Evolução cromossômica no veado-mateiro – Mazama americana (Mammalia; Cervidae)

Estudos com veado-mateiro (Mazama americana) mostram que há muitas controvérsias quanto ao número de subespécies ou até quanto ao desdobramento destas em espécies. Em estudo citotaxonômico foram encontradas variações cromossômicas intra e interpopulacionais em populações de M. americana geograficamente distantes, com número diplóide de 48 a 53 e número fundamental de 46 a 57. Com base nisto, o presente estudo visou compreender como ocorreu a reorganização cromossômica dentro das variantes encontradas durante a evolução do grupo. Para isto, estrutura e organização dos cromossomos de M. americana foram analisadas para identificar os rearranjos que originaram a variação intraespecífica através das técnicas de bandamento cromossômico (bandas G, C, Ag-NOR), hibridação in situ (FISH) com sondas teloméricas e pintura cromossômica com o uso de sondas cromossômicas da espécie Mazama gouazoubira. Foram identificados seis citótipos distribrídos em 12 cariótipos diferentes: Rondônia (2n=42 ou 43 e NF=46; 2n=42 e NF=49), Juína (2n= 43, 44 ou 45 e NF=48; 2n=44 e NF=46), Jarí (2n=49; NF=56, Carajás (2n=50 e NF=54), Santarém (2n=51 e NF=56) e Paraná (2n=51,52 ou 53 e NF=56). O cariótipo básico do citótipo Paraná foi utilizado como base comparativa para os demais. Os rearranjos que originaram essas diferenças foram fusões cêntricas, em tandem e inversões pericêntricas. A análise de complexo sinaptonêmico confirmou a existência de um sistema sexual múltiplo do tipo XX/XY1Y2 através da detecção de uma trivalente sexual. Sítios teloméricos intersticiais evidenciam que a ocorrência de eventos de fusões em tandem foi essencial para a evolução cariotípica desta espécie e a homologia de sondas cromossomo-específicas de M. gouazoubira corroboram que o caminho da reorganização cromossômica entre estas espécies foi principalmente através de fusões.Studies with the red brocket deer (Mazama americana) shown that there are a lot of controversies about the number of subspecies or about the unfolding of these in new species. Citotaxonomic studies found intra and interpopulational chromosomal variations, with diploid number varing from 48 to 53 and fundamental number from 46 to 57. Based on these studies, the aim of the present study was understood how the chromosomal reorganization occurred between this variants during the evolution process. For that, we analyzed the chromosomal structure and organization of M. americana, identifying the rearrangements responsible for the intraspecific variation through chromosome banding (G and C-banding, Ag-NOR), in situ hybridization of telomeric probes and chromosome painting using probes of M. gouazoubira species. It were found six different variants: Rondônia (2n=42 or 43 and FN=46; 2n=42 and FN=49), Juína (2n= 43, 44 or 45 and FN=48; 2n=44 and FN=46), Jarí (2n=49 and FN=56), Carajás (2n=50 and FN=54), Santarém (2n=51 and FN=56) and Paraná (2n=51,52 or 53 and FN=56). The basic karyotype of Paraná variant was choosing for comparative analysis. The rearrangements responsible for these chromosomal differences were centric and tandem fusions and pericentric inversions. The synaptonemal analysis sustained the existence of a multiple sexual system (XX/XY1Y2) with detection of a sexual trivalent. Intersticial telomeric sites shown the occurrence of tandem fusions was essential for the karyotype evolution of this species and the homology with the probes of M. gouazoubira corroborated that the way of chromosomal reorganization between these species was mainly through chromosome fusions.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Chromosome polymorphism in the Brazilian dwarf brocket deer, Mazama nana (Mammalia, Cervidae)

The Brazilian dwarf brocket deer (Mazama nana) is the smallest deer species in Brazil and is considered threatened due to the reduction and alteration of its habitat, the Atlantic Rainforest. Moreover, previous work suggested the presence of intraspecific chromosome polymorphisms which may contribute to further population instability because of the reduced fertility arising from the deleterious effects of chromosome rearrangements during meiosis. We used G- and C-banding, and nucleolus organizer regions localization by silver-nitrate staining (Ag-NOR) to investigate the causes of this variation. Mazama nana exhibited eight different karyotypes (2n = 36 through 39 and FN = 58) resulting from centric fusions and from inter and intraindividual variation in the number of B chromosomes (one to six). Most of the animals were heterozygous for a single fusion, suggesting one or several of the following: a) genetic instability in a species that has not reached its optimal karyotypic evolutionary state yet; b) negative selective pressure acting on accumulated rearrangements; and c) probable positive selection pressure for heterozygous individuals which maintains the polymorphism in the population (in contrast with the negative selection for many rearrangements within a single individual)

