Confirmation of natural hybrids between Gentiana straminea and G. siphonantha (Gentianaceae) based on molecular evidence

A few individuals with intermediate morphology always appeared in the sympatric distributions of Gentiana straminea and G. siphonantha. These intermediate individuals were hypothesized to be the hybrids of two species after a careful evaluation of their morphological characteristics. To test this hypothesis, sequence comparison of the internal transcribed spacer (ITS) regions of the nuclear ribosomal and trnS (GCU)-trnG (UCC) intergenic spacer region of the chloroplast DNA from Gentiana straminea, G. siphonantha and the putative hybrids was performed. The results suggest that most intermediate individuals were the natural hybrids between G. straminea and G. siphonantha. In addition, we examined the sequence variation among the individuals of both parent species and analyzed the possibility leading to the incongruent identification in some individuals based on morphologic and molecular evidences, respectively. The intraspecific diversification of DNA fragments within both parent species and their high variability in hybrid swarms probably resulted from chloroplast genome recombination and incomplete lineage sorting during the early stages of speciation origin of the parent species. __________ Translated from Acta Botanica Yunnanica, 2007, 29 (1): 91–97 [译自:云南植物研究]     

Life‐history traits of Encarsia guadeloupae,a natural enemy of the invasive spiralling whitefly Aleurodicus dispersus

On south‐west Indian Ocean islands, many crops and ornamental plants are threatened by the spiralling whitefly Aleurodicus dispersus (Hemiptera: Aleyrodidae), which is a polyphagous pest that is native to the Caribbean region. Aleurodicus dispersus causes economic damage to various crops on all the islands in the south‐west Indian Ocean. The hymenopteran parasitoid Encarsia guadeloupae (Hymenoptera: Aphelinidae) is a natural enemy of A. dispersus on the Caribbean islands. In this study, we assessed the geographical distribution of the parasitoid in La Réunion, an island in the south‐west Indian Ocean where the parasitoid was first observed in 2004. We also investigated its main life‐history traits. Field surveys indicated that the parasitoid is widespread in most of the low‐lying areas of the island and exhibits high parasitism rates on A. dispersus populations. At 25°C, E. guadeloupae adults had a mean longevity of 33.6 days, and its pre‐imaginal development required 23 days. The lower temperature threshold and thermal constant were estimated to be 7.9°C and 132 degree‐days, respectively. Females of E. guadeloupae preferred to deposit eggs in early rather than in late instars of A. dispersus, and oviposition rates were highest in the second larval instar. Females of E. guadeloupae were able to oviposit in larvae of other species of whiteflies found in La Réunion (Bemisia tabaci and Dialeurolonga simplex), although subsequent development of the parasitoid was not monitored. Finally, we discuss the potential use of E. guadeloupae for the control of whitefly populations on islands in the south‐west Indian Ocean.     

The complete chloroplast genome of Myriophyllum spicatum reveals a 4‐kb inversion and new insights regarding plastome evolution in Haloragaceae

Myriophyllum, among the most species‐rich genera of aquatic angiosperms with ca. 68 species, is an extensively distributed hydrophyte lineage in the cosmopolitan family Haloragaceae. The chloroplast (cp) genome is useful in the study of genetic evolution, phylogenetic analysis, and molecular dating of controversial taxa. Here, we sequenced and assembled the whole chloroplast genome of Myriophyllum spicatum L. and compared it to other species in the order Saxifragales. The complete chloroplast genome sequence of M. spicatum is 158,858 bp long and displays a quadripartite structure with two inverted repeats (IR) separating the large single copy (LSC) region from the small single copy (SSC) region. Based on sequence identification and the phylogenetic analysis, a 4‐kb phylogenetically informative inversion between trnE‐trnC in Myriophyllum was determined, and we have placed this inversion on a lineage specific to Myriophyllum and its close relatives. The divergence time estimation suggested that the trnE‐trnC inversion possibly occurred between the upper Cretaceous (72.54 MYA) and middle Eocene (47.28 MYA) before the divergence of Myriophyllum from its most recent common ancestor. The unique 4‐kb inversion might be caused by an occurrence of nonrandom recombination associated with climate changes around the K‐Pg boundary, making it interesting for future evolutionary investigations.     

