Relationship among five populations of Bactrocera dorsalis based on mitochondrial DNA sequences in western Yunnan, China

Genetic variation in the Oriental fruit fly, Bactrocera dorsalis (Hendel), was analysed using five populations from western Yunnan, China, to elucidate the distribution and likely dispersal patterns of this fly. A 503-bp portion of the mitochondrial cytochrome oxidase gene was sequenced from a minimum of seven individuals from each of five fly populations; 25 haplotypes were observed among 57 individuals in these populations. High genetic diversity within populations was detected. Genetic distances between haplotypes reached 1.2%. Mantel tests did not indicate any isolation because of geographic distance. The Ruili (RL) population was significantly isolated from the others (pairwise Fst ranging from 0.10 to 0.21, and average genetic distances being higher than for all other four population comparisons). RL is geographically separated from the other sites by the Gaoligong Mountains. The Liuku (LK) population had a close genetic relationship with the Lujiangba (LJB) population, suggesting that the LK population probably originated from LJB that is located in the same valley to the south. The Baoshan (BS) and Dali (DL) populations were also geographically isolated from the others, not originating from LJB and RL, where the fly is present year-round. The north-south orientation of mountains and valleys in western Yunnan appears to prevent latitudinal gene exchange by dispersing flies and thus divides the five populations into four relatively independent zones, namely BS, DL, LK-LJB and RL. In addition, air currents that generally flow south to north appear to assist dispersing flies, especially in valleys between the mountain chains.     

Some butterflies do not care much about topography: a single genetic lineage of Erebia euryale (Nymphalidae) along the northern Iberian mountains

The phylogeography of montane species often reveals strong genetic differentiation among mountain ranges. Both classic morphological and genetic studies have indicated distinctiveness of Pyrenean populations of the butterfly Erebia euryale. This hypothesis remained inconclusive until data from the westernmost populations of the distribution area (Cantabrian Mountains) were analysed. In the present study, we set out to describe the population structure of Erebia euryale in western Cantabria, where the species occurs in scattered localities. For this goal, we estimate the genetic diversity and differentiation found in 218 individuals from six Cantabrian (North Spain) localities genotyped by 17 allozyme loci. We also sequence 816 bp of the cytochrome oxidase subunit I mitochondrial gene in 49 individuals from Cantabrian localities and 41 specimens from five other European sites. Mitochondrial data support the recognition of four major genetic groups previously suggested for the European populations based on allozyme polymorphisms. Both mitochondrial and nuclear markers reveal genetic distinctiveness of a single Pyrenean–Cantabrian lineage of E. euryale. The lack of geographical structure and the star‐like topology displayed by the mitochondrial haplotypes indicate a pattern of demographic expansion in northern Iberia, probably related to Upper Pleistocene climatic oscillations. By contrast, within the Pyrenean–Cantabrian lineage, Cantabrian samples are genetically structured in nuclear datasets. In particular, San Isidro is significantly differentiated from the other five populations, which cluster into two groups. We recognize an evolutionary significant unit for Pyrenean–Cantabrian populations of Erebia euryale. Our results also illustrate that the evolutionary history of a species may be shaped by processes undetectable by using mtDNA alone.     

Conservation genetics of three flightless beetle species in southern California

Regional scale conservation decisions can be aided by information on the distribution of intraspecific diversity, especially the extent to which patterns are common to multiple species. We compare patterns of intraspecific mitochondrial cytochrome oxidase I (COI) variation among three flightless beetles (Coleoptera: Tenebrionidae: Nyctoporis carinata LeConte; Staphylinidae: Sepedophilus castaneus (Horn); Carabidae: Calathus ruficollis Dejean) in the southern part of the California Floristic Province biodiversity hotspot. All species exhibit moderate to high levels of total variation, ranging from 2% to 10% (maximum uncorrected distance). Most populations of all species exhibit unique haplotypes, but few populations’ haplotypes constitute exclusive clades. Many adjacent pairs of populations show indications of some, though limited, genetic connectedness, due either to gene flow or ancestral polymorphism. However, in most cases this diminishes sharply over greater distances. By both statistical and phylogenetic measures, Sierra Nevadan populations are highly distinct from those in the coast and transverse ranges. Among the latter, the eastern transverse ranges are generally most unique and isolated, with diversity in the western parts of these ranges showing fewer barriers. Otherwise, few measures agree on areas of highest conservation value, and overall patterns tend to be species-specific.     

Spatial patterns of genetic structure among populations of a stone‐cased caddis (Trichoptera: Tasimiidae) in south‐east Queensland,Australia

1. Gene flow and dispersal among populations of a stone‐cased caddis (Tasimiidae: Tasimia palpata) were estimated indirectly using a 460 bp region of the cytochrome oxidase I gene of mitochondrial DNA. 2. There was no significant differentiation at the largest spatial scale (between catchments) and no correlation between genetic distance and geographic distance. These results are consistent with widespread adult dispersal. 3. Conversely, significant genetic differentiation was detected at the smallest spatial scale examined (among reaches within streams). This pattern was primarily because of significant F_ST values in a single stream (Bundaroo Creek). 4. Bundaroo Creek also had the lowest mean number of haplotypes per population (n = 7) suggesting that a limited number of females may be responsible for recruitment at these sites. Significant F_ST's at the reach scale may be a result of this ‘patchy’ recruitment. However, additional evidence regarding the long‐range dispersal ability and fecundity of T. palpata females is needed to test this hypothesis fully.     

