Dissertations / Theses on the topic 'Mammal surveys'

This study details results of small mammal surveys at 24 sites in four biomes (Nama- and Succulent Karoo, Albany Thicket, Grassland) as part of the Karoo BioGaps project to augment baseline biodiversity information needed to guide proposed fracking activities in the Shale Gas Development Area (SGDA) (Holness et al. 2016). A strategic Environmental Assessment (SEA), commissioned by the South African Government, evaluated the potential to exploit the supposedly substantial reserves of shale gas using hydraulic fracturing (“fracking”) in the Great Karoo Basin of South Africa. Terrestrial micromammals (<500g) were captured using Sherman livetraps (September 2016 to March 2017). Sampling over 6580 trap-nights produced 339 captures of 271 individuals representing 14 taxa. Trapping success was low 5.14% (mean per site 0.37± 0.61%). Most captures (87%) and individuals (83%) were recorded in the Nama-Karoo (294 captures, 226 individuals, 15 sites), whereas only 5 captures were recorded in Albany Thicket (3 sites). Four xerophilous/generalist species (Micaelamys spp. (Rock rats), Gerbilluscus paeba (Hairyfooted Gerbil), Macroscelides proboscideus (Round-eared Sengi), and Elephantulus spp. were numerically dominant at most sites, and within most biomes/bioregions; while five rare species were only ever recorded once. Mean α diversity (observed species richness Sobs) per site (2.88 ±1.99) and Shannon-Wiener diversity (1.70 overall, 1.04 ±0.33 per site) were low, with only 5.47 effective species (mean = 3.04 ±1.08 per site) and low equitability (0.64 overall). Sobs was highest in Nama-Karoo (13 species), and lowest in the Grassland and Albany Thicket biomes (2-5 species). Species accumulation/rarefaction curves did not reach asymptotes, and Sobs values for most sites/biomes/bioregions were significantly lower than Chao1 predicted species richness, suggesting that sampling effort did not accurately estimate species richness. However, trapping efficiency was generally high (56-100%; mean 86.7%) which compares favourably with that of two recent published studies in South Africa. Multiplicative beta diversity (βMt) across the SGDA was 4.56 indicating high species turnover between sites/biomes/bioregions. Species turnover was high across biome boundaries, notably Albany Thicket-Grassland (15), Nama-Karoo-Albany Thicket (14), and Succulent Karoo-Grassland (12). Biomes and bioregions tended to plot apart in ordination analyses with relatively low (40-60%) Sorenson similarity, indicating that most regional small mammal communities were well-differentiated. Despite data limitations, 66 new distribution records for 21 sites are reported for the SGDA. Total species richness (including historical records) was highest in the Nama-Karoo (19), particularly the Upper Karoo bioregion (19, mean 6.45 ±2.16, 11 sites), followed by the Grassland (16), and Albany Thicket (5) biomes. Total species richness records for most sites/regions fell within the iChao2 CI bounds, thus integrating trapping and historical records provided a relatively robust data set for subsequent spatial diversity analyses. However, even the total species richness dataset is likely to underestimate true diversity owing to not sampling arboreal species or detecting some cryptic species. Generalized linear analyses indicated that small mammal diversity indices were significantly associated with certain environmental/climatic parameters (livestock, drought). Despite the west to east increase in precipitation, highest diversity was concentrated in the arid north-west Nama-Karoo where dwarf shrubs and succulents predominate. This suggests that environmental and niche filtering are significant proximate factors shaping small mammal assemblages. No significant effects of biotic interactions (particularly competition following Diamond's (1975) first two rules) or resource-mediated niche limitations were evident for SGDA species assemblages. However, results for the Nama-Karoo (i.e. for a natural phytogeographical rather than geoeconomically-defined area) were significant suggesting that biotic interactions may also be proximate factors shaping local assemblages. Site assemblages were significantly nested, indicating that species at species-poor sites were subsets of those at richer sites; and thus, that site communities may have been structured by either long-term (ultimate) regional biogeographic processes (e.g. immigration and extinction related to distances between sites) or habitat filtering operating at local scales. Data deficiencies notwithstanding, my results present the most comprehensive landscape-level analysis for small mammals, and the only baseline dataset (based on randomized sampling) for the Greater Karoo and SGDA. While my results must be treated with caution, I am confident that the recommendations I make on species, sites and regions potentially vulnerable will be a useful guide to possible impacts of fracking in the study area.

