Population structure and mantle display polymorphisms in the wavy-rayed lampmussel, Lampsilis fasciola (Bivalvia: Unionidae)

Genotypes from 10 polymorphic DNA microsatellite loci were used to make assessments of population structure, measurements of gene flow, and attempts to genetically segregate polymorphic host fish-attracting mantle displays for the wavy-rayed lampmussel, Lampsilis fasciola Rafinesque, 1820 — an endangered species in Canada. Specimens were collected from seven localities — six in the Great Lakes drainages of Ontario, Canada, and one from the Little Tennessee River in North Carolina, USA. Four distinct and sympatric mantle display morphologies were observed on female L. fasciola. Displays could not be distinguished genetically using analysis of molecular variance and genotypic assignment tests. The diversity of mantle displays was correlated with the overall genetic diversity observed among populations of L. fasciola. In managing populations of L. fasciola for propagation, augmentation, and translocation, polymorphic lures should be represented in proportion to what is observed in wild populations. Through moderately high FSTvalues and high assignment to population in genotype assignment tests, genetic structure was evident among the river drainages. Within-drainage gene flow was very high, and sampling localities within the Ontario drainages displayed panmixia. Efforts in artificial propagation and possible translocations to reintroduce or augment populations should be made to maintain the substantial levels of genetic variation while maintaining distinctiveness.

Generation of linear expression constructs by one-step PCR with vaccinia DNA topoisomerase I

Linear expression constructs can facilitate gene function studies. We describe a method to generate linear expression constructs for mammalian cells by one-step polymerase chain reaction (PCR) with vaccinia DNA topoisomerase I (TOPO). Cytomegalovirus (CMV) 5\' promoter, the gene of interest, and V5 bovine growth hormone (BGH) polyA 3\' terminator elements were PCR-amplified with target-specific primers containing vaccinia DNA TOPO-specific sequence and complementary sequence to each other. We amplified specific and complementary sequences. These three elements were directionally joined with vaccinia TOPO. The joined products were then directly transfected into Chinese hamster ovary cells. Compared with the transfection of supercoiled plasmids, comparable expression signals were obtained for green fluorescent protein, chloramphenicol acetyltransferase, and beta-galactosidase proteins using Western blots. This is a quick and efficient method to generate linear expression constructs. Unlike Invitrogen TOPO Tools, our method avoided the secondary round of PCR and more rapidly yielded correct joining products. This method can be easily used in the function test of uncharacterized open reading frames.

Evolution of active host-attraction strategies in the freshwater mussel tribe Lampsilini (Bivalvia: Unionidae)

Most freshwater mussels (Bivalvia: Unionoida) require a host, usually a fish, to complete their life cycle. Most species of mussels show adaptations that increase the chances of glochidia larvae contacting a host. We investigated the evolutionary relationships of the freshwater mussel tribe Lampsilini including 49 of the approximately 100 extant species including 21 of the 24 recognized genera. Mitochondrial DNA sequence data (COI, 16S, and ND1) were used to create a molecular phylogeny for these species. Parsimony and Bayesian likelihood topologies revealed that the use of an active lure arose early in the evolution of the Lampsiline mussels. The mantle flap lure appears to have been the first to evolve with other lure types being derived from this condition. Apparently, lures were lost independently in several clades. Hypotheses are discussed as to how some of these lure strategies may have evolved in response to host fish prey preferences.

Deep genealogical history without population differentiation: discordance between mtDNA and allozyme divergence in the zebra-tailed lizard (Callisaurus draconoides)

The peninsula of Baja California has a complex geological history that has strongly affected the regional biota. Genealogical histories of many species have revealed congruent patterns, which suggest that the peninsula was temporarily submerged at two locations. We sequenced a total of 1953 base pairs (bp) of the mitochondrial genome for 42 specimens of the zebra-tailed lizard (Callisaurus draconoides). The resulting maternal genealogy supports the former existence of a mid-peninsular seaway and a Plio-Quaternary seaway across the Isthmus of La Paz. In addition, a genealogical break is revealed in the vicinity of Loreto. This genealogical break may have resulted from prolonged submergence of the Loreto Basin during Pliocene. The mid-peninsular seaway may have occurred as early as late Miocene, at a time significantly earlier than previously hypothesized. Comparison with other genealogies and geological evidence suggests that current models on the evolution of Baja California's fauna are temporally shallow. The deep genealogical patterns of C. draconoides also disagree with the very limited population differentiation previously reported for allozyme markers, suggesting that maternal history may not be an appropriate approximation for population differentiation.

Old age, multiple formations or genetic plasticity? Clonal diversity in the uniparental Caucasian rock lizard, Lacerta dahli

Allozyme variation at 35 gene loci is investigated in 161 specimens of the uniparental Caucasian lizard Lacerta dahli from several locations in Armenia and Georgia. All individuals are heterozygotic at 12 loci, and homozygotic at 21 loci. Variation at two loci results in five uniparental clones. One clone is widespread whereas four are geographically restricted and are represented by only one or two individuals. Because successful formation of uniparental clones is rare, and because the biparental species forming them are now allopatric, the most probable explanation for the origin of the observed clonal diversity is either mutation or recombination within the common clone. The rare clones have lower levels of enzyme activity at four loci, suggesting that these organisms may be genetically deficient. Although the evidence points to change in a pre-existing clone, the possibility of multiple origins cannot be ruled out.

