DESBIEZ, A.L.J.; SANTOS, S.A.; KEUROGHLIAN, A.; BODMER, R.E. 2009. Niche partitioning among white-lipped peccaries (Tayassu pecari), collared peccaries (Pecari tajacu), and feral pigs (Sus scrofa). Journal of Mammlogy 90(1):119-128.
Abstract. The introduction of a species into an ecosystem with species already occupying a similar trophic level is predicted to lead to a high degree of niche overlap. The feral pig (Sus scrofa), one of the world’s worst invasive species, was introduced to the Pantanal about 200 years ago and is thought to compete with the native whitelipped peccary (Tayassu pecari) and collared peccary (Pecari tajacu). Resource partitioning between the 3 species was examined, including analysis of fruit items and plants in fecal samples as well as encounter rates in different habitats, to help generate hypotheses about competitive interactions among the species. Overlaps in food resources and habitat use between feral pigs and peccaries were found to be lower than expected. In fact, niche overlap as highest between the native species. Results indicate that currently, feral pigs are not a direct threat to the native peccaries in the study area. Differences in morphology and behavior indicate possible mechanisms of niche partitioning between the species. Feral pigs may, nevertheless, impact the wildlife community in other ways as predators of eggs, by destruction of vegetation through rooting, or by functioning as disease reservoirs. Cattle-ranching activities may favor feral pigs and the current anthropogenic changes in the landscape could lead to changes in competitive dynamics between feral pigs and native species.
Mostrando postagens com marcador Cetartiodactyla. Mostrar todas as postagens
Mostrando postagens com marcador Cetartiodactyla. Mostrar todas as postagens
sábado, 10 de janeiro de 2015
sábado, 15 de novembro de 2014
The phylogeny of Cetartiodactyla: the importance of dense taxon sampling, missing data, and the remarkable promise of cytochrome b to provide realiable species-level phylogenies
AGNARSSON, I.; MAY-COLLADO, L.J. 2008. The phylogeny of Cetartiodactyla: the importance of dense taxon sampling, missing data, and the remarkable promise of cytochrome b to provide realiable species-level phylogenies. Molecular Phylogenetics and Evolution 48:964-985.
Abstract. We perform Bayesian phylogenetic analyses on cytochrome b sequences from 264 of the 290 extant cetartiodactyl mammals (whales plus even-toed ungulates) and two recently extinct species, the "Mouse Goad" and the "Irish Elk". Previous primary analyses have included only a small portion of the species diversity within Cetartiodactyla, while a complete supertree analysis lacks resolution and branch lenghts limiting its utility for comparative studies. The benefits of using a single-gene approach include rapid phylogenetic estimates for a large number of species. However, single-gene phylogenies often differ dramatically from studies involving multiple datasets suggesting that they often are unrealiable. However, based on recovery of banchmark clades - clades supported in prior studies based on multiple independent datasets - and recovery of undisputed traditional taxonomic groups, Cytb performs extraordinarily well in resolving cetartiodactyl phylogeny when taxon sampling is dense. Missing data, however, (taxa with partial sequences) can compromise phylogenetic accuracy, suggesting a tradeoff between the benefits of adding taxa and introducing question marks. In the full data, a fez species with a short sequences appear misplaced, however, sequence lenght alone seems a poor predictor of this phenomenon as other taxa with equally short sequences were not conspicuously misplaced. Although we recommend awaiting a better supported phylogenetic hypotheses provided here represent the currently best available tool for comparative species-level studies within this group. Cytb has been sequenced for a large percentage of mammals and appears to be a reliable phylogenetic marker as long as taxon sampling is dense. Therefore, an opportunity exists now to reconstruct detailed phylogenies of most of the major mammalian clades to rapidly provide much needed tools for species-level comparative studies.
