Reinstatement of Grateloupia subpectinata (Rhodophyta, Halymeniaceae) based on morphology and rbcL sequences

Morphological observations and molecular analyses of the north‐western Pacific species of the red algal genus Grateloupia (Halymeniaceae) indicate the presence of an entity, which is somewhat similar in gross morphology to G. asiatica Kawaguchi et Wang but is distinguished from the latter species by some morphological features. These include: (i) a somewhat fleshy texture; (ii) wider and much thicker (4.5–10 mm wide and up to 1300 μm thick) axes, of which an inner cortex consists of more (6–9) cells; (iii) generally longer (up to 17 cm), marginal and surface proliferations that are clearly constricted (terete) at bases; and (iv) much elongated, oblong auxiliary cells. Phylogenetic analysis using the ribulose‐l,5‐bisphosphate carboxylase/ oxygenase (rbcL) gene of G. asiatica and the alga in question shows them to be distantly related and strongly supports the differentiation of these two entities at the species level. Judging from the literature, this entity is actually Grateloupia subpectinata Holmes, which has been placed into synonymy under G. asiatica [as G. filicina (Lamouroux) C. Agardh] or G. prolongata J. Agardh in previous reports, and therefore the Holmes name is reinstated.     

TWO TYPES OF AUXILIARY CELL AMPULLAE IN GRATELOUPIA (HALYMENIACEAE,RHODOPHYTA), INCLUDING G. TAIWANENSIS SP. NOV. AND G. ORIENTALIS SP. NOV. FROM TAIWAN BASED ON rbcL GENE SEQUENCE ANALYSIS AND CYSTOCARP DEVELOPMENT1

Few species in the genus Grateloupia have been investigated in detail with respect to the development of the auxiliary cell ampullae before or after diploidization. In this study, we document the vegetative and reproductive structures of two new species of Grateloupia, G. taiwanensis S.‐M. Lin et H.‐Y. Liang sp. nov. and G. orientalis S.‐M. Lin et H.‐Y. Liang sp. nov., plus a third species, G. ramosissima Okamura, from Taiwan. Two distinct patterns are reported for the development of the auxiliary cell ampullae: (1) ampullae consisting of three orders of unbranched filaments that branch after diploidization of the auxiliary cell and form a pericarp together with the surrounding secondary medullary filaments (G. taiwanensis type), and (2) ampullae composed of only two orders of unbranched filaments in which only a few cells are incorporated into a basal fusion cell after diploization of the auxiliary cell and the pericarp consists almost entirely of secondary medullary filaments (G. orientalis type). G. orientalis is positioned in a large clade based on rbcL gene sequence analysis that includes the type species of Grateloupia C. Agardh 1822 , G. filicina. G. taiwanensis clusters with a clade that includes the generitype of Phyllymenia J. Agardh 1848 , Ph. belangeri from South Africa; that of Prionitis J. Agardh 1851 , Pr. lanceolata from Pacific North America; and that of Pachymeniopsis Y. Yamada ex Kawab. 1954, Pa. lanceolata from Japan. A reexamination of the type species of the genera Grateloupia, Phyllymenia, Prionitis, and Pachymeniopsis is required to clarify the generic and interspecific relationships among the species presently placed in Grateloupia.     

Molecular phylogeography of Troglophilus cave crickets (Orthoptera,Rhaphidophoridae): A combination of vicariance and dispersal drove diversification in the East Mediterranean region

