Speciation and hybridization among Houstonia (Rubiaceae) species: the influence of polyploidy on reticulate evolution

Chloroplast and nuclear DNA sequence variation among populations and species was used to examine the phylogenetic history and hybridization of the North American Houstonia lineage. The ancestral species in the lineage do not show evidence of hybridization; however, the more recently derived species in eastern North America contain a wide degree of morphological and genetic variation both within and among species. Furthermore, there is a clear association between hybridization and polyploidy in the Houstonia lineage, with all potential hybrids occurring among species that contain polyploid populations. This suggests that polyploidy may break down species barriers and allow hybridization among lineages. These results indirectly support speciation models that involve genetic incompatibilities among species arising from gene silencing or genomic reorganization.     

Wing pattern evolution and the origins of mimicry among North American admiral butterflies (Nymphalidae: Limenitis)

The evolution of wing pattern diversity in butterflies has emerged as a model system for understanding the origins and maintenance of adaptive phenotypic novelty. Admiral butterflies (genus Limenitis) are an attractive system for studying wing pattern diversity because mimicry is common among the North American species and hybrid zones occur wherever mimetic and non-mimetic wing pattern races meet. However, the utility of this system has been limited because the evolutionary relationships among these butterflies remain unclear. Here I present a robust species-level phylogeny of Limenitis based on 1911 bp of two mitochondrial genes (COI and COII) and 904 bp of EF1-alpha for all five of the Nearctic species/wing pattern races, the majority of the Palearctic species, and three outgroup genera; Athyma, Moduza (Limenitidini), and Neptis (Limenitidinae: Neptini). Maximum-likelihood and Bayesian analyses indicate that the North American species are a well-supported, monophyletic lineage that is most closely related to the widespread, Palearctic, Poplar admiral (L. populi). Within North America, the Viceroy (L. archippus) is the basal lineage while the relationships among the remaining species are not well resolved. A combined maximum-likelihood analysis, however, indicates that the two western North America species (L. lorquini and L. weidemeyerii) are sister taxa and closely related to the wing pattern subspecies of the polytypic Limenitis arthemis species complex. These results are consistent with (1) an ancestral host-shift to Salicaceae by the common ancestor of the Poplar admiral and the Nearctic admiral lineage, (2) a single colonization of the Nearctic, and (3) a subsequent radiation of the North American forms leading to at least three independent origins of mimicry.     

A species-level phylogenetic study of the Verbena complex (Verbenaceae) indicates two independent intergeneric chloroplast transfers

Two major impediments to infer plant phylogenies at inter- or intra- species level include the lack of appropriate molecular markers and the gene tree/species tree discordance. Both of these problems require more extensive investigations. One of the foci of this study is examining the phylogenetic utility of a combined chloroplast DNA dataset (>5.0kb) of seven non-coding regions, in comparison with that of a large fragment (ca. 3.0kb) of a low-copy nuclear gene (waxy), in a recent, rapidly diversifying group, the Verbena complex. The complex includes three very closely related genera, Verbena (base chromosome number x=7), Glandularia (x=5), and Junellia (x=10), comprising some 150 species distributed predominantly in South and North America. Our results confirm the inadequacy of non-coding cpDNA in resolving relationships among closely related species due to lack of variation, and the great potential of low-copy nuclear gene as source of variation. However, this study suggests that when both cpDNA and nuclear DNA are employed in low-level phylogenetic studies, cpDNA might be very useful to infer organelle evolutionary history (e.g., chloroplast transfer) and more comprehensively understand the evolutionary history of organisms. The phylogenetic framework of the Verbena complex resulted from this study suggests that Junellia is paraphyletic and most ancestral among the three genera; both Glandularia and Verbena are monophyletic and have been derived from within Junellia. Implications of this phylogenetic framework to understand chromosome number evolution and biogeography are discussed. Most interestingly, the comparison of the cpDNA and nuclear DNA phylogenies indicates two independent intergeneric chloroplast transfers, both from Verbena to Glandularia. One is from a diploid North American Verbena species to a polyploid North American Glandularia species. The other is more ancient, from the South American Verbena group to the common ancestor of a major Glandularia lineage, which has radiated subsequently in both South and North America. The commonly assumed introgressive hybridization may not explain the chloroplast transfers reported here. The underlying mechanism remains uncertain.     

