16 resultados para 170-1042B
em Helda - Digital Repository of University of Helsinki
Resumo:
This dissertation provides a synchronic grammatical description of Mauwake, a Papuan (Trans-New Guinea) language of about 2000 speakers on the North Coast of the Madang Province in Papua New Guinea. The theoretical background is that of Basic Linguistic Theory (BLT), used extensively in analysing and writing descriptive grammars. The chapters from morphology to clause level are described from form to function; in the later chapters the function is taken more often as the starting point. Any theory-specific terminology is kept to the minimum and formalisms have been avoided in accordance with BLT principles. Mauwake has a classic 5-vowel system and 14 consonant phonemes. With its simple phonology it is a typical representative of the Madang North Coast languages. For a Papuan language there are relatively few morphophonological alternations. Nouns are either alienably or inalienably possessed. There is no obligatory number marking in nouns or noun phrases. Pronouns have several different forms: five for case and three for other functions. The dative pronouns are treated as [+human] locatives, and they have also grammaticalised as possessives. The verbal morphology is agglutinative and mainly suffixal. Unusual features include two distributive suffixes, and the interaction of the derivational benefactive and the inflectional beneficiary suffixes. The applicative suffix has either transitivising or causative but not benefactive function. The switch-reference system distinguishes between simultaneous and sequential action, as well as same or different subject in relation to the following clause. There are several verbs denoting coming and going, and they may combine with one of three prefixes to indicate bringing and taking. Mauwake is a nominative-accusative type language, and the basic constituent order in a clause is SOV. Subject and object are the only syntactic arguments. There is no indirect object, but a clause can have two or even three objects. A nominalised clause with a finite verb functions as a relative clause or a complement clause; one with a nominalised verb has several different functions. Functional domains described include modality, negation, deixis, quantification, possession and comparison. As there are four negators, Mauwake has more variation in negative expressions than is usual in Papuan languages. Clause chaining is the preferred strategy for joining clauses into sentences, but coordination and subordination of finite clauses are also common. The form of a complement clause depends on whether it is of the fact, action or potential type. Tail-head linkage is used as a cohesive device between sentences. The discourse-level features described are topic and focus.
Resumo:
Tutkielmassa lähestytään sananlaskuja niiden käyttökontekstin kautta. Tarkastelun kohteena on kirjoitettu kertova aineisto, jossa esiintyy sananlaskuja muun kerronnan yhteydessä. Sananlaskuja lähestytään kuulijan näkökulmasta, kuulijan tulkintaan tukeutuen. Aineistona on Kalevalan juhlavuoden 1985 kilpakirjoitus "Perinne elämässäni". Tarkasteltavina ovat kilpakirjoituksen aihepiirit 1. "Koti ja suku" sekä 5. "Sukupuoliroolit ja kasvatus avioliittoon". Tutkielman aineiston muodostavat vastaukset, joissa kerronta käyttää sananlaskuja. Tällaisia vastauksia on yhteensä 170 kerääjän aineistossa (188 vastaajalta) koko kilpakeruun ko. aihepiirien sisältäessä 439 keräystä. Vastaajien ikä vaihtelee 13-90 ikävuoden välillä. Muisteluaineisto käsittelee vuosia 1900-1985. Kilpakeruun vastaukset ovat muistelukerrontaa. Tämän tutkielman aineistossa kertojat muistelevat lapsuuttaan ja tuovat esille kuulijan näkökulman sananlaskujen käyttötilanteista. Sekä arkistotietoon että muistelukerrontaan liittyy olennaisesti aineiston lähdekriittinen tarkastelu. Tutkimuksessa sananlasku on yleisnimitys. Vastaajat ovat