In this study, we investigated the molecular phylogenetic divergence and historical biogeography of cave crickets belonging to the genus Troglophilus (Orthoptera, Rhaphidophoridae) from caves in eastern Mediterranean and Anatolia regions. Three mitochondrial DNA genes (COI, 12S rDNA, and 16S rDNA) and two nuclear ones (18S rDNA and 28S rDNA) were amplified and partially sequenced to reconstruct phylogenetic relationships among most of the known Troglophilus species. Results showed a well‐resolved phylogeny with three main clades representing the Balkan, the Anatolian, and the Cycladian–Cretan lineages. Based on Bayesian analyses, we applied a relaxed molecular clock model to estimate the divergence times between these three lineages. Dating estimates indicate that radiation of the ingroup might have been triggered by the opening of the Mid‐Aegean trench, while the uplift of the Anatolian Plateau in Turkey and the changes of relief, emergence, and disappearance of orographic and hydrographical barriers in the Balkan Peninsula are potential paleogeographic events responsible for the initial diversification of the genus Troglophilus. A possible biogeographic scenario, reconstructed using S‐DIVA with RASP software, suggested that the current distribution of Troglophilus species can be explained by a combination of both dispersal and vicariance events that occurred in particular in the ancestral populations. The radiation of Troglophilus species likely started from the Aegean and proceeded eastward to Anatolia and westward to the Balkan region. Results are additionally compared to those available for Dolichopoda, the only other representative genus of Rhaphidophoridae present in the Mediterranean area.     

The geography of speciation in narrow‐range endemics of the ‘Haenydra’ lineage (Coleoptera,Hydraenidae, Hydraena)

Aim We test whether species of western Mediterranean aquatic Coleoptera of the ‘Haenydra’ lineage (Hydraenidae, Hydraena) originated through: (1) successive periods of dispersal and speciation, (2) range fragmentation by random vicariance, or (3) range fragmentation by geographic isolation owing to a general reduction of population density. Location Europe. Methods To discriminate between scenarios we use contrasting predictions of the relationship between phylogenetic and geographic distance. The phylogeny was based on 3 kb of four mitochondrial and two nuclear gene fragments of about half of the known species of ‘Haenydra’, including most western Mediterranean taxa. Divergences were estimated using a molecular clock. The relationship between phylogenetic and geographic distance was tested using bivariate plots, Mantel tests and comparison of the observed phylogeny with the one minimizing geographic distances between species, as measured using Euclidean minimum spanning trees (EMSTs). Results The monophyly of ‘Haenydra’ was strongly supported, although its phylogenetic placement was not resolved. ‘Haenydra’ was estimated to be of late Miocene age, with most species originating during the Pleistocene. In two clades (Hydraena tatii and Hydraena emarginata clades) there was a significant association between geographic and phylogenetic distance, and the reconstructed phylogeny was identical to that obtained through the EMST, demonstrating a strong non‐randomness of the geographic distribution of the species. In two other clades (Hydraena iberica and Hydraena bitruncata clades) there was no association between geographic and phylogenetic distance, and the observed phylogeny was not the one minimizing geographic distances. In one of the clades this seems to be due to a secondary, recent range expansion of one species (H. iberica), which erased the geographic signal of their distributions. Main conclusions We show that it is possible to obtain strong evidence of stasis of the geographic ranges of narrow‐range endemic species through the study of their phylogenetic relationships and current distributions. In at least two of the studied clades, current species seem to have originated through the fragmentation of a more widely distributed species, without further range movements. A process of range expansion and fragmentation may have occurred repeatedly within the ‘Haenydra’ lineage, contributing to the accumulation of narrow‐range endemics in Mediterranean Pleistocene refugia.     

Grateloupia turuturu (Halymeniaceae,Rhodophyta) is the correct name of the non-native species in the Atlantic known as Grateloupia doryphora

Grateloupia doryphora (Montagne) Howe, originally described from Peru, has repeatedly been reported as an invasive species in Atlantic and Mediterranean waters. Various attempts to explain this species' route of introduction have been unsatisfactory. New evidence from comparative rbcL sequence analysis and morphology suggests that this adventive species in the NE and NW Atlantic corresponds with G. turuturu Yamada, originally described from Japan. This provenance follows a well-recognized trend of invasive marine organisms that have colonized the Atlantic Ocean and Mediterranean Sea from Pacific NE Asia.     