Multiple cryptic species with divergent substrate affinities in the Serpula himantioides species complex

Serpula himantioides is a widespread saprotrophic morphospecies mainly colonising coniferous wood in nature, but it appears frequently in buildings as well. From an earlier study, it is known that at least three divergent lineages occur within the S. himantioides species complex. In this study, a broader sample of S. himantioides isolates has been analysed by multi-locus sequencing, including new isolates from Asia, North and South America. Altogether five phylogenetical species (PS1-5) were detected, all recognised across independent gene phylogenies. A new southern South American phylogenetic species (PS1) was found, representing an early diverging lineage within the S. himantioides species complex. The two closely related PS2 and PS3 lineages included isolates from North America only, and PS4 was also dominated by North American isolates. Most of the investigated isolates (76%) clustered into PS5, a lineage that has been found on most continents, including North America. Overall, little phylogeographical structure was found in PS5, indicating frequent and recent long-distance dispersal events within this widespread lineage. Our analyses indicate that South and North America are the centres of divergence for the S.?himantioides species complex. Some of the lineages seem adapted to various substrates, but PS5 is able to decay a wide array of angiosperms and gymnosperms, which may have facilitated the spread of this lineage throughout the world.     

Species richness in plant genera disjunct between temperate eastern Asia and North America

The species richness of 109 amphi-Pacific disjunct genera was examined in eastern Asia and North America. Although the entire flora of eastern Asia contains approximately one-third more species than that of North America, the difference in species richness among disjunct taxa is less. When woody and herbaceous genera are considered separately, the former exhibit a strong diversity bias favouring eastern Asia whereas there is no significant difference in diversity between continents among herbaceous genera. This result is not due to habitat differences between woody and herbaceous genera, because the disjunct herbs inhabit primarily moist forests and woodlands. This result is also not related to relative phylogenetic advancement, even though older major lineages of plants tend to have a predominance of woody taxa. Woody genera are distributed in lower latitudes than herbaceous genera on both continents, and both woody and herbaceous genera are distributed in lower latitudes in eastern Asia than in North America. The North American temperate flora is primarily a relict of a flora form 7 more widespread throughout the Northern Hemisphere. Contemporary patterns of diversity suggest that the effects of climate changes in the late Tertiary were less severe in eastern Asia and promoted diversification, but were more severe in North America and may have caused widespread extinction. The difference in the effect of climate change on diversity in herbaceous and woody lineages reflects the different ecological relationships of species having these contrasting life forms. Clearly, the contemporary floras of eastern Asia and North America bear the imprint of history and emphasize the important interface between ecological relationships and evolutionary responses.     

A monograph of Boykinia, Peltoboykinia, Bolandra and Suksdorfia (Saxifragaceae)

An evaluation of the limits and infra-generic taxonomy of the genus Boykinia and its allies is presented. In the past, Boykinia has been split into the following segregate genera: Boykinia and Telesonix (from North America) and Neoboykinia and Peltoboykinia (from Japan). The situation is complicated by other closely related genera, the limits of which also need clarification. Narrowly defined, they comprise Suksdorfia, Hemieva, Bolandra, Sullivantia and Jepsonia (all from North America) and Hieronymusia (from South America). This monograph draws on a variety of sources for information, including a morphological comparison of all taxa, using a wide range of both living and herbarium material, and observations on leaf anatomy, trichomes, pollen grains and seeds; reference is also made to our previously published work on flavonoids, chromosome numbers and breeding relationships. General ecological observations were made during field work in western North America. The results of these investigations confirm that the genera form a closely related group. Much of the evidence combines to suggest the following conclusions. Boykinia includes nine species in three sections: section Boykinia (B. aconitifolia , B. intermedia , B. lycoctonifolia , B. major , B. occidentalis and B. rotundifolia) , section Renifolium (B. ruhardsonii) and section Telesonix (B. jamesii and B. heucheriformis). Peltoboykinia (P. tellimoides and P. watanabei ) is recognized as a distinct genus allied to both Saxifraga and Boykinia. Suksdorfia , expanded to include Hemieva and Hieronymusia , has three species: S. violacea, S. alchemilloides and S. ranunculifolia. Bolandra is very closely related to Suksdorfia but is retained as a separate genus containing two species, B. californica and B, oregana. Sullivantia and Jepsonia are accepted as genera related to, but distinct from, Boykinia.     