Thesis (M.S.) --University of Montana, 2008.<br>Title from author supplied metadata. Description based on contents viewed on May 15, 2009. ETD number: etd-01142009-131434. Author supplied keywords: bear rubs ; grizzly bear ; mark-recapture ; noninvasive genetic sampling ; Northern Continental Divide Ecosystem ; Pradel model ; trend monitoring ; Ursus arctos. Includes bibliographical references.

The aim of this paper is to study how Swedish ­Jewish women and non-men relate to widespread notions of Jewish motherhood and the trope of ”the Jewish mother”, through their own  stories. The paper asks how they relate to notions of Jewish motherhood, how these notions  function in the construction of their identities as Jewish and how it relates to processes of  community and nationalism. The material that is analyzed is the narrative of fourteen Jewishidentified women/non-men gathered with a survey interview. It is analyzed through theories  of the relation between motherhood and nationalism, the constitutive terms of a diaspora and an intersectional approach to racialized processes of gender and gendered processes of the  constitution of race and ethnicity. The thesis concludes that through the informants’ stories  the cultural symbol of ”motherhood” is dependent upon certain symbols in its own, such as  food and religious practices, that relate to identity processes among the informants, and to  processes of community and nationalism tied to motherhood. Jewish mothers, potential  mothers and parents are effected by expectations of certain Jewish ways of performing  motherhood in their identification as Jewish and in their sense of belonging to the Jewish  community. They also relate these expectations to portrayals of Jewish mothers from popular culture as well as to the parenting and memories of their own mothers and ancestral women.

Urban development and human encroachment on the natural habitats along the coastline of Florida combined with invasive exotic pressures have resulted in the fragmentation and degradation of habitat quality within Broward County. Native habitats have been significantly altered and fragmented to a fraction their previous size. With loss of habitat area and quality, isolation of breeding populations and anthropogenic pressures, it is important to determine species composition and habitat utilization in order to conserve the remaining biological diversity. It was the intent of this study to determine the small mammal species’ population structure and habitat utilization by season in the four sampled habitats. Previously undocumented species and/or extralimital populations were predicted prior to sampling. John U. Lloyd Beach State Park in Dania Beach, Florida is an understudied location for small mammals. This study surveyed four terrestrial habitats for small mammal species using live trapping and mark/recapture techniques. Data were collected monthly over the span of thirteen months to determine habitat use from maritime hammock, mangrove swamp, coastal dune and ruderal habitat types to determine species composition and mass of individual captures and recaptures. Trapping (3749 trap nights) produced twenty-four captures (including recaptures) in two of the four habitat types: maritime hammock and coastal strand. No animals were captured in the mangrove swamp or ruderal habitats, both of which were dominated by invasive Australian pine (Casuarina equisetifolia) monocultures. Post study, a large habitat restoration project restored the habitats impacted by invasive exotic flora. This survey serves as a baseline for small mammals in the park, documenting the pre-restoration habitat use and species composition. Future study to determine changes in species composition post-restoration is recommended.