Phylogenomics,biogeography, and evolution of the blue‐ or white‐fruited dogwoods (Cornus)—Insights into morphological and ecological niche divergence following intercontinental geographic isolation

The eastern Asian (EA)–eastern North American (ENA) floristic disjunction represents a major pattern of phytogeography of the Northern Hemisphere. Despite 20 years of studies dedicated to identification of taxa that display this disjunct pattern, its origin and evolution remain an open question, especially regarding post‐isolation evolution. The blue‐ or white‐fruited dogwoods (BW) are the most species‐rich among the four major clades of Cornus L., consisting of ~35 species divided into three subgenera (subg. Yinquania, subg. Mesomora, and subg. Kraniopsis). The BW group provides an excellent example of the EA–ENA floristic disjunction for biogeographic study due to its diversity distribution centered in eastern Asia and eastern North America, yet its species relationships and delineation have remained poorly understood. In this study, we combined genome‐wide markers from RAD‐seq, morphology, fossils, and climate data to understand species relationships, biogeographic history, and ecological niche and morphological evolution. Our phylogenomic analyses with RAxML and MrBayes recovered a strongly supported and well‐resolved phylogeny of the BW group with three intercontinental disjunct clades in EA and ENA or Eurasia and North America, of which two are newly identified within subg. Kraniopsis. These analyses also recovered a potential new species but failed to resolve relationships within the C. hemsleyi–C. schindleri complex. In an effort to develop an approach to reduce computation time, analysis of different nodal age settings in treePL suggests setting a node's minimum age constraint to the lower bound of a fossil's age range to obtain similar ages to that of BEAST. Divergence time analyses with BEAST and treePL dated the BW stem back to the very Late Cretaceous and the divergence of the three subgenera in the Paleogene. By integrating fossil ages and morphology, a total evidence‐based dating approach was used in conjunction with time‐slice probabilities of dispersal under a DEC model to resolve ancestral ranges of each disjunct in the Miocene: Eurasia and ENA (disjunct 1), EA and western North America (disjunct 2), and EA (disjunct 3). The dated biogeographic history supports dispersal via the North Atlantic Land Bridge in the late Paleogene in disjunct 1 and dispersal via the Bering Land Bridge in the Miocene for disjuncts 2 and 3. Character mapping with a stochastic model in phytools and comparison of ecological niche, morphospace, and rate of evolution indicated differential divergence patterns in morphology, ecological niche, and molecules between disjunct sisters. Although morphological stasis was observed in most of the characters, evolutionary changes in growth habit and some features of leaf, flower, and fruit morphology occurred in one or both sister clades. A significant differentiation of ecological habitats in temperature, precipitation, and elevation between disjunct sisters was observed, suggesting a role of niche divergence in morphological evolution post‐isolation. The patterns of evolutionary rate between morphology and molecules varied among disjunct clades and were not always congruent between morphology and molecules, suggesting cases of non‐neutral morphological evolution driven by ecological selection. Our phylogenetic evidence and comparisons of evolutionary rate among disjunct lineages lend new insights into the formation of the diversity anomaly between EA and ENA, with particular support of an early diversification in EA. These findings, in conjunction with previous studies, again suggest that the EA–ENA disjunct floras are an assembly of lineages descended from the Mesophytic Forests that evolved from the early Paleogene “boreotropical flora” through varied evolutionary pathways across lineages.     

MOLECULAR PHYLOGENY OF THE UPRIGHT ERYTHROPELTIDALES (COMPSOPOGONOPHYCEAE,RHODOPHYTA): MULTIPLE CRYPTIC LINEAGES OF ERYTHROTRICHIA CARNEA1