Application of petG-trnP sequence to systematic study of Chinese Cupressus species

Chinese Cupressus L. includes five species. The molecular phylogenetic relationship of the Cupressus species and Chamaecyparis L. were determined by comparing 417–479 bp of chloroplast petG-trnP intergenic spacer sequence. In PAUP^* analysis, Platycladus orientalis was used as the functional out group. By using the maximum likelihood method 1 077 trees were examined and the result showed that one tree had a best score of -Ln=2 232.47. The phylogenetic tree clearly showed that Chamaecyparis nootkatensis was diverged from other Chamaecyparis species. Based on the results, together with evidences from other aspects, we consider that Cupressus funebris and Chamaecyparis nootkatensis should be placed in the genus Cupressus. The use of cpDNA intergenic spacer petG-trnP in Cupressus was also discussed. __________ Translated from Journal of Sichuan University (Natural Science Edition), 2005, 42(5): 1033–1037 [译自: 四川大学学报 (自然科学版) 2005, 42(5): 1033–1037]     

The architecture of the chloroplast psbA-trnH non-coding region in angiosperms

The psbA-trnH intergenic region is among the most variable regions in the angiosperm chloroplast genome. It is a popular tool for plant population genetics and species level phylogenetics and has been proposed as suitable for DNA barcoding studies. This region contains two parts differing in their evolutionary conservation: 1) the psbA 3′UTR (untranslated region) and 2) the psbA-trnH intergenic non-transcribed spacer. We compared the sequence and RNA secondary structure of the psbA 3′ UTR across angiosperms and found consensus motifs corresponding to the stem portions of the RNA stem-loop structures and a consensus TTAGTGTATA box. The psbA-trnH spacer exhibited patterns that can be explained by the independent evolution of large inversions in the psbA 3′UTR and mutational hot spots in the remaining portion of the psbA-trnH spacer. We conclude that a comparison of chloroplast UTRs across angiosperms offer clues to the identity of putative regulatory elements and information about selective constraints imposed on the chloroplast non-coding regions.     

Phylogeography and allopatric divergence of cypress species (<Emphasis Type="Italic">Cupressus</Emphasis> L.) in the Qinghai-Tibetan Plateau and adjacent regions

Background  

Although allopatric speciation is viewed as the most common way in which species originate, allopatric divergence among a group of closely related species has rarely been examined at the population level through phylogeographic analysis. Here we report such a case study on eight putative cypress (Cupressus) species, which each have a mainly allopatric distribution in the Qinghai-Tibetan Plateau (QTP) and adjacent regions. The analysis involved sequencing three plastid DNA fragments (trnD-trnT, trnS-trnG and trnL-trnF) in 371 individuals sampled from populations at 66 localities.     

The complex history of the genus Ilex L. (Aquifoliaceae): evidence from the comparison of plastid and nuclear DNA sequences and from fossil data

 A plastid phylogeny of the genus Ilex based on three different loci (the atpB-rbcL spacer, trnL-trnF and rbcL) is compared with its nuclear phylogeny based on two different loci (the ribosomal ITS and the 5S RNA spacer). These two sets of molecular data are then compared to geographical and temporal data from the fossil record. The plastid phylogeny is strongly correlated with the geographic distribution of extant species. However, the nuclear phylogeny is strongly incongruent with the plastid phylogeny, suggesting frequent interlineage hybridizations. Moreover, the comparison of the ribosomal ITS tree and the 5S RNA spacer tree indicates also possible lineage sorting. Particularly interesting is the finding of two different Ilex lineages in the plastid American clade showing different biogeographic patterns in South America. One of them has a simple North American/South American biogeographical relationship. The other has complex biogeographical relationships, some species showing direct Asian/South American biogeographical relationships. During its history, the genus Ilex probably experienced frequent lineage sorting and interlineage hybridization with subsequent nuclear or cytoplasmic introgression, making the study of its history very complex. Received September 24, 2001; accepted August 19, 2002 Published online: November 28, 2002 Addresses of the authors: Jean-Fran?ois Manen (e-mail: manen@cjb.ville-ge.ch), Yamama Naciri-Graven, Conservatoire et Jardin Botaniques, Impératrice 1, CH-1292 Chambésy/Genève, Switzerland. Michael C. Boulter, Palaeobiology Research Unit, University of East London, Romford Road, London E15 4LZ, UK.     