A Floresta Atlântica, principalmente sua porção localizada no interior do Estado de São Paulo, encontra-se altamente fragmentada e seus remanescentes, em sua maioria, encontram-se envoltos por uma matriz essencialmente agrícola. Este estudo foi realizado no Campus "Luiz de Queiroz", Universidade de São Paulo, localizado no município de Piracicaba, Estado de São Paulo. O mesmo encontra-se inserido no perímetro urbano da cidade de Piracicaba, tendo como limite duas rodovias e o Rio Piracicaba. A paisagem da área de estudo caracteriza-se por um mosaico de pequena áreas florestais envoltas por áreas de pastagens, agricultura e florestamento com espécies exóticas. Os objetivos principais do presente estudo foram: levantamento de mamíferos não-voadores, em escala local, incluindo sua distribuição e abundância de acordo com o mosaico de ambientes resultantes do expressivo impacto causado pelo desenvolvimento humano na área. A coleta de pequenos mamíferos ocorreu durante nove meses, entre fevereiro e outubro de 2001, com um esforço de 7056 armadilhas/dia, tendo sido amostrados sete dos ambientes mais representativos do Campus(florestamento de Eucalyptus e Pinus, fragmento florestal nativo, várzea, plantio de seringueira, área de agricultura e área de pastagem). Para o registro de mamíferos de médio e grande portes foi construída uma trilha pelo Campus, que foi percorrida durante 12 meses, entre novembro de 2000 e outubro de 2001, no período da manhã e da tarde. Em todo o Campus foram registradas 16 espécies de mamíferos não-voadores, sendo dez de médio e grande portes e seis de pequeno porte, sendo a capivara (Hydrochaeris hydrochaeris) e o coati (Nasua nasua) as espécies mais abundantes.<br>The remaining portion of the Atlantic Forest within the State of Sao Paulo is highly fragmented and most of the remainders are wrapped up in an essentially agricultural mosaic. This study aims local surveying of non-flying mammals, including their distribution and relative abundance within the humanimpacted environments of Campus "Luiz de Queiroz", University of Sao Paulo, Piracicaba, SP, Brazil, an urbanized area bordered by two highways and the Piracicaba River. The landscape of the study area is characterized by a mosaic of small forest fragments surrounded by pastures, agriculture, and planted forests. Small mammals were captured from February to October, 2001, with an effort of 7056 traps.day -1 , sampling seven of the most representative environments of the Campus – planted Eucalyptus and Pinus forests, native forest fragments, meadow, rubber tree plantation, agriculture and pasture areas. Occurrence of medium and large frame mammals was recorded daily (morning and afternoon) from November of 2000 to October of 2001 along a trail set up to merge the studied environments. Sixteen species of non-flying mammals were recorded, ten of medium or big frames, and six of small frame. Capybara (Hydrochaeris hydrochaeris) and coati (Nasua nasua) were the most abundant species.

I developed acoustic identification methods and studied habitat use in a speciose bat community from southern Italy. I studied echolocation calls from 23 Italian bat species and devised multivariate discriminant functions used for habitat use studies. I described diagnostic Pipistrellus kuhlii social calls. I demonstrated sympatry of Pipistrellus pipistrellus and P. pygmaeus in Italy. I also examined resting frequencies from Rhinolophus euryale and R. mehelyi: juveniles called at lower frequencies than adults. The implications of these findings for acoustic investigations are discussed. Habitat selection at the community level was determined by acoustic surveys. Activity was highest over rivers and lakes. M. daubentonii and M. capaccinii were affected by wind, and temperature influenced Hypsugo savii activity. P. kuhlii, P. pipistrellus and Tadarida teniotis showed no significant habitat preference. Rivers were selected particularly by Myotis bats and Miniopterus schreibersii. Habitat selection by R. euryale was studied by radiotracking. This species selected broadleayed woodland. Urban, open areas and conifer plantations were avoided. The results have clear implications for bat research and conservation in southern Italy and other Mediterranean areas. Acoustic identification by quantitative echolocation and social cgll analysis promises to be a valuable means to investigate habitat use by bats with high intensity echolocation calls in speciose Mediterranean bat communities. Rivers and riparian vegetation need to be adequately protected and managed. Habitats managed or created by humans were also important and should therefore feature in conservation plans. I recommend avoiding the clearance of continuous, large areas of woodland, and not planting conifers. Urbanisation is a threat to R. euryale and other sensitive species, and should be limited in areas of special value for the bat fauna. Linear landscape elements such as tree lines and hedgerows should also be preserved.

