Differences in worker caste behaviour of Oecophylla smaragdina (Hymenoptera: Formicidae) in response to larvae of Anthene emolus (Lepidoptera: Lycaenidae)

The larvae of Anthene emolus (Lycaenidae) cannot survive in the wild without their associated ant Oecophylla smaragdina (Formicidae) . The ants groom the lycaenid larvae for secretions and, in turn, protect them from parasitoids and predators. Both major and minor worker ants tend larvae, although, in the present study, the frequencies of tending by different castes proved to be significantly different. Ants also tended late instars significantly more than young larvae. O. smaragdina ants of the same colony were observed fighting when A. emolus larvae were present. Aggression was exhibited by the major workers against the minor workers that tried to tend secreting larvae. Major ants precluded the minors from the most nutritious secretions, leaving minors to tend the less productive, early instars. On a few occasions, aggression was unchecked and major workers killed the larvae they were tending (presumably accidentally). When larvae were experimentally reared with only one caste of ant, the resulting butterflies showed no differences in dry weight. Mortality was high when larvae were reared with only minor ants or in the absence of ants.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 391–395.     

Reproductive character displacement by inversion of coiling in clausiliid snails (Gastropoda, Pulmonata)

In land snails, a change in the direction of coiling, being associated with a shift in the position of the genital apparatus, may act as a barrier against hybridization between sympatric species. Putative reproductive character displacement by an inversion in chirality has been reported in only a few land snails, based on observations in the field and interbreeding experiments. In this study, we present a new case of possible reproductive character displacement in the direction of coiling, in the clausiliid snail Isabellaria dextrorsa . This species is dextral, in contrast with its nearest relatives, including I. torifera and I. lophauchena , which share plesiomorphic sinistral coiling. Whereas I. dextrorsa occurs in sympatry and even syntopically with I. lophauchena throughout most of its range, the sinistral species have a mosaic distribution. Phylogenetic analyses of mitochondrial cytochrome c oxidase subunit I (COI) sequences demonstrated that I. dextrorsa constitutes a clade with I. torifera . In this clade, a shift in coiling direction occurred at least twice, maybe triggered by the presence of a sympatric congeneric sinistral species. The analyses separated the sequences of all I. dextrorsa samples from those of sympatric and syntopic I. lophauchena samples. The failure to demonstrate gene flow between these species is consistent with the hypothesis of genetic isolation by reproductive character displacement.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 155–164.     

Genomic creativity and natural selection: a modern synthesis

In the early 1930s, the synthesis of Darwinian natural selection, mutation, and Mendelian genetics gave rise to the paradigm of 'modern Darwinism', also known as 'neo-Darwinism'. This has contributed greatly to our understanding. But increasing knowledge of other mechanisms, including endosymbiosis, genetic and genomic duplication, polyploidy, hybridization, epigenetics, horizontal gene transfer in prokaryotes, and the modern synthesis of embryonic development and evolution, has widened our horizons to a diversity of possibilities for change. All of these can be gathered under the umbrella concept of 'genomic creativity', which, in partnership with natural selection, affords a more comprehensive modern explanation of evolution.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 655–672.     

Genetic variation within and between Iliamna corei and I. remota (Malvaceae): implications for species delimitation

Iliamna corei and I. remota are classified as endangered species; however, their designation as separate species has been questioned. In order to address this problem, intersimple sequence repeat (ISSR) data were generated to examine patterns of genetic differentiation within and between these two taxa. ISSRs were used to screen individuals for genetic diversity of I. corei from the single known natural population and two garden populations, and individuals of I. remota from the six natural populations and four garden populations. Using ten primers, 140 informative markers were generated. Ninety-four percent of loci detected revealed polymorphisms. Cluster analysis (neighbour-joining, NJ) revealed that the two species are genetically distinct and that the Illinois populations of I. remota were genetically distinct from the Virginia populations of I. remota . Ordination by Principal Coordinate Analysis (PCoA) supported the findings of the NJ, with a separation of I. corei and I. remota . Analysis of Molecular Variance (AMOVA) revealed that the majority of variation detected was within populations, which is consistent with other self-incompatible plants. The results indicate a correlation between the geographical distributions of the species and gene flow.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 345–354.     