Identification and characterization of plastid trnF(GAA) pseudogenes in four species of Solanum (Solanaceae)

Non-functional trnF pseudogenes that rarely occur in embryophytes have been found in Solanaceae. We have sequenced the trnL-F intergenic spacer of four species of Solanum, and found duplicated regions of the original trnF gene. These repeats were 94–260 bp long causing large length variation in the trnL-F intergenic spacer resulting from differences in pseudogene copy number (2–4). The duplicated trnF regions are comprised of several highly structured motifs, which were partial residues, or entire parts of the Anticodon, T- and D-domains of the original gene, but all lacked the acceptor stems at the 5′- or 3′-end. Pseudogenes included several transitions and transversions in their sequences compared to the original trnF gene. Among pseudogene copies, T-domains were more frequent and fragmented than D-domain elements. Our results demonstrate that although chloroplast evolution is uniform such structural duplications in the sequences used for phylogenetic reconstructions should be treated with great caution.     

The Relative Significance of Host–Habitat,Depth, and Geography on the Ecology,Endemism, and Speciation of Coral Endosymbionts in the Genus Symbiodinium

Dinoflagellates in the genus Symbiodinium are among the most abundant and important group of eukaryotic microbes found in coral reef ecosystems. Recent analyses conducted on various host cnidarians indicated that Symbiodinium assemblages in the Caribbean Sea are genetically and ecologically diverse. In order to further characterize this diversity and identify processes important to its origins, samples from six orders of Cnidaria comprising 45 genera were collected from reef habitats around Barbados (eastern Caribbean) and from the Mesoamerican barrier reef off the coast of Belize (western Caribbean). Fingerprinting of the ribosomal internal transcribed spacer 2 identified 62 genetically different Symbiodinium. Additional analyses of clade B Symbiodinium using microsatellite flanker sequences unequivocally characterized divergent lineages, or “species,” within what was previously thought to be a single entity (B1 or B184). In contrast to the Indo-Pacific where host-generalist symbionts dominate many coral communities, partner specificity in the Caribbean is relatively high and is influenced little by the host’s apparent mode of symbiont acquisition. Habitat depth (ambient light) and geographic isolation appeared to influence the bathymetric zonation and regional distribution for most of the Symbiodinium spp. characterized. Approximately 80% of Symbiodinium types were endemic to either the eastern or western Caribbean and 40–50% were distributed to compatible hosts living in shallow, high-irradiance, or deep, low-irradiance environments. These ecologic, geographic, and phylogenetic patterns indicate that most of the present Symbiodinium diversity probably originated from adaptive radiations driven by ecological specialization in separate Caribbean regions during the Pliocene and Pleistocene periods.     

Phylogeny of Castanea (Fagaceae) based on chloroplast trnT-L-F sequence data

Species in the genus Castanea are widely distributed in the deciduous forests of the Northern Hemisphere from Asia to Europe and North America. They show floristic similarity but differences in chestnut blight resistance especially among eastern Asian and eastern North American species. Phylogenetic analyses were conducted in this study using sequences of three chloroplast noncoding trnT-L-F regions. The trnT-L region was found to be the most variable and informative region. The highest proportion of parsimony informative sites, more and larger indels, and higher pairwise distances between taxa were obtained at trnT-L than at the other two regions. The high A+T values (74.5%) in the Castanea trnT-L region may explain the high proportion of transversions found in this region where as comparatively lower A+T values were found in the trnL intron (68.35%) and trnL-F spacer (70.07%) with relatively balanced numbers of transitions and transversions. The genus Castanea is supported as a monophyletic clade, while the section Eucastanon is paraphyletic. C. crenata is the most basal clade and sister to the remainder of the genus. The three Chinese species of Castanea are supported as a single monophyletic clade, whose sister group contains the North American and European species. There is consistent but weak support for a sister–group relationship between the North American species and European species.     

