Comparison of methyl eugenol metabolites, mitochondrial COI, and rDNA sequences of Bactrocera philippinensis (Diptera: Tephritidae) with those of three other major pest species within the dorsalis complex

Males of the oriental fruit fly, Bactrocera dorsalis (Hendel) and some of its sibling species have strong affinity for methyl eugenol (ME). Methyl eugenol ingested by male flies is biotransformed in the crop to two ME metabolites that eventually accumulate in the rectal gland, which is known to serve as a reservoir for B. dorsalis sex pheromones. When fed with ME, males of laboratory and wild B. philippinensis Drew and Hancock selectively accumulated two metabolites, 2-allyl-4,5-dimethoxyphenol and (E)-coniferyl alcohol, in the rectal gland, as was seen for B. dorsalis sensu stricto, B. invadens Drew, Tsuruta and White, and B. papayae Drew and Hancock. Phylogenetic analysis of COI and rDNA sequence data of these four taxa also revealed a close relationship among B. philippinensis, B. dorsalis s.s., B. invadens, and B. papayae (all four are members of the dorsalis species complex). This result corroborates pheromone analysis. The usefulness of pheromonal analysis as a chemotaxonomy tool to complement molecular and other analysis in differentiation of closely related sibling species within the Bactrocera dorsalis complex, for which use of morphological characters had been inadequate, is highlighted.     

Multi‐gene phylogenetic analysis of south‐east Asian pest members of the Bactrocera dorsalis species complex (Diptera: Tephritidae) does not support current taxonomy

Bactrocera dorsalis sensu stricto, B. papayae, B. philippinensis and B. carambolae are serious pest fruit fly species of the B. dorsalis complex that predominantly occur in south‐east Asia and the Pacific. Identifying molecular diagnostics has proven problematic for these four taxa, a situation that cofounds biosecurity and quarantine efforts and which may be the result of at least some of these taxa representing the same biological species. We therefore conducted a phylogenetic study of these four species (and closely related outgroup taxa) based on the individuals collected from a wide geographic range; sequencing six loci (cox1, nad4‐3′, CAD, period, ITS1, ITS2) for approximately 20 individuals from each of 16 sample sites. Data were analysed within maximum likelihood and Bayesian phylogenetic frameworks for individual loci and concatenated data sets for which we applied multiple monophyly and species delimitation tests. Species monophyly was measured by clade support, posterior probability or bootstrap resampling for Bayesian and likelihood analyses respectively, Rosenberg's reciprocal monophyly measure, P(AB), Rodrigo's (P(RD)) and the genealogical sorting index, gsi. We specifically tested whether there was phylogenetic support for the four ‘ingroup’ pest species using a data set of multiple individuals sampled from a number of populations. Based on our combined data set, Bactrocera carambolae emerges as a distinct monophyletic clade, whereas B. dorsalis s.s., B. papayae and B. philippinensis are unresolved. These data add to the growing body of evidence that B. dorsalis s.s., B. papayae and B. philippinensis are the same biological species, which poses consequences for quarantine, trade and pest management.     

Population structure of <Emphasis Type="Italic">Apis cerana</Emphasis> in Thailand reflects biogeography and current gene flow rather than <Emphasis Type="Italic">Varroa</Emphasis> mite association

Concordance between the mitochondrial haplotypes of the Eastern honey bee, Apis cerana, and its ectoparasitic Varroa mites across the Isthmus of Kra in Thailand has suggested that local host–pathogen co-evolution may be responsible for the geographic distribution of particular genotypes. To investigate nuclear microsatellites population structure in A. cerana, single workers of A. cerana colonies from Thailand were genotyped at 18 microsatellite loci. The loci showed intermediate to high levels of heterozygosity and a range of allele numbers. The analyses confirmed a fundamental subdivision of the Thai A. cerana population into the “Asia Mainland” and “Sundaland” regions at the Isthmus of Kra. However, the nuclear microsatellite differentiation was less distinct than mtDNA haplotype differences, suggesting male-biased dispersal and population admixture. Overall, samples showed a weak isolation-by-distance effect. The isolated population on Samui island was most differentiated from the other samples. The results do not support our initial hypothesis of local host–pathogen co-evolution, which predicts a strict correspondence between the nuclear genome and the lineage of parasitic Varroa mite of the A. cerana samples, because the gene flow indicated by our nuclear microsatellite markers should also mix potential Varroa resistance alleles among subpopulations. Instead, our study suggests that the coincidental distribution of Varroa lineages and A. cerana population structure in Thailand are the result of biogeographic history and current migration patterns.     

