BMC Zoology最新文献

Background: Hippopotamus (Hippopotamus amphibious) is a semi-aquatic mammal that is considered the third largest living land mammal still alive on earth. The main objective of this study was to determine the distribution range and human-hippopotamus conflicts in the Lake Tana Biosphere Reserve, Ethiopia. Data were collected from June 2022 to January 2023. Total count methods were used to estimate the hippopotamus population, and Arc GIS was used to determine the distribution range and habitat suitability of hippopotamus. Structured questionnaire and focus group discussions were used to collect data on human-hippopotamus conflict. Data were analysed using One-way ANOVA, independent t-test, and chi-sqaure test.

Results: The mean population estimation of hippopotamus in in the study area showed 252.67 ± 15.9 with a density of 0.072 individuals per km². The suitable slope analysis of hippopotamus along the the Lake Tana Biosphere Reserve's shoreline revealed that 4.7% of the shoreline was most suitable, 48.4% moderately suitable, and 46.9% not suitable. Variations in the hippopotamus' habitat suitability within the study area have been associated with a number of factors including availability of water, food, elevation, and vegetation cover. Crop raiding and overgrazing were the primary causes for conflict.

Conclusion: In order to conserve hippopotamus in the in the Lake Tana Biosphere Reserve, appropriate conservation measures including habitat protection and restoration, and community engagement and education need to be developed. Moreover, further research on the ecological aspects of the Lake's ecosystem is required to ensure the conservation of hippopotamus.

Background: The Prussian carp (Carassius gibelio) is an invasive fish species from Eurasia that was first found in North America in the Canadian province of Alberta in the early 2000s. In 2018, an established population of Prussian carp was discovered in the neighboring province of Saskatchewan, raising concern for additional spread in Canada and to the USA.

Results: Prussian carp in Saskatchewan have colonized the South Saskatchewan River and tributaries and are moving towards additional connected systems to the northeast. Direct access to most of southern Saskatchewan and the USA is currently prevented only by the Qu'Appelle Dam on the South Saskatchewan River at Lake Diefenbaker. Prussian carp populations in Saskatchewan were age-stratified and ranged from hatch size (20 mm) to a maximum of 42.5 cm total length. Aging using otoliths and scales was unreliable, but the largest fish collected were likely > 10 years old. Saskatchewan Prussian carp had mixed ploidies with diploid, triploid, and tetraploid individuals intermixed. In Lake Diefenbaker, only adult female and juvenile fish were detected, but males were present in the Anerley Lakes at low relative abundance. Emergence of young of the year Prussian carp began in early July and continued through August, indicating an extended period of reproduction; however, most spawning likely occurred during mid-June. The timing of spawning overlaps with that of a variety of native sucker and shiner species, but sperm donors for potential gynogenesis remain unidentified.

Conclusion: Our findings suggest that invasive Prussian carp are well established in Saskatchewan and will likely use provincial waterbodies as a conduit to colonize more areas in North America.

Land use changes can have morphological and physiological impacts on wildlife. This study aimed to explore the influence of anthropogenic land use on the morphology and corticosterone concentrations in two songbirds endemic to the Galapagos archipelago: the granivorous Small Ground Finch Geospiza fuliginosa and the insectivorous Galapagos Yellow Warbler Setophaga petechia aureola in San Cristobal Island. Birds were caught and measured between June and August 2018 and June and July 2019 across four areas with different human land uses: urban green areas in the coastal town of Puerto Baquerizo Moreno, natural deciduous forest in the lowlands, agricultural areas in the highlands, and seasonal evergreen forest in the highlands. Morphological comparisons among study areas were made using ANOVA or the Kurskall-Wallis test. Corticosterone levels obtained from tail feathers were measured with an ELISA test. Linear regression models were employed to explore the effects of the different human land uses on corticosterone concentrations. For G. fuliginosa, we found significant differences (p < 0.05) in weight, wing, and tarsus length between natural and disturbed habitats. The linear regression results showed higher corticosterone concentrations in urban G. fuliginosa than those in agricultural and natural habitats. Additionally, higher corticosterone concentrations were found in finches captured in 2018, a year with much higher precipitation than in 2019. For S. petechia aureola, the only significant difference (p < 0.05) between areas was a wider beak in birds captured in the seasonal forest compared to those from urban areas. Although our sample size does not allow for definitive conclusions, our results provide evidence that the ecology of each species plays a crucial role in shaping their morphological and physiological responses to land use changes and seasonal environmental changes.