A molecular phylogeny and generic rearrangement of the stapelioid Ceropegieae (Apocynaceae-Asclepiadoideae)

 Representatives of nearly all genera of the taxon-rich stem-succulent stapeliads and most of the few related, leafy genera were analyzed. Sequence data from two non-coding molecular markers (ITS region of nrDNA and trnT-L and trnL-F spacers as well as the trnL intron of cpDNA) support the traditional tribal affiliation of the genera, which form a monophyletic group. This monophylum breaks into a basal Neoschumannia/Anisotoma/Riocreuxia/Sisyranthus nk;clade, from which the core Ceropegieae are derived. The four Ceropegia species included are not monophyletic, and their relationship to Brachystelma changes depending on the marker studied. The stem succulent taxa fall in a number of well supported, but unresolved clades, the most prominent being the predominantly southern African clade comprising Orbea, Stapelia and some other genera. The most derived taxa of NE Africa, Duvaliandra and White-sloanea, are basal to this southern African clade. The other clades comprise the more basal genera of stem-succulent stapeliads, including the members of the Caralluma complex. Of the 17 genera accepted by Plowes for the Caralluma complex, seven are recognized: Caralluma, Apteranthes, Australluma, Boucerosia, Caudanthera, Desmidorchis and Monolluma. New combinations are proposed in 15 cases; Caralluma adscendens var. geniculata is raised to specific rank. Anomalluma is reinstated, and Pseudolithos mccoyi is transfered to it. A broadened concept for Orbea (incl. Angolluma and Orbeopsis) is recognized, but Orbeanthus is kept separate. The monotypic Ballyanthus, recently separated from Orbea, is nested within Duvalia. Piaranthus (incl. Huerniopsis) is monophyletic. The bitypic Notechidnopsis is reduced to the type species, N. tessellata, while N. columnaris is transferred to a new genus, Richtersveldia. Received February 25, 2002; accepted June 17, 2002 Published online: November 7, 2002 Address of the authors: Dr. Ulrich Meve (e-mail: ulrich.meve@uni-bayreuth.de) and Prof. Dr. Sigrid Liede (e-mail: sigrid.liede@uni-bayreuth.de), Universit?t Bayreuth, Lehrstuhl für Pflanzensystematik, Universit?tsstrasse 30, D-95440 Bayreuth, Germany.     

Phylogenetic analysis of a polyphyletic African genus of Caesalpinioideae (Leguminosae): Monopetalanthus Harms

 To assess the new taxonomy of Monopetalanthus proposed by Wieringa, a phylogenetic study was performed using the chloroplast trnL intron and psbA-trnH spacer, and the nuclear ITS region of the 18-26S rDNA. The phylogeny clearly indicates the polyphyletic nature of Monopetalanthus. The molecular data support the transfer of M. longiracemosus to Tetraberlinia and the newly defined Aphanocalyx, which now includes all the previous Monopetalanthus species having leaflets with a marginal vein. Our analyses do not support the monophyly of the newly described genus Bikinia, which includes four new species and six species transferred from Monopetalanthus. Bikinia occurs either as paraphyletic with Tetraberlinia (chloroplast DNA data) or as a monophyletic group that also includes the new monotypic genus Icuria sister to Tetraberlinia (ITS data). Nonetheless, the molecular phylogeny generally supports the taxonomy of Wieringa in subdividing the genus Monopetalanthus into distinct groups, none of which retains the name Monopetalanthus. Received May 28, 2001; accepted July 6, 2002 Published online: November 20, 2002 Address of the authors: G. Y. Fannie Gervais, Anne Bruneau (e-mail: bruneaua@irbv.umontreal. ca), Institut de Recherche en Biologie Végétale, Université de Montréal, 4101 Sherbrooke est, Montréal, Québec, Canada, H1X2B2.     