Redefining Phrymaceae: the placement of Mimulus, tribe Mimuleae, and Phryma

Chloroplast trnL/F and nuclear ribosomal ITS and ETS sequence data were used to analyze phylogenetic relationships among members of tribe Mimuleae (Scrophulariaceae) and other closely related families in Lamiales. The results of these analyses led to the following conclusions. (1) The Australian genera Glossostigma and Peplidium and the taxonomically isolated Phryma join four genera of tribe Mimuleae to form a well-supported clade that is distinct from other families in the Lamiales. We refer to that clade as the subfamily Phrymoideae. (2) The genera Mazus and Lancea (tribe Mimuleae) together form a well-supported clade that we recognize as the subfamily Mazoideae. Mazoideae is weakly supported as sister to Phrymoideae. We assign Mazoideae and Phrymoideae to a redefined family Phrymaceae. (3) Mimulus is not monophyletic, because members of at least six other genera have been derived from within it. In light of the molecular evidence, it is clear that species of Phrymaceae (about 190 species) have undergone two geographically distinct radiations; one in western North America (about 130 species) and another in Australia (about 30 species). Phylogenetic interpretations of morphological evolution and biogeographical patterns are discussed.     

Evolution of pipoid frogs:intergeneric relationships of the aquatic frog family Pipidae (Anura)

The 27 species of the aquatic frog family Pipidae are currently arranged in four genera: Xenopus (15 species), Hymenochirus (four species), and the poorly known genus Pseudhymenochirus (one species) occur in Africa; Pipa (seven species) is found in South America and lower Central America. Despite extensive work on the biology of Xenopus from various disciplines, the evolutionary relationships of Xenopus to other pipids have not been resolved. Phylogenetic analyis of morphological features of pipid frogs indicates that, contrary to earlier opinions, Hymenochirus and Pipa are closest relatives (sister-groups); these genera are placed in the subfamily Pipinae. Also, the currently recognized species of Xenopus do not form a natural group; the species tropicalis and epitropicalis are more closely related to Hymenochirus + Pipa than to the remaining species of Xenopus . The two discordant species are transferred to the genus Silurana , which is relegated to the new subfamily Siluraninae; it is the sister-group of the Pipinae. The remaining species of Xenopus constitute a monophyletic group that is placed in the subfamily Xenopodinae as the sister-group of the other genera of pipids.     

Generic delimitation and phylogenetic relationships within the subtribe Chironiinae (Chironieae: Gentianaceae), with special reference to Centaurium: evidence from nrDNA and cpDNA sequences

To better understand the evolutionary history of the genus Centaurium and its relationship to other genera of the subtribe Chironiinae (Gentianaceae: Chironieae), molecular analyses were performed using 80 nuclear ribosomal ITS and 76 chloroplast trnLF (both the trnL UAA intron and the trnL-F spacer) sequences. In addition, morphological, palynological, and phytochemical characters were included to a combined data matrix to detect possible non-molecular synapomorphies. Phylogenetic reconstructions support the monophyly of the Chironiinae and an age estimate of ca. 22 million years for the subtribe. Conversely, both molecular data sets reveal a polyphyletic Centaurium, with four well-supported main clades hereafter treated as separate genera. The primarily Mediterranean Centaurium s.s. is closely related to southern African endemics Chironia and Orphium, and to the Chilean species Centaurium cachanlahuen. The resurrected Mexican and Central American genus Gyrandra is closely related to Sabatia (from eastern North America). Lastly, the monospecific genus Exaculum (Mediterranean) forms a monophyletic group together with the two new genera: Schenkia (Mediterranean and Australian species) and Zeltnera (all other indigenous American centauries). Several biogeographical patterns can be inferred for this group, supporting a Mediterranean origin followed by dispersals to (1) North America, Central America, and South America, (2) southern Africa (including the Cape region), and (3) Australia and Pacific Islands.     