Abstract. We perform Bayesian phylogenetic analyses on cytochrome b sequences from 264 of the 290 extant cetartiodactyl mammals (whales plus even-toed ungulates) and two recently extinct species, the "Mouse Goad" and the "Irish Elk". Previous primary analyses have included only a small portion of the species diversity within Cetartiodactyla, while a complete supertree analysis lacks resolution and branch lenghts limiting its utility for comparative studies. The benefits of using a single-gene approach include rapid phylogenetic estimates for a large number of species. However, single-gene phylogenies often differ dramatically from studies involving multiple datasets suggesting that they often are unrealiable. However, based on recovery of banchmark clades - clades supported in prior studies based on multiple independent datasets - and recovery of undisputed traditional taxonomic groups, Cytb performs extraordinarily well in resolving cetartiodactyl phylogeny when taxon sampling is dense. Missing data, however, (taxa with partial sequences) can compromise phylogenetic accuracy, suggesting a tradeoff between the benefits of adding taxa and introducing question marks. In the full data, a fez species with a short sequences appear misplaced, however, sequence lenght alone seems a poor predictor of this phenomenon as other taxa with equally short sequences were not conspicuously misplaced. Although we recommend awaiting a better supported phylogenetic hypotheses provided here represent the currently best available tool for comparative species-level studies within this group. Cytb has been sequenced for a large percentage of mammals and appears to be a reliable phylogenetic marker as long as taxon sampling is dense. Therefore, an opportunity exists now to reconstruct detailed phylogenies of most of the major mammalian clades to rapidly provide much needed tools for species-level comparative studies.
sábado, 25 de outubro de 2014
Pesquisa de anticorpos contra Leptospira spp. em animais silvestres e em estado feral da região de Nhecolândia, Mato Grosso do Sul, Brasil. Utilização da técnica de imuno-histoquímica para detecção do agente
GIRIO, R.J.S.; PEREIRA, F.L.G.; FILHO, M.M.; MATHIAS, L.A.; HERREIRA, R.C.P.; ALESSI, A.C.; GIRIO, T.M.S. 2004. Pesquisa de anticorpos contra Leptospira spp. em animais silvestres e em estado feral da região de Nhecolândia, Mato Grosso do Sul, Brasil. Utilização da técnica de imuno-histoquímica para detecção do agente. Ciência Rural 34(1):165-169.
Abstract. Three hundred and fifteen serum samples of several animal species living in wild or in feral state in the area of Nhecolândia, Corumbá, MS, Brazil, were examined by the microscopic agglutination test. Of these samples, 67 were of feral bovine (Bos taurus indicus), 39 of feral pigs (Sus scrofa), 39 of buffaloes (Bubalus bubalis), nine of coatis (Nasua nasua), 41 of pampas deer (Ozotoceros bezoarticus), 10 of brocket deer (Mazama americana) and 110 of feral sheep (Ovis aries). In 12 dead animals (six feral pigs, four pampas deer and two feral sheep), isolation attempts and leptospira identification through the immunohistochemistry were accomplished. Sixty-four (20.3%) of the samples reacted to at least one serovar of pathogenic leptospira; 41.0% of the buffaloes, 40.3% of the feral bovine, 17.9% of the feral pigs, 9% of the feral sheep, and 9.7% of the pampas deer serum samples were reactors. All the serum samples of brocket deer and of coatis were not reactors. The most frequent serovars for the studied animal species were: pomona for buffaloes and feral sheep; icterohaemorrhagiae for feral sheep, pampas deer and feral pigs; and copenhageni for pampas deer and feral pigs. The attempts of leptospira isolation resulted negative, and the immunohistochemistry analysis revealed leptospira in the liver of one feral pig. Microscopic examination of the kidney revealed vascular congestion, hemorrhage and infiltration of mononuclear inflammatory cells in the interstice.
Abstract. Three hundred and fifteen serum samples of several animal species living in wild or in feral state in the area of Nhecolândia, Corumbá, MS, Brazil, were examined by the microscopic agglutination test. Of these samples, 67 were of feral bovine (Bos taurus indicus), 39 of feral pigs (Sus scrofa), 39 of buffaloes (Bubalus bubalis), nine of coatis (Nasua nasua), 41 of pampas deer (Ozotoceros bezoarticus), 10 of brocket deer (Mazama americana) and 110 of feral sheep (Ovis aries). In 12 dead animals (six feral pigs, four pampas deer and two feral sheep), isolation attempts and leptospira identification through the immunohistochemistry were accomplished. Sixty-four (20.3%) of the samples reacted to at least one serovar of pathogenic leptospira; 41.0% of the buffaloes, 40.3% of the feral bovine, 17.9% of the feral pigs, 9% of the feral sheep, and 9.7% of the pampas deer serum samples were reactors. All the serum samples of brocket deer and of coatis were not reactors. The most frequent serovars for the studied animal species were: pomona for buffaloes and feral sheep; icterohaemorrhagiae for feral sheep, pampas deer and feral pigs; and copenhageni for pampas deer and feral pigs. The attempts of leptospira isolation resulted negative, and the immunohistochemistry analysis revealed leptospira in the liver of one feral pig. Microscopic examination of the kidney revealed vascular congestion, hemorrhage and infiltration of mononuclear inflammatory cells in the interstice.
