Дисертації з теми "Terrestrial molluscs"

This thesis investigates the potential of using terrestrial molluscs for radiocarbon dating of archaeological sediments. The sequence at the Haua Fteah, Cyrenaica, in Libya provides a case study. Two strands of study were undertaken as part of the ERC funded Cyrenaica Prehistory Project: the examination of the present day radiocarbon ecology of species in the region; and an analysis of archaeological shell from the Haua Fteah cave with the aim of developing a high-resolution chronology for the upper portions of the site. Previously, the dating for many of the key lithic technological phases in the region has been reliant on a patchwork of sites which were anchored by relatively poor dating on a very small number of long sequences, of which the Haua Fteah is one of the most significant. Based on the findings of the modern study, an age offset of 584 ± 170 14C years BP was adopted for the correction of the shell reservoir effect in archaeological Helix melanostoma.The radiocarbon dating of archaeological shell from the Haua Fteah and Hagfet et Gama at a very high stratigraphic resolution found that a complex chronological pattern wf=ls present, with frequent dating reversals through the late quaternary sequence. The high resolution dating of the Late Pleistocene and Early Holocene archaeological sequence in the Haua Fteah provides the first truly detailed chronological analysis of the stratigraphy within the cave and has significantly improved our understanding of the relationship between key archaeological phases (Mousterian/MSA, Dabban/Upper Palaeolithic, Oranian and Capsian/Epipalaeolithic and Neolithic) at this site. It can therefore be concluded that the radiocarbon dating of archaeological shell has great promise when underpinned by radiocarbon ecological assessment of target species.

For the most part, there is no doubt that human impact on biodiversity has been negative: habitat loss and degradation, pollution, overexploitation, and introduction of invasive species had played significant roles in biodiversity decline. However, human impact on Earth is not always so detrimental and its effects are not the same for all taxa. The aim of this thesis was to assess the anthropogenic impact on one of the most endangered and often unnoticed groups - terrestrial molluscs - firstly focusing on natural and then urban context. In Chapter I, effects of forest age as a surrogate for forest continuity on land snail richness and composition in Tuscan evergreen and deciduous woods were assessed. Chapter II explored the role of dispersal and local environment in urban land snail assemblages comparing different human-made habitat types in three cities in central Italy (Grosseto, Siena and Arezzo). Finally the link between man and urban environment has been further elaborated in Chapter III, where a fully synanthropic land snail species (Papillifera papillaris) has been used to assess athmosferic pollution from human activities, especially vehicular traffic, in the urban area of Siena. Concerning results obtained, Chapter I revealed that successional age as surrogate for forest continuity parameter seemed not to be a key factor in controlling land snail species richness and abundances but habitat structure more than forest age was the factor mostly involved in affecting communities; furthermore, no difference was found between evergreen and deciduous oak litter in terms of land snail richness, abundance and diversity. Focusing on urban environment, Chapter II demonstrated that cities can show relatively high land snail richness with values comparable to natural areas. After having accounted and later removed spatial structures influence, urban gradient effect turned out to be the principal component structuring urban land snail assemblages. This finding proved a likely human-mediated transport, which enhances dispersal abilities of organisms normally considered scarcely mobile. However, no establishment there would be in the absence of suitable microhabitat conditions. In particular, “vegetation cover” and “distance from the city centre” were the environmental variables that explained most of the variation in species composition. In Chapter III, results elected Papillifera papillaris a promising species to monitor the metal distribution and bioavailability in urban environments and to evaluate the possible transfer of pollutants to higher levels in food chains. Mollusc soft tissues showed very low concentrations of lithophile elements, and much higher concentrations of anthropogenic metals such as Cd, Cu, Pb, and Zn while excreta and traditional biomonitors such as mosses were the matrices most involved in lithophile contamination. Surprisingly, Papillifera papillaris tissues showed extreme Mn values. These concentations, for their magnitude, have no comparison with those reported in literature for other species of terrestrial gastropods. Excreta showed a high concentration of Pb, demonstrating the scarce bioavailability and absorption of this element and probably its limited impact on urban food chains.