Microsatellite markers for the pest fruit fly,Bactrocera papayae (Diptera: Tephritidae) and other Bactrocera species

The dorsalis complex contains some of the most economically important fruit fly pests of the Asia–Pacific regions, including Bactrocera dorsalis, Bactrocera papayae and Bactrocera carambolae. These species are morphologically indistinct and genetically very similar. We describe the development of 12 microsatellite markers isolated from a representative of the dorsalis complex, B. papayae. We show the potential utility of the B. papayae microsatellites and a set of microsatellites isolated from Bactrocera tryoni as population and species markers for the dorsalis complex.     

One and the same: integrative taxonomic evidence that Bactrocera invadens (Diptera: Tephritidae) is the same species as the Oriental fruit fly Bactrocera dorsalis

The invasive fruit fly Bactrocera invadens Drew, Tsuruta & White, and the Oriental fruit fly Bactrocera dorsalis (Hendel) are highly destructive horticultural pests of global significance. Bactrocera invadens originates from the Indian subcontinent and has recently invaded all of sub‐Saharan Africa, while B. dorsalis principally occurs from the Indian subcontinent towards southern China and South‐east Asia. High morphological and genetic similarity has cast doubt over whether B. invadens is a distinct species from B. dorsalis. Addressing this issue within an integrative taxonomic framework, we sampled from across the geographic distribution of both taxa and: (i) analysed morphological variation, including those characters considered diagnostic (scutum colour, length of aedeagus, width of postsutural lateral vittae, wing size, and wing shape); (ii) sequenced four loci (ITS1, ITS2, cox1 and nad4) for phylogenetic inference; and (iii) generated a cox1 haplotype network to examine population structure. Molecular analyses included the closely related species, Bactrocera kandiensis Drew & Hancock. Scutum colour varies from red‐brown to fully black for individuals from Africa and the Indian subcontinent. All individuals east of the Indian subcontinent are black except for a few red‐brown individuals from China. The postsutural lateral vittae width of B. invadens is narrower than B. dorsalis from eastern Asia, but the variation is clinal, with subcontinent B. dorsalis populations intermediate in size. Aedeagus length, wing shape and wing size cannot discriminate between the two taxa. Phylogenetic analyses failed to resolve B. invadens from B. dorsalis, but did resolve B. kandiensis. Bactrocera dorsalis and B. invadens shared cox1 haplotypes, yet the haplotype network pattern does not reflect current taxonomy or patterns in thoracic colour. Some individuals of B. dorsalis/B. invadens possessed haplotypes more closely related to B. kandiensis than to conspecifics, suggestive of mitochondrial introgression between these species. The combined evidence fails to support the delimitation of B. dorsalis and B. invadens as separate biological species. Consequently, existing biological data for B. dorsalis may be applied to the invasive population in Africa. Our recommendation, in line with other recent publications, is that B. invadens be synonymized with B. dorsalis.     

Heterochrony: The evolution of ontogeny. By Michael L. McKinney and Kenneth J. McNamara. New York: Plenum Press. 1991. XIX + 437 pp. ISBN 0-306-43638-8. $ 49.50 (cloth)

Macaca fascicularis is broadly distributed in Southeast Asia across 30° of latitude and 35° of longitude (Indochinese Peninsula, Isthmus of Kra, Malay Peninsula, Greater and Lesser Sunda Islands, Philippine Islands, and numerous small, neighboring islands). The range is divisible into 1) a core area comprised of mainland Southeast Asia, Borneo, Sumatra, and Java (large land masses interconnected during the last glacial maximum, 18,000 B. P.); 2) shallow-water fringing islands, which are smaller islands connected to the core area during the last glacial maximum; and 3) deep-water fringing islands, which are peripheral islands not connected to the core area during the last glacial maximum. Skull length was used to study effects of latitude and insularity on patterns of size variation. The data are from 802 adult M. fascicularis specimens from 140 core-area localities, 63 shallow-water islands, and 29 deep-water islands. Sex-specific polynomial regressions of skull length on latitude were used to describe skull length variation in the core area. These regressions served as standards for evaluating variation among samples from shallow-water and deep-water islands. The core area exhibits Bergmannian latitudinal size clines through most of the species range. Thus, skull length decreases from about 8°S (Java) to the equator (Sumatra and Borneo), then increases as far north as about 13°N (Isthmus of Kra). Farther north, to the northernmost Indochinese localities at about 17°N, skull length in M. fascicularis decreases with increasing latitude, contrary to Bergmann's rule. Latitudinal size variation in shallow-water fringing islands generally parallels that in the core area. However, skull length tends to be smaller than in the core area at similar latitudes. Deep-water fringing islands are markedly more variable, with relatively small specimens in the Lesser Sunda Islands and relatively large specimens in the Nicobar Islands. These analyses illustrate how a primate species may vary in response to latitudinal temperature variation and to isolation. © 1993 Wiley-Liss, Inc.     

