An integrative systematic revision of the European southern birch mice (Rodentia: Sminthidae, S icista subtilis group)

Penile shape discriminates two cryptic species of Akodon Meyen, 1833 (Mammalia, Rodentia, Cricetidae) from eastern Brazil

Glans penis morphology has been used as a powerful tool in mammal taxonomy to differentiate cryptic species. Neotropical rodent species Akodoncursor and A.montensis are cryptic, and interspecific hybrids are like their parental species. We investigated non-metric and metric phallic characters aiming to differentiate A.cursor from A.montensis. We also evaluated the parental species' influence of the phallic characters on hybrids. We analysed 96 male adults-56 A.cursor, 27 A.montensis, and 13 hybrids, subgrouping species by locality and hybrids by parental species (paternal vs maternal). We verified that A.cursor and A.montensis are distinguishable by penile-shape morphology: A.cursor has an elongated penile form with a flare in the distal portion and A.montensis has a barrel-shaped form. Also, dark spots in ventral view, if present in A.montensis, distinguish A.montensis from A.cursor. Although the non-metric characters differentiate the species, they do not distinguish the subgroups of A.cursor, A.montensis, and hybrids. The metric phallic characters indicated a significant difference between species and hybrids. These characters also differentiate the population groups of A.cursor. However, A.montensis subgroups and hybrids subgroups did not present a significant difference. This study shows the importance of penis morphology in the taxonomy of the cryptic rodent species A.cursor and A.montensis, representing a powerful tool to discriminate male specimens in mammal collections without karyotyping or sequencing, even though the specimens occurred in sympatric areas. Since most taxidermy protocols do not preserve the penis in mammal preparations, liquid preservation of some specimens or the removal of the penis before taxidermy for liquid preservation could be beneficial. We also recommend the organisation in museum collections of a penis bank for the A.cursor species group (or even all rodent species) to avoid losing this important information for species identification.

Molecular systematics of the Sicista tianschanica species complex: a contribution from historical DNA analysis

The Tianshan birch mouse Sicista tianschanica is an endemic of the Central Asian mountains and has previously been shown to include several karyomorphs (“Terskey”, “Talgar”, “Dzungar”); however, the taxonomic status of these forms has remained uncertain. We examined the genetic variation in S. tianschanica based on historical DNA samples from museum collections, including the type series. Mitochondrial and nuclear data indicated that the species complex includes two major clades: Northern (N) and Southern (S) (cytb distance 13%). The N clade corresponds to the “Dzungar” karyomorph (Dzungar Alatau, Tarbagatay). The S clade is comprised of four lineages (S1–S4) divergent at 6–8%; the relationships among which are resolved incompletely. The S1 lineage is found in eastern Tianshan and corresponds to the nominal taxon. The S2 is distributed in central and northern Tianshan and corresponds to the “Terskey” karyomorph. The S3 is restricted to Trans-Ili Alatau and belongs to the “Talgar” karyomorph. The S4 is represented by a single specimen from southeastern Dzungar Alatau with "Talgar" karyotype. No interlineage gene flow was revealed. The validity of S. zhetysuica (equivalent to the N clade) is supported. Based on genetic and karyotypic evidence, lineages S2 and S3 are described as distinct species. The status of the S4 requires further investigation.

Phenotypic plasticity rather than genotype drives reproductive choices in Hydra populations