First record of fossil Mesozoic Ctenopoda (Crustacea, Cladocera)

Pre-Pleistocene representatives of the crustacean order Ctenopoda Sars, 1865 are unknown. Here we describe Mesozoic fossil specimens of ctenopods from two localities in Mongolia: Khotont (Jurassic/Cretaceous boundary, about 145 Mya) and Khutel Khara (Lower Cretaceous, about 129 Mya). All specimens apparently belonged to the tribe Latonini Korovchinsky, 1986 of the subfamily Sidinae Baird, 1850. At the Khotont site, ctenopods were the most numerous microscopic animal fossils. We assigned these cladocerans to a new genus and species Archelatona zherikhini gen. nov., sp. nov. Our findings support a pre-Cretaceous origin for cladocerans.  © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 146 , 269–274.     

Cytological evidence of natural hybridization in Brachiaria brizantha Stapf (Gramineae)

Two accessions of Brachiaria brizantha under cytological analysis showed 2 n  = 5x = 45 chromosomes. Pentaploidy probably resulted from natural hybridization between two species that were not closely related: an apomictic tetraploid male (2 n  = 4x = 36), and a sexual diploid female (2 n  = 2x = 18). The lack of affinity between genomes was clearly indicated by asynchrony during meiosis. The haploid genome ( n  = 9) showed unique behaviour, remaining univalent during prophase I and metaphase I, and undergoing sister-chromatid segregation and lagging at anaphase I. The laggard genome did not always reach the poles in time to be included in the telophase nucleus. However, when the inclusion was effective, this genome was distributed peripherally, changing the otherwise spherical nucleus shape. In the second division, the haploid genome behaved similarly, but as there was sister-chromatid segregation during the first division, the chromatids were slow to reach the poles, forming several micronuclei at telophase II. The two accessions were characterized as allo-autopentaploids, with the tetraploid genome (2 n  = 4x = 36) designated as B (from B. brizantha ) and the haploid genome as X, representing a species with a distinct genome having little affinity with the B genome. Thus, the hybrids' genome composition is represented by BBBBX. By comparing their meiotic behaviour with that observed in synthetic hybrids between B. brizantha and B. ruziziensis analysed previously, B. ruziziensis is the putative diploid sexual parent species in these pentaploid accessions.  © 2006 The Linnean Society of London , Botanical Journal of the Linnean Society , 2006, 150 , 441–446.     

Genetic and morphological differentiation patterns between sister species: the case of Onthophagus taurus and Onthophagus illyricus (Coleoptera, Scarabaeidae)

The present study investigated the morphological and genetic differentiation pattern between two sympatric dung beetle sister species, Onthophagus taurus and Onthophagus illyricus . The geometric morphometric approach coupled with the use of molecular markers allowed examination of the nature of interspecific relationships and an outline of the evolutionary and geographical processes that might have led to interspecific differentiation and the present-day partial sympatric and syntopic pattern of distribution. Geometric morphometrics failed to discrimininate the two species on the ground of external morphological traits, but revealed interspecific differences when the shape of the primary sexual traits was taken into account. The use of two different molecular markers (cytochrome oxidase subunit I gene and amplified fragment-length polymorphism) demonstrates that the two species are genetically well differentiated, forming two distinguishable lineages probably diverged during the Pliocene by allopatric speciation. No evidence of past or recent introgression and no support for hybridization were found, suggesting that sympatry was established subsequently, when speciation was accomplished. Both molecular markers and genital shape indicate that phenotypically intermediate individuals, despite their ambiguous appearance, are members of O. illyricus species rather than hybrids.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 197–211.     

Ribosomal, telomeric and heterochromatin sequences localization in the karyotype of Anemone hortensis