The biogeography of the Isthmus of Kra region: a review

This review examines the evidence for a significant biogeographic divide on the Thai–Malay Peninsula of mainland southeast Asia (SE Asia) associated with the Isthmus of Kra. The divide is believed to be of the same scale as ‘Wallace’s Line’, though it remains less well‐known, less well‐studied, and its location and cause are enigmatic. This review presents relevant geological, geographical, climatic, biogeographic and sea‐level data, discusses some exemplar distributional patterns and concludes with an integrated discussion.     

Integrative taxonomy versus taxonomic authority without peer review: the case of the Oriental fruit fly,Bactrocera dorsalis (Tephritidae)

1. Major global horticultural and food security tephritid fruit fly pests, Bactrocera papayae (papaya fruit fly) and B. invadens (invasive fruit fly), were synonymised with B. dorsalis (Oriental fruit fly) by Schutze et al. (2015a) based on extensive integrative taxonomic evidence from multiple sources. This synonymy was peer reviewed by eight independent experts. 2. Drew & Romig (2016) withdrew B. papayae and B. invadens from synonymy based on opinion drawn primarily from disparate geographical distribution, morphological, and host use information. This reversal was not subjected to peer review. 3. We consider the withdrawal from synonymy as invalid due to significant errors and misrepresentations of the literature provided in the arguments of Drew & Romig (2016) that we propose would not have withstood peer scrutiny. 4. This case reflects a broader issue of individual taxonomic authorities using opinion to challenge extensive evidence generated via scientific hypothesis‐testing methods by discipline specialists. 5. We recommend that taxonomic acts not subjected to peer review, especially of pest species, be actively discouraged by the broader scientific and regulatory community.     

The Indochinese–Sundaic zoogeographic transition: a description and analysis of terrestrial mammal species distributions

Aim We describe the distributions of mammal species between the Indochinese and Sundaic subregions and examine the traditional view that the two faunas show a transition near the Isthmus of Kra on the Thai–Malay peninsula. Location Species distributions are described along a 2000‐km transect from 20° N (northernmost Thailand) to 1° N (Singapore). Methods For the 325 species of native non‐marine mammals occurring along the transect we used published records to provide a database of their distributional records by degree of latitude. Results Along the transect we found 128 Indochinese species with southern range limits, 121 Sundaic species with northern range limits, four un‐assignable endemics and 72 widespread species. In total, 152 southern and 147 northern range limits were identified, and their distribution provides no evidence for a narrow faunal transition near the Isthmus of Kra (10°30′ N) or elsewhere. Range limits of both bats and non‐volant mammals cluster in northernmost peninsular Malaysia (5° N) and 800 km further north, where the peninsula joins the continent proper (14° N). The clusters of northern and southern range limits are not concordant but overlap by 100–200 km. Similarly, the range limits of bats and non‐volant mammals cluster at slightly different latitudes. There are 30% fewer species and range limits in the central and northern peninsula (between 6 and 13° N), and 35 more widely distributed species have range gaps in this region. In addition, we found 70 fewer species at the southern tip of the peninsula (1° N) than at 3–4° N. Main conclusions The deficiencies of both species and species range limits in the central and northern peninsula are attributed to an area effect caused by repeated sea‐level changes. Using a new global glacioeustatic curve developed by Miller and associates we show that there were > 58 rapid sea‐level rises of > 40 m in the last 5 Myr that would have resulted in significant faunal compression and local population extirpation in the narrow central and northern parts of the peninsula. This new global sea‐level curve appears to account for the observed patterns of the latitudinal diversity of mammal species, the concentration of species range limits north and south of this area, the nature and position of the transition between biogeographical subregions, and possibly the divergence of the faunas themselves during the Neogene. The decline of species diversity at the southern end of the transect is attributed to a peninsula effect similar to that described elsewhere.     