Ecomorphological convergence in Eleutherodactylus frogs: a case of replicate radiations in the Caribbean

Replicate radiations, the repeated multiplication of species associated with ecological divergence, have attracted much attention and generated as much debate. Due to the few well‐studied cases, it remains unclear whether replicate radiations are an exceptional result of evolution or a relatively common example of the power of adaptation by natural selection. We examined the case of Eleutherodactylus frogs, which radiated in the Caribbean islands resulting in more than 160 species that occupy very diverse habitats. A time‐calibrated phylogeny revealed that these frogs independently diversified on all larger islands producing species that occupy a broad range of microhabitats in different islands. Using phylogenetic comparative methods, we found an association between morphological traits and particular microhabitats, and for most microhabitats detected significant morphological convergence. Our results indicate Caribbean Eleutherodactylus are a novel example of replicate radiations, and highlight the predictability of evolutionary processes, as similar ecological opportunities can lead to similar outcomes.     

A reassessment of tribal affinities of Cratystylis and Haegiela (Asteraceae) based on three chloroplast DNA sequences

 The tribal affinities of Cratystylis and Haegiela were assessed using three chloroplast DNA sequences, the trnL/F spacer, the trnL intron and the matK coding region. The outgroup was represented by two species of the subfamily Barnadesioideae, whereas one to seven genera (45 species including Cratystylis and Haegiela) of the tribes of the Asteroideae [Anthemideae (6 genera), Astereae (7), Calenduleae (2), Gnaphalieae (7), Heliantheae s.l. (5), Inuleae s.str. (3), Plucheeae (3), Senecioneae (4)] and Cichorioideae, [Arctotideae (1), Cardueae (2), Lactuceae (2), Liabeae (1), Mutisieae (1) and Vernonieae (1)] comprise the ingroup. Phylogenetic analysis indicates that Cratystylis has strong support as a member of the tribe Plucheeae, whereas Haegiela is a member of Gnaphalieae. At some point in their taxonomic history, both genera have been placed in these tribes and there are good morphological and chemical characters that justify these placements. The monotypic Haegiela was once included in Epaltes (Plucheeae) and this study has confirmed the need for the separation of the two genera. The genus Cratystylis appears to be monophyletic. Received August 26, 2002; accepted September 19, 2002 Published online: February 7, 2003     

Diversification of Lupinus (Leguminosae) in the western New World: derived evolution of perennial life history and colonization of montane habitats

Previous phylogenetic studies of Lupinus (Leguminosae) based on nuclear DNA have shown that the western New World taxa form a monophyletic group representing the majority of species in the genus, with evidence for high rates of recent diversification in South America following final uplift of the Andes 2–4 million years ago (Mya). For this study, three regions of rapidly evolving non-coding chloroplast DNA (trnL intron, trnS–trnG, and trnT–trnL) were examined to estimate the timing and rates of diversification in the western New World, and to infer ancestral states for geographic range, life history, and maximum elevation. The western New World species (5.0–9.3 Mya, 0.6–1.1 spp./My) comprise a basally branching assemblage of annual plants endemic to the lower elevations of western North America, from which two species-rich clades are recently derived: (i) the western North American perennials from the Rocky Mountains, Great Basin, and Pacific Slope (0.7–2.1 Mya, 2.0–5.9 spp./My) and (ii) the predominantly perennial species from the Andes Mountains of South America and highlands of Mexico (0.8–3.4 Mya, 1.4–5.7 spp./My). Bayesian posterior predictive tests for association between life history and maximum elevation demonstrate that perennials are positively correlated with higher elevations. These results are consistent with a series of one or more recent radiations in the western New World, and indicate that rapid diversification of Lupinus coincides with the derived evolution of perennial life history, colonization of montane habitats, and range expansion from North America to South America.     