sábado, 7 de junho de 2014
Use of carbon and nitrogen stable isotopes to study the feering ecology of small coastal cetacean populations in southern Brazil
HARDT, F.A.S.; CREMER, M.J.; JUNIOR, A.J.T.; BELLANTE, A.; BUFFA, G.; BUSCAINO, G.; MAZZOLA, S.; BARRETO, A.S.; MARTINELLI, L.A.; ZUPPI, G.M. 2013. Use of carbon and nitrogen stable isotopes to study the feering ecology of small coastal cetacean populations in southern Brazil. Biota Neotropica 13(4):90-98.
Abstract: Samples from individuals of the populations of Sotalia guianensis (Guiana) and Pontoporia blainvillei (Franciscana) dolphins living in the Babitonga Bay estuary (26° 28’ S/48° 50’ W), and samples from individuals of a second population of P. blainvillei from a nearshore area (26° 38’ S/48° 41’ W), were collected and analyzed along with their prey between 2000 and 2006, to determine the carbon and nitrogen stable isotope ratios and to verify differences in their feeding ecology. No differences were found in the median ð15N values of Guiana (15.2‰) and Franciscana (15.9‰) dolphins living in Babitonga Bay, nor of nearshore Franciscana (15.0‰) individuals, suggesting no variation in the trophic level of these populations. However, the lack of more information on the isotopic compositions of their putative prey in the nearshore areas prevents the ability to draw definitive conclusions on this issue. The estuarine Franciscana and Guiana dolphin populations presented mean ð13C values of approximately –15.7‰, which were not statistically different from nearshore Franciscana individuals (–14.8‰). Based on stomach content analyses of these species from a previous study, it was reported that there was little overlap in the diet of estuarine Franciscanas and Guiana dolphins. However, based on the similarity of the ð13C values between these two species and of their putative prey, it appears that in fact there is an overlap in the diet of these two species. Based solely on stable isotope analysis, it was not possible to differentiate between estuarine and nearshore Franciscana populations, making it difficult to conclude whether captured nearshore specimens were indeed yearlong residents of these areas. Finally, this study suggests that Franciscana and Guiana dolphin populations are sharing the same resources, mostly L. brevis, D. rhombeus, and S. rastrifer. Therefore, the combination of resource sharing and commercial exploitation of their prey makes these two cetacean species vulnerable.
Abstract: Samples from individuals of the populations of Sotalia guianensis (Guiana) and Pontoporia blainvillei (Franciscana) dolphins living in the Babitonga Bay estuary (26° 28’ S/48° 50’ W), and samples from individuals of a second population of P. blainvillei from a nearshore area (26° 38’ S/48° 41’ W), were collected and analyzed along with their prey between 2000 and 2006, to determine the carbon and nitrogen stable isotope ratios and to verify differences in their feeding ecology. No differences were found in the median ð15N values of Guiana (15.2‰) and Franciscana (15.9‰) dolphins living in Babitonga Bay, nor of nearshore Franciscana (15.0‰) individuals, suggesting no variation in the trophic level of these populations. However, the lack of more information on the isotopic compositions of their putative prey in the nearshore areas prevents the ability to draw definitive conclusions on this issue. The estuarine Franciscana and Guiana dolphin populations presented mean ð13C values of approximately –15.7‰, which were not statistically different from nearshore Franciscana individuals (–14.8‰). Based on stomach content analyses of these species from a previous study, it was reported that there was little overlap in the diet of estuarine Franciscanas and Guiana dolphins. However, based on the similarity of the ð13C values between these two species and of their putative prey, it appears that in fact there is an overlap in the diet of these two species. Based solely on stable isotope analysis, it was not possible to differentiate between estuarine and nearshore Franciscana populations, making it difficult to conclude whether captured nearshore specimens were indeed yearlong residents of these areas. Finally, this study suggests that Franciscana and Guiana dolphin populations are sharing the same resources, mostly L. brevis, D. rhombeus, and S. rastrifer. Therefore, the combination of resource sharing and commercial exploitation of their prey makes these two cetacean species vulnerable.
sábado, 24 de maio de 2014
External features of the dusk dolphin Lagenorhynchus obscurus (Gray, 1828) from Peruvian waters
WAEREBEEK, K.V. 1993. External features of the dusk dolphin Lagenorhynchus obscurus (Gray, 1828) from Peruvian waters. Estudos Oceanológicos 12:37-53.