Explaining the causes of the zoogeographic transition around the Isthmus of Kra: using bats as a case study

Aim  The causes of a zoogeographic divide in peninsular Thailand around the Isthmus of Kra have not been adequately resolved. We explored climatic, historical and geological perspectives to gain insights into factors that may have contributed to the development and maintenance of this zoogeographic transition, and to determine whether a faunal transition occurs for bats. Location  Southeast Asia, focusing on the Thai Peninsula. Methods  Spatial principal components analysis was used to determine the relationship between climate and species distribution patterns. We studied bats (order Chiroptera) because of their ability to bypass small‐scale geophysical barriers. Spatial data on bat species distributions on the Thai Peninsula were analysed in relation to multivariate measures of climate to determine the possible influence of climatic zonation on distribution patterns. We assessed the effects of the interaction of climatic zonation with the highly dynamic environmental conditions the area has undergone in relation to species distribution patterns. Results  A zoogeographic transition was found, with 44 species (out of 127) restricted to the north of the Isthmus of Kra and 29 restricted to the south, although there were relatively few abrupt changes in distribution at the exact position of the isthmus. Northern and southern species were associated with specific climatic conditions. Major transitions in the distribution of bat species exist at 6–6.5° N and 13–13.5° N, with a smaller peak at 11.0° N. These major peaks fall in the same areas as the borders of climatic zones, and the 6–6.5° N peak falls in the same area as a floristic divide (the Kangar–Pattani Line). Main conclusions  On the mainland, climatic zones cause gradual changes in species distributions. However, in addition to climatic factors, repeated changes in the breadth of the Sunda Shelf during recent glacial cycles may have caused locally high extinction rates at narrow points on the peninsula, exacerbating transitions in species distribution patterns along the region, in the context of a peninsula effect that reduces opportunities for recolonization.     

Sexual maturity and intraspecific mating success of two sibling species of the Bactrocera dorsalis complex

Bactrocera carambolae Drew & Hancock and B. papayae Drew & Hancock (Diptera: Tephritidae), two closely related sibling species in the B. dorsalis (Hendel) complex were shown to have different rates of sexual maturity. The response of B. carambolae males to methyl eugenol was observed to begin 10 days after emergence and increased with age. The attractancy peaked at 28 days after emergence and above. The males were also found to require a higher dosage of methyl eugenol (1 mg) for optimal response. These results are in contrast with those of B. papayae reported previously. The response to methyl eugenol was also observed to correspond with the age when first mating was performed.After eclosion, both sexes of B. carambolae mated approximately 2 weeks later and showed significantly lower matings/individual when compared with B. papayae in a 60-day observation period. Both sexes of B. papayae and males of B. carambolae were able to remate on the next day. However, B. carambolae females required a minimum refractory period of 8 days in order to be sexually receptive again.During the 60-day period, the mating propensity in B. papayae (100% success) was higher than B. carambolae (71–87% success) (P < 0.05). This observation was substantiated by a higher intraspecific mating success of B. papayae as compared to B. carambolae in a field cage (P < 0.001).     

A tentative evaluation for population establishment of Bactrocera dorsalis (Diptera: Tephritidae) by its population modeling: Considering the temporal distribution of host plants in a selected area in Jeju,Korea

The Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae) is a destructive fruit pest in a wide range of cultivated fruit crops and wild plants. This species is a potentially highly invasive fruit fly to Jeju area of Korea. This study was conducted to evaluate the effect of host plants distributed temporally on the population development of B. dorsalis. The temperature-dependent bionomic data for a synonymous group of B. dorsalis, including B. philippinensis, B. papayae, and B. invadens were collected from previous publications and combined to construct a population model of this pest and its thermal constant. We developed a stage-transition model of eggs, larvae and pupae, and an oviposition model for basic population modeling of the four common strains. We investigated the abundance of the host plants of B. dorsalis in a selected site in Jeju and parameterized them in terms of temporal availability to incorporate into the population model. The contribution of host plants for the population growth of B. dorsalis in the selected site was different according to the group of host plants. For example, B. dorsalis populations largely decreased by 93%, when host plants belong to Moraceae (mainly Ficus sp.) were removed in the simulation. Also, we found that the host plants of Prunus persica, Ficus carica, P. mume, Eriobotrya japonica in this order contributed greatly to population abundance of B. dorsalis in the selected area, which was important in terms of mid-season host plants connecting the early adult population of B. dorsalis to citrus plants in the late season. Finally, we discussed a seasonal management strategy against B. dorsalis while considering the availability of host plants and the biology of this fruit fly in an invaded area.     

