Modelos de distribuição de Zygodontomys brevicauda (Allen & Chapman, 1893) (Mammalia: Muridae) nas savanas de Roraima, norte do Brasil

The present study describes the distribution of Zygodontomys brevicauda (Rodentia, Sigmodontinae) relating the presence/absence of the species to a digital database on the vegetation of savannas of the northeastern State of Roraima , Brazil. The study area is situated in the Surumu River region, between 03o58’- 04o27’N and 60o13’-61o16’W, and is composed mainly of savanna formations. In a total effort of 9479 trap days, the trap success for Z. brevicauda was 0.57%. The probability of capture of the species was calculated for each trap station through logistic regression, using structural characteristics of each habitat. The association of capture probabilities with different habitat classes using a LANDSAT-TM satellite image allowed a spatial view of the potential distribution of the species considering the habitat mosaic of the region. The species is at least partially dependent on the savanna-forest boundary. The models show a high frequency of apparently unsuitable areas, especially of open and closed savannas, which might suggest that habitat occupancy is far from saturated. Zygodontomys brevicauda appears to be a colonizing species, and was shown to be associated particularly with the edges of the gallery forests. This habitat type may act as source habitats for open savannas.O presente estudo avalia a distribuição potencial de Zygodontomys brevicauda (Rodentia, Sigmodontinae) relacionando a presença/ausência da espécie através de uma base digital de dados sobre a vegetação das savanas do nordeste do Estado de Roraima, Brasil. A área de estudo situa-se na região do Alto e Médio Rio Surumu (3o58’-4o27’N; 60o13’-61o16’W) e é composta por várias formações, sendo mais extensas as de savana. Foram empregadas 9.479 armadilhas-dia e o sucesso de captura de Z. brevicauda foi de 0.57%. As probabilidades de captura da espécie foram calculadas para cada estação de captura através de regressões logísticas utilizando variáveis estruturais dos hábitats. As associações das probabilidades de captura com as diferentes classes de hábitats, reconhecidas via imagem de satélite LANDSAT-TM, permitiram avaliar a distribuição potencial da espécie no mosaico de hábitats da região. A espécie está parcialmente associada às áreas de contato savana-floresta. O modelo evidenciou alta freqüência de áreas potencialmente vagas, especialmente nas savanas arbóreas abertas e graminosas, sugerindo forte insaturação dos hábitats. Zygodontomys brevicauda é potencialmente uma espécie colonizadora dessas classes de hábitats, com as áreas de borda das matas de galeria atuando como hábitats-fonte para as savanas abertas

Caracterização cromossômica de espécies brasileiras de Calomys Waterhouse, 1837 dos domínios Amazônico, do Cerrado e dos Pampas (Rodentia, Sigmodontinae)

The karyotypes of 31 specimens of six taxa of the genus Calomys (Rodentia, Sigmodontinae) trapped in an extensive area of Brazil (between 11o-32°S and between 46°-61oW) are reported. In the Cerrado domain, C. tener showed 2n=66 and FNa=66 karyotype with 32 pairs of autosomes, 31 of them being decreasing-sized acrocentric pairs, and one medium-to-small biarmed pair; C. expulsus showed a 2n=66 and FNa=68 karyotype, with 30 pairs of acrocentric autosomes and two biarmed elements, a submetacentric pair 1 and the medium-to-small biarmed pair also seen in the karyotype of C. tener; in Ipamerí locality (Caldas Novas, Goiás) a female with 2n=64, FNa=66 and a derivative karyotype of C. expulsus type was also observed. In the Pampas region a C. laucha female with 2n=64, FNa=68 was trapped. In addition to the two biarmed pairs seen in C. expulsus, this individual also possessed a third large biarmed submetacentric element corresponding to the largest pair of the karyotype. In the Amazon region three Calomys specimens were analyzed. Two of them depicted a cytotype similar to that of C. tener (showing nevertheless 2n=64, FNa=64 instead of 2n=66, FNa=66), with an acrocentric pair 1 and the medium-to-small sized biarmed pair, but lacking one unidentified autosomal pair. At the same locality (Pimenta Bueno, Rondônia) C. callidus presented 2n=48, FNa=66.São descritos os cariótipos de 31 exemplares de seis taxa do gênero Calomys (Rodentia, Sigmodontinae) provenientes de uma extensa área do Brasil (entre 11o-32°S e 46°-61oW). Na região do Cerrado foram observados C. tener que mostrou 2n=66 e FNa=66, com um cariótipo constituído por 32 pares de autossomos, 31 deles sendo acrocêntricos de tamanho decrescente e um par metacêntrico de tamanho pequeno a médio; e C. expulsus, com 2n=66 e FNa=68 e um cariótipo com 30 pares de autossomos acrocêntricos e mais dois elementos com dois braços, o par 1 submetacêntrico e o metacêntrico de pequeno a médio também visto no cariótipo de C. tener. Na localidade de Ipamerí (Caldas Novas, Goiás) foi também observada uma fêmea com 2n=64, FNa=66 e com cariótipo do tipo C. expulsus. Na região dos Pampas foi coletada uma fêmea de C. laucha com 2n=64, FNa=68. Além dos dois pares com dois braços vistos em C. expulsus, este indivíduo também apresentou um terceiro elemento com dois braços, um submetacêntrico grande que se constitui no maior par do cariótipo. No Amazonas foram analisados três espécimes de Calomys. Dois deles apresentaram um citotipo similar ao de C. tener (mostrando entretanto 2n=64, FNa=64 em vez de 2n=66, FNa=66), com o par 1 acrocêntrico, e o metacêntrico de pequeno a médio, mas faltando um par não identificado de autossomos. Na mesma localidade (Pimenta Bueno, Rondônia) C. callidus apresentou 2n=48, FNa=66