Abstract. Individual, sexual and developmental variation is quantified in the external morphology and colouration of the dusky dolphin Lagenorhynchus obscurus from Peruvian coastal waters. No significant difference in body length between sexes is found (p = 0.09) and, generally, little sexual dimorphism is present. However, males have a more anteriorly positioned genital slit and anus and their dorsal fin is more curved, has a broader base and a greater surface area than females Although the dorsal fin apparently serves as a secondary sexual character, the use of it for sexing free-ranging dusky dolphins is discouraged because of high overlap in values. Relative growth in 25 body measurements is characterized for both sexes by multiplicative regression equations. The colouration pattern of the dorsal fin, flank patch, thoracic field, flipper stripe and possibly (X², p = 0.08) the eye patch, are independent of maturity status. Flipper blaze and lower lip patch are less pigmented in juveniles than in adults No sexual dimorphism is found in the colour pattern The existence of a discrete "Fitzroy" colour form can not be confirmed from available data. Various cases of anomalous, piebald pigmentation are described, probably equivalent to so-called partial albinism. Adult dusky dolphins from both SW Africa and New Zealand are 8-10 cm shorter than Peruvian specimens, supporting conclusions of separate populations from a recent skull variability study.
Abstract. Individual, sexual and developmental variation is quantified in the external morphology and colouration of the dusky dolphin Lagenorhynchus obscurus from Peruvian coastal waters. No significant difference in body length between sexes is found (p = 0.09) and, generally, little sexual dimorphism is present. However, males have a more anteriorly positioned genital slit and anus and their dorsal fin is more curved, has a broader base and a greater surface area than females Although the dorsal fin apparently serves as a secondary sexual character, the use of it for sexing free-ranging dusky dolphins is discouraged because of high overlap in values. Relative growth in 25 body measurements is characterized for both sexes by multiplicative regression equations. The colouration pattern of the dorsal fin, flank patch, thoracic field, flipper stripe and possibly (X², p = 0.08) the eye patch, are independent of maturity status. Flipper blaze and lower lip patch are less pigmented in juveniles than in adults No sexual dimorphism is found in the colour pattern The existence of a discrete "Fitzroy" colour form can not be confirmed from available data. Various cases of anomalous, piebald pigmentation are described, probably equivalent to so-called partial albinism. Adult dusky dolphins from both SW Africa and New Zealand are 8-10 cm shorter than Peruvian specimens, supporting conclusions of separate populations from a recent skull variability study.
sábado, 3 de maio de 2014
Interactions between Atlantic spotted (Stenella frontalis) and bottlenose (Tursiops truncatus) dolphins off Bimini, The Bahamas, 2003-2007
MELILLO, K.E.; DUDZINSKI, K.M.; CORNICK, L.A. 2009. Interactions between Atlantic spotted (Stenella frontalis) and bottlenose (Tursiops truncatus) dolphins off Bimini, The Bahamas, 2003-2007. Aquatic Mammals 35(2):281-291. DOI: 10.1578/AM.35.2.2009.281
Abstract. Interspecific interactions have been observed in a variety of social animal. Functional explanations include foraging, anti-predatory, and social advantages. These behaviours are poorly understood in marine mammals but are increasingly studied phenomena in sympatric populations. Resident Atlantic spotted dolphins (Stenella frontalis) off Bimini, The Bahamas, have been the subject of ongoing photo-identification and behavioural studies since 2001. A lesser-known population of bottlenose dolphins (Tursiops truncatus) has been observed interacting with these S. frontalis since 2003. To examine the functional significance of these interactions, interspecific behaviours were documented with underwater video using focal animal sampling. Mating or sexual play were the primary activities observed in nearly 50% of interactions, with male T. truncatus as the initiators. Therefore, the most likely functional explanation for these interactions is social. We hypothesize that male T. truncatus which lack acess to T. truncatus females because of sexual immaturity or low social status seek copulations with S. frontalis females as an alternative.