Fourfold polyphyly of the genus formerly known as Upucerthia, with notes on the systematics and evolution of the avian subfamily Furnariinae

The traditional avian subfamily Furnariinae, a group of terrestrial ovenbirds typical of the Andean and Patagonian arid zones, consists of the genera Furnarius, Cinclodes, Geositta, Upucerthia, Chilia, and Eremobius. We investigated phylogenetic relationships within the Furnariinae, with particular attention to the nine species of the genus Upucerthia, using nuclear and mitochondrial DNA sequences from all genera in the subfamily. Upucerthia was found to be highly polyphyletic, its constituent species forming four non-sister clades: (1) a basal lineage consisting of two Upucerthia species, U. ruficaudus and U. andaecola, as well as the monotypic genera Eremobius and Chilia; (2) a lineage consisting of U. harterti and U. certhioides, two species behaviorally divergent from other Upucerthia species; (3) a lineage consisting of U. serrana, which is not closely related to any other Upucerthia species; and (4) a lineage, sister to Cinclodes, consisting of the four Upucerthia species U. dumetaria, U. albigula, U. validirostris, and U. jelskii. The larger Furnariinae was also found to be highly polyphyletic; the terrestrial open country ecotype characteristic of this subfamily occurs in four unrelated clades in the family Furnariidae, including a basal lineage as well as derived lineages. Although the large degree of divergence among Upucerthia clades was not previously recognized, owing to ecological, behavioral, and morphological similarities, the groupings correspond closely to relationships suggested by plumage. This is in contrast to studies of other avian genera in which plumage patterns have been shown to be extensively convergent. The generic names Upucerthia and Ochetorhynchus are available for two of the former Upucerthia clades; new generic names may be warranted for the other two.     

Inferring the biogeographic origins of inter‐continental disjunct endemics using a Bayes‐DIVA approach

The arcto‐Tertiary relictual flora is comprised of many genera that occur non‐contiguously in the temperate zones of eastern Asia, Europe, eastern North America, and western North America. Within each distributional area, species are typically endemic and may thus be widely separated from closely related species within the other areas. It is widely accepted that this common pattern of distribution resulted from of the fragmentation of a once more‐continuous arcto‐Tertiary forest. The historical biogeographic events leading to the present‐day disjunction have often been investigated using a phylogenetic approach. Limitations to these previous studies have included phylogenetic uncertainty and uncertainty in ancestral range reconstructions. However, the recently described Bayes‐DIVA method handles both types of uncertainty. Thus, we used Bayes‐DIVA analysis to reconstruct the stem lineage distributions for 185 endemic lineages from 23 disjunct genera representing 17 vascular plant families. In particular, we asked whether endemic lineages within each of the four distributional areas more often evolved from (1) widespread ancestors, (2) ancestors dispersed from other areas, or (3) endemic ancestors. We also considered which of these three biogeographic mechanisms may best explain the origins of arcto‐Tertiary disjunct endemics in the neotropics. Our results show that eastern Asian endemics more often evolved from endemic ancestors compared to endemics in Europe and eastern and western North America. Present‐day endemic lineages in the latter areas more often arose from widespread ancestors. Our results also provide anecdotal evidence for the importance of dispersal in the biogeographic origins of arcto‐Tertiary species endemic in the neotropics.     

New insights into the phylogeny and biogeography of subfamily Orontioideae (Araceae)

Proto‐Araceae, the earliest diverged lineage within the family Araceae, includes two subfamilies, Gymnostachydoideae (one species) and Orontioideae (eight species). Based on an extensive sampling (a total of 198 accessions) of six chloroplast non‐coding regions (5799 aligned sites), we assessed phylogenetic relationships among the genera and species within subfamily Orontioideae and estimated the timing of intercontinental disjunct events in the Northern Hemisphere. Overall phylogenetic relationships among the genera were consistent with results from previous studies, but several new important findings were discovered, primarily within Symplocarpus Salisb. ex W. P. C. Barton. First, two major lineages within Symplocarpus were identified: one lineage included S. foetidus (L.) Salisb. ex W. Barton, S. nabekuraensis Otsuka & K. Inoue, and S. renifolius Schott ex Tzvelev (Japan), whereas the other included S. nipponicus Makino, S. egorovii N. S. Pavlova & V. A. Nechaev, and S. renifolius (Korea). Symplocarpus renifolius in Japan was tetraploid and closely related to the tetraploid S. foetidus in eastern North America. Populations of S. renifolius in Korea were confirmed to be diploid (2n = 30) and shared the most recent common ancestor with the other diploid species, S. nipponicus. Second, two recently described species, S. nabekuraensis and S. egorovii, were deeply embedded within S. renifolius in Japan and Korea, respectively, and their distinct taxonomic status requires further assessment. Finally, two intercontinental disjunction events in the subfamily, one in Lysichiton Schott between eastern Asia and western North America and the other in Symplocarpus between eastern Asia and eastern North America, were estimated to be between 4.5 and 1.4 million years ago (Pliocene and Pleistocene) and between 1.9 and 0.5 million years ago (Pleistocene), respectively.     