käsitelleet yhdenvertaisesti sananlaskuna niin sananlaskut, sananparret, sanonnat kuin raamatunlauseetkin, joten tutkielmassakin ne on käsitelty sananlaskuina. Tutkimustehtävänä on ollut selvittää yhtäältä kuka sananlaskuja käytti ja toisaalta missä tarkoituksessa sananlaskuja käytettiin. Näkökulma on kuulijan. Ensimmäiseen kysymykseen vastaus haettiin kertomuksissa olleista maininnoista, kuten esimerkiksi "äiti sanoi ...", "kuulin mummoltani ...", "lapsuudessani neuvottiin ...", "isälläni oli tapana sanoa ...". Toista kysymystä lähestyttiin käyttöyhteyden teonsanalla. Oletuksena oli, että kuulija käyttämällään verbillä kertoi, missä mielessä hän sananlaskuja koki käytetyn. Kertomusten mukaan sananlaskujen käytön koettiin liittyvän neuvoviin ja ohjaaviin tapahtumiin, kotona tapahtuneeseen kasvatukseen. Ne olivat osa kasvatuksessa käytettyä puhetta. Toinen aineistossa esiin tullut sananlaskujen käyttöyhteys oli sananlaskujen käyttö retorisena tehokeinona. Väitteitä voitiin todentaa, kumota, vahvistaa jne. sananlaskujen avulla. Sananlaskuja kerrotiin kuullun ennen kaikkea kotona, kotiympäristössä. Niiden alkuperä voi olla joko personoimaton ryhmä tai käyttäjä oli nimetty. Kun kyseessä oli ryhmän personoimaton puhe tai tieto, oli kyse ennen kaikkea vanhojen tiedosta, viisaista lauseista. Milloin sananlaskut on kuultu nimetyltä henkilöltä, oli kyseessä useimmiten äiti tai isoäiti. Tämä selittynee osin sillä, että lasten kasvatuksesta ovat kotiympäristössä huolehtineet suvun ja perheen naiset.
Resumo:
This thesis examines the feasibility of a forest inventory method based on two-phase sampling in estimating forest attributes at the stand or substand levels for forest management purposes. The method is based on multi-source forest inventory combining auxiliary data consisting of remote sensing imagery or other geographic information and field measurements. Auxiliary data are utilized as first-phase data for covering all inventory units. Various methods were examined for improving the accuracy of the forest estimates. Pre-processing of auxiliary data in the form of correcting the spectral properties of aerial imagery was examined (I), as was the selection of aerial image features for estimating forest attributes (II). Various spatial units were compared for extracting image features in a remote sensing aided forest inventory utilizing very high resolution imagery (III). A number of data sources were combined and different weighting procedures were tested in estimating forest attributes (IV, V). Correction of the spectral properties of aerial images proved to be a straightforward and advantageous method for improving the correlation between the image features and the measured forest attributes. Testing different image features that can be extracted from aerial photographs (and other very high resolution images) showed that the images contain a wealth of relevant information that can be extracted only by utilizing the spatial organization of the image pixel values. Furthermore, careful selection of image features for the inventory task generally gives better results than inputting all extractable features to the estimation procedure. When the spatial units for extracting very high resolution image features were examined, an approach based on image segmentation generally showed advantages compared with a traditional sample plot-based approach. Combining several data sources resulted in more accurate estimates than any of the individual data sources alone. The best combined estimate can be derived by weighting the estimates produced by the individual data sources by the inverse values of their mean square errors. Despite the fact that the plot-level estimation accuracy in two-phase sampling inventory can be improved in many ways, the accuracy of forest estimates based mainly on single-view satellite and aerial imagery is a relatively poor basis for making stand-level management decisions.
