BMC Zoology最新文献

Background: Migratory birds differ markedly in their migration strategies, particularly those performing short- versus long-distance migrations. In preparation for migration, all birds undergo physiological and morphological modifications including enlargement of fat stores and pectoral muscles to fuel and power their flights, as well as cardiovascular and biochemical adjustments that improve lipid and oxygen delivery and uptake by flight muscles. While the magnitude of these changes varies in relation to migration strategy, the consequence of these variations on aerobic performance is unknown. We tested whether the aerobic performance of four Old-world flycatcher species (Muscicapidae) varied according to migration strategy by comparing minimum resting metabolic rates (RMR_min), exercise-induced maximum metabolic rates (MMR), and exercise endurance times of short-distance and long-distance migratory birds.

Results: As expected, RMR_min did not vary between short-distance and long-distance migrants but differed between the species within a migration strategy and between sexes. Unexpectedly, MMR did not vary with migration strategy, but MMR and blood haemoglobin content were positively related among the birds tested. Exercise endurance times differed substantially between migration strategies with long-distance migrants sustaining exercise for > 60% longer than short-distance migrants. Blood haemoglobin content had a significant positive effect on endurance among all birds examined.

Conclusions: The lack of difference in RMR_min and MMR between long- and short-distance migrants during this stage of migration suggests that the attributes favouring the greater aerobic endurance of long-distance migrants did not come at the expense of increased maintenance costs or require greater aerobic capacity.

Background: Considering animals as individuals and not as species is becoming increasingly essential to animal welfare management in captive settings. Recent studies on big cat personalities and coping strategies suggest personality can help big cats cope in their surroundings. Yet a large portion of the published literature focuses on understanding either the personality or stress physiology of big cats. Our research shows how integrating an improved understanding of the personality of big cats with stress physiology may enhance welfare, especially for endangered species like African lions. By using a wild cat personality checklist, this study compared the key personality dimensions of 22 African lions with its faecal glucocorticoids and assessed factors influencing their personality and stress physiology.

Results: We found two reliable personality dimensions for African lions (dominance and agreeableness) and identified key factors (sex, age and location) that may influence their personality. Further, on testing if these factors influenced the stress physiology through variations in glucocorticoid levels, there was no significant difference. However, there was a strong negative association between agreeableness and glucocorticoid levels. These results suggest that the behavioural traits loading positively and higher for agreeableness are associated with lower glucocorticoid stress levels, which may assist a lion to cope with stressors in its surroundings.

Conclusions: Our findings highlight this integrated approach of linking personality and stress physiology of big cats can be beneficial for caretakers. For example, during stressful veterinary procedures or in reintroduction programs, recognizing the personality of lions can help in designing or providing them with resources that will alleviate stress. Thus, there is a need for more interdisciplinary approaches that will contribute towards enhancing the individual and overall welfare of big cats.

Background: Pikes, members of genus Esox, are widespread freshwater predators of the northern hemisphere, and important sport fish also. From the Carpathian basin only one species, the northern pike (E. lucius) is noted. At the same time the pike stocks living in this area show high level of phenotypic variance (e.g. various body pattern) and its growth varies highly both among and within populations. These features usually explained by the environmental diversity of the area. Whereas we think that genetic reasons -e.g. the appearance of other/new pike species in the area- may also be responsible for these observed features. Since as no detailed information have been published from the pike populations of this area, so far; we conducted phylogenetic and morphological assay on 88 pike specimens, collected from 49 Middle Danubian sampling sites.

Results: Our phylogenetic surveys showed that the northern pike appear in the study area solely, but all the three of its major lineages (Northern, Circumpolar, Southern) were indicated. Only six specimens represent the Northern lineage, collected from the western part of the study area. The Circumpolar and Southern lineages were common in the Carpathian basin, but the Southern lineage showed higher levels of haplotype diversity than the Circumpolar clade. Which indicates that only the Southern lineage is native in the area, while the other two groups could have appeared in the Middle Danubian system either spontaneously or by human introduction. Moreover, the different clades appeared in the same populations, suggesting the opportunity of inter-lineage hybridisation. From the studied morphologicalal features, the number of scales on the lateral line and the head length showed significant differences among the lineages. At the same time the body pattern of the studied individuals seems to be rather influenced by the ontogenic changes than phylogeny.