The phylogeny of morphologically simple algae is problematic due to insufficient morphological characters to aid in distinguishing species and relationships. The problem is further compounded because multiple evolutionary lineages of morphologically similar species occur in most well‐sampled biogeographic locations; therefore, location cannot be used as a proxy for species. The phylogeny of the upright members of the Erythropeltidales is partially clarified by combining molecular data, unialgal culture observations, and worldwide sampling. Our results show that there are several well‐supported lineages within the Erythropeltidales with only two morphologically recognizable taxa at present. The first is the genus Porphyrostromium, with a well‐developed basal crust, which includes two Erythrotrichia species (Porphyrostromium ligulatum comb. nov. and Porphyrostromium pulvinatum comb. nov.). The second is the branched species Erythrotrichia welwitschii (Rupr.) Batters. There are also six strongly supported Erythrotrichia carnea–like lineages. While not completely satisfactory, we propose that one lineage (lineage 2) with samples close to the type locality be designated as E. carnea with a specific isolate as an epitype. The lack of morphology to differentiate the other lineages leads to a taxonomy based solely on gene sequencing and molecular phylogeny, with rbcL sequences differentiating the lineages proposed. We hold off on proposing more species and genera until more data and samples can be gathered.     

THE INFLUENCE OF POLLINATOR PHYLOGEOGRAPHY AND MATE PREFERENCE ON FLORAL DIVERGENCE IN A SEXUALLY DECEPTIVE DAISY

Divergent mate preferences and subsequent genetic differentiation between populations has been demonstrated, but its effects on interspecific interactions are unknown. Associated species exploiting these mate preferences, for example, may diverge to match local preferences. We explore this idea in the sexually deceptive, fly‐mimicking daisy, Gorteria diffusa, by testing for association between genetic structure in the fly pollinator (a proxy for mate preference divergence) and geographic divergence in floral form. If genetic structure in flies influences interactions with G. diffusa, we expect phylogeographically distinct flies to be associated with different floral forms. Flies associated with forms exploiting only feeding behavior often belonged to several phylogeographic clades, whereas flies associated with forms exploiting male‐mating behavior always belonged to distinct clades, indicating the possibility of pollinator‐mediated floral divergence through phylogeographic variation in mating preferences of male flies. We tested this hypothesis with reciprocal presentations using male flies from distinct clades associated with separate floral forms. Results show that males from all clades exhibit similar preferences, making pollinator driven divergence through geographic variation in mate preference unlikely. Males, however, showed evidence of learned resistance to deceptive traits, suggesting antagonistic interactions between plants and pollinators may drive deceptive floral trait evolution in G. diffusa.     

Navigating the mtDNA road map out of the morphological maze: interpreting morphological variation in the diverse Monomorium rothsteini (Forel) complex (Hymenoptera: Formicidae)

Monomorium is a large and diverse ant genus with speciose radiations in both the Afrotropical and Australian regions. According to the most recent taxonomic revision, many Australian species are characterised by very broad distributions and variable morphology, which suggests that some species may be unrecognised species complexes. With a continent‐wide distribution and diverse yet overlapping morphology, M. rothsteini (Forel) is representative of the greater challenge that exists in Australian Monomorium systematics. Here we investigate species boundaries in M. rothsteini using a molecular phylogenetic framework to interpret the complex overlap of nine morphological characters (with 31 states) and examine biogeographic relationships among the lineages. Bayesian inference resolved 38 mtDNA lineages that were morphologically separable, at least from their sister lineage. Although the morphological characters were intermixed across the phylogeny, instances of inseparable morphology among sister clades was rare. Seventeen lineages exhibited complete morphological overlap with one or more other lineages and could not be separated by Principal Component Analysis based on 12 morphometric variables. Two‐thirds of all lineages occurred sympatrically with one or more both genetically and morphologically divergent lineages. The two nuclear markers EF1αF2 and wingless were used to generate haplotype networks which were characterised by a star‐like pattern indicative of a rapid and recent radiation. Several haplotypes for both nuclear gene regions were shared among individuals occurring in separate mtDNA clades which we were also unable to distinguish morphologically or that were occurring in sympatry, indicating possible introgression in both the mtDNA and nuclear genomes. Clear biogeographic affinities among samples within a lineage were detected but there was no overall pattern in the biogeographic relationships among the lineages. We conclude that M. rothsteini is a large species complex that has undergone a complex evolutionary history following aridification of the Australian continent, and discuss the implications of this conclusion for the systematics of Australian Monomorium more generally.     