A population of spotted-tailed quolls Dasyurus maculatus was studied for three years (2002-2004) in the lower catchment of the Jacobs River, in the Byadbo Wilderness Area of southern Kosciuszko National Park, south-eastern New South Wales, Australia. Survey and monitoring of quoll latrine sites and prey populations, dietary analysis and live-trapping was carried out for one year before and two years after the widespread wildfires of January 2003, which had a very high impact on the study area. Survey for spotted-tailed quoll latrine sites was successful in locating a total of 90 latrine sites in the Jacobs River study area over the three years of the study. These were found throughout all parts of the topography among large, complex granite outcrops and along rocky sections of riparian habitat. After the fire in 2003, lower numbers of latrines were in use than observed pre-fire, and there was a lower level of usage (number of scats) of individual latrines. Continued monitoring in 2004 revealed that many latrines that had become inactive in 2003 following the fire were re-activated in the second breeding season following fire. 1466 spotted-tailed quoll scats were collected from latrines and live-trapped quolls over the three years of the study. Hair analysis from scats identified twenty-two different species of mammal in the diet of the spotted-tailed quoll from the Jacobs River study area, representing the majority of all prey identified (98.5% occurrence) and contributing almost all of the biomass consumed (99.6%). Medium-sized mammals were the most important prey category, followed by small mammals, large mammals (most likely taken as carrion) and non-mammalian prey (birds, reptiles, insects and plants). Brushtail possums were the most important single prey item by both frequency of occurrence and percentage biomass in all years, followed by lagomorphs (rabbits and hares), Rattus spp., and swamp wallabies. There was a significant difference in the composition of the diet by major prey category across the years of the study as a result of the fire, indicated by a shift in utilisation of food resources by quolls in response to significant changes in prey availability. Monitoring of prey populations revealed that brushtail possums, lagomorphs and bandicoots were all significantly less abundant in the study area in the winter directly following the fire, followed by a significant increase in abundance of lagomorphs, but not of possums, in the second winter after the fire. Quolls adapted well to this altered prey availability. While there was a significant decrease in occurrence of brushtail possum in scats after the fire, significantly more scats contained hair of lagomorphs, to the point where almost equal proportions of lagomorphs and possum hair occurred in scats by the winter of 2004. Other fire-induced changes to the diet were evident, such as a significant drop in the occurrence of small mammals in scats for both winters after the fire, and a peak in occurrence of large mammals in the winter directly following the fire that strongly suggests there was a short-term increase in the availability of carrion. A large, high-density population of spotted-tailed quolls was live-trapped and marked during the winter breeding season of 2002. Twenty-two quolls (13 male and 9 female) were present in the study area in 2002, and subsequent trapping over the 2003 and 2004 winter breeding seasons following the fire revealed that the high-intensity wildfire did not result in the extinction of the local population. There was evidence of a small, short-term decline in the number of quolls present in the study area in the 2003 breeding season, with 16 individual quolls captured. Males were outnumbered two-to-one by females, due either to mortality or emigration. Trapping in 2004 showed a recovery of the population to numbers exceeding that observed prior to the fire, with 26 individuals captured (16 male, 10 female), most likely as a result of immigration. There was some evidence that recruitment of young from the post-fire breeding season in 2003 was reduced because of the fire. This study took advantage of an unplanned wildfire event to monitor the response of a population of spotted-tailed quolls and their prey. In this regard it was fortuitous since it has been recognised that the use of replicates and controls in the study of the impacts of wildfire on such species is likely to be logistically impossible. Consequently, the effects of fire on forest and woodland fauna such as the spotted-tailed quoll are poorly understood, with many authors expressing concern that, potentially, wildfires are likely to be highly detrimental to resident quoll populations. The results of this study, however, concur with the few other studies in which forest mammal populations have been monitored before and after wildfire in suggesting that wildfires may not be as destructive to fauna as that imagined. The results of this work will provide information to assist in the preparation of management strategies for the species, such as recovery plans, as well as information for land managers preparing management plans, including fire management plans, for habitats in which spotted-tailed quolls are found throughout their range.