The karyotype of the Mediterranean species Anemone hortensis L. (Ranunculaceae) was characterized with emphasis on heterochromatin distribution and localization of ribosomal (18S−5.8S−26S and 5S rDNA) and telomeric repeats (TTTAGGG). Diploid chromosome complement, 2 n  = 2 x  = 16, common to all investigated populations, consisted of three acrocentric, one meta-submetacentric and four metacentric chromosomes ranging in size from 6.34 to 10.47 µm. Fluorescence in situ hybridization (FISH) with 18S and 5S rDNA probes revealed two 18S−5.8S−26S rDNA loci on a satellite and secondary constriction of acrocentric chromosome pair 2 and terminally on acrocentric chromosome pair 3, and two 5S rDNA loci in the pericentromeric region of meta-submetacentric chromosome pair 4 and in the proximity of the 18S−5.8S−26S rDNA locus on chromosome pair 2. The only GC-rich heterochromatin, as revealed by fluorochrome Chromomycin A3 staining, was that associated with nucleolar organizer regions, whereas AT-rich heterochromatin, stained with 4,6-diamino-2-phenylindole (DAPI), was distributed intercalarly and terminally on the long arm of all three acrocentric chromosomes, and terminally on chromosomes 4 and 5. FISH with Arabidopsis -type telomeric repeats (TTTAGGG) as a probe revealed two classes of signals, small dot-like and large bands, at chromosome termini exclusively, where they corresponded to terminal DAPI-stained heterochromatin. Heteromorphism of chromosome pair 4, which refers to terminal DAPI bands and FISH signals, was observed in populations of Anemone hortensis . Chromosome pairing during meiosis was regular with formation of localized chiasmata proximal to the centromere.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 150 , 177–186.     

Hybrid origins of Ixeris nakazonei (Asteraceae, Lactuceae) in the Ryukyu Archipelago, Japan: evidence from molecular data

The proposed hybrid origin of Ixeris nakazonei collected in the Ryukyu Archipelago (Okinawajima) and the Atsumi Peninsula (Koijigahama) of central Japan was examined using nuclear DNA (nDNA) and chloroplast DNA (cpDNA) markers. The results indicated that most tetraploids of I. nakazonei (2 n  = 32) had nDNA of both putative parents, I. debilis (2 n  = 48) and I. repens (2 n  = 16). The first tetraploid of I. nakazonei must have arisen directly from interspecific hybridization between I. debilis and I. repens , considering the intermediacy of the chromosome number. All tetraploids on Okinawajima had cpDNA of I. repens , while those in the Atsumi Peninsula had cpDNA of I. debilis , indicating that the tetraploid has at least two independent origins. All hexaploids of I. nakazonei (2 n  = 48), on the other hand, had cpDNA of I. debilis , but some of the hexaploids had nDNA of both putative parents. Ixeris debilis and I. repens may also be involved in the origin of the hexaploid, although the establishment process of this cytotype is still obscure. Since the hexaploid of I. nakazonei is cytologically indistinguishable from I. debilis , it can backcross with I. debilis . Introgression from diploid I. repens to hexaploid I. debilis mediated by I. nakazonei possibly occurs on Okinawajima.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 141 , 379–387.     

The internodal species concept: a response to 'The tree, the network, and the species'

Samadi and Barberousse attempt to provide a precise, formal definition of the species category that is faithful to the internodal species concept (Samadi S, Barberousse A. 2006. The tree, the network, and the species. Biological Journal of the Linnean Society 89: 509–521). Here, it is argued that their study is technically flawed. Most of the necessary corrections to their definitions are provided in order to accurately portray the internodal concept. It is then argued that the internodal concept is fundamentally flawed; it does not solve the 'classical problems' that Samadi and Barberousse claim it does. In particular, it does not allow for the possibility of interspecies hybridization. In addition, the proposal is unworkable in practice, and also theoretically problematic because it entails that, in many lineages, speciation events are taking place every few generations.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 865–869.     

Hybridization, developmental stability, and functionality of morphological traits in the ground beetle Carabus solieri (Coleoptera, Carabidae)

The assessment of developmental stability in hybrids can provide valuable information in the study of species formation because it allows an evaluation of the degree of incompatibility of genetic systems that control developmental processes. The present study assessed the impact of two hybridization events, assumed to have occurred at different times, on developmental instability in the ground beetle Carabus solieri . Developmental instability was estimated in 678 individuals from 27 populations from the fluctuating asymmetry (FA) levels of four morphological traits: the tibia length of middle and hind legs, which are functional structures, and the length and the proximal width of the hind wings, which are vestigial and thus nonfunctional structures. Significant variations of FA levels between populations were shown only for the wing width. For this trait, FA levels in hybrids were higher than in their parental entities for both hybridization events, indicating a significant divergence of the gene systems controlling development between the parental entities in the two hybridization cases. As expected, wing traits exhibited FA levels at least three times higher than leg trait. Finally, the potential interest of vestigial traits in the particular context of hybridization is discussed.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 151–158.     