DEEP DIVERSIFICATION AND LONG‐TERM PERSISTENCE IN THE SOUTH AMERICAN ‘DRY DIAGONAL’: INTEGRATING CONTINENT‐WIDE PHYLOGEOGRAPHY AND DISTRIBUTION MODELING OF GECKOS

The relative influence of Neogene geomorphological events and Quaternary climatic changes as causal mechanisms on Neotropical diversification remains largely speculative, as most divergence timing inferences are based on a single locus and have limited taxonomic or geographic sampling. To investigate these influences, we use a multilocus (two mitochondrial and 11 nuclear genes) range‐wide sampling of Phyllopezus pollicaris, a gecko complex widely distributed across the poorly studied South American ‘dry diagonal’ biomes. Our approach couples traditional and model‐based phylogeography with geospatial methods, and demonstrates Miocene diversification and limited influence of Pleistocene climatic fluctuations on P. pollicaris. Phylogeographic structure and distribution models highlight that persistence across multiple isolated regions shaped the diversification of this species complex. Approximate Bayesian computation supports hypotheses of allopatric and ecological/sympatric speciation between lineages that largely coincide with genetic clusters associated with Chaco, Cerrado, and Caatinga, standing for complex diversification between the ‘dry diagonal’ biomes. We recover extremely high genetic diversity and suggest that eight well‐supported clades may be valid species, with direct implications for taxonomy and conservation assessments. These patterns exemplify how low‐vagility species complexes, characterized by strong genetic structure and pre‐Pleistocene divergence histories, represent ideal radiations to investigate broad biogeographic histories of associated biomes.     

GENETIC DIVERSITY AND ORIGIN OF THE HAWAIIAN ISLANDS COTTON,GOSSYPIUM TOMENTOSUM

Gossypium tomentosum is the only member of the cotton genus endemic to the Hawaiian archipelago. It is morphologically distinct from other allopolyploid Gossypium species, and its phylogenetic relationships with them are uncertain. Chloroplast and ribosomal DNA restriction site variation were used to estimate the phylogeny of the allopolyploids. Gossypium mustelinum is resolved as sister to the remaining allopolyploid species, which include two species-pairs, G. barbadense-G. darwinii and G. hirsutum (including G. lanceolatum)-G. tomentosum. This indication that G. tomentosum is sister to G. hirsutum is supported by allozyme data. Gossypium tomentosum is proposed, based on biogeographic evidence and molecular data, to have originated by transoceanic dispersal from a Mesoamerican progenitor. Few restriction site variants were observed among the allopolyploids, suggesting that present lineages diverged relatively rapidly following polyploidization. Allozyme analysis of 30 G. tomentosum accessions collected from seven islands revealed relatively low levels of genetic diversity: 11 of 50 loci were polymorphic, mean number of alleles per locus was 1.24, and mean panmictic heterozygosity was 0.033. Little geographic patterning of allelic distributions was observed. Despite historical cultivation of G. barbadense and G. hirsutum in Hawaii and the existence of their naturalized derivatives, no allozyme evidence of interspecific introgression into G. tomentosum was detected.     

Molecular phylogeny and biogeography of the eastern Tapaculos (Aves: Rhinocryptidae: Scytalopus, Eleoscytalopus): Cryptic diversification in Brazilian Atlantic Forest

Scytalopus and the recently erected Eleoscytalopus are among the Neotropical groups of birds whose taxonomy is most difficult to resolve given their very conservative morphology. We investigated the phylogeny and species limits of Eleoscytalopus and the eastern Scytalopus using two mitochondrial genes and two nuclear introns of multiple individuals from all species of these groups. The eastern Scytalopus are separated in three well defined clades also supported by morphological or vocal characteristics, although the relationships between these clades could not be resolved. We found several allopatric and very divergent lineages in these genera whose characteristics are consistent with species-level divergence, especially in S. speluncae. The great divergence between E. psychopompus and its sister species supports the former as a valid species. Our results corroborate the importance of the Bahia refuge as an avian center of endemism.     

