6 research outputs found
Functional histology of the skin in the subterranean African giant mole-rat: thermal windows are determined solely by pelage characteristics
Excavation of burrows is an extremely physically demanding activity producing a large amount of metabolic heat. Dissipation of its surplus is crucial to avoid the risk of overheating, but in subterranean mammals it is complicated due to the absence of notable body extremities and high humidity in their burrows. IR-thermography in a previous study on two species of African mole-rats revealed that body heat was dissipated mainly through the ventral body part, which is notably less furred. Here, we analyzed the dorsal and ventral skin morphology, to test if dermal characteristics could contribute to higher heat dissipation through the ventral body part. The thickness of the epidermis and dermis and the presence, extent and connectivity of fat tissue in the dermis were examined using routine histological methods, while vascular density was evaluated using fluorescent dye and confocal microscopy in the giant mole-rat Fukomys mechowii. As in other hitherto studied subterranean mammals, no subcutaneous adipose tissue was found. All examined skin characteristics were very similar for both dorsal and ventral regions: relative content of adipose tissue in the dermis (14.4 ± 3.7% dorsally and 11.0 ± 4.0% ventrally), connectivity of dermal fat (98.5 ± 2.8% and 95.5 ± 6.8%), vascular density (26.5 ± 3.3% and 22.7 ± 2.3%). Absence of large differences in measured characteristics between particular body regions indicates that the thermal windows are determined mainly by the pelage characteristics
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Population co-divergence in common cuttlefish (Sepia officinalis) and its dicyemid parasite in the Mediterranean Sea.
Population structure and biogeography of marine organisms are formed by different drivers than in terrestrial organisms. Yet, very little information is available even for common marine organisms and even less for their associated parasites. Here we report the first analysis of population structure of both a cephalopod host (Sepia officinalis) and its dicyemid parasite, based on a homologous molecular marker (cytochrome oxidase I). We show that the population of common cuttlefish in the Mediterranean area is fragmented into subpopulations, with some areas featuring restricted level of gene flow. Amongst the studied areas, Sardinia was genetically the most diverse and Cyprus the most isolated. At a larger scale, across the Mediterranean, the population structure of the parasite shows co-diversification pattern with its host, but a slower rate of diversification. Differences between the two counterparts are more obvious at a finer scale, where parasite populations show increased level of fragmentation and lower local diversities. This discrepancy can be caused by local extinctions and replacements taking place more frequently in the dicyemid populations, due to their parasitic lifestyle