Endocrine disrupting compounds (EDCs) together with potentially toxic metals (PTMs), are present in large amounts in sewage sludge which was used as a tool to expose terrestrial molluscs to environmental concentrations of these pollutants. Pastures fertilised with sewage sludge had significantly fewer adult slugs collected per replicate (C: 58.4; T: 26.2; S.E.D. 0.14; p<.05) and eggs (C: 16.6; T: 9.1; S.E.D. 0.17; p<0.05).  No differences with treatment, in tissue concentrations of EDCs or PTMs or in hepatopancreas or gonad structure, were detected.  However, hepatopancreatic proteins (cyclophilin, paramyosin and trypsin) were significantly altered (p<0.01). In a laboratory study, exposure, via feed, to 0x (Control), 1x (T1), 10x (T2) or 110x (T3) the environmental dose of sludge extract resulted in a dose-related increase in mean mortality rates (relative to controls) in adult slugs (Deroceras reticulatum).  Exposure for 3 weeks induced no measurable differences in tissue pollutant concentrations or hepatopancreas or gonad histology. Fewer slug eggs exposed to sludge and/or dehydration (2x2; 10 eggs/replicate); hatched following sludge exposure (C hydrated 64.5%;T hydrated 24.5%; p<0.05; S.E.D. 2.169; C dehydrated 48.9%; T dehydrated 17.4%; p<0.05; S.E.D. 4.256) but not following dehydration.  There was no significant interaction between sludge exposure and dehydration but survival was lowest in animals exposed to both. Slug behaviour was affected by exposure to sludge, including increasing avoidance and huddling behaviours. The results indicate that terrestrial molluscs may be used as invertebrate sentinels to assess the effects of ECD and PTM exposure.

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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
O conhecimento dos aspectos biológicos, morfológicos e comportamentais dos moluscos terrestres é importante para o desenvolvimento de medidas de controle de pragas e de estratégias de conservação de espécies. O presente trabalho teve como objetivo caracterizar os padrões de biologia, conquiliomorfometria e comportamento da espécie Dysopeas muibum e verificar os efeitos do isolamento e do fotoperíodo sobre seu ciclo de vida e a morfometria da concha, em condições de laboratório. Foi realizado o acompanhamento do crescimento da concha, da liberação de filhotes e da mortalidade de 160 moluscos, dos quais 40 foram mantidos isolados e 120 agrupados (10 moluscos por grupo; 40 em condições naturais de temperatura, umidade relativa do ar e fotoperíodo, e 80 tendo estas condições controladas – 40 com dias longos e 40 com dias curtos), desde o nascimento até 180 dias de vida, quando então foram aferidas as medidas da concha. Para verificar o horário de atividade e compor o etograma, 30 moluscos adultos (10 moluscos por grupo) foram observados durante 24 horas contínuas, através do método de varredura, com registro dos atos comportamentais a intervalos de 20 minutos. Já para verificar a ocorrência de agregação e a preferência por sítio de repouso, durante cinco dias, a intervalos de 24 horas, foram observados de 30 moluscos adultos (10 moluscos por grupo): número de agregações, de indivíduos agregados e isolados, e de indivíduos sob o disco com alimento, sob o disco sem alimento, sobre o substrato, enterrados e na parede do terrário. Para todas as análises, os moluscos foram criados em terrários plásticos vedados com tecido de algodão e elástico, contendo como substrato terra vegetal esterilizada e umedecida com água de torneira, e alimentados com ração para frangos de corte enriquecida com carbonato de cálcio. Foi verificado que a espécie ocorre no município de Juiz de Fora, Minas Gerais, possui parte mole amarelada e concha pequena e alongada, e é capaz de se reproduzir por autofecundação. Possui crescimento indeterminado, fecundidade aumentando com o tamanho corporal, iteroparidade e baixa mortalidade antes e após a maturidade sexual, não tendo o fotoperíodo efeito sobre esses padrões. As condições controladas de temperatura, umidade relativa do ar e fotoperíodo favoreceram o crescimento, maiores valores conquiliomorfométricos e o rápido alcance da maturidade sexual, enquanto a diminuição do comprimento do dia favoreceu a fecundidade. O isolamento aumentou o número total de filhotes, o número de filhotes por molusco parental e o intervalo entre eventos reprodutivos, reduziu o número de eventos reprodutivos e de filhotes por evento, e não influenciou o crescimento, o alcance da maturidade sexual, a relação crescimento-reprodução, a mortalidade e a conquiliomorfometria. O etograma foi composto por oito atos comportamentais: repousar, estar enterrado, deslocar, enterrar, explorar, alimentar, emergir e interagir. A espécie apresentou maior tendência ao repouso e a locomoção foi o ato comportamental de atividade prevalente, não apresentou horário de atividade predominantemente noturno e comportamento agregativo, e seu sítio preferido para o repouso foi o enterramento no substrato.