THE INVASIVE GENUS ASPARAGOPSIS (BONNEMAISONIACEAE,RHODOPHYTA): MOLECULAR SYSTEMATICS,MORPHOLOGY, AND ECOPHYSIOLOGY OF FALKENBERGIA ISOLATES1

The genus Asparagopsis was studied using 25 Falkenbergia tetrasporophyte strains collected worldwide. Plastid (cp) DNA RFLP revealed three groups of isolates, which differed in their small subunit rRNA gene sequences, temperature responses, and tetrasporophytic morphology (cell sizes). Strains from Australia, Chile, San Diego, and Atlantic and Mediterranean Europe were identifiable as A. armata Harvey, the gametophyte of which has distinctive barbed spines. This species is believed to be endemic to cold‐temperate waters of Australia and New Zealand and was introduced into Europe in the 1920s. All isolates showed identical cpDNA RFLPs, consistent with a recent introduction from Australia. Asparagopsis taxiformis (Delile) Trevisan, the type and only other recognized species, which lacks spines, is cosmopolitan in warm‐temperate to tropical waters. Two clades differed morphologically and ecophysiologically and in the future could be recognized as sibling species or subspecies. A Pacific/Italian clade had 4–8° C lower survival minima and included a genetically distinct apomictic isolate from Western Australia that corresponded to the form of A. taxiformis originally described as A. sanfordiana Harvey. The second clade, from the Caribbean and the Canaries, is stenothermal (subtropical to tropical) with some ecotypic variation. The genus Asparagopsis consists of two or possibly three species, but a definitive taxonomic treatment of the two A. taxiformis clades requires study of field‐collected gametophytes.     

A COMPARATIVE STUDY OF THE RED ALGA GRATELOUPIA FILICINA (HALYMENIACEAE) FROM THE NORTHWESTERN PACIFIC AND MEDITERRANEAN WITH THE DESCRIPTION OF GRATELOUPIA ASIATICA, SP. NOV.

Morphological observations and molecular analyses of the red alga Grateloupia filicina (Halymeniaceae) from two geographically distant regions, eastern Asia (Japan and northern China) in the northwestern Pacific and Italy in the Mediterranean, reveal the presence of two distinct entities. Morphologically, the eastern Asian entity differs substantially from the Italian entity in the following ways: 1) thin and soft thalli with wider axes, 2) denser medullary filaments, 3) scattered reproductive structures over the entire thallus, and 4) a mature auxiliary cell that is oval and slightly larger than other ampullary cells. Phylogenetic analysis based on the ribulose-1,5-bisphosphate carboxylase/oxygenase gene ( rbc L) sequences revealed that the eastern Asian and Italian entities are phylogenetically far apart, strongly supporting the differentiation of these two entities at the species level. The eastern Asian entity is therefore described as a new species, Grateloupia asiatica. This species can be distinguished from most known species of Grateloupia that have widely flattened thalli by its compressed to narrowly flattened axes with numerous pinnate proliferations and from a few species with similar thalli by a particular combination of features, including a gelatinous texture, mostly simple and narrower axes, a thinner cortex, and the absence of catenate proliferations.     