The amphipod Parhyale hawaiensis is a tropical species and of interest for use as a live feed in warm water marine aquaculture. Prior to the establishment of large scale culture optimal culture conditions need to be determined. The effects of temperature (20 °C, 23 °C, 26 °C, and 29 °C) on juvenile growth, survival, and generation time of the marine amphipod P. hawaiensis were assessed in this study. Growth was followed for 12 weeks, survival for 16 weeks and hatchling-to-hatchling generation time for 20 weeks. During juvenile production data concerning precopula behavior and mating pair productivity were obtained. Higher growth (length, weight) was seen at 26 °C (4.4 ± 0.58 mm, 2.8 ± 1.4 mg) and 29 °C (4.6 ± 0.8 mm, 2.3 ± 0.89 mg) and higher survival at 23 °C (25.2 ± 12.2%) and 26 °C (31.9 ± 3.2%). The hatchling-to-hatchling generation time at 26 °C and 29 °C was 16 weeks but was not determined at lower temperatures, as no hatchlings were observed by 20 weeks. Mating pairs were formed within two days and the productivity rate of mating pairs was 1.32 ± 0.31 juveniles per pair, at ambient room temperature (~ 21 °C). The data suggests culturing P. hawaiensis at 26 °C would enhance production. This study provides valuable data that may be used to establish large-scale production of this species.

Background: The development of larger monogeneans and their survival on more active hosts is thought to have led to the emergence of haptoral suckers and, in some instances, anchors, enabling a more stable anchorage. Because of their strict host specificity, the morphological variation of anchors in genus Diplorchis (Monogenea: Polystomatidae) may be determined to a large degree by adaptation to the host species, its habitat and ecological environment to ensure stable attachment.

Methods: In this study, we estimated the interspecific and intraspecific differences of haptoral anchors and other morphological characteristics in six recorded species of Diplorchis and one unidentified species parasitizing Sylvirana maosonensis (Bourret, 1937) in China using geometric morphometrics.

Results: Geomorphometric analyses revealed significant differences in the shape and size of the anchors among the seven species, indicating that the morphological differences in anchors can be used as a basis for species identification within the genus Diplorchis. In addition, we found that the same Diplorchis species collected from different localities not only differed significantly in anchor form, but also in body size and haptor size, as well as haptoral sucker size. This may reflect the effect of different habitat environments on biological/behavioral activities of the same host, thus further affecting the stable attachment of flatworms within species. Interestingly, in two species collected from the same localities, we found no significant differences in anchor or sucker size, while body size and haptor size all differed significantly. Meanwhile, the significant differences in anchor shape may suggest that the attachment mechanism of the different Diplorchis species is related to the variation in anchor shape.

Conclusions: From the perspective of morphological adaptation to the environment, the study not only indicated that the morphological variation of Diplorchis anchors can be used as an auxiliary tool to distinguish species, but also found that the morphological differences in the anchors were influenced by factors such as host species, habitat and ecological environment. This may provide a basis for a better understanding of host-parasite interaction.

Background: Spiders are highly adaptable hunters found in nearly all terrestrial ecosystems and play an important role in biological control by preying on pest insects. Spiders' body size and shape are vital for their survival, particularly in prey capture, and these morphological features are often utilized in cladistic analyses. This study employed geometric morphometrics to investigate prosoma shape and size variations between two populations of Nigma conducens spiders and between sexes within each population. Principal Component Analysis (PCA) explored shape variation, while Canonical Variate Analysis (CVA) compared shape differences between populations and sexes. Multivariate regression analysis was used to check for allometry.

Results: MANOVA results revealed significant shape variations in spider prosoma between the two populations and between sexes, though the degree of these differences was small. The considerable overlap in individual shapes between populations may indicate a response to microhabitat similarity. Additionally, sexual dimorphism was observed in the prosoma shape of N. conducens, likely due to sexual selection or adaptive divergence related to different microhabitats. Size differences between sexes were insignificant in either population, particularly in the first, suggesting that prosoma size does not contribute to reproductive success. Moreover, the non-allometric relationship indicated that shape variations between the populations were independent of size.

