Phylogenetic evaluation of systematics and biogeography of the leech family Glossiphoniidae

The evolutionary patterns of divergence of seven euhirudinean families were investigated by cladistic analysis of 33 euhirudinean species. Oligochaetes, Acanthobdella peledina, and branchiobdellidans were included as outgroup taxa. Cladistic analysis employed 1.8 kb of nuclear 18S ribosomal DNA and 651 bp of mitochondrial cytochrome c oxidase subunit I in addition to morphological data. The use of two molecular data sets, one nuclear gene and one mitochondrial gene, as well as morphological data combined historical information evolving under a variety of different constraints and therefore was less susceptible to the biases that could confound the use of only one type of data. Results suggest that the nuclear 18S rDNA gene yields a meaningful historical signal for determining higher level relationships. The more rapidly evolving CO-I gene was informative for recent or local areas of the evolutionary hypothesis, such as within-family relationships. Analyses combining all data from the three character sets yielded one most-parsimonious tree. Most of the higher taxa in recent leech systematics were well corroborated in the resulting topology. However, these results suggested paraphyly of the order Rhynchobdellida, which contradicts the presence of a proboscis as a synapomorphy. The medicinal leech family Hirudinidae was polyphyletic because Haemadipsidae and Haemopidae each have a hirudinid ancestor. In addition, all but one of the genera within the family Erpobdellidae must be either abandoned or renamed. Unusual findings included compelling evidence of historical plasticity in bloodfeeding behavior, having been lost at least four times in the course of euhirudinean evolution. Biogeographic patterns supported a New World origin for Arhynchobdellida. Copyright 1999 Academic Press.

The phylogeny and phylogeography of Emys orbicularis was inferred from mitochondrial nucleotide sequences of the cytochrome b gene analysed by DNA sequencing and RNA heteroduplex analysis. Within the family Emydidae the monotypic genus Emys is affiliated with the nearctic taxa Emydoidea blandingii and Clemmys marmorata. The analysis of 423 individuals of E. orbicularis, originating throughout its distribution range, revealed a remarkable intraspecific differentiation in 20 different haplotypes with distinct geographical ranges. Maximum parsimony analysis produced a star-like phylogeny with seven main lineages which may reflect separations in the late Pliocene. The haplotype distribution examined by partial Mantel tests and analysis of molecular variance revealed a substantial effect of glacial periods. This historical perspective suggests the existence of multiple glacial refugia and considerable Holocene range expansion which was modulated by climatic traits. Further support is gained for the occurrence of long-term parapatry in glacial refugia.

Phylogenetic relationships among major clades of anuran amphibians were studied using partial sequences of three nuclear protein coding genes, Rag-1, Rag-2, and rhodopsin in 26 frog species from 18 families. The concatenated nuclear data set comprised 2,616 nucleotides and was complemented by sequences of the mitochondrial 12S and 16S rRNA genes for analyses of evolutionary rates. Separate and combined analyses of the nuclear markers supported the monophyly of modern frogs (Neobatrachia), whereas they did not provide support for the monophyly of archaic frog lineages (Archaeobatrachia), contrary to previous studies based on mitochondrial data. The Neobatrachia contain two well supported clades that correspond to the subfamilies Ranoidea (Hyperoliidae, Mantellidae, Microhylidae, Ranidae, and Rhacophoridae) and Hyloidea (Bufonidae, Hylidae, Leptodactylidae, and Pseudidae). Two other families (Heleophrynidae and Sooglossidae) occupied basal positions and probably represent ancient relicts within the Neobatrachia, which had been less clearly indicated by previous mitochondrial analyses. Branch lengths of archaeobatrachians were consistently shorter in all separate analyses, and nonparametric rate smoothing indicated accelerated substitution rates in neobatrachians. However, relative rate tests confirmed this tendency only for mitochondrial genes. In contrast, nuclear gene sequences from our study and from an additional GenBank survey showed no clear phylogenetic trends in terms of differences in rates of molecular evolution. Maximum likelihood trees based on Rag-1 and using only one neobatrachian and one archaeobatrachian sequence, respectively, even had longer archaeobatrachian branches averaged over all pairwise comparisons. More data are necessary to understand the significance of a possibly general assignation of short branches to basal and species-poor taxa by tree-reconstruction algorithms.