The most dramatic shifts in the classification relative to previous works concern the groups that have traditionally been included in the Chytridiomycota and Zygomycota. The Chytridiomycota is retained in a restricted sense, with Blastocladiomycota and Neocallimastigomycota representing segregate phyla of flagellated Fungi. Taxa traditionally placed in Zygomycota are distributed among Glomeromycota and several subphyla incertae sedis, including Mucoromycotina, Entomophthoromycotina, Kickxellomycotina, and Zoopagomycotina. Microsporidia are included in the Fungi, but no further subdivision of the group is proposed. Several genera of 'basal' Fungi of uncertain position are not placed in any higher taxa, including Basidiobolus, Caulochytrium, Olpidium, and Rozella.

Vertical transmission (VT) and associated manipulation of host reproduction are widely reported among prokaryotic endosymbionts. Here, we present evidence for widespread use of VT and associated sex-ratio distortion in a eukaryotic phylum. The Microspora are an unusual and diverse group of eukaryotic parasites that infect all animal phyla. Following our initial description of a microsporidian that feminizes its crustacean host, we survey the diversity and distribution of VT within the Microspora. We find that vertically transmitted microsporidia are ubiquitous in the amphipod hosts sampled and that they are also diverse, with 11 species of microsporidia detected within 16 host species. We found that infections were more common in females than males, suggesting that host sex-ratio distortion occurs in five out of eight parasite species tested. Phylogenetic reconstruction demonstrates that VT occurs in all major lineages of the phylum Microspora and that sex-ratio distorters are found on multiple branches of the phylogenetic tree. We propose that VT is either an ancestral trait or evolves with peculiar frequency in this phylum. If the association observed here between VT and host sex-ratio distortion holds true across other host taxa, these eukaryotic parasites may join the bacterial endosymbionts in their importance as sex-ratio distorters.

Ironside, J. E. (2010). No amicable divorce? Challenging the notion that sexual antagonism drives sex chromosome evolution. Bioessays, 32, (8), 718-726. IMPF: 04.47 RONO: 00Although sexual antagonism may have played a role in forming some sex chromosome systems, there appears to be little empirical or theoretical justification in assuming that it is the driving force in all cases of sex chromosome evolution. In many species, sex chromosomes have diverged in size and shape through the accumulation of mutations in regions of suppressed recombination. It is commonly assumed that recombination is suppressed in sex chromosomes due to selection to resolve sexually antagonistic pleiotropy. However, the requirement for a sex chromosome-specific mechanism for suppressing recombination is questionable, since more general models of recombination suppression on autosomes also appear to be applicable to sex chromosomes. Direct tests of the predictions of the sexual antagonism hypothesis offer only limited support in specific sex chromosome systems and circumstantial evidence remains open to interpretation.Peer reviewe

Blood flukes within the genus Schistosoma still remain a major cause of disease in the tropics and subtropics and the study of their evolution has been an area of major debate and research. With the advent of modern molecular and genomic approaches deeper insights have been attained not only into the divergence and speciation of these worms, but also into the historic movement of these parasites from Asia into Africa, via migration and dispersal of definitive and snail intermediate hosts. This movement was subsequently followed by a radiation of Schistosoma species giving rise to the S. mansoni and S. haematobium groups, as well as the S. indicum group that reinvaded Asia. Each of these major evolutionary events has been marked by distinct changes in genomic structure evident in differences in mitochondrial gene order and nuclear chromosomal architecture between the species associated with Asia and Africa. Data from DNA sequencing, comparative molecular genomics and karyotyping are indicative of major constitutional genomic events which would have become fixed in the ancestral populations of these worms. Here we examine how modern genomic techniques may give a more in depth understanding of the evolution of schistosomes and highlight the complexity of speciation and divergence in this group.