Ecological consequences of ontogenetic changes in head shape and bite performance in the Jamaican lizard Anolis lineatopus

It has been documented extensively that body size affects the physiology and musculoskeletal function of organisms. However, less well understood is how body size affects the ecology of organisms through its effects on physiology and performance. We explored the effects of body size on morphology and performance in different ontogenetic classes and sexes of a common Anolis lizard ( A. lineatopus ). Next, we tested whether these morphological and performance differences may affect functional aspects of the diet such as prey size and prey hardness. Our data showed that males, females and juveniles differ significantly in head size, head shape and bite force. Multiple regression models indicated that head shape and bite force are significantly correlated to prey size and hardness. Yet juveniles had relatively large heads and bit disproportionately hard for their size, allowing them to eat prey as large as those of females. However, for a given prey size, males and females ate more robust prey than did juveniles. Additionally, males ate relatively harder prey than did juveniles. These data suggest that: (1) body size affects the dietary ecology of animals through its effect on head size and bite force; (2) changes in head morphology independent of changes in overall size also have important effects on performance and diet.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 443–454.     

A new dwarf Coffea (Rubiaceae) from southern Cameroon

A distinctive new species of dwarf monocaulous Coffea (Rubiaceae) from Cameroon is described and illustrated. Coffea mapiana is the second dwarf monocaulous known from Cameroon. Its diagnostic characters are elucidated and its taxonomic affinities are discussed; a conservation assessment is provided.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 425–430.     

Spartina anglica C. E. Hubbard: a natural model system for analysing early evolutionary changes that affect allopolyploid genomes

Spartina anglica arose during the end of the 19th century in England by hybridization between the indigenous Spartina maritima and the introduced East American Spartina alterniflora and following genome duplication of the hybrid ( S.  ×  townsendii ). This system allows investigations of the early evolutionary changes that accompany stabilization of a new allopolyploid species in natural populations. Various molecular data indicate that S. anglica has resulted from a unique parental genotype. This young species contains two distinctly divergent homoeologous genomes that have not undergone extensive change since their reunion. No burst of retroelements has been encountered in the F₁ hybrid or in the allopolyploid, suggesting a 'structural genomic stasis' rather than 'rapid genomic changes'. However, modifications of the methylation patterns in the genomes of S.  ×  townsendii and S. anglica indicate that in this system, epigenetic changes have followed both hybridization and polyploidization.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 82 , 475–484.     

Notes on some new records and new species of cetrarioid lichens from India

Additional occurrences of cetrarioid lichens in India are documented. Tuckneraria sikkimensis Divakar & Upreti sp. nov. is described as a new species. Tuckneraria ahtii Randlane & Saag, T. togashii (Asahina) Randlane & A. Thell and Cetrelia sinensis W.L. Culb. & C.F. Culb. are reported as new records.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 150 , 249–251.     

A new Mantalania species (Rubiaceae) from Madagascar

Mantalania longipedunculata De Block & A.P. Davis, a new species of Rubiaceae (Gardenieae) from Île Sainte Marie, Madagascar, is described, illustrated, and compared with the three other species in the genus. An extinction risk assessment is given, using the categories and criteria of the World Conservation Union (IUCN).  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 151 , 421–424.     

The tree, the network, and the species

To enrich the Hennigian internodal conception of species, a new formalization of the definition of the species concept is proposed. This rigorous definition allows for considerable unification of the various, and sometimes conflicting, techniques of species delimitation used in practice. First, the domain of such a definition is set out, namely, the set of all organisms on Earth, past, present, and future. Next, the focus is on the genealogical relationship among organisms, which provides the key to analysing the giant or global genealogical network (GGN) connecting all these organisms. This leads to the construction of an algorithm revealing the topological structure of the GGN, from families to lineages, ending up with a definition of species as equivalence classes of organisms corresponding to branches of the 'tree of life'. Such a theoretical definition of the species concept must be accompanied by various recognition criteria to be operational. These criteria are, for example, the ill-named 'biological species concepts', 'phylogenetic species concepts', etc., usually, but wrongly, presented as definitions of the species concept. Besides clarifying this disputed point, the definition in the present study displays the huge diversity of the scales (time-scale and population size) involved in actual species, thus explaining away the classical problems raised by previous attempts at defining the species concept (uniparental reproduction, temporal depth of species, and hybridization).  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 89 , 509–521.