Abstract. Interspecific interactions have been observed in a variety of social animal. Functional explanations include foraging, anti-predatory, and social advantages. These behaviours are poorly understood in marine mammals but are increasingly studied phenomena in sympatric populations. Resident Atlantic spotted dolphins (Stenella frontalis) off Bimini, The Bahamas, have been the subject of ongoing photo-identification and behavioural studies since 2001. A lesser-known population of bottlenose dolphins (Tursiops truncatus) has been observed interacting with these S. frontalis since 2003. To examine the functional significance of these interactions, interspecific behaviours were documented with underwater video using focal animal sampling. Mating or sexual play were the primary activities observed in nearly 50% of interactions, with male T. truncatus as the initiators. Therefore, the most likely functional explanation for these interactions is social. We hypothesize that male T. truncatus which lack acess to T. truncatus females because of sexual immaturity or low social status seek copulations with S. frontalis females as an alternative.
sábado, 29 de março de 2014
Analysis of the distribution patterns of southern right whale off the southern Brazilian coast
SANTO, S.E.; FRANCO, D.; GROCH, K. 2013. Analysis of the distribution patterns of southern right whale off the southern Brazilian coast. Neotropical Biology and Conservation 8(3):143-149.
Abstract. The southern right whale, Eubalaena australis, is a migratory baleen whale that uses southern Brazilian waters as a nursery and breeding ground from June to November. This study aims to determine the distribution patterns and main aggregation sites of southern right whales off the southern Brazilian coast from around Santa Catarina Island to Osório, and to investigate the population distribution according to the coastline and bathymetric features. The methods consisted in obtaining geographical coordinates for each individual, sighted through helicopter expeditions over a transect along the coastline, conducted once a year in September, from 2001 to 2010. This data was used to generate a density estimate surface map of southern right whales using the Kernel Density Estimator. Additionally, a digital bathymetry was overlaid to the density estimate map. The results pointed out a region of high density estimate of southern right whales, located from 28°12’22”S, 48°39’25”W to 28°33’58”S 48°47’19”W, respectively, from Imbituba to Santa Marta Cape. The largest aggregations were observed where the shelf declivity is higher, as a result from the bathymetric lines of 10 m and 40 m being closer to each other, and where the coastline shows great amount of bays. We highlight the importance of monitoring the southern right whales distribution patterns observed in this study, aiming to identify possible habitat changes that can be indicative of disturbances on their populations.
Abstract. The southern right whale, Eubalaena australis, is a migratory baleen whale that uses southern Brazilian waters as a nursery and breeding ground from June to November. This study aims to determine the distribution patterns and main aggregation sites of southern right whales off the southern Brazilian coast from around Santa Catarina Island to Osório, and to investigate the population distribution according to the coastline and bathymetric features. The methods consisted in obtaining geographical coordinates for each individual, sighted through helicopter expeditions over a transect along the coastline, conducted once a year in September, from 2001 to 2010. This data was used to generate a density estimate surface map of southern right whales using the Kernel Density Estimator. Additionally, a digital bathymetry was overlaid to the density estimate map. The results pointed out a region of high density estimate of southern right whales, located from 28°12’22”S, 48°39’25”W to 28°33’58”S 48°47’19”W, respectively, from Imbituba to Santa Marta Cape. The largest aggregations were observed where the shelf declivity is higher, as a result from the bathymetric lines of 10 m and 40 m being closer to each other, and where the coastline shows great amount of bays. We highlight the importance of monitoring the southern right whales distribution patterns observed in this study, aiming to identify possible habitat changes that can be indicative of disturbances on their populations.
sábado, 15 de fevereiro de 2014
Variabilidade genética en géneros de ciervos neotropicales (Mammalia: Cervidae) según loci microsatelitales
RUIZ-GARCÍA, M.; MARTINEZ-AGÜERO, M.; ÁLVAREZ, D.; GOODMAN, S. 2009. Variabilidade genética en géneros de ciervos neotropicales (Mammalia: Cervidae) según loci microsatelitales. Revista de Biología Tropical 57(3):879-904.
Abstract. Genetic variability in Neotropical deer genera (Mammalia: Cervidae) according to DNA
microsatellite loci. Species conservation programs are highly based on analyses of population genetics. We compared eight Neotropical Cervidae (Mazama americana, M. gouzaoubira, M. rufina, Odocoileus virginianus, Hippocamelus antisensis, Pudu mephistopholes, Ozotoceros bezoarticus and Blastoceros dichotomus) and some European and Asian Cervidae (Cervus elaphus, C. nippon, Capreolus capreolus, C. pygargus and Dama dama). The European species C. elaphus was our standard for a high degree of genetic variability: we used a Scottish population originated in the mix of diverse Western European subspecies. On the contrary, Cervus nippon (a population from Scotland with a founder effect) was our standard for a depauperated population. The M. americana, M. gouzaoubira and O. virginianus samples had high diversity values close to our C. elaphus population (H= 0.64, 0.70 and 0.61, respectively), while M. rufina was very low, close to C. nippon. Several sample sets of Mazama and Odocoileus yielded a homozygote excess, probably due to the Wahlund (subdivison) effect. There was no evidence of recent bottleneck events.