Identifying Mazama gouazoubira (Artiodactyla; Cervidae) chromosomes involved in rearrangements induced by doxorubicin

Abstract The process of karyotype evolution in Cervidae from a common ancestor (2n = 70, FN = 70) has been marked by complex chromosomal rearrangements. This ancestral karyotype has been retained by the current species Mazama gouazoubira (Fischer 1814), for which a chromosomal polymorphism (Robertsonian translocations and the presence of B chromosomes) has been described, presumably caused by a chromosome fragility. Thus, this study has identified doxorubicin-induced chromosome aberrations and mapped the regions involved in breaks, which may be related to the chromosome evolution process. G-banding pattern showed that 21 pairs of chromosomes presented chromosomal aberrations, 60% of the total chromosome number of the species M. gouazoubira. Among chromosomes that carry aberrations, the region where they were most frequently concentrated was distal relative to the centromere. These data suggest that certain chromosomal regions may be more susceptible to chromosome fragility and consequently could be involved in karyotype differentiation in species of the family Cervidae

Elucidating the Evolution of the Red Brocket Deer Mazama americana Complex (Artiodactyla; Cervidae)

The red brocket deer Mazama americana is a neotropical species that exhibits extensive karyotype variation under an unvarying morphotype. In order to deduce red brocket deer genetic units for conservation, gene flow between populations, and genetic variation, we initiated a cytogenetic and molecular genetic study based on representative samples from throughout their Brazilian geographic range. These data represent the first cytotaxonomical and molecular systematics, and although sample sizes are limited, our results clearly suggest that red brocket deer populations are significantly differentiated with respect to karyotypes and the mitochondrial sequences analyzed. We clearly recognized 2 independent species, and we will be focusing further research in analyzing the meiotic dynamic to determine the existence of other evolutionarily significant units under the red brocket complex. Copyright (C) 2010 S. Karger AG, BaselFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

The role of chromosome variation in the speciation of the red brocket deer complex: the study of reproductive isolation in females

Background: The red brocket deer, Mazama americana, has at least six distinct karyotypes in different regions of South America that suggest the existence of various species that are today all referred to as M. americana. From an evolutionary perspective, the red brockets are a relatively recent clade that has gone through intense diversification. This study sought to prove the existence of post-zygotic reproductive isolation in deer offspring between distinct chromosome lineages. To achieve this, inter-cytotype and intra-cytotype crosses were performed, which resulted in both F1 hybrid (n = 5) and pure offspring (n = 3) in captivity.Results: F1 females were analyzed in terms of their karyotypes, ovarian histology, estrous cycles and in vitro embryo production. Pure females presented parameters that were similar to those previously reported for M. Americana; however, the parameters for hybrid females were different. Two hybrids were determined to be sterile, while the remaining hybrids presented characteristics of subfertility.Conclusions: The results support the existence of well-established reproductive isolation among the most distant karyotype lineages and elucidates the need to define all karyotype variants and their geographical ranges in order to define the number of species of red brocket.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Avaliação do risco de extinção do veado-cambuta Mazama nana Hensel, 1872, no Brasil.

O estado de conservação do veado cambuta, Mazama nana (Hensel, 1872), foi avaliado de acordo com os critérios da IUCN (2001), com base nos dados disponíveis até 2010. Síntese do processo de avaliação pode ser encontrada em Peres et al. (2011) e Beisiegel et al. (2012). A categoria proposta para o táxon é Vulnerável (VU) segundo os critérios A4cde, ou seja, ameaçado, de acordo com informações sobre declínio populacional passado e projeção de declínio populacional futuro. Justificativa – Mazama nana, com no máximo 15 Kg de peso corporal, é a menor espécie do gênero. Sua distribuição geográfica atual, bastante fragmentada, restringe-se ao sul do Brasil Esta classificação mantém o status da espécie em relação à lista oficial de fauna ameaçada (MMA 2003). Justifica-se pela suspeita de redução de população maior ou igual a 30%, sem perspectiva de cessar os impactos. Esta redução é causada por efeito de borda nos pequenos fragmentos, caça, predação por cães domésticos, agrotóxicos e enfermidades de ungulados domésticos. A extensão de ocorrência da espécie é maior que 20.000 km2 e sua área de ocupação é maior que 2.000 km2; sua população total é maior do que 10.000 indivíduos maduros, portanto a espécie não está ameaçada sob os critérios B, C e D. Não há análise quantitativa de probabilidade de extinção para esta espécie. Não existem evidências de emigração ou imigração diferencial de indivíduos desta espécie entre o Brasil e os países vizinhos, portanto a categoria da espécie não é alterada quando se aplica a avaliação regional