Integrative zoology最新文献

Morphological traits are central to traditional taxonomy, yet convergent and divergent evolution can lead to inconsistencies between morphological classification and molecular phylogenetics. The distinctive "sunken head and humpback" morphology of Cromileptes altivelis and its close phylogenetic relationship with Epinephelus make it an ideal model for evaluating the weighting of morphological traits in taxonomic classification and refining the classification system. We measured and analyzed the morphological specialization process of C. altivelis, identifying key developmental stages leading to its humpback phenotype. This trait develops through cranial remodeling, involving changes in the supraoccipital, frontal, and lateral occipital bones, with structural support from predorsal bones and the first neural arch and spine. Examining the Hox gene family, we found that C. altivelis possesses 49 highly conserved Hox genes, with no significant differences in gene copy number, arrangement, or exon count among groupers. However, unique amino acid variations were identified in the Hoxa7a, Hoxa10b, and Hoxc1a proteins of C. altivelis, which are otherwise highly conserved among other teleost fishes. Functional assays confirmed that mutations in these genes enhance gene transcription activity, promoting osteoblast proliferation and differentiation. qPCR analysis showed that the expression of hoxa7a and hoxa10b was significantly upregulated during the humpback stage, implicating their contribution to the morphological specialization of C. altivelis. hoxa10b remained elevated post-humpback, suggesting a role in bone strength and homeostasis, whereas hoxc1a exhibited consistently low expression, indicating limited involvement. Our findings provide insights into resolving taxonomic discrepancies in C. altivelis and offer a framework for understanding its adaptive evolution and speciation.

Avian haemosporidian infections have been associated with disease outbreaks in zoos and rehabilitation centers globally. This study aimed to determine the occurrence and genetic diversity of avian haemosporidian parasites in captive birds at the National Zoological Garden in South Africa. One hundred and eighty-three blood samples from five orders and 15 species of captive flamingos, vultures, owls, ibises and parrots were analyzed for haemosporidia by nested polymerase chain reaction assays. The samples were collected as part of the zoo's studbook and archived at South African National Biodiversity Institute's Wildlife Biobank. The overall infection rate was 36.1%, and infections by Leucocytozoon spp. (33.3%) were significantly higher than Haemoproteus spp. (14.8%) (p < 0.001). Twenty-one samples (11.5%) had mixed Haemoproteus and Leucocytozoon infections. The Spotted Eagle Owl (Bubo africanus) and Barn Owl (Tyto alba) had the highest infection rates. Twenty-six sequences, similar to published sequences of Leucocytozoon spp. (lineages lCHRKLA02, lCIAE02, and lBUVIR02) and Haemoproteus spp. (lineage hTYTAL6) were obtained. Two new lineages (lBUBCAP01 and hBOSHAG02) are described in this study. This is the first molecular survey of haemosporidian parasites in captive birds of the orders Accipitriformes, Pelecaniformes, Psittaciformes, Phoenicopteriformes, and Strigiformes in South Africa. This study provides new geographical and host records of known and novel haemosporidian lineages. It highlights the need for intensive surveys of these parasites in populations of captive and free-ranging birds in South Africa, regular monitoring of infections, updated screening methods, and insect control in the zoo's animal collection to avoid disease outbreaks.

Prenatal hypoxia poses significant risks to mammalian brain development, often leading to long-term cognitive and memory deficits. However, certain hypoxia-tolerant species, such as Brandt's vole (Lasiopodomys brandtii), have evolved unique adaptations to thrive in low-oxygen environments. This study explores the effects of prenatal environmental hypoxia on the cognitive abilities and molecular responses of Brandt's voles in adulthood. Using behavioral tests (novel object recognition and Y maze) and transcriptomic analysis, we found that Brandt's voles exposed to prenatal environmental hypoxia exhibited intact cognitive and memory functions, contrasting with the deficits observed in model organisms. Transcriptomic profiling, validated by RT-qPCR experiments, revealed adaptive changes in energy metabolism, oxygen transport, and neuroprotective mechanisms, particularly in voles exposed to hypoxia both prenatally and in adulthood. These findings suggest that moderate prenatal environmental hypoxia exposure induces developmental plasticity in Brandt's voles, enhancing their hypoxia tolerance in adulthood, which contrasts with the detrimental effects observed in model organisms under similar conditions. Our study highlights the importance of investigating non-model organisms with natural hypoxia exposure histories, providing novel insights into the mechanisms of hypoxia adaptation and potential strategies for mitigating hypoxia-related neurological damage.