Resumo:
Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) is the most common hereditary vascular dementia. CADASIL is a systemic disease of small and medium-sized arteries although the symptoms are almost exclusively neurological, including migraineous headache, recurrent ischemic episodes, cognitive impairment and, finally, subcortical dementia. CADASIL is caused by over 170 different mutations in the NOTCH3 gene, which encodes a receptor expressed in adults predominantly in the vascular smooth muscle cells. The function of NOTCH3 is not crucial for embryonic development but is needed after birth. NOTCH3 directs postnatal arterial maturation and helps to maintain arterial integrity. It is involved in regulation of vascular tone and in the wound healing of a vascular injury. In addition, NOTCH3 promotes cell survival by inducing expression of anti-apoptotic proteins. NOTCH3 is a membrane-spanning protein with a large extracellular domain (N3ECD) containing 34 epidermal growth factor-like (EGF) repeats and a smaller intracellular domain with six ankyrin repeats. All CADASIL mutations are located in the EGF repeats and the majority of the mutations cause gain or loss of one cysteine residue in one of these repeats leading to an odd number of cysteine residues, which in turn leads to misfolding of N3ECD. This misfolding most likely alters the maturation, targetting, degradation and/or function of the NOTCH3 receptor. CADASIL mutations do not seem to affect the canonical NOTCH3 signalling pathway. The main pathological findings are the accumulation of the NOTCH3 extracellular domain on degenerating vascular smooth muscle cells (VSMCs), accumulation of granular osmiophilic material (GOM) in the close vicinity of VSMCs as well as fibrosis and thickening of arterial walls. Narrowing of the arterial lumen and local thrombosis cause insufficient blood flow, mainly in small arteries of the cerebral white matter, resulting in tissue damage and lacunar infarcts. CADASIL is suspected in patients with a suggestive family history and clinical picture as well as characteristic white matter alterations in magnetic resonance imaging. A definitive verification of the diagnosis can be achieved by identifying a pathogenic mutation in the NOTCH3 gene or through the detection of GOM by electron microscopy. To understand the pathology underlying CADASIL, we have generated a unique set of cultured vascular smooth muscle cell (VSMC) lines from umbilical cord, placental, systemic and cerebral arteries of CADASIL patients and controls. Analyses of these VSMCs suggest that mutated NOTCH3 is misfolded, thus causing endoplasmic reticulum stress, activation of the unfolded protein response and increased production of reactive oxygen species. In addition, mutation in NOTCH3 causes alterations in actin cytoskeletal structures and protein expression, increased branching and abnormal node formation. These changes correlate with NOTCH3 expression levels within different VSMCs lines, suggesting that the phenotypic differences of SMCs may affect the vulnerability of the VSMCs and, therefore, the pathogenic impact of mutated NOTCH3 appears to vary in the arteries of different locations. Furthermore, we identified PDGFR- as an immediate downstream target gene of NOTCH3 signalling. Activation of NOTCH induces up-regulation of the PDGFR- expression in control VSMCs, whereas this up-regulation is impaired in CADASIL VSMCs and might thus serve as an alternative molecular mechanism that contributes to CADASIL pathology. In addition, we have established the congruence between NOTCH3 mutations and electron microscopic detection of GOM with a view to constructing a strategy for CADASIL diagnostics. In cases where the genetic analysis is not available or the mutation is difficult to identify, a skin biopsy is an easy-to-perform and highly reliable diagnostic method. Importantly, it is invaluable in setting guidelines concerning how far one should proceed with the genetic analyses.