Knowledge of biological, morphological and behavioral characteristics of terrestrial molluscs is important for the development of pest control measures and strategies for the conservation of species. This study aimed to characterize the patterns of biology, conchiliomorphometric and behavior of the species Dysopeas muibum and check the effects of isolation and photoperiod on its life cycle and shell morphometry, under laboratory conditions. We conducted monitoring growth of the shell, release of puppies and mortality of 160 molluscs, of which 40 were kept isolated and 120 grouped (10 molluscs per group; 40 in natural conditions of temperature, relative humidity and photoperiod, and 80 with controlled conditions – 40 with long days and 40 with short days), from birth to 180 days of life, when the measures of the shell were taken. To check the schedule of activity and compose the ethogram, 30 adult molluscs (10 molluscs per group) were observed for 24 continuous hours, through the scanning method, with a record of behavioral acts at intervals of 20 minutes. For verifying the occurrence of aggregation and the preference for resting place, for five days, at 24 hour intervals, were observed in 30 adult molluscs (10 molluscs per group): number of aggregations, of aggregates and isolated individuals, and of individuals below the disc with food, below the disc without food, on the substrate, buried and in the wall of terrarium. For all analyzes, the molluscs were reared in plastic terrariums sealed with cotton fabric and elastic, containing plant soil sterile and moistened with tap water, and fed with food to broilers enriched with calcium carbonate. It was found that the species occurs in the Juiz de Fora City, MG, Brazil, has the soft yellowish and small and elongated shell, and is able to reproduce by self-fertilization. It has indeterminate growth, fecundity increases with body size, iteroparity and low mortality before and after sexual maturity, not having the photoperiod effect on these patterns. The controlled conditions of temperature, relative humidity and photoperiod favored growth, conchiliomorphometric values higher and fast reach sexual maturity, while the decrease in day length favored fecundity. The isolation increased the total number of pups, number of pups per parent mollusc and the interval between reproductive events, reduced the number of reproductive events and pups per event, and did not influence growth, reach sexual maturity, growth-reproduction relation, mortality and conchiliomorphometric. The ethogram was composed of eight behavioral acts: lie, lie buried, move, bury, explore, food, emerge and interact. The species had a greater tendency to rest and locomotion was the behavioral act prevalent activity, showed no activity time predominantly nocturnal and affiliative behavior, and their favorite place to rest was buried in substrate.

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Existem evidências da relação entre morfologia da concha e pressões ambientais. Entretanto, não se sabe, se os mecanismos responsáveis por essa variabilidade da forma da concha seriam decorrentes de uma plasticidade fenotípica, determinação genética ou até mesmo efeito materno. Alguns estudos, abordam apenas os aspectos da concha, desconsiderando a relação entre a morfologia da concha, proteção contra dessecação e reprodução. Neste contexto, o presente estudo teve dois grandes objetivos: o primeiro, verificar se a existência de dois padrões morfológicos (conchas abauladas e conchas alongadas) observados para espécie Leptinaria unilamellata a existência de um antagonismo entre proteção contra dessecação e sucesso reprodutivo. E a segunda pergunta seria: qual o papel da plasticidade fenotípica em relação a esses dois padrões? Para investigar a resposta, foi realizado um estudo morfométrico comparativo entre duas populações em gerações sucessivas de laboratório e quantificado o número de filhotes produzidos por cada indivíduo do primeiro evento reprodutivo em cada geração. Para verificar o efeito da dessecação sobre a morfologia da concha ao longo das gerações sucessivas, os moluscos foram submetidos as duas condições de tratamentos. Os resultados do presente estudo confirmam a hipótese de que as variáveis morfométricas que influenciam a forma da volta corporal e a dimensão da abertura da concha influenciam o sucesso reprodutivo da espécie. Foi observado também que as variáveis morfométricas entre as duas populações se tornaram menos evidentes ao longo das gerações sucessivas de laboratório, evidenciando uma resposta adaptativa rápida de Leptinaria unilamellata, decorrente do efeito materno. A maior produção de filhotes foi observada para população de Chácara em todas as gerações, onde a forma abaulada, determina a presença de volta corporal e aberturas maiores, permitindo uma expansão do oviduto. Os resultados evidenciam também que moluscos com conchas mais alongadas e aberturas menores não investem em filhotes maiores.
