Flavia Annesi

Systematics of the Microtus savii complex (Rodentia, Cricetidae) via mitochondrial DNA analyses: paraphyly and pattern of sex chromosome evolution.

The genus Microtus underwent a rapid evolutionary radiation that resulted in the extant 59 species distributed throughout the Palaearctic and Nearctic regions (Musser and Carleton, 2005; Conroy and Cook, 1999). The rapidity of speciation events within the genus is reflected in the widespread low interspecific morphological divergence, with the presence of many sibling species (Musser and Carleton, 2005). However, high intraspecific morphological variation of dental and other skull characters has led to the proliferation of subspecific names, causing even more confusing systematics of the genus (Koenigswald, 1980). Studies on karyotypes and DNA sequences have revealed extensive variation among species. Hence, a genetic approach is essential to delimit species and assess the phylogenetic relationships of the groups (Conroy and Cook, 1999, 2000; Mazurok et al., 2001; Jaarola et al., 2004; Li et al., 2006). The Italian endemic voles belonging to the Microtus savii complex represent another case of this systematic uncertainty. The taxa of this species complex are slightly different morphologically and have a variable karyotype. The diploid number is 2n = 54, with a constant autosomal set and variation in the shape and size of the sex chromosomes. This chromosomal and morphological polytypism has led to the identification of five taxa (see Table 1 and

Molecular phylogenetics of the Italian Podarcis lizards (Reptilia, Lacertidae)

Abstract Phylogenetic relationships within the Italian species of the lacertid genus Podarcis were examined by parsimony analysis of mitochondrial DNA sequences from the genes encoding the small ribosomal RNA and the phenyl transfer RNA. Lacerta viridis was used as outgroup and Teira dugesii was also included in the ingroup. The 80 phylogenetically informative positions produced four most parsimonious trees, with the Italian Podarcis split into three groups: the first comprised P. filfolensis, P. melisellensis. P. wagleriaria, P. muralis, and P. raffonei, the second P. sicula with its various subspecies. The third lineage was that of P. tiliguerta, whose relationships were resolved as more closely related to the first clade, when weighting transversion three times transitions. Bootstrap analyses on a subset of sequences representing all species herein studied, supported the results from the larger dataset. The present results are only partly in agreement with previous hypotheses based on morphology, immun...

Molecular systematics and evolutionary biogeography of the genus Talpa (Soricomorpha: Talpidae).

The range of the genus Talpa covers almost all Europe up to Western Asia. This genus has never been the object of comprehensive systematic studies using molecular and genetic techniques, such that the evolutionary relationships among species remain unclear. Talpa shows high levels of endemism, and the influence of past glaciation cycles on the distribution pattern of several species has been hypothesized. In this work, we assessed the molecular systematics of the genus using the mitochondrial gene cytochrome b from eight of the nine extant species of Talpa moles. Furthermore, molecular clock estimations were used to hypothesize a biogeographic scenario in concordance with fossil data. Results suggest a monophyletic origin of the genus and a common ancestor for the western European moles T. europaea, T. caeca, T. romana and T. occidentalis. The eastern species T. altaica and T. caucasica are basally divergent. The estimated ages of divergence among lineages are in accordance with a Miocene origin of the extant moles. The genus likely originated in Asia, spreading into Europe during the Pliocene. The evolution of moles appears to have been driven by changes in moisture levels that influenced extinction and speciation events during the Miocene and the Pliocene. Pleistocene climatic oscillations likely caused the range shrinkages and expansions that led to the current distribution pattern of most Talpa species.