Variations in leopard cat (Prionailurus bengalensis) skull morphology and body size: sexual and geographic influences

The leopard cat, Prionailurus bengalensis (Kerr, 1792), is one of the most widespread Asian cats, occurring in continental eastern and southeastern Asia. Since 1929, several studies have focused on the morphology, ecology, and taxonomy of leopard cats. Nevertheless, hitherto there has been no agreement on basic aspects of leopard cat biology, such as the presence or absence of sexual dimorphism, morphological skull and body differences between the eleven recognized subspecies, and the biogeography of the different morphotypes. Twenty measurements on 25 adult leopard cat skulls from different Asian localities were analyzed through univariate and multivariate statistical approaches. Skull and external body measurements from studies over the last 77 years were assembled and organized in two categories: full data and summary data. Most of this database comprises small samples, which have never been statistically tested and compared with each other. Full data sets were tested with univariate and multivariate statistical analyses; summary data sets (i.e., means, SDs, and ranges) were analyzed through suitable univariate approaches. The independent analyses of the data from these works confirmed our original results and improved the overview of sexual dimorphism and geographical morphological variation among subspecies. Continental leopard cats have larger skulls and body dimensions. Skulls of Indochinese morphotypes have broader and higher features than those of continental morphotypes, while individuals from the Sunda Islands have skulls with comparatively narrow and low profiles. Cranial sexual dimorphism is present in different degrees among subspecies. Most display subtle sex-related variations in a few skull features. However, in some cases, sexual dimorphism in skull morphology is absent, such as in P. b. sumatranus and P. b. borneoensis. External body measurement comparisons also indicate the low degree of sexual dimorphism. Apart from the gonads, the longer hind foot of male leopard cats is the main feature of sexual dimorphism among P. b. bengalensis (and probably among P. b. horsfieldii too). External body measurements also indicated the absence of sexual dimorphism among individuals of P. b. borneoensis. Inter-subspecific skull comparisons provided a morphometric basis for differentiating some subspecies. Prionailurus b. horsfieldii and P. b. bengalensis were distinguished only by a subtle difference in PM4 size, indicating that overall skull morphology does not appear to support their separate taxonomical status, in spite of the marked differences reported in their coat patterns. Geological events affecting the Sunda Shelf connection between the Sunda Islands and the mainland during the Last Glacial Maximum seem to have influenced directly the morphological pattern shown by leopard cat subspecies nowadays

Achilles heel of a powerful invader: restrictions on distribution and disappearance of feral pigs from a protected area in Northern Pantanal, Western Brazil

This paper focuses on a rare case of natural disappearance of feral pigs (Sus scrofa) in an extensive area without using traditional methods of eradication programs. The study was conducted both in the Private Reserve of Natural Heritage (PRNH) Sesc Pantanal and in an adjacent traditional private cattle ranch. In 1998, feral pigs were abundant and widely distributed in the PRNH. However, the feral pigs gradually disappeared from the area and currently, the absence of pigs in the PRNH contrasts with the adjacent cattle ranch where the species is abundant. To understand the current distribution of the species in the region we partitioned the effects of variation of feral pigs’ presence considering the habitat structure (local), landscape composition and the occurrence of potential predators. Additionally, we modeled the distributions of the species in Northern Pantanal, projecting into the past using the classes of vegetation cover before the PRNH implementation (year 1988). Our results show areas with more suitability for feral pigs in regions where the landscape is dominated by pastures and permeated by patches of Seasonal Dry Forest. The species tends to avoid predominantly forested areas. Additionally, we recorded that the environmental suitability decreases exponentially as the distance from water bodies increases. The disappearance of feral pigs in the PRNH area seems to be associated with changes in the landscape and vegetation structure after the removal of the cattle. In the Brazilian Pantanal, the feral pigs’ occurrence seems strongly conditioned to environmental changes associated to livestock activity

Lowland tapir distribution and habitat loss in South America

The development of species distribution models (SDMs) can help conservation efforts by generating potential distributions and identifying areas of high environmental suitability for protection. Our study presents a distribution and habitat map for lowland tapir in South America. We also describe the potential habitat suitability of various geographical regions and habitat loss, inside and outside of protected areas network. Two different SDM approaches, MAXENT and ENFA, produced relative different Habitat Suitability Maps for the lowland tapir. While MAXENT was efficient at identifying areas as suitable or unsuitable, it was less efficient (when compared to the results by ENFA) at identifying the gradient of habitat suitability. MAXENT is a more multifaceted technique that establishes more complex relationships between dependent and independent variables. Our results demonstrate that for at least one species, the lowland tapir, the use of a simple consensual approach (average of ENFA and MAXENT models outputs) better reflected its current distribution patterns. The Brazilian ecoregions have the highest habitat loss for the tapir. Cerrado and Atlantic Forest account for nearly half (48.19%) of the total area lost. The Amazon region contains the largest area under protection, and the most extensive remaining habitat for the tapir, but also showed high levels of habitat loss outside protected areas, which increases the importance of support for proper management