We investigated the phenological variation of three genera of blood parasites of lizards (Schellackia, Karyolysus, and Lankesterella) using samples of 275 adult Psammodromus algirus and 138 Acanthodactylus erythrurus collected from April to September in 2021 and 2022. Both years experienced heatwaves, and 2022 had the warmest summer on historical record for the region. We captured lizards in two close areas that differed in vegetation quality due to differential human pressure. We found that Schellackia and Karyolysus more frequently infected P. algirus, whereas Lankesterella infected A. erythrurus. We fitted generalized additive models to explain parasite intensity, including the non-linear effect of phenology sorted by sex and the linear effects of body length, body condition, host sex, heterophil–lymphocyte ratio, distance to a road, and microclimate. We found a positive effect of body length on parasite intensity across parasite genera. The intensity of Schellackia was higher in female hosts, contradicting the dogma of higher male susceptibility to infections. The intensity of Lankesterella was lower closer to the road, indicating that parasite transmission success can vary at the microgeographic scale. We found a non-linear significant increase of Karyolysus across the activity period, suggesting a relaxation of the antiparasitic control upon this genus toward the end of the activity period. For Lankesterella, we observed a phenological increase only in female lizards, suggesting sexual differences in immunocompetence. We found higher intensity of Karyolysus and Lankesterella in 2022, conforming to the idea that heat waves may impair lizards' immunocompetence.

The physiological traits of animals can be strongly influenced by climatic fluctuations, and future climate changes may have negative impacts. However, the magnitude of these effects likely depends on the type of animal and its specific environment. In fossorial animals, soil alterations can affect their physiological traits, but adaptations to fossoriality may lead to different effects when compared to epigeal animals. We experimentally examined the hydric physiology and the effects of soil hydric stress (i.e., a simulated drought) on the physiological state of the amphisbaenian Blanus cinereus, a strictly fossorial reptile. Individuals selected substrates with moderately low moisture levels in a laboratory gradient but avoided the wettest substrates. The evaporative water loss rates of amphisbaenians were temperature-dependent, but notably low compared to other epigeal reptiles of similar size and climatic niche. In the hydric stress experiment, amphisbaenians buried in dry substrates did not gain body weight and showed increased glucocorticoid (GC) levels, whereas those in wet substrates gained weight without an increase in GC levels. However, immune response was unaffected by the drought or elevated GC levels, and individuals exposed to hydric stress recovered their weight after a subsequent recovery period under normal conditions. Additionally, amphisbaenians compensated for drought conditions behaviorally, more often selecting soils under rocks where conditions could be more favorable. These results suggest that soil drought imposes moderate, temporary costs, but that amphisbaenians can cope with, at least, moderately short droughts, likely as a result of their adaptations to the underground environment.

Parasite distributions are under the influence of host occurrence and tolerable environmental conditions. In vector-borne disease systems, including avian malaria, they are further constrained by the environmental niche of the vectors. The fact that avian haemosporidians occur in a large number of migratory and non-migratory species means the role of bird migration in the global distribution of avian haemosporidians is an open question. Because avian haemosporidians refer to a large number of genetic lineages that are well characterized in terms of host and geographic range, we introduce an ecoregion pairwise analysis that sets out to explain the similarity in lineages in pairs of ecoregions as a function of the pair's similarity in migratory and non-migratory bird communities, as well as environmental conditions. We identify important roles for each of these factors in explaining the overall geographic distribution of lineages, including strong support for the role of migratory birds in moving lineages between environmentally dissimilar ecoregions.