Resumo:
Essential thrombocythaemia (ET) is a myeloproliferative disease (MPD) characterized by thrombocytosis, i.e. a constant elevation of platelet count. Thrombocytosis may appear in MPDs (ET, polycythaemia vera, chronic myeloid leukaemia, myelofibrosis) and as a reactive phenomenon. The differential diagnosis of thrombocytosis is important, because the clinical course, need of therapy, and prognosis are different in patients with MPDs and in those with reactive thrombocytosis. ET patients may remain asymptomatic for years, but serious thrombohaemorrhagic and pregnancy-related complications may occur. The complications are difficult to predict. The aims of the present study were to evaluate the diagnostic findings, clinical course, and prognostic factors of ET. The present retrospective study consists of 170 ET patients. Two thirds had a platelet count < 1000 x 109/l. The diagnosis was supported by an increased number of megakaryocytes with an abnormal morphology in a bone marrow aspirate, aggregation defects in platelet function studies, and the presence of spontaneous erythroid and/or megakaryocytic colony formation in in vitro cultures of haematopoietic progenitors. About 70 % of the patients had spontaneous colony formation, while about 30 % had a normal growth pattern. Only a fifth of the patients remained asymptomatic. Half had a major thrombohaemorrhagic complication. The proportion of the patients suffering from thrombosis was as high as 45 %. About a fifth had major bleedings. Half of the patients had microvascular symptoms. Age over 60 years increased the risk of major bleedings, but the occurrence of thrombotic complications was similar in all age groups. Male gender, smoking in female patients, the presence of any spontaneous colony formation, and the presence of spontaneous megakaryocytic colony formation in younger patients were identified as risk factors for thrombosis. Pregnant ET patients had an increased risk of complications. Forty-five per cent of the pregnancies were complicated and 38 % of them ended in stillbirth. Treatment with acetylsalicylic acid alone or in combination with platelet lowering drugs improved the outcome of the pregnancy. The present findings about risk factors in ET as well as treatment outcome in the pregnancies of ET patients should be taken into account when planning treatment strategies for Finnish patients.
Resumo:
Objectives: To evaluate the applicability of visual feedback posturography (VFP) for quantification of postural control, and to characterize the horizontal angular vestibulo-ocular reflex (AVOR) by use of a novel motorized head impulse test (MHIT). Methods: In VFP, subjects standing on a platform were instructed to move their center of gravity to symmetrically placed peripheral targets as fast and accurately as possible. The active postural control movements were measured in healthy subjects (n = 23), and in patients with vestibular schwannoma (VS) before surgery (n = 49), one month (n = 17), and three months (n = 36) after surgery. In MHIT we recorded head and eye position during motorized head impulses (mean velocity of 170º/s and acceleration of 1 550º/s²) in healthy subjects (n = 22), in patients with VS before surgery (n = 38) and about four months afterwards (n = 27). The gain, asymmetry and latency in MHIT were calculated. Results: The intraclass correlation coefficient for VFP parameters during repeated tests was significant (r = 0.78-0.96; p < 0.01), although two of four VFP parameters improved slightly during five test sessions in controls. At least one VFP parameter was abnormal pre- and postoperatively in almost half the patients, and these abnormal preoperative VFP results correlated significantly with abnormal postoperative results. The mean accuracy in postural control in patients was reduced pre- and postoperatively. A significant side difference with VFP was evident in 10% of patients. In the MHIT, the normal gain was close to unity, the asymmetry in gain was within 10%, and the latency was a mean ± standard deviation 3.4 ± 6.3 milliseconds. Ipsilateral gain or asymmetry in gain was preoperatively abnormal in 71% of patients, whereas it was abnormal in every patient after surgery. Preoperative gain (mean ± 95% confidence interval) was significantly lowered to 0.83 ± 0.08 on the ipsilateral side compared to 0.98 ± 0.06 on the contralateral side. The ipsilateral postoperative mean gain of 0.53 ± 0.05 was significantly different from preoperative gain. Conclusion: The VFP is a repeatable, quantitative method to assess active postural control within individual subjects. The mean postural control in patients with VS was disturbed before and after surgery, although not severely. Side difference in postural control in the VFP was rare. The horizontal AVOR results in healthy subjects and in patients with VS, measured with MHIT, were in agreement with published data achieved using other techniques with head impulse stimuli. The MHIT is a non-invasive method which allows reliable clinical assessment of the horizontal AVOR.