Mitochondrial DNA analysis reveals hidden genetic diversity in captive populations of the threatened American crocodile (Crocodylus acutus) in Colombia

Identification of units within species worthy of separate management consideration is an important area within conservation. Mitochondrial DNA (mtDNA) surveys can potentially contribute to this by identifying phylogenetic and population structure below the species level. The American crocodile (Crocodylus acutus) is broadly distributed throughout the Neotropics. Its numbers have been reduced severely with the species threatened throughout much of its distribution. In Colombia, the release of individuals from commercial captive populations has emerged as a possible conservation strategy that could contribute to species recovery. However, no studies have addressed levels of genetic differentiation or diversity within C. acutus in Colombia, thus complicating conservation and management decisions. Here, sequence variation was studied in mtDNA cytochrome b and cytochrome oxidase I gene sequences in three Colombian captive populations of C. acutus. Two distinct lineages were identified: C. acutus‐I, corresponding to haplotypes from Colombia and closely related Central American haplotypes; and C. acutus‐II, corresponding to all remaining haplotypes from Colombia. Comparison with findings from other studies indicates the presence of a single “northern” lineage (corresponding to C. acutus‐I) distributed from North America (southern Florida), through Central America and into northern South America. The absence of C. acutus‐II haplotypes from North and Central America indicates that the C. acutus‐II lineage probably represents a separate South American lineage. There appears to be sufficient divergence between lineages to suggest that they could represent two distinct evolutionary units. We suggest that this differentiation needs to be recognized for conservation purposes because it clearly contributes to the overall genetic diversity of the species. All Colombian captive populations included in this study contained a mixture of representatives of both lineages. As such, we recommend against the use of captive‐bred individuals for conservation strategies until further genetic information is available.     

Phylogeographic structuring of Plasmodium lineages across the North American range of the house finch (Carpodacus Mexicanus)

The determinants of the geographic distribution of avian hematozoa are poorly understood. Sampling parasites from one avian host species across a wide geographic range is an accepted approach to separate the potential influence of host species distribution from geographic effects not directly related to host species biology. We used polymerase chain reaction to screen samples for hematozoan infection from 490 house finches (Carpodacus mexicanus) collected at 8 sites spanning continental North America. To explore geographic patterns of parasite lineage distributions, we sequenced a portion of the mitochondrial cytochrome b gene of Plasmodium species infecting 77 house finches. We identified 5 distinct Plasmodium haplotypes representing 3 lineages that likely represent 3 species. One lineage was common at all sites where we detected Plasmodium species. The second lineage contained 3 haplotypes that showed phylogeographic structuring on a continent-wide scale, with 1 haplotype common in eastern North America and 2 common in western North America. The third divergent lineage was recovered from 1 individual host. Considered together, the partial phylogeographic structuring of Plasmodium cytochrome b lineages over the range of the house finch suggests that parasite lineage distribution is not solely dependent on host species distribution, and other factors such as arthropod vector competence and distribution may be important.     

Historical biogeography at the crossroads of the northern continents: molecular phylogenetics of red-backed voles (Rodentia: Arvicolinae)

Evolutionary relationships of red-backed voles and their relatives were examined and used to test biogeographic hypotheses. Sequences of the mitochondrial cytochrome b gene were obtained for 25 individuals representing Alticola macrotis, Clethrionomys californicus, C. gapperi, C. glareolus, C. rutilus, and C. rufocanus. These were combined with 21 partial sequences from GenBank for C. regulus, C. rex, C. rufocanus, C. rutilus, Eothenomys imaizumii, E. melanogaster, Phaulomys andersoni, and P. smithii. Complete sequences of three species of Microtus (M. montanus, M. oeconomus, and M. pennsylvanicus), representative species of other arvicoline genera (Myopus, Synaptomys, Arvicola, Ellobius, Ondatra, Lemmus, Dicrostonyx, and Phenacomys), and a sigmodontine representative (Peromyscus) were included as outgroups. We used maximum parsimony, maximum likelihood, distance, and Bayesian based methods and conducted statistical tests on proposed hypotheses of phylogenetic relationships and biogeographic histories. A close relationship of species representing the genera Alticola, Clethrionomys, and Eothenomys was supported (Clethrionomyini); however, the genus Clethrionomys was paraphyletic with respect to both Alticola and Eothenomys. Three major clades were identified as Asian (Eothenomys andersoni, E. smithii, C. rex, C. regulus, and C. rufocanus), Trans-beringian (Alticola macrotis, C. californicus, C. gapperi, C. glarelolus, and C. rutilus), and Taiwanese (E. melanogaster). These results are consistent with the fossil record which indicates an initial diversification in Asia followed by colonization of the Nearctic on at least two occasions. The holarctic species, C. rutilus, appears to have either reinvaded Asia from North America or colonized North America more recently (late Pleistocene) than the two species of Clethrionomys (C. gapperi and C. californicus) that are endemic to North America (early to mid-Pleistocene). Finally, C. gapperi, appears to be comprised of an eastern and a western species, the former with affinities to the Asian C. glareolus and the latter more closely related to C. californicus.     