MOLECULAR PHYLOGEOGRAPHY, RETICULATION, AND LINEAGE SORTING IN MEDITERRANEAN SENECIO SECT. SENECIO (ASTERACEAE)

Abstract The Mediterranean species complex of Senecio serves to illustrate evolutionary processes that are likely to confound phylogenetic inference, including rapid diversification, gene tree‐species tree discordance, reticulation, interlocus concerted evolution, and lack of complete lineage sorting. Phylogeographic patterns of chloroplast DNA (cpDNA) haplotype variation were studied by sampling 156 populations (502 individuals) across 18 species of the complex, and a species phylogeny was reconstructed based on sequences from the internal transcribed spacer (ITS) regions of nuclear ribosomal DNA. For a subset of species, randomly amplified polymorphic DNAs (RAPDs) provided reference points for comparison with the cpDNA and ITS datasets. Two classes of cpDNA haplotypes were identified, with each predominating in certain parts of the Mediterranean region. However, with the exception of S. gallicus, intraspecific phylogeographic structure is limited, and only a few haplotypes detected were species‐specific. Nuclear sequence divergence is low, and several unresolved phylogenetic groupings are suggestive of near simultaneous diversification. Two well‐supported ITS clades contain the majority of species, amongst which there is a pronounced sharing of cpDNA haplotypes. Our data are not capable of diagnosing the relative impact of reticulation versus insufficient lineage sorting for the entire complex. However, there is firm evidence that S. flavus subsp. breviflorus and S. rupestris have acquired cpDNA haplotypes and ITS sequences from co‐occurring species by reticulation. In contrast, insufficient lineage sorting is a viable hypothesis for cpDNA haplotypes shared between S. gallicus and its close relatives. We estimated the minimum coalescent times for these haplotypes by utilizing the inferred species phylogeny and associated divergence times. Our data suggest that ancestral cpDNA polymorphisms may have survived for ca. 0.4–1.0 million years, depending on molecular clock calibrations.     

MOLECULAR AND GEOLOGIC EVIDENCE OF SHARED HISTORY BETWEEN HERMIT CRABS AND THE SYMBIOTIC GENUS HYDRACTINIA

The paleobiogeographic histories of three North Atlantic hermit crab lineages were compared with a single-copy DNA-DNA hybridization phylogeny of their symbiotic hydroid genus Hydractinia to test hypotheses of shared history between these host and symbiont lineages. A survey of the geologic literature suggests that two vicariance events in the Quaternary are responsible for existing range disjunctions of the host hermit crab lineages. The Hydractinia phylogeny revealed two distinct clades, one with a primarily northern and the other with a primarily southern distribution. In two of three cases, hydroids associated with closely related hermits on both sides of the range disjunction appear as sister taxa in the phylogeny. A linear scaling between a measure of hydroid sequence divergence and independent geologic estimates of the timing of the vicariant events believed to have established the hermit crab range disjunctions is consistent with the claim of temporal coincidence of cladogenic and vicariance events. These findings provide evidence for shared history of symbiotic associations in two of the three cases.     

THE IMPORTANCE OF PREADAPTED GENOMES IN THE ORIGIN OF THE ANIMAL BODYPLANS AND THE CAMBRIAN EXPLOSION

The genomes of taxa whose stem lineages branched early in metazoan history, and of allied protistan groups, provide a tantalizing outline of the morphological and genomic changes that accompanied the origin and early diversifications of animals. Genome comparisons show that the early clades increasingly contain genes that mediate development of complex features only seen in later metazoan branches. Peak additions of protein‐coding regulatory genes occurred deep in the metazoan tree, evidently within stem groups of metazoans and eumetazoans. However, the bodyplans of these early‐branching clades are relatively simple. The existence of major elements of the bilaterian developmental toolkit in these simpler organisms implies that these components evolved for functions other than the production of complex morphology, preadapting the genome for the morphological differentiation that occurred higher in metazoan phylogeny. Stem lineages of the bilaterian phyla apparently required few additional genes beyond their diploblastic ancestors. As disparate bodyplans appeared and diversified during the Cambrian explosion, increasing complexity was accommodated largely through changes in cis‐regulatory networks, accompanied by some additional gene novelties. Subsequently, protein‐coding genic richness appears to have essentially plateaued. Some genomic evidence suggests that similar stages of genomic evolution may have accompanied the rise of land plants.     