Primers for identification of type and other archived specimens of Aphrodes leafhoppers (Hemiptera, Cicadellidae)

Primers were developed for leafhoppers of the genus Aphrodes amplifying 84-244 bp fragments of the mitochondrial cytochrome oxidase subunit I gene. DNA was extracted from legs of over 100-year-old archived museum specimens, amplified and sequenced. The fragments contain sufficient variation to unequivocally identify the different species. The majority of the analysed museum specimens, including three specimens of the syntype series for the UK endemic species A. aestuarina (Edwards 1908), were found to have been assigned to the wrong species. This work clearly underlines the need to validate museum specimens using molecular methods where identity is in doubt, based on reliable standards for species discrimination.     

Independent colonization and extensive cryptic speciation of freshwater amphipods in the isolated groundwater springs of Australia's Great Artesian Basin

The groundwater-dependent springs of the Great Artesian Basin (GAB) in arid inland Australia represent a unique and threatened ecosystem. These incredibly isolated springs support a diverse array of endemic flora and fauna. One of the common faunal groups in the GAB springs is the freshwater amphipods of the family Chiltoniidae. The morphological conservatism and taxonomic uncertainty associated with these amphipods has ensured their true biodiversity, phylogeographical history and evolutionary affinities have remained unknown. We have used mitochondrial DNA and allozyme data to unravel a complicated history of isolation, extinction and dispersal among spring amphipod populations across the GAB. The results provide evidence for multiple independent colonizations in the GAB springs, particularly within the Lake Eyre group of springs. The inclusion of a group of Western Australian (WA) stygobitic amphipods from populations up to 1500 km away found surprising evidence for a shared evolutionary history between stygobitic and GAB spring amphipods. Approximate dating of the diversity found between major clades suggests the majority of lineages originated in the late Miocene, around the time of the aridification of inland Australia. The large number of independent lineages and the close connection between GAB spring and WA stygobitic amphipods suggest that a significantly rich amphipod fauna existed in the much wetter environment that once existed in inland Australia. The results also provide evidence for a gross underestimation of the species diversity within the springs, with 12 putative species identified, a conclusion with significant implications for the ongoing conservation of the GAB springs.     

New insights into the mitochondrial phylogeny of the whitefly Bemisia tabaci (Hemiptera: Aleyrodidae) in the Mediterranean Basin

The whitefly Bemisia tabaci is vector of plant infecting viruses and it is considered as one of the most important agricultural pests around the Mediterranean basin. At present, five biotypes of B. tabaci have been reported in the Mediterranean Basin: B, Q, S, T and M. To establish the phylogeographic relationship of these Mediterranean biotypes with others, 54 samples collected in Europe and Africa were analysed by sequencing the mitochondrial cytochrome oxidase I gene (mtCOI). The phylogeny showed that Spanish samples corresponding to the biotype S were related to the haplotype Uganda 2 of the African clade, associated with recent epidemic upsurges of cassava mosaic virus (CMD) in that country. This phylogeographic relationship gave support to a distinct subgroup revealed within the African clade. Bemisia tabaci collected from Euphorbia plants in Italy (biotype T) formed one of the three distinct subgroups existing within the Southeast/Far East Asian clade, while samples from Turkey (biotype M) clustered together with reference mitochondrial sequences from whiteflies from Pakistan and Thailand. Recent reports indicate that Bemisia populations corresponding to the biotypes S and T are distributed in areas larger than those initially delimited. Other results indicated that samples collected in Sudan grouped within the Mediterranean–North Africa clade together with reference sequences of the biotype Q corresponding to insects collected in Spain and Morocco. Mitochondrial haplotypes of B. tabaci samples collected on sweet potato in Ghana clustered with reference sequences of samples from Cameroon corresponding to one of the five Sub-Saharan subgroups already described in the African clade. These data extends the phylogenetic information of the B. tabaci species complex and present new questions to be investigated.     

云南桔小实蝇五个地理种群的遗传分化研究

对云南省瑞丽、景洪、化念、元江、河口的桔小实蝇5个地理种群共27个个体的线粒体细胞色素氧化酶Ⅰ(COⅠ) 基因进行了部分序列测定。序列的碱基变化中转换明显多于颠换、无碱基的插入和缺失。5个地理种群中共有27个多态位点和23种单倍型,其中2种为共享单倍型。桔小实蝇5个地理种群的Fst值在0.0364～0.1364之间(P>0.05), Nm值在3.88～13.25之间。对其所有单倍型聚类分析发现,单倍型在系统树中的分布散乱、混杂,没有显示出明显的地理分布族群。分析认为5个地理种群间已存有一定程度的遗传分化,但分化的程度还比较低。造成5个种群这种遗传分化的因素主要与地理隔离有关,而种群间低程度的遗传 分化估计与桔小实蝇在云南的发展历史及生态适应有关。