Phylogeography of the endemic St. Lucia whiptail lizard Cnemidophorus vanzoi: Conservation genetics at the species boundary

Vicariance and isolation leading to speciation of reptiles on islands is well exemplified in a number of taxa in the Caribbean. The St. Lucia whiptail (Cnemidophorus vanzoi), considered a single species, is found on two small islets (Maria Major and Maria Minor) off the main island of St. Lucia. From lizards collected from both localities, we gathered morphological measurements and analysed the genetic divergence between populations, using a molecular survey of ∼ ∼2800 mtDNA base pairs and 8 microsatellites. There are significant differences in body size and general form and fixed but small mtDNA differences between island populations. Microsatellites reveal low diversity within populations but very high differentiation between islands with non-overlapping allele size ranges at all except one microsatellite and two loci exhibiting single-base polymorphism, fixed between islands. Based on these results, we examine published criteria to determine whether the studied island forms could be considered true species. According to the phylogenetic species concept and Moritz’s evolutionary significant unit (ESU) criteria, the two lizard populations can be considered separate entities. Crandall et al.’s (2000, Trends Ecol. Evol., 15, 290–295) broader categorization of population distinctiveness, based on concepts of ecological and genetic exchangeability, produces conflicting results depending on the interpretation of the observed ecological data. Following Fraser and Bernatchez’s (2001, Mol. Ecol., 10, 2741–2752) framework for management decisions when ecological data are not sufficient we propose that the lizard populations on the Maria islands are on differing evolutionary trajectories and thus at the species boundary. The populations are of high priority to conservation, thus meriting separate management.     

Genetic evidence for hybridization between the native Spartina maritima and the introduced Spartina alterniflora (Poaceae) in South-West France: Spartina × neyrautii re-examined

 Spartina alterniflora, a perennial grass native to the North American Atlantic coast, was introduced during the 19th century in western Europe (Southern England and western France) where it hybridized with the native Spartina maritima. In England, the sterile hybrid S. × townsendii gave rise by chromosome doubling to the highly fertile allopolyploid Spartina anglica, which has now invaded many salt marshes and estuaries in western Europe, and has been introduced in several continents. In South-West France, another sterile hybrid was discovered in 1892 in the Bidassoa Estuary, and named Spartina × neyrautii. According to their morphology, some authors suggested that S. × neyrautii and S. × townsendii result from reciprocal crosses. During the 20th century, the hybridization site was severely disturbed, and surviving of S. × neyrautii was questioned. In this paper, various Spartina populations are investigated in the Basque region (France and Spain), and compared to the hybrid taxa formed in England (S. × townsendii and S. anglica). The samples were analyzed using molecular fingerprinting (RAPD and ISSR) and Chloroplast DNA sequence (trnL-trnT spacer, trnL intron and trnL-trnF spacer). In the Bidassoa estuary, a hybrid isolated clone has been found, that displays additive species-specific nuclear markers of S. maritima and S. alterniflora, and that is subsequently considered as a surviving clone of S. × neyrautii. The molecular analyses indicate that S. × neyrautii and S. × townsendii share the same maternal (S. alterniflora), and paternal (S. maritima) parental species, but also that the two independent hybridization events have involved different parental (nuclear) genotypes in England and in South-West France. Received July 12, 2002; accepted October 4, 2002 Published online: March 20, 2003     