Disjunct habitats as islands: genetic variability in the Caucasian rock lizard Lacerta portschinskii

Genetic diversity at 37 allozyme loci was surveyed in Lacerta portschinskii from contiguous populations and from a disjunct population. Indices of genetic diversity (heterozygosity, number of alleles per locus, and percentage of loci polymorphic) were greater in contiguous populations than in the smaller disjunct population. In this regard, disjunct populations appear to be similar to island populations. Indices of genetic diversity in Caucasian Lacerta are less than those reported from vagile lizard taxa and more similar to those of sit-and-wait predators.

Allozyme variation patterns and multiple hybridization origins: clonal variation among four sibling parthenogenetic Caucasian rock lizards

Allozyme electrophoresis of four sibling parthenogenetic Caucasian rock lizards Darevskia unisexualis, D. uzzelli, D. sapphirina, and D. bendimahiensis found seven clones and five variable loci. The data supported the hypothesis that D. raddei and D. valentini are the parental species of all four parthenogens. Variation patterns in Darevskia were summarized. Species that originated from a single F1 typically consisted of one widespread clone with a few rare clones. Species with multiple origins displayed variation only slightly higher than species with a single origin. This is contrary to other genera of parthenogenetic lizards, in which cases massive clonal variations were observed.

The Coachella valley fringe-toed lizard (Uma inornata): genetic diversity and phylogenetic relationships of an endangered species

A phylogeny was reconstructed for 23 populations of fringe-toed lizards (genus Uma) from the three most northern species of the genus, including the Mojave fringe-toed lizard U. scoparia, the Colorado Desert fringe-toed lizard U. notata, and the endangered Coachella Valley fringe-toed lizard U. inornata. The outgroup taxa were the zebra-tailed lizard, Callisaurus draconoides; the lesser earless lizard, Holbrookia maculata; and the greater earless lizard, Cophosaurus texanus. Evaluation of 1630 combined nucleotide sequence from the mitochondrial genes ATPase 6 and cytochrome b yielded 10 most parsimonious trees. Reweighting the characters using the rescaled consistency index eliminated eight of these trees. The remaining two trees differ only in the placement of two individuals from the Superstition Mountains which either formed a monophlyetic unit or grouped with one individual from the Anza-Borrego population. The preferred phylogeny, one more consistent with geography, had two primary clades: one consisting of U. scoparia and the other placing U. inornata inside the clade containing U. notata. Uma inornata was most closely related to nearby U. notata notata, as opposed to more distant U. notata rufopunctata.

Genetic variability among endangered Chinese giant salamanders, Andrias davidianus

The endangered Chinese giant salamander (Andrias davidianus) is endemic to mainland China. Genetic divergence among six populations of the species was investigated by means of isozyme electrophoresis and mitochondrial DNA (mtDNA) sequences. Forty allozyme loci were resolved for all populations; the amount of genetic divergence among populations was comparable to that in other amphibians. mtDNA sequences showed a similar level of divergence. The population from Huangshan is distinct from other populations, indicating the existence of localized divergence. Both allozyme and mtDNA data failed to associate the populations into a pattern corresponding to the three Chinese river systems, which may be the consequence of human relocation. Conservation policies should emphasize the protection of localized populations and cessation of human-facilitated introductions. Future studies should focus on investigating the divergence among localized populations from isolated mountain regions, particularly using more fine-grained techniques such as microsatellite DNA.

Limited genetic variation in Lacerta mixta and its parthenogenetic daughter species: evidence from cytochrome b and ATPase 6 gene DNA sequences

Little mtDNA variation was observed among populations of the bisexual Caucasian rock lizard Lacerta mixta and unisexual L. dahli and L. armeniaca. Three haplotypes were detected in L. mixta and the maximum pairwise difference among the samples was 0.67%. No intra- and interspecific variation was found among populations of either L. armeniaca or L. dahli. Moreover, both unisexual species were identical to one of the three haplotypes of L. mixta. The limited variation in L. mixta is likely the result of bottleneck effect, although the small sample size may also be responsible. The lack of variation in the unisexual was attributed to the restricted variation among the maternal parents, limited involvement of females in the hybridization, and recent origin.

Phylogeny of east asian bufonids inferred from mitochondrial DNA sequences (Anura: amphibia)

We investigated the relationships of Asian bufonids using partial sequences of mitochondrial DNA genes. Twenty-six samples representing 14 species of Bufo from China and Vietnam and 2 species of Torrentophryne from China were examined. Three samples of Bufo viridis from Armenia and Georgia were also sequenced to make a comparison to its sibling tetraploid species B. danatensis. Bufo americanus, from Canada, was used as the outgroup. Sequences from the 12S ribosomal RNA, 16S ribosomal RNA, cytochrome b, and the control region were analyzed using parsimony. East Asian bufonids were grouped into two major clades. One clade included B. andrewsi, B. bankorensis, B. gargarizans, B. tibetanus, B. tuberculatus, its sister clade B. cryptotympanicus, and the 2 species of Torrentophryne. The second clade consisted of B. galeatus, B. himalayanus, B. melanostictus, and a new species from Vietnam. The placement of three taxa (B. raddei, B. viridis, and its sister species, B. danatensis) was problematic. The genus Torrentophryne should be synonymized with Bufo to remove paraphyly. Because B. raddei does not belong to the clade that includes B. viridis and B. danatensis, it was removed from the viridis species group. The species status of B. bankorensis from Taiwan is evaluated.

Discriminating and locating character covariance: an application of permutation tail probability (PTP) analyses

The ability of permutation tail probability (PTP) analyses to discriminate between character covariance and noise is investigated with both hypothetical and published data sets. PTP is shown to be a powerful tool, not only for detecting character covariance, but also for locating that covariance on trees. PTP is especially useful for evaluating DNA sequence data that may have a high level of homoplasy. A three-step PTP procedure for locating covaried characters is presented.