Abstract. Genetic variability in Neotropical deer genera (Mammalia: Cervidae) according to DNA
microsatellite loci. Species conservation programs are highly based on analyses of population genetics. We compared eight Neotropical Cervidae (Mazama americana, M. gouzaoubira, M. rufina, Odocoileus virginianus, Hippocamelus antisensis, Pudu mephistopholes, Ozotoceros bezoarticus and Blastoceros dichotomus) and some European and Asian Cervidae (Cervus elaphus, C. nippon, Capreolus capreolus, C. pygargus and Dama dama). The European species C. elaphus was our standard for a high degree of genetic variability: we used a Scottish population originated in the mix of diverse Western European subspecies. On the contrary, Cervus nippon (a population from Scotland with a founder effect) was our standard for a depauperated population. The M. americana, M. gouzaoubira and O. virginianus samples had high diversity values close to our C. elaphus population (H= 0.64, 0.70 and 0.61, respectively), while M. rufina was very low, close to C. nippon. Several sample sets of Mazama and Odocoileus yielded a homozygote excess, probably due to the Wahlund (subdivison) effect. There was no evidence of recent bottleneck events.
sábado, 31 de agosto de 2013
Interactions between short-beaked common dolphin (Delphinus delphis) and the winter pelagic pair-trawl fishery off Southwest England (UK)
BOER, M.N.; SAULINO, J.T.; LEOPOLD, M.F.; RIJNDERS, P.J.H.; SIMMONDS, M.P. 2012. Interactions between short-beaked common dolphin (Delphinus delphis) and the winter pelagic pair-trawl fishery off Southwest England (UK). International Journal of Biodiversity and Conservation 4(13):481-499. doi: 10.5897/IJBC12.016
Abstract. During offshore and onshore studies (2004 to 2009), the interactions between pair-trawls and shortbeaked common dolphins (Delphinus delphis) were studied to better understand the impact of bycatch. A ‘hotspot’ area where pair-trawls overlapped with high dolphin abundance was identified. We made comparisons between boat-based data collected in absence and presence of pair-trawlers. The relative abundance and group-size of dolphins was significantly higher in the presence of pair-trawlers. Dolphins were observed associating with towing and hauling procedures. Significantly, more carcasses occurred in areas with hauling-activity than those without. Body-temperatures obtained from carcasses found near operating pair-trawlers indicated that bycatch mostly occurred at night. During necropsy studies, difficulties were encountered in identifying the fishing-gears responsible. Strandings data highlighted that the number of dead stranded dolphins was probably much higher than previously reported and there was a significant difference in the age and gender-composition of carcasses. Mature/sub-adult males appeared at greater risk from entanglement in pair-trawls offshore, whilst females with young appeared more vulnerable to inshore gillnets. Our findings show that the overlap between pelagic fisheries and the common dolphin hotspot is causing direct mortality through bycatch and, together with recent range-shifts, may have contributed to a localised decline of this species in this winter hotspot since 2007.
Abstract. During offshore and onshore studies (2004 to 2009), the interactions between pair-trawls and shortbeaked common dolphins (Delphinus delphis) were studied to better understand the impact of bycatch. A ‘hotspot’ area where pair-trawls overlapped with high dolphin abundance was identified. We made comparisons between boat-based data collected in absence and presence of pair-trawlers. The relative abundance and group-size of dolphins was significantly higher in the presence of pair-trawlers. Dolphins were observed associating with towing and hauling procedures. Significantly, more carcasses occurred in areas with hauling-activity than those without. Body-temperatures obtained from carcasses found near operating pair-trawlers indicated that bycatch mostly occurred at night. During necropsy studies, difficulties were encountered in identifying the fishing-gears responsible. Strandings data highlighted that the number of dead stranded dolphins was probably much higher than previously reported and there was a significant difference in the age and gender-composition of carcasses. Mature/sub-adult males appeared at greater risk from entanglement in pair-trawls offshore, whilst females with young appeared more vulnerable to inshore gillnets. Our findings show that the overlap between pelagic fisheries and the common dolphin hotspot is causing direct mortality through bycatch and, together with recent range-shifts, may have contributed to a localised decline of this species in this winter hotspot since 2007.