Thesis (M.S.)--University of Wisconsin--Madison, 1999.<br>Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 46-55).

Forest carnivores such as the fisher have frequently been the target of conservation concern due to their association with older forests and assumed sensitivity to landscape-level habitat alteration. Although the fisher has been extirpated from most of its former range in the western U.S., it is still found throughout much of northwestern California. However, fisher distribution is still poorly known in the majority of this region where surveys have not been conducted. In order to predict fisher distribution across the region, a multiple logistic regression model was created using data from 682 previously surveyed locations and a GIS vegetation coverage created from satellite imagery. A moving-average function was used to derive landscape level indices of vegetation variables from the GIS layer. Moving averages of canopy closure, tree size class, and percent conifer were found to have strong correlations with fisher presence. Regional gradients as represented by either precipitation or a trend surface derived from spatial coordinates were also significant predictors in the model. The model was validated with new data collected from 240 survey locations and proved to be accurate in predicting fisher presence in unsurveyed areas. The model was used to generate hypotheses as to the mechanisms controlling habitat selection and the scales at which these operate and to evaluate the representation of fisher habitat in existing protected areas. These insights may be valuable in designing conservation reserve networks that insure the long-term viability of forest carnivore populations.<br>Graduation date: 1998

Tese de Doutoramento em Genética Molecular Comparativa e Tecnológica<br>As causas genéticas do cancro incluem várias alterações genómicas nomeadamente substituições/amplificações/deleções e epigenéticas que normalmente ocorrem em genes críticos de cancro, como o ERBB2 e o TWIST1. Nas lesões mamárias de gato (CML), tal como para o cancro de mama humano (HBC), os marcadores moleculares têm uma importância vital na categorização dos subtipos de lesões. Neste trabalho de doutoramento foram estudados os oncogenes ERBB2 e TWIST1 no gato, no que diz respeito ao DNA, RNA e respetivas proteínas (neste caso, apenas para o ERBB2), os quais podem estar relacionados com o início e progressão de CML. Deste modo, as potenciais correlações entre os resultados obtidos e as características das CML foram também analisadas. Este trabalho de doutoramento começou com a optimização da extracção de DNA genómico (gDNA) de elevada qualidade a partir de tecidos fixados-em-formalina e embebidosem- parafina (FFPET), que resultou num protocolo já publicado. O elevado nível da informação obtida ao longo do trabalho deveu-se à qualidade do gDNA e ao número e tamanho das sequências amplificadas, tanto nas amostras das lesões como das normais, que permitiu a deteção de variantes de sequência nos diferentes fragmentos dos genes ERBB2 e TWIST1. No primeiro estudo conduzido no gene ERBB2 no gato, o fragmento analisado incluiu os exões 17 a 20. A análise genómica revelou que 2/5 das variantes de sequência (SVs) e 2/6 dos haplotipos detetados, são exclusivos das amostras de CML. Uma associação promissora foi ainda identificada entre as variantes de haplotipos e dois fatores de prognóstico de CML: tamanho do tumor primário e número de massas. A análise bioinformática permitiu concluir que 4 das SVs detetadas podem ser responsáveis pela ocorrência de transcriptos alternativos e, consequentemente, de isoformas diferentes da proteína erbB-2. Num segundo passo, foi possível isolar a região entre os exões 10 a 15 do ERBB2 no gato. Neste fragmento foi observada uma categorização clara de haplotipos entre o normal e as CMLs. Foi ainda obtido um modelo de homologia 3D para a proteína erbB-2 do gato. A análise de 3 SVs não-sinónimas correspondentes a 3 alterações de aminoácidos, provavelmente responsáveis por danos na estrutura 3D da