中国与北美苔藓植物区系关系的探讨

关于中国和北美间苔藓植物区系关系的研究是在20世纪90年代开始的。研究表明中国和北美苔类和藓类的种间关系疏远,这一事实说明两个大陆在第三纪后期分离后,由于地质、地理、气候等因素的差异致使苔藓植物区系成分也产生明显分异。虽然它们在科、属方面差异较小,但两个大陆已各自形成地区特有的苔类和藓类的属。已知的中国特有及东亚特有的苔类属有5个,藓类属有22个;而已知北美地区特有的苔类属有4个、藓类属有5个。北美东部和西部形成于不同地质时期,在苔藓植物方面与中国共同分布的科、属和种存在一定差异。从神农架藓类植物研究表明,从共同分布的种来看,北美东部与中国比北美西部与中国的相似性系数高约6％。从两地区间苔类和藓类植物的雌雄同株或雌雄异株及孢子直径大小而论,这两个因素似乎并不是影响苔藓植物在两大地区间分布的主要原因,但对苔藓植物的分布仍然十分重要。本文作者认为结合中国和北美的地史、地理条件及苔藓植物自身的特点,可以认为白令海峡不是阻碍中国和北美苔藓植物交流的绝对自然屏障;中国和北美苔藓植物区系关系目前的状况,是长期多次交流融合和分异的结果。     

Discordance between phylogenetics and coalescent-based divergence modelling: exploring phylogeographic patterns of speciation in the Carex macrocephala species complex

We fit a molecular data set, consisting of the rpL16 cpDNA marker and eight microsatellite loci, to the isolation-with-migration model as implemented in IM a to test a well-supported phylogenetic hypothesis of relationships within the Carex macrocephala species complex (Cyperaceae). The phylogenetic hypothesis suggests C. macrocephala from North America is reciprocally monophyletic and is sister to a reciprocally monophyletic clade of C. kobomugi . The North American C. macrocephala and C. kobomugi clade form a sister clade with a lineage of Asian C. macrocephala , thereby forming a paraphyletic C. macrocephala species. Not only does the phylogenetic hypothesis suggest C. macrocephala is paraphyletic, but it also suggests that the two lineages which share a partially overlapping distribution, Asian C. macrocephala and C. kobomugi , are not the most closely related. To test these relationships, we used coalescent-based population genetic models to infer divergence time for each lineage pair within the species complex. The coalescent-based models account for the stochastic forces which drive population divergence, and can account for the lineage sorting that occurs prior to lineage divergence. A drawback to phylogenetic-based phylogeographical analyses is that they do not account for stochastic lineage sorting that occurs between gene divergence and lineage divergence. By comparing the relative divergence time of the three main lineages within this group, Asian C. macrocephala , North American C. macrocephala , and C. kobomugi , we concluded that the phylogenetic hypothesis is incorrect, and the divergence between these lineages occurred during the Late Pleistocene epoch.     