Comparative sensitivity to methyl eugenol of four putative Bactrocera dorsalis complex sibling species – further evidence that they belong to one and the same species B. dorsalis

Males of certain species belonging to the Bactrocera dorsalis complex are strongly attracted to, and readily feed on methyl eugenol (ME), a plant secondary compound that is found in over 480 plant species worldwide. Amongst those species is one of the world’s most severe fruit pests the Oriental fruit fly, Bactrocera dorsalis s.s., and the former taxonomic species Bactrocera invadens, Bactrocera papayae and Bactrocera philippinensis. The latter species have been recently synonymised with Bactrocera dorsalis based on their very similar morphology, mating compatibility, molecular genetics and identical sex pheromones following consumption of ME. Previous studies have shown that male fruit fly responsiveness to lures is a unique phenomenon that is dose species-specific, besides showing a close correlation to sexual maturity attainment. This led us to use ME sensitivity as a behavioural parameter to test if Bactrocera dorsalis and the three former taxonomic species had similar sensitivity towards odours of ME. Using Probit analysis, we estimated the median dose of ME required to elicit species’ positive response in 50% of each population tested (ED₅₀). ED₅₀ values were compared between Bactrocera dorsalis and the former species. Our results showed no significant differences between Bactrocera dorsalis s.s., and the former Bactrocera invadens, Bactrocera papayae and Bactrocera philippinensis in their response to ME. We consider that the Bactrocera males’ sensitivity to ME may be a useful behavioural parameter for species delimitation and, in addition to other integrative taxonomic tools used, provides further supportive evidence that the four taxa belong to one and the same biological species, Bactrocera dorsalis.     

Mitotic and polytene chromosomes analysis of the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)

The Oriental fruit fly, Batrocera dorsalis s.s. (Hendel) is one of the most destructive agricultural pests, belonging to a large group of difficult to distinguish morphologically species, referred as the B. dorsalis complex. We report here a cytogenetic analysis of two laboratory strains of the species and provide a photographic polytene chromosome map from larval salivary glands. The mitotic complement consists of six chromosome pairs including a heteromorphic sex (XX/XY) chromosome pair. Analysis of the polytene complement has shown a total of five polytene chromosomes (10 polytene arms) that correspond to the five autosomes. The most important landmarks of each polytene chromosome and characteristic asynapsis at a specific chromosomal region are presented and discussed. Chromosomal homology between B. dorsalis and Ceratitis capitata has been determined by comparing chromosome banding patterns. The detection of chromosome inversions in both B. dorsalis strains is shown and discussed. Our results show that the polytene maps presented here are suitable for cytogenetic analysis of this species and can be used for comparative studies among species of the Tephritidae family. They also provide a diagnostic tool that could accelerate species identification within the B. dorsalis complex and could shed light on the ongoing speciation in this complex. Polytene chromosome maps can facilitate the development of biological control methods and support the genome mapping project of the species that is currently in progress.     

Genetic variation,demographic history and phylogeography of tire track eel,Mastacembelus favus (Synbranchiformes: Mastacembelidae) in Southeast Asia

The complex climatic and geological history of Southeast Asia has been hypothesised to determine the most important aspects of the current phylogeographical structure and distribution of living organisms throughout the region. To test existing hypotheses, the genetic structure of the tire track eel, Mastacembelus favus, was investigated using 823 bp of mitochondrial DNA cytochrome b from 469 individuals from 51 localities encompassing its native range. The results classified all haplotypes into two major lineages, Lineage 1, which was further divided into Lineages 1a (lower Mekong, eastern Gulf of Thailand and Malay—Thai Peninsula), 1b (Banpakong River), 1c (Chao Phraya, Gulf of Thailand and Malay—Thai Peninsula) and 1d (Khlang Yai River), and Lineage 2, the upper reaches of the lower Mekong and the middle Mekong. Strong genetic discontinuities dated approximately 5 MYA were discovered in the Mekong with limited geographical overlap, suggesting a historically dissected drainage between two sections and species colonisation via different routes. The widespread Lineage 1 showed a strong signature of population expansion during the Pleistocene climate oscillation. Haplotype characteristics in the Malay—Thai Peninsula are hypothesised to result from postglacial dispersal from the Mekong and Chao Phraya through an extended Pleistocene drainage network.