There is evidence of the relation between shell morphology and environmental pressures. However, it is not known whether the mechanisms responsible for the shell shape variability results from phenotypic plasticity, genetic determination or even to maternal effect. Some studies address just shell aspects and disregard the relation among shell morphology, protection against desiccation and reproduction. Thus, the present study has two main aims. The first aim is to investigate whether the existence of two morphological patterns (rotund shells and elongate shells) found in Leptinaria unilamellata the antagonism between protection against desiccation and reproductive success. The second one is to find the answer to the following question: what is the role played by phenotypic plasticity in these two patterns? A morphometric study comparing two populations derived from successive laboratory generations was performed to find such answer. In addition, the number of progenies produced by each individual born in the first reproductive event in each generation was quantified. The mollusks were subjected to two treatment conditions to investigate the effect of desiccation on shell morphology over successive generations. The results of the present study confirmed the hypothesis that the morphometric variables influencing the body whorls’ shape and the shell opening size have also influenced the species’ reproductive success. The morphometric variables between the two populations became less evident throughout the successive laboratory generations, thus showing the fast-adaptive response of Leptinaria unilamellata resulting from the maternal effect. The highest progeny production was found in the population of Chácara in all generations, wherein the rotund shape determined the presence of body whorls and larger openings, which enabled oviduct expansion. The results have also shown that mollusks presenting more elongated shells and smaller openings do not invest in large progenies.

Les donnees sur la transition tardiglaciaire-holocene (de 14500 a 6000 bp) s'appuient sur les resultats livres par le gisement de st. Thibaud-de-couz (savoie, chartreuse) et une dizaine de sites a stratigraphies developpees qui ont fait l'objet de fouilles recentes. Ces sites representent des remplissages karstiques qui permettent d'avoir une vision precise mais ponctuelle sur les modalites du passage du dernier glaciaire a l'interglaciaire actuel. L'approche chronostratigraphique assure les bases chronologiques des evolutions naturelles et culturelles. L'etude d'une douzaine de sequences stratigraphiques a permis de distinguer quelques types d'enregistrement sedimentaire propres a chaque phase de l'evolution climato-sedimentaire. La reconstruction de l'evolution paleoclimatique a ete faite selon deux approches complementaires: 1) la sedimentologie met particulierement en evidence les manifestations de l'humidite qui sous climat froid engendre une importante sedimentation detritique et sous climat chaud des depots carbonates ; 2) l'etude des faunes de mollusques terrestres permet de preciser les conditions paleoecologiques et climatiques locales ; la presence d'une association a columella de type periglaciaire est significative. Les resultats mettent particulierement en evidence le caractere instable du climat. Le probleme des occupations humaines est aborde a travers l'etude des outillages lithiques sous deux aspects: 1) l'etude petrographique permet de localiser les gites d'approvisionnement en silex et d'avoir des indications sur les territoires parcourus ; 2) la caracterisation des systemes culturels est basee sur les series lithiques considerees en terme d'ensembles structures ; dans ce but une methode de classement hierarchise est proposee. Les grandes etapes de l'evolution chronoculturelle sont precisees ; elles sont marquees par de profondes mutations qui caracterisent les cultures de la fin du paleolithique superieur au mesolithique et par l'emergence des premieres phases de la neolithisation. Une synthese integrant l'ensemble des donnees bioclimatiques et culturelles permet de proposer un modele de transition dernier glaciaire-interglaciaire actuel caracterisee par une succession de cycles a regimes climatiques contrastes situes a la charniere de deux periodes a climats plus stables. La mise en parallele des donnees culturelles suggere une relation forte entre evolutions culturelles et changements bioclimatiques

碩士
國立臺灣師範大學
生命科學研究所
98
Chemosensory search is one of the most important foraging behaviors for snakes. The survival of snakes is directly influenced by the efficiency of chemosensory search. Taiwan slug snake, Pareas formosensis, is a dietary specialist feeding on land snails, especially the Pulmonata. The aim of this study is to investigate the trailing behavior of Taiwan slug snake on the terrestrial mollusks mucus. A Y-shaped observation area was used to exam the trailing behavior of Taiwan slug snake to the mucus of terrestrial slugs (Incilaria bilineata) and two snails (Nesiohelix swinhoei and Cyclophorus formosensis). The results showed that Taiwan slug snakes preferred to trail the mucus of I. bilineata and N. swinhoei; The trailing rate was 87.5% and 62.5%, respectively. Taiwan slug snakes showed no significant preference between the trailing rate of C. formosensis (4.2%) and distilled water (0%). Testing by three kinds of mucus Taiwan slug snakes showed the greatest preference of I. bilineata, then N. swinhoei, and C. formosensis. I exposed each mucus to the air for 0, 15, 30, and 60 minutes, the result showed that the mucus trailing rates declined according to the increase of mucus exposure time. Taiwan slug snakes could not discriminate the direction of prey by mucus trails. Two parts of terrestrial slugs’ mucus were separated by centrifugation, namely small-molecules and macro-molecules. Nevertheless, Taiwan slug snakes showed no significant difference in tracing either small-molecules or macro-molecules.