Conclusions: The high phenotypic variability of Middle Danubian northern pike populations may be due that all of its three major clades appeared and came in secondary contact in the area. In the within watershed spread of the non-native lineages the human stocking/transfer may play a considerable role.

Background: Most amphibians use a repertoire of acoustic signals to propagate signals in social contexts. The description of these repertoires provides a key towards the understanding of the behaviour of individuals and the evolutionary functions of calls. Here, we assessed the variations in advertisement calls within and between two fossorial sympatric species, Uperodon systoma and Uperodon globulosus, that share their breeding season and breeding sites. For each species, we applied Beecher's index of total information capacity (H_S) for the individual vocal signature, determined the difference in call properties and demonstrated the segregation in the calling microhabitat niche between the two species.

Results: Our results demonstrated that the advertisement calls of U. systoma are pulsatile with a call rate of 3.00 ± 0.97 calls per second while those of U. globulosus are not pulsatile with a lower call rate of 0.53 ± 0.22 calls per second. For both species, the variations in call properties among individuals was higher than that within individual, a pattern consistent with that of other fossorial anurans. The body condition and air temperature did not significantly impact the call properties of either species. The outcome of the Beecher's index (H_S) showed that the calls of U. systoma can be used to identify 14 different individuals and the calls of U. globulosus can be used to identify 26 different individuals. The statistical analyses on the advertisement call of the two species showed a significant difference in the temporal properties as the call duration, and fall time and rise time were significantly different between the two species. Lastly, we successfully demonstrated that there is a clear segregation in calling site microhabitat between the two species, where U. globulosus calls floating close to the bank of the waterbody while U. systoma calls floating further away from the bank.

Conclusion: This study highlights the potential for pre-mating isolation, character displacement and assortative mating in two syntopic fossorial anurans, leading to association between acoustic, calling microhabitat niche and body index divergence as important behavioural and ecological traits.

Background: The sky-island Ligidium species fauna in southwest China is poorly known. Before this study, six of the seven sky-island species of the genus were known to be endemic to southwest China. In morphology, Ligidium species are often difficult to identify, and an appraisal of integrative taxonomy is needed.

Results: We integrated morphology and molecular analyses to delimit Ligidium species. Molecular species delimitation based on distance- and evolutionary models recovered seven-candidate lineages from five gene markers (COI, 12S rRNA, 18S rRNA, 28S rRNA and NAK). We also estimated that the species divergences of sky-island Ligidium in southwest China started in late Eocene (40.97 Mya) to middle Miocene (15.19 Mya). Four new species (L. duospinatum Li, sp. nov., L. acuminatum Li, sp. nov., L. rotundum Li, sp. nov. and L. tridentatum Li, sp. nov.) are described. Morphological confusion among L. denticulatum Shen, 1949, L. inerme Nunomura & Xie, 2000 and L. sichuanense Nunomura, 2002 is clarified by integrative taxonomy.

Conclusion: This work confirms that an integrative approach to Ligidium taxonomy is fundamental for objective classification, and deduced the uplift of Qinghai-Tibetan Plateau in the late Eocene and middle Miocene as one of the principal reasons for the species divergences of sky-island Ligidium in southwest China. We also inferred that sky-island mountains have a huge reserve of higher Ligidium species diversity.

Background: Freshwater planarians of the genus Dugesia (Platyhelminthes, Tricladida, Dugesiidae) are distributed in a major part of the Old World and Australia, although until recently only very few species were known from China.