Conclusion: Overall, these findings highlight the complexity of morphological adaptations in N. conducens in response to ecological pressures and sexual selection.

Background: The Mandarin Duck (Aix galericulata) has recently been recognized as a partial migrant in China. The resident population of this species is primarily recorded in southern China, which is not only the traditional wintering range, but also the southernmost breeding sites. However, little information is known about their abundance and habitat requirements during breeding periods. This study provided the first report on the structure of the resident population and the habitat used during the post-breeding period at a tributary of the Wu River in Guizhou Province, Southwest China, which was one of the recently identified breeding sites within the traditional wintering range.

Results: A total of 36 Mandarin ducks were recorded among 15 sites, and the mean population density was estimated to be 3.51 ± 3.06 ind./km. The observed adults sex ratio of males to females was 0.44:1. At the microhabitat scale, the results of logistic regression models indicated that the key habitat variables included the distance to the nearest forest edge (dist.forest), opening extent of valley (deg.valley) and distance to the nearest human settlement (dist.settlement). The Mandarin Duck preferred to use foraging sites near forest edges, where dense marginal growth of woodland and shrubs was present.

Conclusion: These findings suggested that dense vegetation along rivers could play a positive, important role in habitat use by the resident population of Mandarin ducks. Compared to traditional breeding ranges, both adults and ducklings of this species were more likely to experience human-related disturbances due to the limited availability of ancient trees outside villages. This information will contribute to provide baseline knowledge on the resident population of Mandarin ducks, and enhance understanding of the causes and consequences of breeding partial migration.

This field study investigated the population structure, distribution pattern and habitat utilization of Yellow-wattled Lapwings. The line transect method was used to estimate the density of Yellow-wattled Lapwings. An average of 394 individuals including 77 chicks of Yellow-wattled Lapwings have been registered with an average density of 38 birds per km. The outcome of the GLM analysis exhibited, that Bakshi Ka Talab had the highest lapwing count while, Malihabad had the lowest lapwing count. A significant lapwing count in the year 2021 was confirmed. The winter season had the lowest lapwing counts, whereas the summer season had the highest values. Moreover, the largest lapwing counts were estimated in uncultivated while, the lowest lapwing count was documented in river habitat types. There was a significant difference in the mean flock size across the seasons and the habitat types. Being sighted in flocks of various sizes the distribution pattern was found to be clumped in Yellow-wattled Lapwings. The results of the factorial ANOVA showed a significant difference in the habitat utilization of Yellow-wattled Lapwings across study sites, years, seasons and habitat types. Uncultivated habitat types were the most utilized habitat types during summer seasons.

Background: The crested ibis, a species that relies on wetland ecosystems for survival, was once found throughout East Asia but has declined to near extinction in Korea, Russia, and Japan, except China. Artificial propagation of seven individuals found in Yangxian, Shaanxi Province, China has resulted in a stable population. Furthermore, South Korea and Japan are working on restoring populations through donations from China. Artificial propagation began in 2008, and in 2019, 40 individuals born between 2014 and 2018 were released into the natural habitat for the first time. We conducted this study to analyze the habitat environment, home range, and habitat usage patterns of a 2016-born male and a 2017-born female who attempted to reproduce naturally for the first time.

Results: After forming a breeding pair on April 3, 2020, the pair made two breeding attempts, built a nest in Pinus densiflora, and succeeded in hatching the chicks, but failed to raise them. The home range analysis showed that the area was 1.777-2.425 km² for MCP 100%, and 0.347-2.085 km² for 95% KDE. Meanwhile, the core habitat ranged from 0.007 to 0.296 km² (KDE 50%), indicating differences depending on the time of year and the individual being studied. Breeding pairs were estimated to spend over 50% of their recorded occurrences within 50 m during nesting for incubation, resting, and other activities. They mainly used in paddy fields, but from April to June, when onions and garlic were growing, they searched for food in fields, cemeteries, reservoirs, and other areas.

Conclusion: Breeding pairs have increasingly become more active near the nest, and Changnyeong-gun, where they were released, has large agricultural land suitable for crested ibis habitat. However, there is a problem that during the breeding season from April to June, most paddy fields are maintained as garlic and onion fields, which are then converted back for rice cultivation from May to June through double-cropping. Accordingly, for stable laying and rearing, it is necessary to contemplate how to maintain rice paddies, which serve as feeding grounds in the core habitats.