erbB-2, podendo ainda interferir na interacção entre a erbB-2 e o anticorpo terapêutico trastuzumab. Foi ainda analisado o status do ERBB2 em gato tendo-se concluído que não se encontra amplificado, apresentando ainda um nível mais baixo de expressão nas lesões mamárias em relação às amostras normais. Os baixos níveis de expressão de RNA do gene ERBB2, bem como da proteína foram já indicados como estando relacionados com malignidade e com mau prognóstico nas CML. Neste trabalho de doutoramento, foi pela primeira vez caracterizado o gene TWIST1 no gato, tendo sido sequenciado um fragmento de DNA com 960 bp em amostras normais. O isolamento e sequenciação de um fragmento de cDNA deste mesmo gene (201 bp) revelam que o TWIST1 é transcrito no gato, tendo-se observado um elevado grau de similaridade das sequências de DNA e cDNA desta espécie com o Homem. Foi ainda realizado o mapeamento físico in silico do gene TWIST1 no ideograma do gato, localizando-se especificamente o gene no cromossoma A2, banda q21.3. Na tentativa de compreender o papel das SVs do TWIST1 no processo tumoral mamário do gato, foram pesquisadas variantes na sequência de DNA do gene, tendo sido detetadas 2 SVs, classificadas como potenciais variantes da linha germinativa, sendo improvável a sua associação com o processo neoplásico. A análise do mRNA do gene TWIST1 no gato por qRTPCR revelou um nível mais baixo de expressão nas lesões malignas em comparação com as benignas. Os nossos resultados sugerem que a função do gene TWIST1 nas CML não está, provavelmente, relacionado com as SVs encontradas, à semelhança do que o ocorre em HBC. De uma forma geral, a importância clínica do nível reduzido e/ou da variação na expressão do TWIST1 durante o processo tumoral, sugere uma maior associação com o “switch” inicial da neoplasia e da progressão para a metastização. Em conclusão, este trabalho representa o primeiro esforço na investigação de variantes de sequência em tecidos normais e em lesões mamárias da espécie Felis catus para ambos os genes ERBB2 e TWIST1. As SVs, os haplotipos, os transcritos e as alterações detetadas na proteína do gene ERBB2 analisado e correlacionados com as características clinicopatológicas das lesões mamárias de gato, revelaram a importância deste gene nas CMLs, tal como ocorre no Homem e realçam a importância destes estudos moleculares, especialmente nos subtipos HER2 negativos. Adicionalmente, vários foram os dados obtidos e publicados ao longo deste trabalho que indicam a utilização dos tumores mamários espontâneos de gata como modelo para o HBC. No que diz respeito à avaliação do gene TWIST1 em CMLs, os níveis baixos de expressão observados nas lesões malignas estão de acordo com evidências recentes em HBC. O comportamento similar do gene nas duas espécies é encorajador para a prossecução da sua investigação, na tentativa de melhor caracterizar os padrões de expressão ao nível do RNA e da proteína em CMLs. Mais uma vez, os resultados apresentados nesta tese reúnem evidências para uma análise comparativa direita entre as lesões mamarias de gato e o cancro de mama humano.<br>The genetic causes of cancer include genomic sequence switches/amplifications/deletions and epigenetic alterations that often occur in cancer critical genes as ERBB2 and TWIST1 oncogenes. In cat mammary lesions (CML), as for human breast cancer (HBC), the molecular markers are greatly important to categorise lesion subtypes that define clinical and therapeutic groups. In this PhD work, cat ERBB2 and TWIST1 oncogenes were studied, concerning DNA, RNA and protein alterations (this last one, only for ERBB2), which may be related with the initiation and progression of CML. Therefore, the potential correlations between the data achieved and CMLs clinicopathological features were also analysed. This PhD work started with the optimization of genomic DNA (gDNA) extraction with high quality from formalin-fixed paraffin-embedded tissues (FFPET) that resulted in a published protocol. The high standard in the obtained data was achieved by the gDNA quality and by the number