Molluscs are an important component of South Africa’s biodiversity. The assessment of distribution patterns and factors influencing the biogeographic distribution are an integral part of assessing the conservation status of molluscs and their conservation management needs. The existing terrestrial mollusc data from South Africa were assessed in terms of their value to biodiversity conversation planning and management. Although the data on terrestrial molluscs are incomplete and would be misleading in terms of identifying specific areas for protection, the data do illustrate significant patterns and trends of mollusc endemism and diversity, which can be used to improve biodiversity conservation and management efforts. The distribution of molluscs across the South African landscape illustrated ten broad biogeographical patterns. Two of these patterns reflected ancient distribution patterns of molluscs and consisted of molluscs of the Gondwanaland/southern relict and Laurasian origins. Three biogeographic patterns occurred across the eastern regions. These patterns were defined as the tropical/subtropical east African, subtropical east of southern Africa and east African afromontane patterns. The biogeographic patterns in the west consisted of the characteristic temperate ‘Mediterranean’ Cape centre and the arid regions of northwestern Cape, Namibia and parts of Botswana. An additional biogeographic pattern identified as the nama karoo/central west was recognised. The final two biogeographical patterns described taxa that were widely distributed and taxa that exhibited disjunct distributions. Twenty-six families and forty-three genera were associated with more than one biogeographical pattern. The dominant biogeographic pattern was the tropical/subtropical east African component. Twenty-one families and forty-eight genera were associated with this biogeographical pattern. The east African Afromontane pattern was also a conspicuous biogeographic element in South Africa. Fewer families and genera were distributed in the western and central regions. The distributions of terrestrial molluscs were influenced by a combination of various factors, which included the presence of rivers, the escarpment, altitude, humidity, precipitation, temperature and biomes. Rivers could possibly restrict the distribution of certain mollusc taxa but did not appear to be the dominant factor that influenced the distribution of molluscs across the landscape. In terms of the effect of temperature on the distribution of molluscs, the mean daily and mean annual temperatures appeared to have more of an influence on the distribution patterns than the mean daily maximum and minimum temperatures. Mean annual temperatures influenced the distribution of all families and genera. The mean daily maximum temperature appeared to have little or no effect on the distribution of mollusc taxa. Humidity and biomes also appeared to influence the distribution of taxa. The least inhabited biome was the succulent biome. Many mollusc taxa occurred in the wetter, warmer areas with high humidity levels. Areas of high species richness and high endemic species richness in South Africa were identified using two systems of endemism, one based on distinctive gaps in the frequency distribution of terrestrial molluscs in South Africa and the other based on an existing classification of invertebrate endemism (Hamer & Slotow, 2002). Areas of high mollusc species richness and endemism were also compared to areas of high millipede species richness and endemism. The total number of South African mollusc endemics was 370 (83 % of 447 indigenous species). The dominant mollusc families in South Africa were Achatinidae, Charopidae, Streptaxidae, Subulinidae and Urocyclidae. The first system of endemism identified 56 site endemics (species with only one locality), 50 local endemics (0 < maximum distance < 60 km) and 145 regional endemics (60 km < maximum distance < 330 km). The Hamer & Slotow (2002) classification of endemism classed 67 species as site endemics (maximum distance between localities < 10 km), 47 as local (11 km < maximum distance < 70 km) endemics and 59 as regional endemics (71 km < maximum distance < 150 km). The analysis of mollusc data, with both systems of endemism, showed similar areas of high species and endemic species richness. Quarter-degree grid cells with highest species richness overlapped with grid cells with the highest number of endemic species. However these grid cells coincide with areas that have been intensively sampled and this bias limits the application of the data in conservation planning. The patterns of endemism for molluscs and millipedes within the provinces differed, indicating that the inclusion of a single taxon in conservation planning would inadequately reflect the diversity of invertebrates in South Africa. A preliminary list of specific priority endemic sites for terrestrial mollusc conservation was identified. It is essential that the existing data on invertebrates be evaluated and used to identify key patterns and trends in invertebrate diversity as this will allow for the inclusion of invertebrates in biodiversity conservation planning and management. The analysis of the existing mollusc data identified bio geographical patterns that are important to conservation planning both at the local and national level as well as commonalities and differences between molluscs and millipede distributions. The analysis also highlighted the importance of municipal areas for conservation of hotspots of diversity, particularly in the eastern coastal areas of South Africa.
Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2007.

碩士
國立臺北教育大學
自然科學教育學系
105
The main purpose of this study was to comprehend the relationship between land snail species diversity and their micro-habitat environment in Yisheng Village. Six smapling lines and one smapling point were selected for research from Feb, 2016 to May,2017. 29 species with 262 living land snails and 8 species land snail shells were recorded during this investigation. There were 65.6% arboreal land snails, 19.1% sheltered ground land snails and 15.3% exposed round land snails in total living land snails. The environmental factors were measured at the location of land snails were found, with 68% confidence interval, the temperatures of land snail micro-habitats were between 21.5 ℃ ~ 29.0 ℃, the humidities were between 76.5% ~ 87.2% and the light levels were between 108.5 Lux ~ 517.5 Lux. Xiaowulai scenic hiking trails and Shueiyuandi trails had the narrow land for Alocasia odora and Elatostema platyphylloides growing which provided habitats for arboreal land snail species, the leaf litter of bamboo forest in these area provided habitats for epigeal land snail species. The snail habitats were broken by steep slope of three mountain trails which had plenty of land snail species with few population. The steep slope of mountains and rivers prevented the migratioin of exotic species, therefore land snail species in Yisheng elementary school and in the entrance of Shueiyuandi trails were significantly different from land snail species in Xiaowulai scenic hiking trails and in the three mountain trails. According to historical record of biogeography, some districts of northern Taiwan had more than 10 as same land snail species as in Yisheng Village, most of these districts also belong to Xue Mountain Range, this phenomenon might indicate land snail species in Yisheng Village expanded their population through Xue Mountain Range.

Tese de mestrado, Biologia Evolutiva e do Desenvolvimento, Universidade de Lisboa, Faculdade de Ciências, 2017
Os processos geográficos e demográficos deixam marcas nos padrões de variabilidade genética das espécies. Sendo a diversidade genética essencial para garantir capacidade de adaptação das populações a alterações ambientais, a baixa diversidade genética representa um risco mais elevado para os endemismos, que exibem geralmente diversidade mais empobrecidas. Candidula coudensis é uma das 12 espécies de Candidula, um género de gastrópodes terrestres, recentemente identificada em Portugal. A espécie constitui um endemismo do Vale da Couda, no distrito de Leiria, com distribuição geográfica extremamente reduzida (13,5 km2). Dada a potencial vulnerabilidade de um endemismo tão localizado, foram usadas sequências do ADN mitocondrial (COI: citocromo oxidase subunidade I) e nuclear (ITS1: espaçador interno transcrito subunidade 1), e produzidos modelos de nicho ecológico, para avaliar a diversidade genética e a demografia histórica dos indivíduos do Vale da Couda e, ainda, mapear a sua potencial distribuição geográfica. De forma a determinar se os indivíduos de Vale da Couda constituem um grupo monofilético, foi construída, a partir das sequências de ADN mitocondrial, uma filogenia com as espécies do género presentes em Portugal. A população do Vale da Couda apresentou elevados valores de diversidade genética, existindo um elevado número de haplótipos que se dividem em quatro grupos não monofiléticos. Não parece existir nenhum padrão filogeográfico com os haplogrupos distribuídos de forma não uniforme nos diferentes locais de amostragem. A história demográfica dos indivíduos do Vale da Couda indica sinais de expansão demográfica, sendo necessária uma taxa de mutação de 15%MY para que esta date do Último Máximo Glacial (UMG). O modelo de nicho ecológico determinou que as características ecológicas mais importantes na restrição da distribuição de C. coudensis são a litologia, a isotermalidade e a precipitação anual. Durante o Último Máximo Glaciar (UMG) a distribuição desta espécie localizar-se-ia mais a sul do que a distribuição atual, numa região onde provavelmente coexistiriam outras espécies de Candidula, como C. setubalensis e C. arrabidensis, que presentemente habitam aquela região. Com o final do UMG terá havido uma re-colonização para norte até ao local actualmente ocupado, onde as condições ambientais são apropriadas à