sábado, 4 de maio de 2013
Anomalous color in Neotropical mammals: a review with new records for Didelphis sp. (Didelphidae, Didelphimorphia) and Arctocephalus australis (Otariidae, Carnivora)
ABREU, M.S.L.; MACHADO, R.; BARBIERI, F.; FREITAS, N.S.; OLIVEIRA, L.R. 2013. Anomalous color in Neotropical mammals: a review with new records for Didelphis sp. (Didelphidae, Didelphimorphia) and Arctocephalus australis (Otariidae, Carnivora). Brazilian Journal of Biology 73(1):185-194.
Abstract. Anomalous colourations occur in many tropical vertebrates. However, they are considered rare in wild populations, with very few records for the majority of animal taxa. We report two new cases of anomalous colouration in mammals. Additionally, we compiled all published cases about anomalous pigmentation registered in Neotropical mammals, throughout a comprehensive review of peer reviewed articles between 1950 and 2010. Every record was classified as albinism, leucism, piebaldism or eventually as undetermined pigmentation. As results, we report the new record of a leucistic specimen of opossum (Didelphis sp.) in southern Brazil, as well as a specimen of South American fur seal (Arctocephalus australis) with piebaldism in Uruguay. We also found 31 scientific articles resulting in 23 records of albinism, 12 of leucism, 71 of piebaldism and 92 records classified as undetermined pigmentation. Anomalous colouration is apparently rare in small terrestrial mammals, but it is much more common in cetaceans and michrochiropterans. Out of these 198 records, 149 occurred in cetaceans and 30 in bats. The results related to cetaceans suggest that males and females with anomolous pigmentation are reproductively successful and as a consequence their frequencies are becoming higher in natural populations. In bats, this result can be related to the fact these animals orient themselves primarily through echolocation, and their refuges provide protection against light and predation. It is possible that anomalous colouration occurs more frequently in other Neotropical mammal orders, which were not formally reported. Therefore, we encourage researchers to publish these events in order to better understand this phenomenon that has a significant influence on animal survival.
Abstract. Anomalous colourations occur in many tropical vertebrates. However, they are considered rare in wild populations, with very few records for the majority of animal taxa. We report two new cases of anomalous colouration in mammals. Additionally, we compiled all published cases about anomalous pigmentation registered in Neotropical mammals, throughout a comprehensive review of peer reviewed articles between 1950 and 2010. Every record was classified as albinism, leucism, piebaldism or eventually as undetermined pigmentation. As results, we report the new record of a leucistic specimen of opossum (Didelphis sp.) in southern Brazil, as well as a specimen of South American fur seal (Arctocephalus australis) with piebaldism in Uruguay. We also found 31 scientific articles resulting in 23 records of albinism, 12 of leucism, 71 of piebaldism and 92 records classified as undetermined pigmentation. Anomalous colouration is apparently rare in small terrestrial mammals, but it is much more common in cetaceans and michrochiropterans. Out of these 198 records, 149 occurred in cetaceans and 30 in bats. The results related to cetaceans suggest that males and females with anomolous pigmentation are reproductively successful and as a consequence their frequencies are becoming higher in natural populations. In bats, this result can be related to the fact these animals orient themselves primarily through echolocation, and their refuges provide protection against light and predation. It is possible that anomalous colouration occurs more frequently in other Neotropical mammal orders, which were not formally reported. Therefore, we encourage researchers to publish these events in order to better understand this phenomenon that has a significant influence on animal survival.
sábado, 13 de abril de 2013
Revisão sobre o fenômeno da hibridização em cetáceos e pinípedes
SCHAURICH, M.N.; LOPES, F.R.V.; OLIVEIRA, L.R. 2012. Revisão sobre o fenômeno da hibridização em cetáceos e pinípedes. Neotropical Biology and Conservation 7(3):199-209.