Allium ursinum L. in Germany – surprisingly low genetic variability

Allium ursinum s.l. is a widely spread species of the herb layer in beech forests throughout Europe. Little is known about its phylogenetic origin and its biogeographic history. Molecular genetic analyses of eleven populations from Germany were used to clarify the relationship between populations of A. ursinum s.l. and its relationship to several other species of the genus Allium. The study focused mainly on the Teutoburg Forest in Lower Saxony and the Franconian mountain area in Bavaria. Sequences of the nuclear internal transcribed spacer ITS, and the external transcribed spacer ETS, as well as the plastidic trn L‐rpl 32 and the trn L‐trn F spacer regions were compared. No variation was detected within the species. Even sequences of populations from Belfast, Ireland did not differ from populations of Germany. The closest relative to Allium ursinum s.l. turned out to be Allium moly or Allium scorzonerifolium from the section Molium. Random amplified polymorphic DNA fingerprinting was performed and revealed 29% polymorphic bands. Genetic distances of the populations within the Teutoburg Forest coincided with geographical distances. Three populations (Osnabrück Westerberg, Osnabrück Honeburg and Leer, East Frisia) out of eleven analysed populations were identified as garden escapes. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Molecular markers reveal a strong genetic differentiation between two European relic tree species: Zelkova abelicea (Lam.) Boissier and Z. sicula Di Pasquale, Garfì & Quézel (Ulmaceae)

Chloroplast (trnL) and ribosomal (ITS2)sequences and chloroplast DNA (PCR-RFLP andSSR) markers were analysed in two relicUlmaceae tree species: Zelkova abelicea,from Crete, and Z. sicula, from Sicily.The analysis of the plastidial trnLintron and of ITS2 ribosomal sequences revealedtheir divergence from the related speciesZ. carpinifolia, widespread in the Caucasianregion; one base substitution in the trnLintron was detected between the twoMediterranean species, thus suggesting theirrecent separation. Molecular markers(plastidial PCR-RFLP and SSR) showed an evidentgenetic differentiation between Z. siculaand Z. abelicea, the two species beingcharacterised by different haplotypes. Nowithin population variation was detected usingdifferent chloroplast markers inZ. abelicea and Z. sicula. Paleobotanicaldata proved that the genus Zelkova wasabundant and widespread in central Italy untilit became extinct in the continental part ofEurope during last glaciation events andsurvived only in two Mediterranean islands. Thesegregation of the two Mediterranean relicspecies might have occurred as a consequence ofthe strong reduction of their distribution andthe following geographic isolation. Geneticdrift may have determined the drastic reductionof within stand diversity as observed in othersmall, peripheral and geographically isolatedplant populations. The priorities forconservation programs are discussed in thelight of the different genetic resourcesrepresented by the two taxa.     

Diet composition of post-metamorphic bullfrogs (Rana catesbeiana) in the Zhoushan archipelago, Zhejiang Province, China

Bullfrogs (Rana catesbeiana) are listed as one of the 100 worst invasive alien species in the world. They are generalist predators and thus may affect native species through predation. In previous studies, the food contents of bullfrogs were mostly examined at a single site. In the present study, the diet composition of post-metamorphic bullfrogs on eight islands (Daishan, Liuheng, Xiushan, Fodu, Taohua, Xiashi, Cezi, and Putuoshan) in the Zhoushan Archipelago, Zhejiang Province of China, were examined by using the stomach flushing method from June 30 to August 11 in 2005. A total of 391 individual frogs were measured, including 113 adults and 278 juveniles. The analysis of the stomach contents shows that, for adult bullfrogs, the most important prey (by diet volume) overall were Decapoda, Coleoptera, Odonata, Mesogastropoda, Raniformes, and Cypriniformes. For juvenile bullfrogs, these were Decapoda, Coleoptera, Cypriniformes, Odonata, Orthoptera, Hymenoptera, Lepidoptera larvae, Mesogastropoda, and Raniformes. Moreover, the prey size and diet volume increased with the body size of both adult and juvenile bullfrogs. The diet composition of primary preys of bullfrogs was significantly different among the islands. The results indicate that bullfrogs exert different predatory influences on native fauna at different sites and that bullfrogs are generalist predators with extensive ecological impacts on native fauna. __________ Translated from Biodiversity Science, 2006, 14 (5): 363–371 [译自: 生 物多样性]