Owing to its temperature dependence and low vagility, the asp viper (
Vipera aspis) is an interesting model species to study the effects of Pleistocene climatic fluctuations on vertebrate genomes. We ...genotyped 102 specimens from the whole Italian distribution range at three mitochondrial DNA regions (2278 characters, total) and six microsatellite DNA loci (Short Tandem Repeats, STR). The molecular phylogeny was constructed according to Bayesian, Neighbour Joining, Maximum Parsimony and Maximum Likelihood procedures. All methods grouped individuals of the three morphological subspecies (
V. a. aspis,
V. a. francisciredi,
V. a. hugyi) into five different haploclades. Specimens assigned to
hugyi clustered in two highly differentiated clades, one being sister group to the complex comprising the second clade of
hugyi (i.e., a paraphyletic status), plus two clades of
francisciredi. The Bayesian clustering of the STR variability disclosed only two groups, the first including
aspis and
francisciredi, the second all
hugyi. Introgressive hybridization and capture of
francisciredi-like lineages in the
hugyi mitochondrial genome were suggested to explain the discordance between mitochondrial and nuclear data. The phylogeographic pattern was compatible with population contractions in three glacial refuges. Plausibility of derived hypothesis was checked using coalescence simulations as
post hoc tests. Long-term drift and serial founder effects, rather than selection, appeared the main factors affecting the genetic make-up of the Italian asp viper.
The red‐legged partridge, Alectoris rufa (Phasianidae), is a game bird hunted throughout its range (Italy, France with Corsica Island, Iberian Peninsula). The release into the wild of farmed birds of ...unknown origin coupled to the hybridization with the exotic chukar Alectoris chukar (East Mediterranean to East Asia) has led to the reduction of the spatial component of genetic variability and to the pollution of the genome of A. rufa, respectively. On the mainland, A. chukar genes occur according a decreasing gradient from Italy to the Iberian Peninsula. Corsica hosts a number of A. rufa×A. chukar hybrids, but at a much lower incidence than nearby Italy. We sampled 97 red‐legged partridges in different habitats of Corsica lower‐Mediterranean: Desertu di l'Agriate; rural: Nessa‐Felicetu; mountainous: Vivariu‐Venacu and Fium'Orbu‐Taravu (FT). We investigated kinship between Corsican and continental A. rufa populations by sequencing the mitochondrial DNA (mtDNA) Cytochrome‐b gene in a subset (n=60) of island specimens as well as in 105 partridges sampled on mainland Europe. All 97 Corsican partridges were genotyped at eight microsatellite DNA loci in order to estimate intraspecific relationships at a finer scale. We also used microsatellite data from previous studies to compare the genotypes of A. rufa reared in the only island farm with those of wild conspecifics. Corsican partridges grouped in the only statistically reliable and diverging mtDNA clade. Microsatellites provided evidence for the genetic isolation of the FT mountain population, whose low level of hybridization with A. chukar had been unveiled in a former paper. Both mtDNA and microsatellite markers revealed that released captive partridges did not enter the wild breeding populations to any great extent. We suggested banning A. rufa translocation from Corsica to the continent to comply with the disclosed genetic kinship, and vice versa to contain the spreading of A. chukar genes in to the A. rufa population.
The strong hunting pressure on the red-legged partridge,
Alectoris rufa, warranted its inclusion into the list of species of European conservation concern. During the last decades, restocking plans ...with farmed specimens have counterbalanced the hunting drawings from wild populations. Our concern was the study of
A. rufa in the easternmost part of its range, the central Italy, to gain insights into the effects of this compensation practice on the genetic structure of its populations. Partridges from both a geographically isolated, long-time protected, wild population (Pianosa island, Tuscan Archipelago National Park) and two Tuscan farms (Bieri and Scarlino) were investigated. All the specimens were very similar in outward appearance, looking much like to
A. rufa. Ninety-six sequences of both Cytochrome
b and D-loop Control Region of mitochondrial DNA (mtDNA) were analysed to get evidence of ancestry at the population level, whereas, the Random Amplified Polymorphic DNA (RAPD) technique was employed to get fingerprinting at the individual level. Pianosa and Bieri populations showed both the
A. rufa and
Alectoris chukar mtDNA lineages, whereas the Scarlino one only the
A. rufa-mtDNA line. However, a spread overall pattern of
A. rufa
×
A. chukar hybridisation among specimens, whatever their mtDNA lineage could result to be, was disclosed by means of RAPD species-specific markers. This is the first genetically documented record of the
A. rufa
×
A. chukar hybrids. The occurrence of the pure, native
A. rufa genome in the easternmost part of the species’ geographical range may be guessed to be virtual.
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► Monophyly of each of the Asian francolins and of the spotted group. ► Far East origin (about 17.3Ma) and alleged monophyly of the Asian francolins. ► Indian sub-continent origin and ...westwards adaptive radiation of the black francolin. ► Relict black francolin population of Indian origin in the Pakistani range of the Great Rann of Kachchh.