sua persistência. Os padrões de elevada variabilidade genética e divergência entre haplogrupos no Vale da Couda podem ser tentativamente explicados por um cenário biogegráfico em que as condições do UMG tenham favorecido um isolamento de populações a um nível micro-geográfico, potenciando a diferenciação entre as mesmas e aumentando a variabilidade intraespecíficica. O Vale da Couda terá então sido colonizado pelas várias linhagens que se formaram durante o UMG, o que explica a existência dos vários haplogrupos existentes actualmente nessa região. O facto de a análise demográfica demonstrar que existiu uma expansão da população corrobora esta hipótese. Actualmente, a elevada variabilidade genética desta população é mantida devido à grande dimensão da mesma. Concluíndo, a população do Vale da Couda contraria a ideia de que populações com distribuição limitada apresentam diversidades genéticas diminuidas, acrescentando este exemplo à lista de excepções a esta regra. Uma vez que, a elevada diversidade genética está associada a uma elevada população efectiva, e com tempo de geração curto, não há sinais de que a população de Vale da Couda precise de especial protecção do ponto de vista da conservação.
Patterns of genetic variability are shaped by a combination of geographic, demographic and evolutionary processes. Genetic diversity is the raw material for adaptation. Populations and species with restricted geographic distributions usually display low levels of diversity, which represent an evolutionary risk. Candidula coudensis is an endemic species of land snails from Vale da Couda, Portugal, with an extremely restricted distribution (13.5 km2). Mitochondrial (cytochrome oxidase I) and nuclear (internal transcribed spacer 1) DNA sequences of species of the genus Candidula from Vale da Couda and other locations in Portugal were used to evaluate the monophyly of C. coudensis,patterns of genetic diversity and the species demographic history. Ecological niche models (ENM) for both present and Last Glacial Maximum (LGM) distributions of C. coudensis were constructed to assess possible shifts in the distribution that might have influenced the evolutionary history of this species. The population of Vale da Couda showed unexpected levels of genetic variability given its striking restricted geographic range. We found a high number of haplotypes which are part of four non-monophyletic haplogroups, unevenly distributed among sites. The putative past and contemporary models of geographic distribution of Vale da Couda lineages are compatible with a scenario of species co-existence in more southern locations during the last glacial maximum (LGM) followed by a post-LGM northern dispersal, tracking the species to optimal thermal, humidity and soil physical conditions. LGM conditions may have favoured population isolation at a micro-geographical level, promoting intra-specific diversification. This diversity is maintained presently due to a large effective population size. Mismatch analysis indicated a population expansion during the LGM, which corroborates our biogeographic scenario. The high divergence and non-monophyly between haplogroups prompts the need for future molecular taxonomy studies of the Candidula genus in Portugal to clarify the identity of species that seem to be non-monophyletic.

This thesis focuses on the genetical and morphological diversity of plaited door snail (Cochlodina laminata). While small distribution ranges are typical for most species belonging to genus Cochlodina, the distribution range of C. laminata covers most of the European continent, except for its coolest and warmest parts. It has been previously suggested that this species might in fact be a complex of several species and large genetical as well as morphological diversity has been mentioned - however, yet undescribed - in previous studies. Sequences of two mitochondrial genes were used (16S rDNA, COI) and thirteen morphological characteritics have been assessed to investigate this diversity. I discovered that the current concept of C. laminata as a species is not in accordance with the discovered genetical nor morphological variability. The original species C. laminata/C. dubiosa form a common species complex and also interpretation of C. fimbriata will need to be assessed in more detail in the future. Other Central European species are valid species.