BMC Zoology最新文献

Grant's gazelles (Nanger granti) are classified as of least concern by the IUCN, although their number is declining due to several factors. A few research studies have been conducted on Grant's gazelle in Ethiopia. Thus, the present study was carried out to determine the population size and habitat association of Grant gazelle in the Ene Forest of western Ethiopia, comprising the dry and wet seasons. The study area was stratified into four habitats: woodland, mixed woodland, riverine forest, and grassland habitats. The data were collected using the direct observation technique. The data were analyzed using descriptive statistics and Pearson's chi-square (χ²) test. The average estimated Grant gazelle population was 136 ± 23 individuals, with a density of 9/km². The adult male-to-adult female sex ratio was 1:1.40 and 1:1.26 during the wet and dry seasons, respectively. The largest herd size (N = 6) was observed during the wet season, and the smallest (N = 4) was observed during the dry season. The highest numbers of Grant gazelles were observed in the grassland habitat during the wet season and in the woodland during the dry season. More Gazelles (N = 65) were observed in the woodland habitat compared to the other habitat types. The continued existence of the Grant's gazelle population in the area and the suitability of the environment depend significantly on ongoing assessments of habitat change and management intervention.

Background: The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) is critically endangered and has suffered from extensive habitat loss and fragmentation. Knowledge of its habitat preference could assist the conservation of the species and associated ecosystem. In the present study, spatiotemporal variations and driving factors of habitat use of a Yangtze finless porpoise population were studied in a 30-km section of the Yangtze mainstream. Seasonal variation in porpoise occurrences was observed based on visual surveys conducted from 2022 to 2023, with five surveys during the dry season and seven surveys during the wet season. Biological and environmental factors were synchronously sampled in both seasons. The maximum entropy model (MaxEnt) was applied to get the effects of biological and environmental variables on porpoise habitat preference.

Results: Within the study area, high-suitability habitats of the finless porpoises accounted for 19.0% and 15.4% of the area during the dry and wet seasons, respectively. The high-suitability habitat shifted from the mainstream in the dry season to the sandbar head and tributary area in the wet season. In the dry season, variables influencing the distribution were phytoplankton biomass, water velocity, and zooplankton biomass, which contributed 97.05% variation in the MaxEnt modeling. In the wet season, water depth, surface water temperature, and zooplankton biomass accounted for 97.69% variation of the distribution. Above results highlight that food availability plays an important role in porpoises distribution regardless of seasons, particularly in the dry season. This is because plankton is the primary food source for filter-feeding and omnivorous fish, especially those in the upper-middle layer which are frequently preyed on by finless porpoises.

Conclusion: Suitable areas for finless porpoises, particularly those with high suitability, differed significantly across seasons at a fine-scale in the Yangtze mainstream. Seasonal variations in habitat were driven by different factors. But food availability plays an important role in porpoises distribution regardless of seasons, particularly in the dry season. These results suggest prioritizing conservation of the finless porpoise in the dry season when fish resources are relatively scarce. Measures including monitoring and evaluating prey resources should be considered. More attention should also be paid on management of shipping in the dry season given that the high-suitability habitat of the finless porpoises shifts to the mainstream.

Background: The tropical gar (Atractosteus tropicus), a member of the Lepisosteidae family, is native to regions extending from southeastern Mexico to southern Costa Rica. This species serves as a unique bridge between tetrapods and teleosts due to its phylogenetic position, slow evolutionary rate, dense genetic map, gene similarities with humans, and ease of laboratory cultivation. As a taxonomic sister group to teleosts like the zebrafish (Danio rerio), known for its high regenerative capacity, it remains unclear whether the tropical gar shares a similar ability for regeneration.

Results: This study aims to elucidate the caudal fin regeneration process in tropical gar through skeletal and histological staining methods. Juvenile specimens were observed over a two-month period, during which they were fed brine shrimp, and anesthetized with 1% eugenol for caudal fin amputation. Samples were collected at various days post-amputation (dpa). Alcian blue and alizarin red staining were used to highlight skeletal regeneration, particularly the formation of new cartilage, while histological staining with hematoxylin and eosin was performed to observe tissue regeneration at the amputation site.

Conclusions: The findings reveal a remarkable ability for caudal fin regeneration in juvenile tropical gar. Given the Garfish evolutionary relationship with teleosts, this opens new avenues for research into tissue regeneration across different groups of Actinopterygii.