     

Evolutionary history of the Paradoxurus palm civets – a new model for Asian biogeography

Aim Using molecular data and dental features, we investigated the genetic and morphological diversity among species of palm civets in the genus Paradoxurus, with a focus on the common palm civet, Paradoxurus hermaphroditus (Carnivora, Viverridae), in order to address biogeographic scenarios and provide recommendations for a taxonomic revision. Location Asia: Pakistan to the Lesser Sunda Islands. Methods We investigated the genetic diversity within Paradoxurus using two mitochondrial (cytochrome b, control region) and one nuclear (intron 7 of the β‐fibrinogen) markers. We used samples from 85 individuals of P. hermaphroditus (including 20 museum specimens) and one representative of each of the other species in the genus Paradoxurus: Paradoxurus jerdoni and Paradoxurus zeylonensis. DNA sequences were analysed using phylogenetic and haplotype network methods, and divergence dates were estimated for the clades retrieved. Furthermore, we examined dental characters from a large series of specimens and compared the morphological variation with the molecular data. Results Our phylogenetic analyses revealed that P. hermaphroditus is paraphyletic. We identified three major lineages distributed: (1) in the Indian subcontinent, south China, Hainan and in areas above 200 m in Indochina; (2) in Peninsular Malaysia, Java, Sumatra and in areas below 200 m in Indochina; and (3) in Borneo, the Philippines and the Mentawai archipelago. Our morphological observations were congruent with these three molecular lineages. Divergence date estimates inferred a Pliocene origin for Paradoxurus (2.8–5.7 Ma), with the three main clades diversifying from the mid–Early Pliocene to the end of the Pliocene. We suggest that the flooding of the Isthmus of Kra during the Pliocene was a major event shaping the diversification of Paradoxurus palm civets. We also hypothesize that the elevational segregation of the two lineages on the mainland could have resulted from the vegetational changes that were induced by Late Pliocene glacial episodes. Main conclusions The Isthmus of Kra is a major boundary between two major lineages of P. hermaphroditus. There is a need for a taxonomic revision for P. hermaphroditus, and we suggest that this species should be split into at least three species.     

Climatic niche and neutral genetic diversity of the six Iberian pine species: a retrospective and prospective view

Quaternary climatic fluctuations have left contrasting historical footprints on the neutral genetic diversity patterns of existing populations of different tree species. We should expect the demography, and consequently the neutral genetic structure, of taxa less tolerant to particular climatic extremes to be more sensitive to long‐term climate fluctuations. We explore this hypothesis here by sampling all six pine species found in the Iberian Peninsula (2464 individuals, 105 populations), using a common set of chloroplast microsatellite markers, and by looking at the association between neutral genetic diversity and species‐specific climatic requirements. We found large variation in neutral genetic diversity and structure among Iberian pines, with cold‐enduring mountain species (Pinus uncinata, P. sylvestris and P. nigra) showing substantially greater diversity than thermophilous taxa (P. pinea and P. halepensis). Within species, we observed a significant positive correlation between population genetic diversity and summer precipitation for some of the mountain pines. The observed pattern is consistent with the hypotheses that: (i) more thermophilous species have been subjected to stronger demographic fluctuations in the past, as a consequence of their maladaptation to recurrent glacial cold stages; and (ii) altitudinal migrations have allowed the maintenance of large effective population sizes and genetic variation in cold‐tolerant species, especially in more humid regions. In the light of these results and hypotheses, we discuss some potential genetic consequences of impending climate change.     

