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Microcycas calocoma is the monotypic species from the critical endangered and endemic cycad genus Microcycas in Cuba, an important taxon to study the evolution of extant gymnosperms. Here we report the complete chloroplast sequences of M. calocoma and characterize the genome structure of this species. The genome size of M. calocoma is 165,667 bp in length which contains 135 genes, including 88 protein-coding genes, eight ribosomal RNA genes and 39 transfer RNA genes. The GC content of this genome is 39.6%. Phylogenomic study shows M. calocoma is mostly closely related to the cycad genus Zamia, which corresponds to previous studies based on multiple nuclear genes and combined plastid and nuclear evidence. The plastome information of M. calocoma offered by this study can contribute to further comparative chloroplast genome in cycads/gymnosperms as well as conservation genetic studies of M. calocoma.

Vertebrates exhibit structural changes in their cardiovascular and gas exchange systems in response to hypoxic conditions in high altitude environments. In highland neotenic mole salamanders, as other amphibians, the majority of gases exchange is carried out for skin and gills. But, in high altitude environments, the available oxygen is lower than it is in the air thus, the scarcity of oxygen limits the survival of organisms. Many studies on this subject have focused on understanding the hematological mechanisms that amphibians exhibit in response to hypoxia. However, little is known about possible morphological changes in respiratory structures that may permit increased gas exchange during respiration in high altitude amphibians like Ambystoma leorae and A. rivulare, two threatened Mexican salamander species. The aim of the present study was to describe and compare the histological characteristics of the gills and dorsal skin of A. leorae and A. rivulare from populations at low and high altitudes. We found that, in comparison to lowland organisms, highland ones exhibited more pronounced skin folds, greater numbers of secondary branches in the gills, thinner dorsal and gill epidermises, and greater quantity of melanin surrounding the gill blood vessels. These differences permit a greater capacity for gas exchange and also increase thermoregulatory capacity in high altitude environments. [ABSTRACT FROM AUTHOR]

Microcycas calocoma is the monotypic species from the critical endangered and endemic cycad genus Microcycas in Cuba, an important taxon to study the evolution of extant gymnosperms. Here we report the complete chloroplast sequences of M. calocoma and characterize the genome structure of this species. The genome size of M. calocoma is 165,667 bp in length which contains 135 genes, including 88 protein-coding genes, eight ribosomal RNA genes and 39 transfer RNA genes. The GC content of this genome is 39.6%. Phylogenomic study shows M. calocoma is mostly closely related to the cycad genus Zamia, which corresponds to previous studies based on multiple nuclear genes and combined plastid and nuclear evidence. The plastome information of M. calocoma offered by this study can contribute to further comparative chloroplast genome in cycads/gymnosperms as well as conservation genetic studies of M. calocoma. [ABSTRACT FROM AUTHOR]

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• Chondrilla chondrilloides is a rare and threatened character species of alpine streams and alluvial fans, endemic to the calcareous Eastern Alps. • This review compiles all available data on the species' taxonomy, morphology, distribution, habitat preferences and ecology. • This information is supplemented by unpublished research data including an assessment of its phylogenetic placement. Chondrilla chondrilloides (Asteraceae) is a rare and endangered early-successional plant species endemic to the Eastern European Alps. Its distribution is restricted to near-natural braided rivers and to alluvial fans. The species was common along Alpine gravel rivers, but has declined markedly due to river regulation and degradation in the 19th and 20th century, while some recent restoration projects benefit the plant. Its population declines were caused by habitat fragmentation and destruction as a consequence of extensive hydro-engineering. This paper summarises the published material on taxonomy, morphology, habitat requirements and distribution of the species. The review is complemented by own research data and a phylogenetic assessment of extant and extinct populations within the infrageneric context. A summary on location, size and structure of the remaining populations in the north-eastern and south-eastern Alps is combined with data on seed germination and the habitat niche of the species, with a particular focus on differences between northern and southern populations. Chondrilla chondrilloides forms meta-populations on consolidated gravel bars and older terraces, with extinction and recolonisation due to floodplain dynamics; small populations quickly recover from few founder individuals. Populations in the southern parts of the species' range are larger with bigger plants and more reproduction, while germination is very high in all populations. Thus, C. chondrilloides has characteristics that allow it to respond rapidly to degradation and restoration of its habitats along gravel rivers in the Eastern Alps. [ABSTRACT FROM AUTHOR]