A molecular phylogenetic study of the genus Ribeiroia (Digenea): trematodes known to cause limb malformations in amphibians

Species of Ribeiroia (Trematoda: Psilostomidae) are known to cause severe limb malformations and elevated mortality in amphibians. However, little is known regarding the number of species in this genus or its relation to other taxa. Species of Ribeiroia have historically been differentiated by slight differences among their larval stages. To better understand the systematics and biogeography of this genus and their potential relevance to the distribution of malformed amphibians, specimens identified as Ribeiroia were collected across much of the known range, including samples from 5 states in the United States (8 sites) and 2 islands in the Caribbean (Puerto Rico and Guadeloupe). A cercaria from East Africa identified as Cercaria lileta (Fain, 1953), with attributes suggestive of Ribeiroia (possibly R. congolensis), was also examined. The intertranscribed spacer region 2 (ITS-2) of the ribosomal gene complex was sequenced and found to consist of 429 nucleotides (nt) for R. ondatrae (United States) and 427 nt for R. marini (Caribbean), with only 6 base differences noted between the 2 species. The ITS-2 region of C. lileta (429 nt) aligned closely with those of the 2 other Ribeiroia species in a phylogenetic analysis that included related trematode genera. This evidence suggests that a third Ribeiroia species exists in tropical Africa. Variation in ITS-2 within R. ondatrae was nonexistent among the 8 populations from North America. Our study further suggests that Ribeiroia spp. originally parasitized Biomphalaria sp., and that a host switch to a closely related snail, Helisoma sp., may have occurred in the lineage represented by R. ondatrae. However, relationships within the Echinostomatidae are not understood well enough to make any robust conclusions at this time.     

Phylogeny of North American fireflies (Coleoptera: Lampyridae): implications for the evolution of light signals

Representatives of the beetle family Lampyridae ("fireflies", "lightningbugs") are well known for their use of light signals for species recognition during mate search. However, not all species in this family use light for mate attraction, but use chemical signals instead. The lampyrids have a worldwide distribution with more than 2000 described species, but very little is known about their phylogenetic relationships. Within North America, some lampyrids use pheromones as the major mating signal whereas others use visual signals such as extended glows or short light flashes. Here, we use a phylogenetic approach to illuminate the relationships of North American lampyrids and the evolution of their mating signals. Specifically, to establish the first phylogeny of all North American lampyrid genera, we sequenced nuclear (18S) and mitochondrial (16S and COI) genes to investigate the phylogenetic relationships of 26 species from 16 North American (NA) genera and one species from the genus Pterotus that was removed recently from the Lampyridae. To test the monophyly of the NA firefly fauna we sequenced the same genes from three European lampyrids and three Asian lampyrids, and included all available Genbank data (27 additional Asian lampyrids and a former lampyrid from Asia, Rhagophthalmus). Our results show that the North American lampyrids are not monophyletic. Different subgroups are closely related to species from Europe, Asia and tropical America, respectively. The present classification of fireflies into subfamilies and tribes is not, for the most part, supported by our phylogenetic analysis. Two former lampyrid genera, Pterotus and Rhagophthalmus, which have recently been removed from this family, are in fact nested within the Lampyridae. Further, we found that the use of light as a sexual signal may have originated one or four times among lampyrids, followed by nine or four losses, respectively. Short flashes originated at least twice and possibly three times independently among our study taxa. The use of short flashes as a mating signal was replaced at least once by the use of long glows, and light signals as mating signals were lost at least three times in our study group and replaced by pheromones as the main signal mode.     

Megafaunal extinctions and the disappearance of a specialized wolf ecomorph

The gray wolf (Canis lupus) is one of the few large predators to survive the Late Pleistocene megafaunal extinctions [1]. Nevertheless, wolves disappeared from northern North America in the Late Pleistocene, suggesting they were affected by factors that eliminated other species. Using skeletal material collected from Pleistocene permafrost deposits of eastern Beringia, we present a comprehensive analysis of an extinct vertebrate by exploring genetic (mtDNA), morphologic, and isotopic (delta(13)C, delta(15)N) data to reveal the evolutionary relationships, as well as diet and feeding behavior, of ancient wolves. Remarkably, the Late Pleistocene wolves are genetically unique and morphologically distinct. None of the 16 mtDNA haplotypes recovered from a sample of 20 Pleistocene eastern-Beringian wolves was shared with any modern wolf, and instead they appear most closely related to Late Pleistocene wolves of Eurasia. Moreover, skull shape, tooth wear, and isotopic data suggest that eastern-Beringian wolves were specialized hunters and scavengers of extinct megafauna. Thus, a previously unrecognized, uniquely adapted, and genetically distinct wolf ecomorph suffered extinction in the Late Pleistocene, along with other megafauna. Consequently, the survival of the species in North America depended on the presence of more generalized forms elsewhere.