyses

Aim To examine the phylogeography and population structure of three dung beetle species of the genus Trypocopris (Coleoptera, Geotrupidae). We wanted to test whether genetic differences and genealogies among populations were in accordance with morphologically described subspecies and we aimed to establish times of divergence among subspecies to depict the appropriate temporal framework of their phylogeographical differentiation. We also wished to investigate the historical demographic events and the relative influences of gene flow and drift on the distribution of genetic variability of the different populations. Location Europe (mostly Italy). Methods We collected adult males from dung pats from 15 Italian localities over the period 2000–2002. For sequence analysis, some dried specimens from Albania, Croatia, Slovakia and Spain were also used. We applied cytochrome oxidase I mitochondrial DNA sequencing and the amplified fragment length polymorphism (AFLP) technique to determine whether phylogeographical patterns within the three species support the proposed hypotheses of subspecies designations, and to detect further structure among populations that might mediate diversification. Results and main conclusions The results show a high concordance between the distribution of mtDNA variation and the main morphological groups recognized as subspecies, which thus may represent independent evolutionary units. The degree of mitochondrial divergence suggests that speciation events occurred during the Pliocene, while diversification of the main subspecific lineages took place in the Pleistocene, from c. 0.3 to 1.5 Ma. Mitochondrial and nuclear data also reveal that there is phylogeographical structuring among populations within each of the main groups and that both contemporary and historical processes determined this pattern of genetic structure. Geographical populations form monophyletic clades in both phylogenetic and network reconstructions. Despite the high levels of intrapopulational diversity, F_ST values indicate moderate but significant genetic differentiation among populations, and a Bayesian clustering analysis of the AFLP data clearly separates the geographical populations. Nucleotide and gene diversity estimates reveal interspecific differences in the degree of diversification among populations that may be related to the different ecological requirements of the three species.     

Phylogeographic patterns and high levels of chloroplast DNA diversity in four Packera (asteraceae) species in southwestern Alberta

Chloroplast DNA (cpDNA) haplotype variation is compared among alpine and prairie/montane species of Packera from a region in southwestern Alberta that straddles the boundary of Pleistocene glaciation. The phylogeny of the 15 haplotypes identified reveals the presence of two groups: one generally found in coastal and northern species and the other from species in drier habitats. The presence of both groups in all four species and most populations from southwestern Alberta is evidence of past hybridization involving species or lineages that may no longer be present in the region. With the exception of the alpine P. subnuda (phiST = 1.0), interpopulational subdivision of haplotype variation is low (phiST < 0.350), suggesting that interpopulational gene flow is high. However, based on haplotype distribution patterns, we propose that Pleistocene hybridization and incomplete lineage sorting have resulted in reduced subdivision of interpopulational variation so that gene flow may not be as high as indicated. Drift has been more important in the alpine species populations, especially P. subnuda.     

基于多基因序列和形态性状的牡丹组种间关系

牡丹被认为是中国的国花,具有很高的医学、观赏和经济价值.野生牡丹被认为是栽培牡丹的野生祖先,因此弄清牡丹组的种间亲缘关系具有重要的理论和实践意义.由于受到信息量的限制,根据单基凼数据或形态数据往往无法对牡丹组的种间关系得到明确的结果.本研究用12份样品代表野生牡丹组(Paeonia section Moutan DC.,Paeoniaceae)8个种,利用包括核基因(Adh1A、Adh2和GPAT)和叶绿体基因(trnS-trnG和rps16-trnQ)的DNA序列以及形态性状的多套数据来探讨野牛牡丹的种间关系.合并分析得到具高支持率的牡丹组物种间的系统发育关系.结果表明,芍药属牡丹组8个野生种分为两个亚组,即肉质花盘亚组subseet.Delavayanae和革质花盘亚组subsect.Vaginatae.肉质花盘亚组包括滇牡丹P delavayi和大花黄牡丹P.ludlowii;革质花盘亚组包括其余6个种.革质花盘亚组中,四川牡丹P.decomposita ssp.decomposita和紫斑牡丹P. rockii ssp. rockii关系密切;卵叶牡丹P.qiui和矮牡丹P. jishanenMs关系密切;银屏牡丹P. suffruticosa ssp.yinpingmudan与风丹P. ostii关系 密切,并且后两个分支为姊妹群.     

The genetic diversity of SMLS (Sitobion miscanthi L type symbiont) and its effect on the fitness,mitochondrial DNA diversity and Buchnera aphidicola dynamic of wheat aphid,Sitobion miscanthi (Hemiptera: Aphididae)

SMLS (Sitobion miscanthi L type symbiont) is a recently discovered aphid secondary symbiont. Using evidence extracted from 16S rRNA sequences, previous studies indicate that SMLS is the most widely distributed and most recently transferred secondary symbiont in Chinese Sitobion miscanthi populations. Here, we further investigated genetic diversity among SMLS geographic strains with multiloci data. Furthermore, the influence of SMLS on S. miscanthi was uncovered with ecological and evolutionary evidence. The results indicated that there was limited influence of infection with SMLS on variation and evolutionary patterns of S. miscanthi mitochondrial DNA. By hemolymph injection, the SMLS‐infected and SMLS‐uninfected S. miscanthi clones with the identical genetic background were built in this study. Although similar Buchnera aphidicola dynamics were observed between SMLS‐infected and SMLS‐uninfected S. miscanthi population, B. aphidicola density of SMLS‐infected S. miscanthi population was always significantly higher than SMLS‐uninfected ones. The results of fitness measurements indicated that under laboratory rearing conditions, transfection of SMLS could confer modest advantages to some fitness components of S. miscanthi, that is, total number of offspring, longevity, age of first reproduction and weight of adult. However, as SMLS is not strictly associated with S. miscanthi, further investigations are needed to uncover the mechanisms responsible for this inconceivable association.