Comparative structure analysis of vertebrate U17 small nucleolar RNA (snoRNA)

Intron-encoded U17 RNA is a member of the H/ACA box class of small nucleolar RNAs (snoRNAs) involved in ribosomal RNA (rRNA) maturation. U17 snoRNA shows typical characteristics of guide RNAs, which specify sites of pseudouridylation on the precursor rRNA (pre-rRNA). However, in spite of the presence of H and ACA boxes and short regions complementary to the pre-rRNA, its secondary structure does not show any evident pseudouridylation pocket. Moreover, its length is larger than the typical one of snoRNAs and it shows a more complex secondary structure compared to the canonical hairpin–hinge–hairpin–tail architecture. Greater knowledge of eukaryotic U17 snoRNA structure is needed to understand its precise function. Comparative molecular studies of this snoRNA with different vertebrates is still limited to a few cases. With the aim of increasing our understanding of the U17 snoRNA secondary structure, we cloned the U17 snoRNA coding sequence from 10 additional vertebrate taxa. On the basis of structure homology derived from sequence comparison and thermodynamic prediction, we propose a vertebrate consensus secondary structure and novel conserved sequence boxes for U17 snoRNA. Host gene localization of U17 coding sequence and its ability to serve as a guide sequence for RNA/RNA interaction has been evolutionarily traced from fish to mammals. It is interesting to note that turtle U17 snoRNAs show a noncanonical ACA box, mainly consisting in the GCA box. Microinjections in X. laevis oocytes of in vitro synthesized turtle transcripts containing the U17 RNA sequence which have canonical ACA, wild-type GCA, and mutated CCA and UCA boxes resulted in efficient production of mature U17 snoRNA.

Origin and evolution of Western European moles (genus Talpa, Insectivora): a multidisciplinary approach

ABSTRACT The European representatives of the subfamily Talpinae belong to the monophyletic genus Talpa. Five out of the nine species of Talpa occur in Western Europe. A wide central area is occupied by Talpa europaea, while the small sized Talpa caeca occurs in southern Europe. Three endemic species are restricted to the peripheral areas of the genus range and show a parapatric distribution with respect to T. europaea, i.e. the Iberian T. occidentalis, the southern Italian T. romana and the Balkan T. stankovici. The karyotypes of moles are very conservative, with the majority of the species showing 2n = 34. Allozyme data first allowed to assess the specific status of endemic taxa and the low levels of heterozygosity. Neis genetic distances suggest that T. occidentalis, T. romana and T. stankovici early diverged from an europaea–caeca line. Preliminary results from mtDNA analyses strongly support the monophyly of Western European moles, but are still not able to solve the relationships within this clade. Estimates of time of divergences indicate a basal split of an Eastern and a Western lineage during the Miocene-Pliocene transition, while the divergence among the Western European moles should have occurred in association to the Pliocene-Pleistocene climatic oscillations.

Integrative taxonomy of the Italian pine voles, Microtus savii group (Cricetidae, Arvicolinae)

The Italian endemic voles belonging to the Microtus savii group (de Sélys‐Longchamps, 1838) include five controversial taxa, namely M. savii savii, M. s. niethammericus Contoli ; M. s. tolfetanus Contoli , M. s. nebrodensis (Minà‐Palumbo, 1868) and M. brachycercus (Lehamann, 1961). A previous mtDNA phylogenetic analysis revealed three main mtDNA lineages that do not correspond to the recognized taxa. Here, we perform a comprehensive univariate and multivariate analysis of craniodental measurements in 151 specimens from 54 geographic samples belonging to the three main phylogroups. Qualitative data on the skull of 126 specimens were also obtained from 54 localities. Moreover, we sequenced the nuclear DNA β‐fibrinogen intron 7 (β‐fibint7) of 23 specimens from 12 localities and Cyt b sequences of 11 new specimens from seven localities. The pattern of morphological and cytogenomic divergence does not corroborate the current taxonomic framework and indicates that M. nebrodensis is a Sicilian endemic species.