and size of the genomic sequences amplified, from several CMLs and cat disease free samples. The large genomic sequences amplified allowed the detection of several sequence variants from several fragments of ERBB2 and TWIST1 genes. In the first study of cat ERBB2, the total fragment analysed included exons 17 to 20. The genomic analysis revealed that 2/5 of sequence variants (SVs) and 2/6 of the haplotypes detected, were exclusive of CML samples. A promising association was identified between variant haplotypes and two CMLs prognostic factors: primary tumour size and number of masses. Bioinformatics analysis indicated that 4 SVs might be responsible for alternative transcripts and, consequently, for different erbB-2 protein isoforms. In a second step, cat ERBB2 genomic sequence from exons 10 to 15 was completely obtained. Also, for the first time a tri-dimensional homology model for erbB-2 cat protein was accomplished. In ERBB2 DNA fragment, an undoubtedly haplotype categorisation distinguishes the normal from CML samples. The analysis of the 3 non synonymous SVs detected revealed to correspond to 3 amino acid changes, proposed to be probably damaging for cat erbB-2 tri-dimensional structure and may interfere with the interaction between erbB-2 protein and the therapeutic antibody trastuzumab. It was also analysed the expression status of cat ERBB2, showing no DNA amplification and a lower mRNA and protein expression levels in mammary lesions than in normal samples. Additionally, ERBB2 RNA and erbB-2 protein low expression levels were indicated as being correlated with malignity and worse clinical outcome of the mammary lesions. In this PhD work, for the first time, it was characterized the cat TWIST1 gene. A genomic fragment from the cat TWIST1 gene was isolated and sequenced in cat normal samples. The isolation and sequencing of a cat TWIST1 complementary DNA fragment (201 bp), also demonstrated that this is a transcribed gene, showing the cat TWIST1 sequences a high similarity with the human counterpart. In this work it was also in silico physically mapped TWIST1 gene in the cat G-banding ideogram, namely in chromosome A2, band q21.3. In an attempt to understand TWIST1 gene SVs role in cat mammary oncology, we searched for variants in TWIST1 DNA sequence. We detected 2 SVs, classified as potential germline variants, being improbable its association with neoplasia. The cat TWIST1 mRNA analysis by qRT-PCR revealed lower expression levels in malignant than in benign mammary lesions. Our results suggest that the role of TWIST1 gene in CML is probably not related with the observed genomic changes as referred for HBC studies. Generally, the clinical importance of the low and/or variable TWIST1 expression levels during the multistep process, point toward a major association with the initial “switch” to neoplasia and with the final progression toward metastasis. In conclusion, this work represents the first attempt to examine genomic sequence variants in normal tissues and mammary lesions from Felis catus, to both genes, ERBB2 and TWIST1. The SVs, haplotypes, transcripts and the protein changes disclosed in ERBB2 gene, associated to the CML clinicopathological features, revealed the importance of these molecular studies in CML analysis, as it happens in human and highlight the importance of these molecular studies, particularly for HER2 negative subtypes. Additionally, several were the outcomes from this work indicating the use of cat naturally occurring mammary tumours as model for human breast oncology. Considering the TWIST1 evaluation in CML, the lower RNA expression levels observed in malignant lesions are in agreement with the recent evidences for HBC. The similar behaviour of the gene in the two species encourages the development of new investigation, trying to deeper characterize its expression patterns at the level of RNA and Protein in CMLs. Once again, the results shown in this thesis gather evidences for a straightforward comparative analysis between cat mammary tumour lesions and human breast cancer.