农学最新文献

Appropriate root system architecture (RSA) can improve alfalfa yield, yet its genetic basis remains largely unexplored. This study evaluated six RSA traits in 171 alfalfa genotypes grown under controlled greenhouse conditions. We also analyzed five yield-related traits in normal and drought stress environments and found a significant correlation (0.50) between root dry weight (RDW) and alfalfa dry weight under normal conditions (N_DW). A genome-wide association study (GWAS) was performed using 1 303 374 single-nucleotide polymorphisms (SNPs) to explore the relationships between RSA traits. Sixty significant SNPs (-log ₁₀ (P) ≥ 5) were identified, with genes within the 50 kb upstream and downstream ranges primarily enriched in GO terms related to root development, hormone synthesis, and signaling, as well as morphological development. Further analysis identified 19 high-confidence candidate genes, including AUXIN RESPONSE FACTORs (ARFs), LATERAL ORGAN BOUNDARIES-DOMAIN (LBD), and WUSCHEL-RELATED HOMEOBOX (WOX). We verified that the forage dry weight under both normal and drought conditions exhibited significant differences among materials with different numbers of favorable haplotypes. Alfalfa containing more favorable haplotypes exhibited higher forage yields, whereas favorable haplotypes were not subjected to human selection during alfalfa breeding. Genomic prediction (GP) utilized SNPs from GWAS and machine learning for each RSA trait, achieving prediction accuracies ranging from 0.70 for secondary root position (SRP) to 0.80 for root length (RL), indicating robust predictive capability across the assessed traits. These findings provide new insights into the genetic underpinnings of root development in alfalfa, potentially informing future breeding strategies aimed at improving yield.

Since Darwin's era, speciation has been one of the most central issues in evolutionary biology studies. Understanding the processes of species origin is crucial in deepening our understanding of the formation of species biodiversity, which is essential for their protections. However, speciation research has been challenging due to the rather complex evolutionary histories of many extant species. In recent years, with the continuous advancements in genomic sequencing techniques, significant advances have been achieved in the field of speciation researches. In this review, we overview speciation study advances, especially in the concepts and latest developments in research methods for studying speciation in the genomic era, encompassing the major research aspects: species delimitation, bifurcating speciation, hybrid speciation, polyploid speciation, reproductive isolation genes and speciation genes. Furthermore, we discuss the limitations of these studies and methods. Finally, we provide the outlook on the future challenges and directions in speciation researches.

The northern part of Asia, including Siberia, the Mongolian Plateau, and northern China, is not only a crossroads for population exchange on the Eurasian continent but also an important bridge connecting the American continent. This region holds a unique and irreplaceable significance in exploring the origins of humanity, tracking human migration routes, and elucidating evolutionary mechanisms. Despite the limited number of samples unearthed, varying preservation conditions, and constraints of technical means, our understanding of the interactions among populations in northern Asia is still in its infancy. However, the development of high-throughput sequencing technology and its advancement in ancient DNA research have provided us with a new perspective for delving into the genetic history of ancient populations from a molecular level. In this review, we synthesize the changes in the genetic structure of ancient populations in different stages of northern Asia, aiming to reveal the patterns of interaction among ancient populations in this region, the evolutionary process of their genetic structure, and their genetic contributions to modern populations. It will also discuss the adaptive strategies of humans in response to extreme natural conditions. This will not only deepen our understanding of the origins and migration processes of humanity but also provide a solid foundation for studying the evolutionary mechanisms and adaptive strategies of humans under environmental selective pressures.

Over the past decade, the continuous development of ancient genomic technology and research has significantly advanced our understanding of human history. Since 2017, large-scale studies of ancient human genomes in East Asia, particularly in China, have emerged, resulting in a wealth of ancient genomic data from various time periods and locations, which has provided new insights into the genetic history of East Asian populations over tens of thousands of years. Especially since 2022, there emerged a series of new research progresses in the genetic histories of the northern and southern Chinese populations within the past 10,000 years. However, there is currently no systematic review focused on these recent ancient genomic studies in East Asia. Therefore, this article emphasizes the study of ancient human genomes in China and systematically reviews the genetic patterns and migration history of populations in East Asia since the Late Paleolithic. Existing research indicates that by at least 19,000 years ago, there was a north-south differentiation among ancient East Asian populations, leading to different genetic lineages divided by the Qinling-Huaihe line. Gene flow and interactions between northern and southern East Asians began in the Early Neolithic and were further strengthened from the Mid-Neolithic. By the historical period, northern East Asian ancestry played a profound role in the genetic components of southern populations, shaping the genetic structure of present-day Chinese populations. Throughout this process, ancient populations in northern and southern China also engaged in extensive interactions through coastal and inland routes with populations from surrounding regions, including Siberia, Japan, Korea, Southeast Asia, and Pacific islands, playing a crucial role in the formation of different linguistic groups. These studies have charted the evolutionary and interaction history of East Asian populations over tens of thousands of years; yet, many unresolved mysteries remain. Further exploration is needed through ancient genomic data from additional time periods and broader geographic areas to facilitate a more comprehensive and detailed investigation, thereby advancing related scientific questions.

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.

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.

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.