Hibernation involves complex physiological adaptations enabling animals to survive extreme conditions. During hibernation, body temperature, metabolic rate, and heart rate change significantly but are quickly restored upon arousal. Despite extensive research, the underlying mechanisms remain unclear. This study used proteomics to examine cardiac and hepatic protein levels in food-hoarding hibernator Siberian chipmunk (Tamias sibiricus) during torpor and arousal. Results show that, unlike the fat-storing hibernators, the liver of chipmunks maintains glucose, lipid, and bile acid synthesis throughout hibernation due to changes in proteins like GALE, SLC2A3, GSK-3α, HMGCS2, ACAT2, and AMACR. In contrast, reduced mitochondrial autophagy (PINK1 and PARKIN) and enhanced anti-apoptotic mechanisms (TFRC, WFS1, and NDRG1) help maintain energy balance in the heart. These findings provide new insights into cardio-protection in food-hoarding hibernators and improve our understanding of adaptive mechanisms in mammalian hibernators.

The flexibility of digestive tract morphology and the composition of gut microbiota play crucial roles in the environmental adaptation of reptiles. To evaluate the contributions of the dietary niches to the gut microbiota, we performed 16S rDNA sequencing and metabolite profiling for three sympatric lizard species-Teratoscincus roborowskii, Phrynocephalus axillaris, and Eremias roborowskii-and compared their goblet cell and enzyme activities of the digestive tract. The results revealed that goblet cell densities in the stomach body and pylorus were significantly higher in both T. roborowskii and E. roborowskii, which occasionally include fruit in their diets. Lipase activity was significantly higher in the insectivorous P. axillaris, while the α-amylase and cellulase activities were elevated in the omnivorous T. roborowskii and E. roborowskii. All three lizard species shared the same dominant microbiota at the phylum level. However, dietary niche differences led to P. axillaris having a higher abundance of Desulfovibrionaceae, while E. roborowskii had a significantly higher abundance of Bacteroidetes. Metabolomic profiling revealed that the metabolites involved in carbohydrate metabolism were highly upregulated in E. roborowskii, corresponding to the host's diet and metabolic pathways. Notably, a strong correlation was observed between digestive enzymes, gut microbiota, and fecal metabolites. Overall, our study suggests that the dietary niche may promote divergence or convergence of microbiota across host species, facilitating the establishment of host-specific intestinal adaptation strategies. Our findings provide insights into lizard adaptation to extreme deserts from the perspectives of the gut microbiome and digestive physiology.

The Neotropical region stands out as one of the most taxonomically diverse areas on the planet, garnering significant attention in the context of marine incursions and their role in shaping this diversity. Among marine-derived taxa, pleuronectiform fishes exhibit distinctive morphological characteristics that have attracted significant scientific interest. The broad distribution of a single species across multiple South American river basins positions Hypoclinemus mentalis as an ideal candidate for biogeographic studies within South America, with an emphasis on the detection of cryptic lineages associated with major drainage basins. This study aimed to investigate the monotypic status of Hypoclinemus, its evolutionary history, and whether historical paleogeographical events could play a role in the dispersion of H. mentalis in the Neotropical region, utilizing mitochondrial and nuclear markers. In our study, we employed mitochondrial and nuclear markers to investigate the potential existence of such lineages within the broader context of a molecular phylogeny that encompasses all valid genera in the flatfish family Achiridae. Our findings reveal that Hypoclinemus comprises seven operational taxonomic units (OTUs), as deduced from specimens collected across the majority of its documented range. Furthermore, our phylogeographic analyses support the hypothesis that colonization of freshwater habitats occurred through connections between the Caribbean Sea and Lake Pebas approximately 21.28 million years ago. Moreover, we observed that differentiation of lineages within the Hypoclinemus genus was significantly influenced by pronounced sea level fluctuations during the Plio-Pleistocene epoch, underscoring the impact of glaciations and interglacial periods on the biogeographic patterns.