Molecular systematics and biogeography of the western Mediterranean stonefly genus Tyrrhenoleuctra (Insecta, Plecoptera)

The stonefly genus Tyrrhenoleuctra includes species living in western Mediterranean temporary freshwater streams, sometimes also at sea level, a very unusual habitat for most Plecoptera. Traditional morphological approaches proved unsuccessful in drawing both taxonomic and phylogenetic patterns, thus hampering discussion of biogeographical patterns for this interesting group. We aimed at: (a) assessing the taxonomic status of populations of Tyrrhenoleuctra covering the geographic range of the genus; (b) studying the phylogenetic relationships among the recognized species; and (c) describing biogeographic patterns. We used phylogenetic analyses to infer the phylogenetic history of this group of stoneflies based on a combined data set of 1666 bp including fragments of the 12S ribosomal (12S) and cytochrome oxidase I (CO‐I) mtDNA genes, with maximum likelihood and Bayesian methods. Two main clades have been identified: a Sardo‐Corsican one, including Tyrrhenoleuctra zavattarii, and an Ibero‐Maghrebian one including four lineages of unkown taxonomic rank from the Balearic Islands (Maiorca), from northern Africa (Ceuta) and southernmost Spain (Algeciras), and a complex preliminarily referred herein to T. minuta (Klapálek, 1901), which includes two lineages, one from Cordoba, and one from Sierra de Grazalema (El Cerro) and Portugal (Tellhares) respectively. Dating the nodes by fixing the split of the Ibero‐Maghrebian clade from the Sardo‐Corsican one at 29 million years ago (Mya), yielded dates referring to the major geological events in the Mediterranean basin. Estimated molecular evolutionary rates ranged from 0.02–0.09% per million years (my) in the T. zavattarii lineages, to 0.2–0.7% per MY in the Ibero‐Maghrebian clade. The phylogenetic pattern emerged from the present study is congruent with the known paleo‐history of the western Mediterranean basin, with the divergence of the two main Tyrrhenoleuctra lineages corresponding to the split of the Sardo‐Corsican microplate from the Iberian block. Vicariance events have characterized the history of this stonefly group along its entire biogeographical history. Surprisingly low evolutionary rates, previously supposed by Fochetti (1991, 1994) and Fochetti et al. (2004) based on nuclear markers (allozymes), have been herein found also in mitochondrial markers.     

GEOGRAPHIC POPULATION STRUCTURE AND SPECIES DIFFERENCES IN MITOCHONDRIAL DNA OF MOUTHBROODING MARINE CATFISHES (ARIIDAE) AND DEMERSAL SPAWNING TOADFISHES (BATRACHOIDIDAE)

Restriction-fragment length polymorphisms in mitochondrial DNA (mtDNA) were used to evaluate population-genetic structure and matriarchal phylogeny in four species of marine fishes that lack a pelagic larval stage: the catfishes Arius felis and Bagre marinus, and the toadfishes Opsanus tau and O. beta. Thirteen informative restriction enzymes were used to assay mtDNAs from 134 specimens collected from Massachusetts to Louisiana. Considerable genotypic diversity was observed in each species. However, major mtDNA phylogenetic assemblages in catfish and toadfish (as identified in Wagner networks and UPGMA phenograms) exhibited contrasting patterns of geographic distribution: in catfish, distinct mtDNA clades were widespread, while such clades in toadfish tended to be geographically localized. By both the criteria of species' ranges and the geographic pattern of intraspecific mtDNA phylogeny, populations of marine catfish in the western Atlantic have had greater historical interconnectedness than have toadfish. Results are also compared to previously published mtDNA data in freshwater and other marine fishes. Although mtDNA differentiation among conspecific populations of continuously distributed marine fishes is usually lower than that among discontinuously distributed freshwater species inhabiting separate drainages, it is apparent that historical biogeographic factors can importantly influence genetic structure in marine as well as freshwater species.