农学最新文献

Speciation research represents our thinking and exploration about how new species are generated and maintained, and it is one of the most important parts of evolutionary biology. Revealing new species formation modes, processes of reproductive isolation establishment and their intrinsic genetic mechanisms, are not only important issues and primary tasks in the field of speciation, but also the key clues for our understandings about the species diversity in nature. Here, by focusing on animal groups, we first introduced different definitions of species concept, and then summarized present research progress and important breakthroughs made in the speciation modes and molecular mechanism of reproductive isolation. We also pointed out some limitations in current studies. Finally, we discuss the potential opportunities and new breakthroughs that can be made in the future studies of animal speciation.

Due to the unique geographical features of large numbers, isolated by water and diverse formation histories, islands have become natural laboratories for ecological and evolutionary research. Islands have a high proportion of endemic species and disharmony in representing the species compared with that in the continent, which provides a good opportunity to explore the formation of island biodiversity. In this review, we focuse on island ecosystems and describes the progress of research in island biogeography in recent years from three aspects: formation, maintenance, and loss of island biodiversity. First, we take several representative island systems in the world as examples to introduce the formation mechanism of island biodiversity from species dispersal and immigration, population establishment and selection, species evolution and adaptive radiation. Based on the Equilibrium Theory of Island Biogeography, we then review the species-area relationship and species-isolation relationship and focus on the research progress in community assembly, including Diamond's rule, nestedness pattern, the framework of community structure of island biota, and species interactions on islands. We also discuss the high extinction risks of island species threatened from natural and human disturbances, especially from the impact of habitat loss and change, climate change, alien species invasion and the synergistic effect of these factors on the loss of island biodiversity. Finally, based on the status of island biodiversity, we summarized the current conservation practices for island biodiversity and possible research frontiers in island biogeographic studies.

It has been more than 40 years since the beginning of exploring the genetic composition of ancient organisms from the perspective of ancient DNA. In the recent 20 years, with the development and application of high-throughput sequencing technology platforms and the improved efficiency of retrieving highly fragmented DNA molecules, ancient DNA research moved forward to a brand-new era of deep-time paleogenomics. It not only solved many controversial phylogenetic problems, enriched the migration and evolution details of various organisms including humans, but also launched exploration of the molecular responses to climate changes in terms of "whole genomic-big data-multi-species" level. Moreover, it expanded the sample age from no more than 100,000 years to the Early Pleistocene, ~2 million years ago. Recently, Chinese scientists have made many influential breakthroughs in evolution and migration integration of East Asian populations and thus filled an important gap in the evolutionary process of modern human. Compared to the situation in human paleogenomic studies, less attention has been paid to the study of ancient DNA from vertebrates remains. In this review, we introduce a series of advances in ancient DNA investigations of large mammals in Late Quaternary in China, summarize the research breakthroughs in revealing the systematic evolutionary relationship between ancient and extant groups, gene flow, and molecular responses of mammalian populations to climate change, and explore the opportunities and key challenges in the field of mammalian paleogenomics.

Being the most magnificent plateau in elevation and size on Earth, the Qinghai-Tibet Plateau has a profound impact on biodiversity due to the unique geographic and climatic conditions. Here we review the speciation patterns and genetic diversity of the birds from the Qinghai-Tibet Plateau in relation to the geological history and climatic changes. First, the uplift of the Qinghai-Tibet Plateau forms a geographic barrier and promotes interspecific and intraspecific genetic differentiation. Second, the uplift of the Qinghai-Tibet Plateau has provided new ecological niches for many endemic birds and facilitated their speciation. Third, the emigration and immigration of bird species between the Qinghai-Tibet Plateau and adjacent zoological regions have promoted species divergence, colonization and dispersal. Furthermore, Pleistocene glaciations and associated climate change drive postglacial colonization and lead to secondary contact, which influenced the genetic divergence of the conspecific populations and sister species. The multi-omics approach has increasingly been used in the studies on the ecological adaptive evolution of birds in Qinghai-Tibet Plateau. Future studies should focus on the role of geological and climatic factors in species differentiation, develop integrative approach with multi-omics methods, and explore the ecological mechanisms of high-elevation adaptation of plateau species. As an important region for biodiversity conservation, more efforts should be implemented to maintain the stability and sustainability of the Qinghai-Tibet Plateau and its ecosystem in light of global change.