Results: Two new species of Dugesia from Southern China are described on the basis of an integrative taxonomic approach. BI and ML phylogenetic trees based on the independent genes and on the concatenated dataset had similar topologies, only differing in some nodes that were weakly supported. Phylogenetic trees based on the concatenated dataset revealed that D. adunca Chen & Sluys, sp. nov. and D. tumida Chen & Sluys, sp. nov. are not closely related and belong to different clades. The two new species occupy separate long branches with high support values and, thus, are well-differentiated from their congeners. Separate species status of D. adunca and D. tumida is supported also by the genetic distances between the species included in our analysis, albeit that COI distances varied greatly among species. Dugesia adunca from Guangxi Province is characterized by the following features: living mature animals rather small; asymmetrical openings of the oviducts into the bursal canal; penis papilla with shape of an aquiline bill, albeit with a blunt tip; asymmetrical penis papilla, with a large antero-dorsal lip and a much smaller ventro-posterior lip; very large seminal vesicle, provided with trabeculae; small diaphragm; mixoploid karyotype with diploid complements of 2n = 2x = 16 and triploid complements of 2n = 3x = 24, with all chromosomes being metacentric. Dugesia tumida from Guangdong Province is characterized by a penis papilla provided with a large, symmetrical penial valve from the middle of which arises the small, distal section of the papilla; a duct intercalated between the seminal vesicle and the small diaphragm; ventrally displaced ejaculatory duct curving upwards before opening to the exterior; penis papilla highly asymmetrical, having a slim and long ventral portion and a short and stubby dorsal part; vasa deferentia separately opening into antero-dorsal portion of seminal vesicle; oviducts openings symmetrically into ventral portion of the bursal canal, near its opening into the atrium; mixoploid karyotype, with diploid chromosome portraits of 2n = 2x = 16, and triploid complements of 2n = 3x = 24, with all chromosomes being metacentric. In the context of the various kinds of mixoploidy and the sexualization of specimens, reproductive modalities within the genus Dugesia are shortly discussed.

Conclusion: Molecular, morphological, and karyological markers show that the two populations examined represent members of the genus Dugesia and constitute two new, distinct species.

Background: Hoplobatrachus rugulosus (Anura: Dicroglossidae) is distributed in China and Thailand and the former can survive substantially lower temperatures than the latter. The mitochondrial genomes of the two subspecies also differ: Chinese tiger frogs (CT frogs) display two identical ND5 genes whereas Thai tiger frogs (TT frogs) have two different ND5 genes. Metabolism of ectotherms is very sensitive to temperature change and different organs have different demands on energy metabolism at low temperatures. Therefore, we conducted studies to understand: (1) the differences in mitochondrial gene expression of tiger frogs from China (CT frogs) versus Thailand (TT frogs); (2) the differences in mitochondrial gene expression of tiger frogs (CT and TT frogs) under short term 24 h hypothermia exposure at 25 °C and 8 °C; (3) the differences in mitochondrial gene expression in three organs (brain, liver and kidney) of CT and TT frogs.

Results: Utilizing RT-qPCR and comparing control groups at 25 °C with low temperature groups at 8 °C, we came to the following results. (1) At the same temperature, mitochondrial gene expression was significantly different in two subspecies. The transcript levels of two identical ND5 of CT frogs were observed to decrease significantly at low temperatures (P < 0.05) whereas the two different copies of ND5 in TT frogs were not. (2) Under low temperature stress, most of the genes in the brain, liver and kidney were down-regulated (except for COI and ATP6 measured in brain and COI measured in liver of CT frogs). (3) For both CT and TT frogs, the changes in overall pattern of mitochondrial gene expression in different organs under low temperature and normal temperature was brain > liver > kidney.

Conclusions: We mainly drew the following conclusions: (1) The differences in the structure and expression of the ND5 gene between CT and TT frogs could result in the different tolerances to low temperature stress. (2) At low temperatures, the transcript levels of most of mitochondrial protein-encoding genes were down-regulated, which could have a significant effect in reducing metabolic rate and supporting long term survival at low temperatures. (3) The expression pattern of mitochondrial genes in different organs was related to mitochondrial activity and mtDNA replication in different organs.

