Priorities for conserving global species richness and endemism

The Convention on Biological Diversity aims to encourage and enable countries to conserve biological diversity, to use its components sustainably and to share benefits equitably. Species richness and endemism are two key attributes of biodiversity that reflect the complexity and uniqueness of natural ecosystems. National data on vertebrates and higher plants indicate global concentrations of biodiversity and can assist in defining priorities for action. Projections indicate that species and ecosystems will be at maximum risk from human activities during the next few decades. Prompt action by the world community can minimise the eventual loss of species. Highest priorities should be to: (i) strengthen the management of ecosystems containing a large proportion of global biodiversity; (ii) help developing countries complete their biodiversity strategies and action plans, monitor their own biodiversity, and establish and maintain adequate national systems of conservation areas; (iii) support actions at the global level, providing benefit to all countries in managing their own biodiversity. Generally, resources will best be spent in safeguarding ecosystems and habitats that are viable and important for global biodiversity, and which are threatened by factors that can be controlled cost-effectively. Other important criteria are representativeness, complementarity and insurance.     

Relationships between the density of two potential restoration tree species and plant species abundance and richness in a degraded Afromontane forest of Kenya

In recent years, there have been considerable efforts to restore degraded tropical montane forests through active restoration using indigenous tree species. However, little is known about how these species used for restoration influence other species. In this study, two potential restoration species, Albizia gummifera and Neoboutonia macrocalyx, are investigated with regard to the relationship between their density and the abundance and richness of other plant species. The study was conducted in a degraded forest consisting of disturbed transition zones and secondary forest. Our results show positive relationships between the density of A. gummifera and the abundance of tree seedling and sapling richness in the transition zones and in the secondary forest. Shrub richness was negatively related to the density of A. gummifera. Abundance and richness of tree saplings and shrubs were positively related to N. macrocalyx density both in the transition zones and in the secondary forest. Herb species richness declined with N. macrocalyx density in the transition zones but increased with N. macrocalyx density in the secondary forest. The positive relationships between the density of the two tree species and species richness of other woody species suggest that both A. gummifera and N. macrocalyx can be suitable for active restoration of degraded mountain forests within their natural range.     

Regional patterns of diversity and estimates of global insect species richness

The total number of insect species in the world is an important if elusive figure. We use a fresh approach to estimate global insect species richness, based on biogeographic patterns of diversity of well or better documented taxa. Estimates generated by various calculations, all variations on a theme, largely serve to substantiate suggestions that insect species are likely to number around 10 million or less.     

Cryptic diversity,reproductive isolation and cytoplasmic incompatibility in a classic biological control success story

Molecular genetics and symbiont diagnostics have revolutionized our understanding of insect species diversity, and the transformative effects of bacterial symbionts on host life history. Encarsia inaron is a parasitoid wasp that has been shown to harbour two bacterial endosymbionts, Wolbachia and Cardinium. Known then as E. partenopea, it was introduced to the USA in the late 1980s from populations collected in Italy and Israel for the biological control of an ornamental tree pest, the ash whitefly, Siphoninus phillyreae. We studied natural populations from sites in the USA, the Mediterranean and the Middle East as well as from a Cardinium‐infected laboratory culture established from Italy, with the aims of characterizing these populations genetically, testing reproductive isolation, determining symbiont infection status in their native and introduced range, and determining symbiont role. The results showed that the two Encarsia populations introduced to the USA are genetically distinct, reproductively isolated, have different symbionts and different host–symbiont interactions, and can be considered different biological species. One (‘E. inaron’) is doubly infected by Wolbachia and Cardinium, while only Cardinium is present in the other (‘E. partenopea’). The Cardinium strains in the two species are distinct, although closely related, and crossing tests indicate that the Cardinium infecting ‘E. partenopea’ induces cytoplasmic incompatibility. The frequency of symbiont infection found in the native and introduced range of these wasps was similar, unlike the pattern seen in some other systems. These results also lead to a retelling of a successful biological control story, with several more characters than had been initially described.     

DNA barcoding provides support for a cryptic species complex within the globally distributed and fishery important opah (Lampris guttatus)

The cornerstone of fisheries management relies on a solid taxonomic base and an understanding of how animals can be grouped into coherent management units. Surprisingly, little is known about the basic biology and ecology of opah (Lampris guttatus), a globally distributed species that is commercially exploited and regionally common in the North Pacific. Recent efforts to collect life history data on this species uncovered evidence of two North Pacific morphotypes. Sequencing of the mitochondrial cytochrome c oxidase I gene (655 bp) for these morphotypes and other specimens collected worldwide (n = 480) produced five strongly diverged and well‐supported clades. Additional sequence data from the cytochrome b gene (1141 bp) as well as the nuclear recombination activating gene 1 (1323 bp) corroborated these results, suggesting these five clades probably represent separate species. Our conclusion that opah is a complex of five separate species has implications for management and indicates a need to gather additional data on these poorly understood fishes.     

Early events in speciation: Cryptic species of Drosophila aldrichi

Understanding the earliest events in speciation remains a major challenge in evolutionary biology. Thus identifying species whose populations are beginning to diverge can provide useful systems to study the process of speciation. Drosophila aldrichi, a cactophilic fruit fly species with a broad distribution in North America, has long been assumed to be a single species owing to its morphological uniformity. While previous reports either of genetic divergence or reproductive isolation among different D. aldrichi strains have hinted at the existence of cryptic species, the evolutionary relationships of this species across its range have not been thoroughly investigated. Here we show that D. aldrichi actually is paraphyletic with respect to its closest relative, Drosophila wheeleri, and that divergent D. aldrichi lineages show complete hybrid male sterility when crossed. Our data support the interpretation that there are at least two species of D. aldrichi, making these flies particularly attractive for studies of speciation in an ecological and geographical context.     