Facultative clonality is associated with complex life cycles where sexual and asexual forms can be exposed to contrasting selection pressures. Facultatively clonal animals often have distinct developmental capabilities that depend on reproductive mode (e.g., negligible senescence and exceptional regeneration ability in asexual individuals, which are lacking in sexual individuals). Understanding how these differences in life history strategies evolved is hampered by limited knowledge of the population structure underlying sexual and asexual forms in nature. Here we studied genetic differentiation of coexisting sexual and asexual Hydra oligactis polyps, a freshwater cnidarian where reproductive mode-dependent life history patterns are observed. We collected asexual and sexual polyps from 13 Central European water bodies and used restriction-site associated DNA sequencing to infer population structure. We detected high relatedness among populations and signs that hydras might spread with resting eggs through zoochory. We found no genetic structure with respect to mode of reproduction (asexual vs. sexual). On the other hand, clear evidence was found for phenotypic plasticity in mode of reproduction, as polyps inferred to be clones differed in reproductive mode. Moreover, we detected two cases of apparent sex change (males and females found within the same clonal lineages) in this species with supposedly stable sexes. Our study describes population genetic structure in Hydra for the first time, highlights the role of phenotypic plasticity in generating patterns of life history variation, and contributes to understanding the evolution of reproductive mode-dependent life history variation in coexisting asexual and sexual forms.

Phylogeny, species delimitation and population structure of the steppe-inhabiting land snail genus Helicopsis in Eastern Europe

We here study the steppe-inhabiting land snail genus Helicopsis (Gastropoda: Geomitridae: Helicellinae) across Eastern Europe using mitochondrial 16S rDNA sequences and nuclear AFLP markers and compare the biogeographical patterns with those of other steppe-inhabiting organisms. The subdivision of Central and Eastern European Helicopsis reflects the geographical subdivision of the European steppe belt in Pontic, Pannonian and Northern steppes. The subdivision within Helicopsis is deeper, at the species level, than in most other steppe-inhabiting groups. Helicopsis populations from the Pontic steppes can be classified into two sister-species. Helicopsis lunulata includes mainly populations with depressed conical shells previously identified as H. striata, but also populations with disc-like shells previously identified as H. instabilis, and it is distributed mainly west of the Dnieper River. Most Helicopsis populations from east of the Dnieper, especially from Crimea, belong to the variable H. filimargo that includes H. gasprensis, H. retowskii, H. arenosa, H. luganica, H. martynovi and H. subfilimargo. The species inhabiting the Pannonian Basin and the Northern steppes form a well-supported monophylum, including H. hungarica in the Pannonian Basin, H. austriaca at the fringe of the Eastern Alps and H. striata mainly in the Northern steppes.

Genetic variation in the Sicista subtilis (Pallas, 1773) species group (Rodentia, Sminthidae), as compared to karyotype differentiation

Genetic variation in chromosomally polymorphic Sicista subtilis complex and related Sicista betulina species group was analysed using two mitochondrial markers (COI and Cytb). The S. subtilis group is shown to include six lineages, five of which correspond to species currently recognized based on cytogenetic and genetic data: Sicista nordmanni, Sicista trizona, S. subtilis sensu stricto, Sicista severtzovi and Sicista cimlanica. A previously unknown genetic lineage of S. subtilis was found in the North Caucasus. The existence of two divergent lineages within Sicista strandi is supported. It is suggested that the speciation rate in Sicista was strongly affected by rapid chromosomal evolution.

Reconstructed historical distribution and phylogeography unravels non-steppic origin of Caucasotachea vindobonensis (Gastropoda: Helicidae)

Existing data on the phylogeography of European taxa of steppic provenance suggests that species were widely distributed during glacial periods but underwent range contraction and fragmentation during interglacials into "warm-stage refugia." Among the steppe-related invertebrates that have been examined, the majority has been insects, but data on the phylogeography of snails is wholly missing. To begin to fill this gap, phylogeographic and niche modeling studies on the presumed steppic snail Caucasotachea vindobonensis were conducted. Surprisingly, reconstruction of ancestral areas suggests that extant C. vindobonensis probably originated in the Balkans and survived there during the Late Pleistocene glaciations, with a more recent colonization of the Carpatho-Pannonian and the Ponto-Caspian regions. In the Holocene, C. vindobonensis colonized between the Sudetes and the Carpathians to the north, where its recent and current distribution may have been facilitated by anthropogenic translocations. Together, these data suggest a possible non-steppic origin of C. vindobonensis. Further investigation may reveal the extent to which the steppic snail assemblages consist partly of Holocene newcomers.