Background: Host range is a fundamental trait to understand the ecological and evolutionary dynamics of symbionts. Increasing host specificity is expected to be accompanied with specialization in different symbiont traits. We tested this specificity-specialization association in a large group of 16 ant-associated silverfish species by linking their level of host specificity to their degree of behavioural integration into the colony and to their accuracy of chemically imitating the host's recognition system, i.e. the cuticular hydrocarbon (CHC) profile.

Results: As expected, facultative associates and host generalists (targeting multiple unrelated ants) tend to avoid the host, whereas host-specialists (typically restricted to Messor ants) were bolder, approached the host and allowed inspection. Generalists and host specialists regularly followed a host worker, unlike the other silverfish. Host aggression was extremely high toward non-ant-associated silverfish and modest to low in ant-associated groups. Surprisingly, the degree of chemical deception was not linked to host specificity as most silverfish, including facultative ant associates, imitated the host's CHC profile. Messor specialists retained the same CHC profile as the host after moulting, in contrast to a host generalist, suggesting an active production of the cues (chemical mimicry). Host generalist and facultative associates flexibly copied the highly different CHC profiles of alternative host species, pointing at passive acquisition (chemical camouflage) of the host's odour.

Conclusions: Overall, we found that behaviour that seems to facilitate the integration in the host colony was more pronounced in host specialist silverfish. Chemical deception, however, was employed by all ant-associated species, irrespective of their degree of host specificity.

Background: In lacertid lizards from Mediterranean islands, frugivory is common, particularly under prey scarcity, a characteristic of small islands. In several populations, the diet of the Balearic lizard, Podarcis lilfordi, is extremely variable and includes fleshy fruits. However, frugivory is sporadic and there are very few examples of dominant fruit consumption.

Results: We describe the existence of an extraordinary fruit consumption of a single plant species, the juniper, Juniperus phoenicea, by the Balearic lizard, P. lilfordi. In addition, for the first time in Lacertidae, we describe the existence of scat piling in the population of these lizards inhabiting Cabrera Island (Balearic Islands, Spain). Scat piling was detected in an isolated location with hundreds of scats deposited by several individuals at a particular place.

Conclusions: The high population density of lizards at the island of Cabrera and the great versatility of foraging behavior of this species allows us to hypothesize that scat piles could act as an attractor for numerous individuals, that is, as inadvertent social information. If that hypothesis is correct, it would result in the concentration of several individuals foraging on a single or a few ripening plants. We cannot, however, rule out that individuals concentrated due to the scarcity of ripening plants in other areas, without any influence of the presence of several lizards, as attractors to the site. Our findings modify previous descriptions of the diet of the Balearic lizard in Cabrera made with smaller samples. In some places and periods of the year, frugivory on a single plant species can be extremely intense and only large sample sizes of scats allow to find these particular trends in the foraging ecology of insular lizards.

Background: The 'snow-melt mosquito' aedes (rusticoidus) refiki is a rare species with a wide distribution in Europe that is usually defined as an aggressive mosquito for mammals, including humans. During a mosquito survey in a peri-urban area in south-central mainland Spain, adult Ae. refiki females were captured and identified by morphological traits. The presence of this species of mosquito has never been molecularly confirmed under continental dry Mediterranean climatic influence with scarce number of days with snow on soil. The aim of this study was to confirm by amplification and sequencing of mitochondrial cytochrome c oxidase subunit I (COI) and internal transcribed spacer 2 (ITS2) region.

Results: We also successfully amplified and typed the species molecularly by COI and ITS2 regions. The peri-urban area where Ae. refiki was found contrasts with the reported cold, humid and snowy environments required by the species to breed.

Conclusions: This finding suggests that the species is already adapted to continental dry Mediterranean environments, questioning whether it is a truly stenotopic species of cold snowy environments.