Background: Rodents are mammals of the order Rodentia, which are found in all continents except Antarctica. They are the most diverse groups of mammals representing 41% of all mammals and they are known with 33 families, 481 genera, and about 2277 species. The present study was conducted from December 2018 to August 2019 both during the dry and wet seasons using Sherman traps and live traps. Four trap sites namely forest, bushland, grassland, and sugarcane plantation were selected for data collection. Shannon-Wiener diversity index (H') was used to compute rodent species diversity, Simpson's index (D) to assess the number and abundance of rodents in the different habitats, and one-way ANOVA and independent samples t-test were used for data analysis.

Results: A total of 163 individual rodents were captured in 1776 trap nights of which 125 individuals were captured using live traps in 1176 trap nights and 38 individuals using snap traps in 600 trap nights. Among the total individual rodents captured in the Bahir Dar Blue Nile River Millennium Park, 63.8% (n = 104) were males and 36.2% (n = 59) were females. Males outnumbered females in all the grids and the difference was significant (t = 31.5, df = 10, p < 0.05). The relative abundance of rodent species indicated that 42.4% (n = 53) were Arvicanthis niloticus, 26.4% (n = 33) Rattus rattus, 17.6% (n = 22) Mus musculus, 8% (n = 10) Mastomys natalensis, and 5.6% (n = 7) Arvicanthis abyssinicus. There are more individual specimens of A. niloticus than other species identified in the area (F = 698.22, df = 4, p < 0.05). Distribution of rodents varied among the different habitats. As a result, the bushland habitat showed more diversity of rodents (H = 0.98) and comprised relatively the highest (51.2%, n = 64) number of individuals captured, while the forest habitat supported the lowest number of rodents (4%, n = 5), and the difference showed a significant difference (F = 873.37, df = 3, p < 0.05). Population density with 95% confident interval estimated as 166 individuals/ha (95% CI:164.43-167.57).

Conclusion: The present study provides basic information about population dynamics of rodents and contributes to design conservation strategies for rodents in particular and other biota of the area in general.

Background: The diaphragm, the main muscle involved in respiration and one of those responsible for maintaining life, is still little explored in terms of its morphology in wild animals. There are few studies on the anatomy of Eira barbara, a carnivorous mustelid that is a victim of the urbanization process. In order to contribute to the conservation of the species, we described the topography and morphology of the diaphragm, which may be involved in injuries caused by the impacts of human activities.

Results: We studied five specimens of Eira barbara, whose diaphragmatic muscle had a dorsal insertion on the 14th thoracic vertebra, laterally between the 8th and 13th intercostal space (EIC) and ventrally on the 8th EIC, with attachment to the xiphoid process. Consisting of three muscle regions (lumbar, costal and sternal), the diaphragm in Eira barbara showed radially arranged bundles, with the right costal muscle being slimmer than the left; the left pillar wider than the right and between them were the aortic and esophageal hiatuses. The Y-shaped tendinous center housed the foramen of the vena cava bordering the right costal region. In the most dorsal portion of the diaphragm, between the costal regions and the diaphragmatic pillar, we found two triangular-shaped regions devoid of muscle.

Conclusions: Our findings, when compared with the current literature, indicate that the location and positioning of the diaphragm are independent of the physical conformation of the species, and that the right costal region, as well as the triangular areas devoid of musculature, may be fragile points for herniation in cases of Eira barbara being run over.

Background: Determining the density of mammalian wildlife in an ecosystem is very important for the ecosystem conservation. The aim of this study is to reveal mammalian wildlife density and compare the effect human footprint index (HFI) on the Mediterranean ecosystems. The mammalian wildlife surveys were conducted between August 2013 and December 2013, using 21 camera traps with 2175 camera trap days in a Mediterranean forest ecosystem in İzmir, Türkiye. We used random encounter model (REM) method to estimate densities.

Results: The population density for 5 mammals were; for red fox 7.89 ind./km² (± 0.82 SE), wild boar 4.36 ind./km² (± 0.46 SE), European hare 15.33 ind./km² (± 03.37 SE), beech marten 0.99 ind./km² (± 0.10 SE) and golden jackal 0.50 ind./km² (± 0.05 SE). These results were compared with mammal community which was previously studied in another Mediterranean ecosystem in Muğla, Türkiye, includes caracal and has a lower human footprint index.

Conclusions: According to results of this study human activity which can be revealed by Human footprint index (HFI) is one of the main parameter on Mediterranean ecosystem and it is effecting the density and occurence of species in mammal community. Both a higher human footprint index and the absence of caracal might cause higher density of red fox and European hare in İzmir, Türkiye. This study also suggests that caracal might be a serious suppressor on red fox which could be explained by competition. Caracal may also control the European hare in Mediterranean forest ecosystem of Anatolia. Thus, decreasing human footprint index and maintaining caracal suppressor effect are crucial for the conservation of the whole Mediterranean ecosystem.