Resumo:
We present three measurements of the top-quark mass in the lepton plus jets channel with approximately 1.9 fb-1 of integrated luminosity collected with the CDF II detector using quantities with minimal dependence on the jet energy scale. One measurement exploits the transverse decay length of b-tagged jets to determine a top-quark mass of 166.9+9.5-8.5 (stat) +/- 2.9 (syst) GeV/c2, and another the transverse momentum of electrons and muons from W-boson decays to determine a top-quark mass of 173.5+8.8-8.9 (stat) +/- 3.8 (syst) GeV/c2. These quantities are combined in a third, simultaneous mass measurement to determine a top-quark mass of 170.7 +/- 6.3 (stat) +/- 2.6 (syst) GeV/c2.
Resumo:
We present three measurements of the top-quark mass in the lepton plus jets channel with approximately 1.9 fb-1 of integrated luminosity collected with the CDF II detector using quantities with minimal dependence on the jet energy scale. One measurement exploits the transverse decay length of b-tagged jets to determine a top-quark mass of 166.9+9.5-8.5 (stat) +/- 2.9 (syst) GeV/c2, and another the transverse momentum of electrons and muons from W-boson decays to determine a top-quark mass of 173.5+8.8-8.9 (stat) +/- 3.8 (syst) GeV/c2. These quantities are combined in a third, simultaneous mass measurement to determine a top-quark mass of 170.7 +/- 6.3 (stat) +/- 2.6 (syst) GeV/c2.
Resumo:
One of the effects of the Internet is that the dissemination of scientific publications in a few years has migrated to electronic formats. The basic business practices between libraries and publishers for selling and buying the content, however, have not changed much. In protest against the high subscription prices of mainstream publishers, scientists have started Open Access (OA) journals and e-print repositories, which distribute scientific information freely. Despite widespread agreement among academics that OA would be the optimal distribution mode for publicly financed research results, such channels still constitute only a marginal phenomenon in the global scholarly communication system. This paper discusses, in view of the experiences of the last ten years, the many barriers hindering a rapid proliferation of Open Access. The discussion is structured according to the main OA channels; peer-reviewed journals for primary publishing, subject- specific and institutional repositories for secondary parallel publishing. It also discusses the types of barriers, which can be classified as consisting of the legal framework, the information technology infrastructure, business models, indexing services and standards, the academic reward system, marketing, and critical mass.
Resumo:
Det är helt naturligt att konsumenterna sprider marknadsinformation genom att sinsemellan prata om sina konsumtionserfarenheter. Även om man i marknadsföringslitteraturen betonar den konsumentdominerade informella marknadskommunikationens genuina karaktär jämfört med den företagsdominerade formella marknadskommunikationen, så har man rätt dåliga kunskaper om företagets möjligheter att systematiskt utnyttja denna typ av marknadskommunikation. Min analys tyder på att den beteendevetenskapliga och den företagsekonomiska word-of-mouth-forskningen anlägger olika perspektiv som inte möter varandra. Den beteendevetenskapliga word-of-mouth-forskningen har tydligare satt fokus på själva företeelsen informell marknadskommunikation, men perspektivet har inte varit speciellt företagsorienterat. Den företagsekonomiska word-of-mouth-forskningen har i sin tur varit betydligt tydligare fokuserad på möjligheterna att använda informell marknadskommunikation, men däremot har man inte fäst speciellt mycket uppmärksamhet vid själva företeelsen informell marknadskommunikation. Min kontribution till den vetenskapliga diskussionen om företagens möjligheter att systematisera utnyttjandet av informell marknadskommunikation består i att överbrygga denna dualism inom word-of-mouth-forskningen genom att anlägga ett företagsperspektiv på den sociala dynamiken för informell marknadskommunikation. Denna ansats har sin teoretiska förankring hos de s.k. moderna men bortglömda pionjärerna, med vilka jag avser Johan Arndt, Donald Cox och Ernest Dichters kontribution till den företagsorienterade word-of-mouth-forskningen redan i slutet av 1960-talet. Efter det har deras synpunkter och insikter varken förts vidare eller vidareutvecklats, vilket jag betraktar som ett bakslag för den företagsorienterade word-of-mouth-forskningen. Föreliggande studie har bidragit till word-of-mouth-forskningen på tre olika sätt: genom 1) bidrag baserat på litteraturanalys, 2) bidrag baserat på empirianalys och 3) bidrag baserat på begreppsligande av informell marknadskommunikation. Min litteraturanalys framställer word-of-mouth-forskningens uppkomst och utveckling i ny dager. Min empirianalys har genererat empiriska begrepp, dels för att beskriva informell marknadskommunikation som företeelse, dels för att beskriva företagens förfarande för att systematisera utnyttjandet av sådan marknadskommunikation. Den begreppsliga kontributionen accentueras i informell marknadskommunikation som ett samlingsbegrepp för olika typer av interkonsumentkommunikation.