Population genetics of three at-risk tiger beetles Habroscelimorpha dorsalis dorsalis,H. d. media,and Ellipsoptera puritana

Many tiger beetles (Family Cicindelidae) are critically imperiled due to their dependence on small patches of suitable habitat that are frequently threatened by natural and anthropogenic disturbances. In the eastern United States, conservation of three tiger beetles - Habroscelimorpha dorsalis dorsalis, H. dorsalis media, and Ellipsoptera puritana - has been inhibited by the absence of population genetic information that is needed for effective recovery planning and potential reintroductions. Using microsatellite panels, we performed population genetic analyses and compared patterns in diversity and differentiation within and between taxa. Nearly all collections of the three taxa had less observed heterozygosity than expected under Hardy-Weinberg Equilibrium, and there was a strong latitudinal gradient in genetic diversity in H. d. dorsalis distributed along the eastern and western shores of the Chesapeake Bay. We also found clear spatial patterns of genetic differentiation which reflected strong isolation-by-distance within all three taxa and between collections of H. d. dorsalis and H. d. media. However, there was evidence of admixture in current (mouth of the Chesapeake Bay) and former (coastal New Jersey) contact zones of H. d. dorsalis and H. d. media. Taken together, our study suggests that relatively few adult tiger beetles may maintain many populations, and that gene flow among nearby habitat patches is common in all three taxa – a characteristic that may help tiger beetles persist in dynamic coastal environments. Results of our analyses can be used to support conservation and management by identifying the spatial scale of metapopulation connectivity and locating populations at the greatest risk of extirpation.

     

A tale of two haplotype groups: evaluating the New World Junonia ring species hypothesis using the distribution of divergent COI haplotypes

The New World Junonia butterflies are a possible ring species with a circum‐Caribbean distribution. Previous reports suggest a steady transition between North and South American forms in Mesoamerica, but in Cuba the forms were thought to co‐exist without interbreeding representing the overlapping ends of the ring. Three criteria establish the existence of a ring species: a ring‐shaped geographic distribution, gene flow among intervening forms and genetic isolation in the region of range overlap. We evaluated mitochondrial cytochrome oxidase I haplotypes in Junonia from nine species in the Western Hemisphere to test the Junonia ring species hypothesis. Junonia species are generally not monophyletic with respect to COI haplotypes, which are shared across species. However, two major COI haplotype groups exist. Group A predominates in South America, and Group B predominates in North and Central America. Therefore, COI haplotypes can be used to assess the degree of genetic influence a population receives from each continent. Junonia shows a ring‐shaped distribution around the Caribbean, and evidence is consistent with gene flow among forms of Junonia, including those from Mesoamerica. However, we detected no discontinuity in gene flow in Cuba or elsewhere in the Caribbean consistent with genetic isolation in the region of overlap. Although sampling is still very limited in the critical region, the only remaining possibility for a circum‐Caribbean discontinuity in gene flow is at the Isthmus of Panama, where there may be a transition from 98% Group B haplotypes in Costa Rica to 85–100% Group A haplotypes in South America.     

The <Emphasis Type="Italic">Bactrocera dorsalis</Emphasis> species complex: comparative cytogenetic analysis in support of Sterile Insect Technique applications

Background

The Bactrocera dorsalis species complex currently harbors approximately 90 different members. The species complex has undergone many revisions in the past decades, and there is still an ongoing debate about the species limits. The availability of a variety of tools and approaches, such as molecular-genomic and cytogenetic analyses, are expected to shed light on the rather complicated issues of species complexes and incipient speciation. The clarification of genetic relationships among the different members of this complex is a prerequisite for the rational application of sterile insect technique (SIT) approaches for population control.

Results

Colonies established in the Insect Pest Control Laboratory (IPCL) (Seibersdorf, Vienna), representing five of the main economic important members of the Bactrocera dorsalis complex were cytologically characterized. The taxa under study were B. dorsalis s.s., B. philippinensis, B. papayae, B. invadens and B. carambolae. Mitotic and polytene chromosome analyses did not reveal any chromosomal characteristics that could be used to distinguish between the investigated members of the B. dorsalis complex. Therefore, their polytene chromosomes can be regarded as homosequential with the reference maps of B. dorsalis s.s.. In situ hybridization of six genes further supported the proposed homosequentiallity of the chromosomes of these specific members of the complex.

Conclusions

The present analysis supports that the polytene chromosomes of the five taxa under study are homosequential. Therefore, the use of the available polytene chromosome maps for B. dorsalis s.s. as reference maps for all these five biological entities is proposed. Present data provide important insight in the genetic relationships among the different members of the B. dorsalis complex, and, along with other studies in the field, can facilitate SIT applications targeting this complex. Moreover, the availability of 'universal' reference polytene chromosome maps for members of the complex, along with the documented application of in situ hybridization, can facilitate ongoing and future genome projects in this complex.