Morphological evidence that the molecularly determined Ciona intestinalis type A and type B are different species: Ciona robusta and Ciona intestinalis

Ciona intestinalis is considered a widespread and easily recognizable tunicate, the sister group of vertebrates. In recent years, molecular studies suggested that C. intestinalis includes at least two cryptic species, named ‘type A’ and ‘type B’, morphologically indistinguishable. It is dramatic to certify that two different species may be hidden under the name of a species widely used as a model species in biological researches. This raised the problem of identifying diagnostic morphological characters capable of distinguishing these types. We compared the morphology of specimens belonging to the two types and found that only type A specimens possess tunic tubercular prominences, allowing unambiguous discrimination. Remarkably, these structures were already described as distinctive of the Japanese species Ciona robusta, Hoshino and Tokioka, 1967; later synonymized under C. intestinalis (sensu Millar, 1953). In this study, we have confirmed that C. intestinalis type A corresponds to C. robusta. Based on the geographic distribution of C. intestinalis type B, and considering that the original C. intestinalis species was described from North European waters, we determined that C. intestinalis type B corresponds to C. intestinalis as described by Millar in 1953 and possibly to Linnaeus' Ascidia intestinalis L., 1767 for which we have deposited a neotype (from Roscoff, France) and for which we retain the name Ciona intestinalis (Linnaeus, 1767).     

Prevalence,geographic distribution and phylogenetic relationships among cryptic species of Plasmopara viticola in grape‐producing regions of Georgia and Florida,USA

Previous phylogenetic studies of the grape downy mildew pathogen, Plasmopara viticola, revealed five cryptic species in eastern North America that differed in their host range and geographic distribution. Preliminary comparative studies also documented differences in temperature responses during infection between certain cryptic species, indicating the biological relevance of knowing which cryptic species of the pathogen are present in a given region. However, limited information is available regarding the presence, prevalence and dynamics of cryptic species of P. viticola in the southeastern United States. Here, 301 P. viticola isolates obtained from cultivated grape species in five distinct grape‐growing regions of Georgia and Florida were subjected to cleaved amplified polymorphic sequence analysis and multilocus sequencing (internal transcribed spacer region of the rDNA, actin and β‐tubulin) to identify cryptic species and infer phylogenetic relationships. Three cryptic species, P. viticola clade aestivalis (Pva), clade vinifera (Pvv) and clade vulpina (Pvu), were identified in Georgia, whereas two, Pva and Pvv, were found in Florida; all three cryptic species are reported here for the first time in Georgia, whereas Pva is reported for the first time in Florida. Pva was the most prevalent cryptic species (72.1% of isolates) and was distributed widely from the North Georgia Mountains to Mid‐Florida, whereas Pvv (27.2%) and Pvu (0.7%) were found only in the Coastal Plain region of the two states. Interestingly, Pvu was obtained from French American hybrid Blanc du Bois and could be subcultured on Vitis vinifera Chardonnay, suggesting a broader host range than only the wild species Vitis vulpina reported previously.     

DNA barcoding of Bradysia (Diptera: Sciaridae) for detection of the immature stages on agricultural crops

We investigated the usefulness of mitochondrial cytochrome c oxidase (COI) DNA barcoding of the genus Bradysia for the detection of immature stages and cryptic species complex. Although the larvae of some species in this genus are agricultural pests, immature stages are rarely identified due to the lack of key morphological characteristics. We constructed partial sequences of the COI gene for 25 species of Bradysia as a first step towards a DNA barcode. Using these data, Bradysia impatiens, B. procera and B. peraffinis were identified from larval specimens collected, respectively, from paprika, ginseng and oak sawdust beds used for cultivating shiitake. Our findings reveal a complex of three species within the B. tilicola group. These species were all identified as important pest B. ocellaris based on the morphology of male genital structures; however, the interspecific genetic divergence of the COI region was significantly greater (16.1–19.4%) than the intraspecific variation in each species. Therefore, B. ocellaris may consist of at least three species. The results demonstrate that COI DNA barcodes are useful for Bradysia species identification.     

Pacific Coast Iris species delimitation using three species definitions: biological, phylogenetic and genealogical

Morphological characters are used to discriminate the five Oregon species of the Pacific Coast irises ( Iris series Califomicae ). In nearly every case, fixed differences were found between species, revealing that they are good phylogenetic species. However, when the biological species concept is applied, the whole series is found to be one biological species. Sequence data were generated from the chloroplast DNA region between the atp β and rbc L genes. For this 700 bp region, the maximum divergence observed in the series was one percent. These sequences, together with three restriction site characters, were used to produce a cladogram for multiple individuals of all species in the group. On the resulting consensus cladogram, the different individuals from each species do not cluster together. This could result from either introgressive hybridization or the retention of ancestral polymorphism. When the genealogical species concept is applied, only one species can be identified: the whole Series Califomicae. There are therefore two natural levels at which taxa can be defined. It is recommended that the phylogenetic species be used as the taxonomic species in this group.