Concordant phylogeography and cryptic speciation in two Western Palaearctic oak gall parasitoid species complexes

Little is known about the evolutionary history of most complex multi‐trophic insect communities. Widespread species from different trophic levels might evolve in parallel, showing similar spatial patterns and either congruent temporal patterns (Contemporary Host‐tracking) or later divergence in higher trophic levels (Delayed Host‐tracking). Alternatively, host shifts by natural enemies among communities centred on different host resources could disrupt any common community phylogeographic pattern. We examined these alternative models using two Megastigmus parasitoid morphospecies associated with oak cynipid galls sampled throughout their Western Palaearctic distributions. Based on existing host cynipid data, a parallel evolution model predicts that eastern regions of the Western Palaearctic should contain ancestral populations with range expansions across Europe about 1.6 million years ago and deeper species‐level divergence at both 8–9 and 4–5 million years ago. Sequence data from mitochondrial cytochrome b and multiple nuclear genes showed similar phylogenetic patterns and revealed cryptic genetic species within both morphospecies, indicating greater diversity in these communities than previously thought. Phylogeographic divergence was apparent in most cryptic species between relatively stable, diverse, putatively ancestral populations in Asia Minor and the Middle East, and genetically depauperate, rapidly expanding populations in Europe, paralleling patterns in host gallwasp species. Mitochondrial and nuclear data also suggested that Europe may have been colonized multiple times from eastern source populations since the late Miocene. Temporal patterns of lineage divergence were congruent within and across trophic levels, supporting the Contemporary Host‐tracking Hypothesis for community evolution.     

Molecular Characterization of a Cytoplasmic Dynein from Dictyostelium

Cytoplasmic dynein is a high molecular weight, microtubule-based mechanochemical ATPase that is believed to provide motive force for a number of intracellular motilities, including transport of membrane-bound organelles. Cytoplasmic dynein also localizes to the mitotic spindles of some organisms and to the kinetochore regions of some condensed chromosomes, where it may play an active role in spindle assembly, spindle position, and/or chromosome movement during cell division. Despite active research efforts from a number of laboratories, little detail is yet available about dynein-based cellular activities. This paper describes our efforts to characterize cytoplasmic dynein from Dictyostelium and to use this protist as a molecular genetic factory to probe structure-function relationships of this molecule.     

A re-valuation of the Araphidineae/Centrales index as an indicator of lake trophic status

SUMMARY. Comparisons of pre- and post-settlement diatom assemblages from the sediment of twenty-five Minnesota lakes reveals that Stephanodiscus hantzschii percentages are more consistent indicators of human disturbance than the Araphidineae/Centrales (A/C) index. In a set of eighty surface sediment samples from lakes whose water chemistry is known, S. hantzschii , a centric diatom, is abundant as a microfossil in lakes with total phosphorus > 15 μg I⁻¹ and alkalinity > 1.5 m-equiv. I⁻¹. High Araphidineae/Centrales indices are characteristic of lakes with only moderate total phosphorus levels and very low alkalinities.     

Phylogenetic relationships within the South American fish family Anostomidae (Teleostei,Ostariophysi, Characiformes)

Analysis of a morphological dataset containing 152 parsimony‐informative characters yielded the first phylogenetic reconstruction spanning the South American characiform family Anostomidae. The reconstruction included 46 ingroup species representing all anostomid genera and subgenera. Outgroup comparisons included members of the sister group to the Anostomidae (the Chilodontidae) as well as members of the families Curimatidae, Characidae, Citharinidae, Distichodontidae, Hemiodontidae, Parodontidae and Prochilodontidae. The results supported a clade containing Anostomus, Gnathodolus, Pseudanos, Sartor and Synaptolaemus (the subfamily Anostominae sensu Winterbottom) albeit with a somewhat different set of relationships among the species within these genera. Anostomus as previously recognized was found to be paraphyletic and is split herein into two monophyletic components, a restricted Anostomus and the new genus Petulanos gen. nov. , described herein. Laemolyta appeared as sister to the clade containing Anostomus, Gnathodolus, Petulanos, Pseudanos, Sartor and Synaptolaemus. Rhytiodus and Schizodon together formed a well‐supported clade that was, in turn, sister to the clade containing Anostomus, Gnathodolus, Laemolyta, Petulanos, Pseudanos, Sartor and Synaptolaemus. Anostomoides was sister to the clade formed by these nine genera. Leporinus as currently defined was not found to be monophyletic, although certain clades within that genus were supported, including the species with subterminal mouths in the former subgenus Hypomasticus which we recognize herein as a genus. Abramites nested in Leporinus, and Leporellus was found to be the most basal anostomid genus. The presence of cis‐ and trans‐Andean species in Abramites, Leporellus, Leporinus and Schizodon, all relatively basal genera, suggests that much of the diversification of anostomid species pre‐dates the uplift of the Andean Cordilleras circa 11.8 million years ago. Several important morphological shifts in anostomid evolution are illustrated and discussed, including instances of convergence and reversal. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154 , 70–210.