Resumo:
Recent research documents that institutional or large investors act as antagonists to other investors by showing opposite behavior following disclosure of new information. Using an extremely comprehensive official transactions data set from Finland, we set out to explore the interrelation between investor size and behavior. More specifically, we test whether investor size is positively (negatively) correlated with investor reaction following positive (negative) news. We document robust evidence of that investor size affects investor behavior under new information, as larger investors on average react more positively (negatively) to good (bad) news than smaller investors. In the light of this study it seems increasingly feasible that several recent findings of heterogeneous investor behavior are functions of differences in overconfidence.
Resumo:
Tämän maisterin tutkielman tarkoituksena oli testata eri maitohappobakteerien ja niiden annostustason vaikutusta säilörehun käymislaatuun ja aerobiseen stabiilisuuteen. Biologisilla säilöntäaineilla eli ympeillä säilöttyjen rehujen laatua verrattiin kontrolleina toimiviin painorehuun ja muurahaishapolla tehtyyn rehuun. Koerehut tehtiin Helsingin yliopiston Maataloustieteiden laitoksella 7.6.2010. Timotei (Phleum pratense) - nurminata (Festuca pratensis) kasvusto korjattiin tähkimisen alkuvaiheessa D-arvon ollessa 711 g/kg ka. Nurmikasvuston kuiva-ainepitoisuus oli 170 g/kg heti niiton jälkeen määritettäessä ja neljän tunnin esikuivauksen jälkeen 208 g/kg. Rehuraaka-aine jaettiin kuuteen erään, joihin lisättiin säilöntäaine. Säilöntäainekäsittelyt olivat: 1) ei säilöntäainetta (painorehu), 2) muurahaishappo (100 %:na 4 l/t), 3) Lactobacillus plantarum ja Pediococcus acidilactici 1x10? pmy/g sekä pektinaasi-, ksylanaasi- ja sellulaasientsyymi, 4) L. plantarum 1x10? pmy/g, 5) L. plantarum 1x10? pmy/g ja 6) L. plantarum ja L. buchneri 2x10? pmy/g. Rehut säilöttiin laboratoriosiiloissa kolmena rinnakkaisena. Laboratoriosiilojen lisäksi rehua säilöttiin jokaisesta säilöntäainekäsittelystä kuuteen rinnakkaiseen minisiiloon säilönnän alkuajan fermentaation ja rehujen pH:n muutoksen seuraamiseksi. Minisiiloista seurattiin kaasuntuotantoa 21 päivän ajan. Raaka-aineen koostumus ja rehujen säilönnällinen laatu sekä aerobinen stabiilisuus määritettiin. Säilörehujen kuiva-ainepitoisuus oli suhteellisen pieni (n. 210 g/kg), jotta voitiin testata biologisten säilöntäaineiden tehoa märässä rehussa. Kosteassa rehussa biologisten säilöntäaineiden toiminnan onnistuminen on haastavaa. Koska raaka-aineen sokeripitoisuus oli kuitenkin erittäin suuri (196 g/kg ka), onnistui ymppirehujen säilöntä hyvin. Kaikkien koerehujen pH oli alle 4:n. Painorehu ei täyttänyt hyvän rehun kriteerejä ammoniumtypen osalta. Muurahaishapporehu oli laadultaan tyydyttävää etikkahapon pitoisuuden osalta. Rehussa tapahtui epätyypillistä etanolikäymistä hiivojen toimesta, jonka johdosta rehussa muodostui suuri määrä kaasua säilönnän aikana. Muurahaishapporehu ei kuitenkaan lämmennyt aerobisen stabiilisuuden mittauksen aikana, johtuen todennäköisesti suuresta etikkahapon määrästä ja toisaalta pienestä sokerin määrästä. Maitohappobakteerisäilöntäaineilla saatiin käymislaadultaan parempaa säilörehua verrattuna painorehuun, lukuun ottamatta maitohappobakteeri-entsyymirehua. Entsyymilisäyksestä