Abstract. The hybridism is the result of mating between two individuals from different and reproductively isolated gene pools accepted as species that usually generate infertile offspring. The evolutionary consequences of this phenomenon vary depending on the mating system, hybrid’s frequency, the degree of reproductive isolation and the genetic differences between the parental species as well as their speciation process. Hybrids have been recorded frequently in aquatic and terrestrial mammals, both in nature and captivity. We review studies published in peer-reviewed journals between 1940 and 2010, in which hybrid cases were reported for cetaceans and pinnipeds. We found 37 scientific papers recording 1,201 hybrids: 57 in cetaceans (nature = 27; captivity = 30) and 1,144 in pinnipeds (nature = 1,137; captivity = 7). A possible explanation for this phenomenon in the wild could be the close phylogenetic relatedness between parental species and also the potential absence of conspecific breeding partners. This last factor could be a result of population decline due to commercial exploitation occurred in the past. This fact is valid for pinnipeds, but especially true for blue whales, Balaenoptera musculus. It is important to note that about 99% of pinniped hybrids were reported in sympatric breeding colonies along the subantarctic islands, which facilitate the hybridization. Outbreeding depression followed by loss of genetic variability and reduction of evolutionary potential and consequently increasing the risk of extinction are the most important results of the hybridism.
Abstract. The hybridism is the result of mating between two individuals from different and reproductively isolated gene pools accepted as species that usually generate infertile offspring. The evolutionary consequences of this phenomenon vary depending on the mating system, hybrid’s frequency, the degree of reproductive isolation and the genetic differences between the parental species as well as their speciation process. Hybrids have been recorded frequently in aquatic and terrestrial mammals, both in nature and captivity. We review studies published in peer-reviewed journals between 1940 and 2010, in which hybrid cases were reported for cetaceans and pinnipeds. We found 37 scientific papers recording 1,201 hybrids: 57 in cetaceans (nature = 27; captivity = 30) and 1,144 in pinnipeds (nature = 1,137; captivity = 7). A possible explanation for this phenomenon in the wild could be the close phylogenetic relatedness between parental species and also the potential absence of conspecific breeding partners. This last factor could be a result of population decline due to commercial exploitation occurred in the past. This fact is valid for pinnipeds, but especially true for blue whales, Balaenoptera musculus. It is important to note that about 99% of pinniped hybrids were reported in sympatric breeding colonies along the subantarctic islands, which facilitate the hybridization. Outbreeding depression followed by loss of genetic variability and reduction of evolutionary potential and consequently increasing the risk of extinction are the most important results of the hybridism.
sábado, 20 de agosto de 2011
A complete phylogeny of the whales, dolphins and even-toed hoofed mammals (Cetartiodactyla)
PRICE, S.A.; BININDA-EMONDS, O.R.P.; GITTLEMAN, J.L. 2005. A complete phylogeny of the whales, dolphins and even-toed hoofed mammals (Cetartiodactyla). Biology Review 80:445-473.
Abstract. Despite the biological and economic importance of the Cetartiodactyla, the phylogeny of this clade remains controversial. Using the supertree approach of matrix representation with parsimony, we present the first phylogeny to include all 290 extant species of the Cetacea (whales and dolphins) and Artiodactyla (even-toed hoofed mammals). At the family-level, the supertree is fully resolved. For example, the relationships among the Ruminantia appear as (((Cervidae, Moschidae) Bovidae) (Giraffidae, Antilocapridae) Tragulidae). However, due to either lack of phylogenetic study or contradictory information, polytomies occur within the clades Sus, Muntiacus, Cervus, Delphinidae, Ziphiidae and Bovidae. Complete species-level phylogenies are necessary for both illustrating and analysing biological, geographical and ecological patterns in an evolutionary framework. The present species-level tree of the Cetartiodactyla provides the first opportunity to examine comparative hypotheses across entirely aquatic and terrestrial species within a single mammalian order.
Abstract. Despite the biological and economic importance of the Cetartiodactyla, the phylogeny of this clade remains controversial. Using the supertree approach of matrix representation with parsimony, we present the first phylogeny to include all 290 extant species of the Cetacea (whales and dolphins) and Artiodactyla (even-toed hoofed mammals). At the family-level, the supertree is fully resolved. For example, the relationships among the Ruminantia appear as (((Cervidae, Moschidae) Bovidae) (Giraffidae, Antilocapridae) Tragulidae). However, due to either lack of phylogenetic study or contradictory information, polytomies occur within the clades Sus, Muntiacus, Cervus, Delphinidae, Ziphiidae and Bovidae. Complete species-level phylogenies are necessary for both illustrating and analysing biological, geographical and ecological patterns in an evolutionary framework. The present species-level tree of the Cetartiodactyla provides the first opportunity to examine comparative hypotheses across entirely aquatic and terrestrial species within a single mammalian order.
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