We investigated the evolution of the Asian francolins, five little known species in the genus Francolinus (Phasianidae). Evolutionary affinities of two of these species, F. gularis (swamp francolin) and F. pondicerianus (grey francolin), has long remained unclear. In contrast, the other three species, F. pintadeanus (Chinese francolin), F. pictus (painted francolin) and F. francolinus (black francolin) have been cast among the “spotted francolins” on a morphological and ecological basis. Previous molecular DNA investigations including Asian francolins mostly relied upon partial gene sequencing of one specimen per species (no more than three species and with the exclusion of F. pictus). Therefore, fundamental questions do persist. What relationship exists among the spotted and the other Asian francolins? What is the geographic origin of the black francolin, the species with the largest distribution range? How did the geological history influence the diversification of francolins across Asia? We sequenced the entire Control Region of the mitochondrial DNA in 228 samples of all five Asian francolin species, which were collected in 16 countries (from East Europe to East Asia). We constructed a molecular phylogeny according to four different procedures. We showed the monophyly of each of the Asian francolins and the spotted group, while that of the entire Asian group was presumed according to a biogeographical model we proposed. The splitting of the genus Francolinus occurred ∼17.4Ma (95% HPD: 13.4–22.1) while the spotted francolins diverged ∼10.5Ma (7.0–14.9). We resolved the most recent common ancestor to painted and black francolin as being in the Indian sub-continent, thus suggesting a westwards adaptive radiation of the latter. In Pakistan, we identified F. f. asiae representatives in the Northern Areas and in the Sindh. The latter represents a relict population of Indian fauna within the Pakistani range of the Great Rann of Kachchh.
Type assignment systems with intersection and union types are introduced. Although the subject reduction property with respect to β-reduction does not hold for a natural deduction-like system, we ...manage to overcome this problem in two, different ways. The first is to adopt a notion of parallel reduction, which is a refinement of Gross-Knuth reduction. The second is to introduce type theories to refine the system, among which is the theory called Π that induces an assignment system preserving β-reduction. This type assignment system further clarifies the relation with the intersection discipline through the decomposition, first, of a disjunctive type into a set of conjunctive types and, second, of a derivation in the new type assignment system into a set of derivations in the intersection type assignment system. For this system we propose three semantics and prove soundness and completeness theorems.
The Chukar (Alectoris chukar cypriotes) is the most common game bird in Cyprus. Since 1990 the Cypriot Government has established a restocking program with captive–reared birds. However, this program ...has not been guaranteed by checking the genetic nature of wild and farmed samples, either in the areas controlled by the Cypriot Government or in northern Cyprus. The sequencing of both Cytochrome–b and Control Region of the mitochondrial DNA was carried out for 61 Cypriot representatives and 14 specimens of the same subspecies from Crete and Israel. Only the A. chukar maternal lineage was found. A partitioning of Cypriot specimens among different clades was not reliably supported, whereas robust bootstrap values weighted for an evolutionary divergence between Cypriot and Cretan Chukars. An overall genetic homogeny of the Cypriot populations was disclosed, whatever their status (captive vs. wild stocks) and origin (Government controlled vs. occupied areas) would be, a higher nucleotide diversity of the wild vs. captive representatives notwithstanding.
Key words: Chukar, Control Region, Cytochrome–b, Genetic diversity, mtDNA, Partridges.
Invariance of interpretation by
β
-conversion is one of the minimal requirements for any standard model for the
λ
-calculus. With the intersection-type systems being a general framework for the study ...of semantic domains for the
λ
-calculus, the present paper provides a (syntactic) characterisation of the above mentioned requirement in terms of characterisation results for intersection-type assignment systems.
Instead of considering conversion as a whole, reduction and expansion will be considered separately. Not only for usual computational rules like
β
,
η
, but also for a number of relevant restrictions of those. Characterisations will be also provided for (intersection) filter structures that are indeed
λ
-models.
A full continuous model of polymorphism Barbanera, Franco; Berardi, Stefano
Theoretical computer science,
2003, 2003-01-00, 20030101, Letnik:
290, Številka:
1
Journal Article
Recenzirano
Odprti dostop
We introduce a model of the second-order lambda calculus. Such a model is a Scott domain whose elements are themselves Scott domains, and in it polymorphic maps are interpreted by generic continous ...maps.
We introduce aλ-calculus with symmetric reduction rules and “classical” types, i.e., types corresponding to formulas of classical propositional logic. The strong normalization property is proved to ...hold for such a calculus, as well as for its extension to a system equivalent to Peano arithmetic. A theorem on the shape of terms in normal form is also proved, making it possible to get recursive functions out of proofs ofΠ02formulas, i.e., those corresponding to program specifications.
The physiological effects on isotropically heated populations of Oxytricha bifaria cultured at 24 degree C were investigated. At 34.6 degree C ciliates became inert, and did not adaptively react to ...either cold or warm microgradients; they neither moved towards the favorable cold thermal source nor escaped from the unfavorable warm one. The inert oxytrichas were only able to perform the Side-Stepping Reaction (SSR) on the same spot. However, mobile ciliates at 31.6 degree C reacted to the cold microgradient by immediately orienting themselves towards its source, without accelerating but reducing their SSR frequency. Moreover, in a warm microgradient such ciliates immediately increased their SSR frequency, then moved away from the thermal source. At 34.6 degree C the behavior of ciliates was not-adaptive--not acting to guide the organisms to more favorable conditions--whereas at 31.6 degree C it was still clearly adaptive. Therefore, the locomotory inertness of the oxytrichas at 34.6 degree C was the result of thermal stress rather than their behavioral response to the environmental isotropy, in contrast to populations of the same species made inert at 9 degree C.
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