ei todennäköisesti ollut hyötyä rehun säilöntälaadun kannalta. Raaka-aineen suuren sokeripitoisuuden johdosta säilörehussa oli koko säilönnän ajan tarpeeksi sokeria maitohappobakteerien käytettäväksi ja sokeri toimi siten substraattina haitallisille mikrobeille tuottaen suuren etikkahappopitoisuuden. Maitohappobakteeri-entsyymiseoksella tehty rehu oli etikkahappopitoisuuden perusteella heikkolaatuista. Lactobacillus plantarumin molemmilla annostustasoilla (1x10? ja 1x10? pmy/g rehua) saatiin laadultaan hyvää rehua. Suuri sokeripitoisuus molemmissa rehuissa johtui todennäköisesti raaka-aineen tavallista suuremmasta sokerin määrästä. Molempien rehujen maitohappo-etikkahappo-suhde oli melko korkea, viitaten homofermentatiiviseen maitohappokäymiseen. Lactobacillus buchneri –lisäyksellä rehu oli säilönnälliseltä laadultaan hyvää. Heterofermentatiivisen ympin lisäys nosti tyypillisesti rehun pH:ta sekä pienensi maitohappoetikkahappo-suhdelukua verrattuna homofermentatiiviseen ymppiin. L. buchneri –lisäys paransi hieman säilörehun aerobista stabiilisuutta verrattuna homofermentatiivisella maitohappobakteerilla säilöttyyn rehuun, mutta tulos ei ollut tilastollisesti merkitsevä.
Resumo:
The Iberian Peninsula is recognized as an important refugial area for species survival and diversification during the climatic cycles of the Quaternary. Recent phylogeographic studies have revealed Iberia as a complex of multiple refugia. However, most of these studies have focused either on species with narrow distributions within the region or species groups that, although widely distributed, generally have a genetic structure that relates to pre-Quaternary cladogenetic events. In this study we undertake a detailed phylogeographic analysis of the lizard species, Lacerta lepida, whose distribution encompasses the entire Iberian Peninsula. We attempt to identify refugial areas, recolonization routes, zones of secondary contact and date demographic events within this species. Results support the existence of 6 evolutionary lineages (phylogroups) with a strong association between genetic variation and geography, suggesting a history of allopatric divergence in different refugia. Diversification within phylogroups is concordant with the onset of the Pleistocene climatic oscillations. The southern regions of several phylogroups show a high incidence of ancestral alleles in contrast with high incidence of recently derived alleles in northern regions. All phylogroups show signs of recent demographic and spatial expansions. We have further identified several zones of secondary contact, with divergent mitochondrial haplotypes occurring in narrow zones of sympatry. The concordant patterns of spatial and demographic expansions detected within phylogroups, together with the high incidence of ancestral haplotypes in southern regions of several phylogroups, suggests a pattern of contraction of populations into southern refugia during adverse climatic conditions from which subsequent northern expansions occurred. This study supports the emergent pattern of multiple refugia within Iberia but adds to it by identifying a pattern of refugia coincident with the southern distribution limits of individual evolutionary lineages. These areas are important in terms of long-term species persistence and therefore important areas for conservation.