Mitochondrial sequences and karyotypes reveal hidden diversity in African pouched mice (subfamily Cricetomyinae, genus Saccostomus)

The African rodent genus Saccostomus is common and widespread in the savannas, scrubby areas and cultivated fields from south Ethiopia and Somalia through East Africa down to the Cape Province. Its systematics and taxonomy are however poorly known, with two species currently recognized, S. mearnsi and S. campestris , the former is typical of the Somali–Maasai domain and the latter is typical of Zambezian–South African. The karyotypic findings and the analysis of the mitochondrial gene cytochrome b for some populations from Somalia, Tanzania, Zambia and South Africa are presented showing that the diversity within the genus is much higher than previously reported and believed, and that S. mearnsi and S. campestris rather represent species complexes, still actively speciating. The times of cladogenetic events and the extent of chromosomal variability within the genus that may be coupled with speciation are discussed. Finally, the possible taxonomy is considered in the context of the wide karyotypic variation shown by each species, the extent and the boundaries of which are still largely unknown, limiting therefore their definitive taxonomic assignment.

Mitochondrial phylogeography of the black rat supports a single invasion of the western Mediterranean basin

Abstract The black rat Rattus rattus is recognized as one of the world’s most harmful invasive species. It has spread across the globe by passive human transport and the dynamics of colonization have been investigated in several areas of the world. However, data for the Mediterranean basin are still lacking. We investigated the black rat colonization of the western Mediterranean basin by means of mitochondrial genes. Mitochondrial control region and cytochrome b gene were sequenced in order to quantify genetic diversity of western Mediterranean black rats. Maximum likelihood phylogenetic analysis based on cytochrome b was used to assign specimens to a specific lineage of the R. rattus species complex. The mitochondrial control region was used to reconstruct phylogeographic pattern by statistical parsimony network and to asses historical demography of western Mediterranean black rats. The results show an unexpectedly low diversity considering that the Mediterranean basin has been a trade route since very ancient times. The results mtDNA analysis are compatible with a single event of invasions of western Mediterranean by R. rattus.

The first cytogenetic description of Euleptes europaea (Gené, 1839) from Northern Sardinia reveals the highest diploid chromosome number among sphaerodactylid geckos (Sphaerodactylidae, Squamata)

Abstract The karyotype of a sphaerodactylid gecko Euleptes europaea (Gené, 1839) was assembled for the first time in this species. It is made of 2n = 42 gradually decreasing in size chromosomes, the highest chromosome number so far acknowledged in the family Sphaerodactylidae. The second chromosome pair of the karyotype appears slightly heteromorphic in the male individual. Accordingly, FISH with a telomeric probe revealed an uneven distribution of telomeric repeats on the two homologues of this pair, which may be indicative of an XY sex-determination system in the species, to be further investigated.

Morphometric and genetic divergence in island and mainland populations of Anolis nebulosus (Squamata: Polychrotidae) from Jalisco (Mexico): an instance of insular gigantism

Abstract The clouded anole Anolis nebulosus (Squamata: Polychrotidae) is widespread on the Pacific coast of Mexico. The species also inhabits Don Panchito, a small islet located near the coast of the Chamela-Cuixmala Biosphere Reserve in the state of Jalisco. We studied the extent of intraspecific differences in morphology (absolute size and body proportions) and in mtDNA sequences (16S and NDH2) between the population living on the islet (N = 18 for morphometry; N = 12 for mtDNA) and the one on the facing mainland (N = 38 for morphometry; N = 16 for mtDNA). The individuals on the islet are larger than those on the mainland with little overlap in size for either males (islet: 52.79 ± 1.82 mm; mainland: 40.96 ± 2.99 mm) or females (islet: 46.18 ± 3.24 mm; mainland 37.14 ± 2.13 mm). The presence of insular gigantism, as here found in A. nebulosus, seems uncommon in the genus and could be explained as a combination of low predation pressure and higher intraspecific competition on the island. Moreover, we found that sexual dimorphism (SD) is higher in the island population than in the mainland one. The molecular analysis shows the absence of shared haplotypes between the island and mainland populations. Ten mtDNA haplotypes belonged to the mainland population and three to the island population. The shape of the minimum spanning network and of the mismatch distribution indicates a single colonization event. These molecular data indicate a certain degree of isolation of the island population notwithstanding its proximity to the coast. The morphological characteristics of the anoles on Don Panchito match with the expectation of the so-called “reversed island syndrome” theory, which predicts an increased body size and sexual dimorphism in lizards living on very small islands characterized by unpredictable environmental conditions.