We analysed 20 allozyme and 22 putative random amplified polymorphic DNA (RAPD) loci in two populations of Pinus sylvestris (L.) from northern Sweden. Genotypes for individual allozyme and RAPD loci were inferred from segregation patterns in haploid macrogametophytes. Therefore, it was possible to distinguish between homo-and heterozygotes carrying a RAPD fragment and to estimate directly the frequencies of RAPD fragments. The percentage of polymorphic loci and the expected and observed heterozygosity were lower for allozymes than for RAPDs. Average fixation indices for both types of markers were negative indicating a heterozygote excess over panmictic expectations. The apportionment of genetic variation within and among the investigated populations was similar for allozymes and RAPDs and showed that most of the variation resided within populations. RAPD genotypes inferred from haploid material were subsequently converted to diploid phenotypes and used to estimate indirectly the frequencies of RAPD fragments. Gene diversity measurements derived from indirectly estimated RAPD frequencies were distinctly lower than those based on directly estimated RAPD frequencies. This result was caused by the absence of the null homozygote at many loci which appeared as monomorphic in the diploid data set. Population differentiation coefficients based on the indirectly estimated RAPD frequencies were not concordant with those based on directly estimated RAPD frequencies. Our present results indicate that when complete genotype information can be obtained, RAPD analysis provides genetic information similar to that revealed by analysis of allozyme variation. On the other hand, our results are concordant with theoretical results suggesting that analysis of RAPD variation in diploid material can produce unreliable estimates of population-genetic parameters.

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The ongoing SARS-CoV-2 pandemic has exposed major gaps in our knowledge on the origin, ecology, evolution, and spread of animal coronaviruses. Porcine epidemic diarrhea virus (PEDV) is a member of the genus Alphacoronavirus in the family Coronaviridae that may have originated from bats and leads to significant hazards and widespread epidemics in the swine population. The role of local and global trade of live swine and swine-related products in disseminating PEDV remains unclear, especially in developing countries with complex swine production systems. Here we undertake an in-depth phylogeographic analysis of PEDV sequence data (including 247 newly sequenced samples) and employ an extension of this inference framework that enables formally testing the contribution of a range of predictor variables to the geographic spread of PEDV. Within China, the provinces of Guangdong and Henan were identified as primary hubs for the spread of PEDV, for which we estimate live swine trade to play a very important role. On a global scale, the United States and China maintain the highest number of PEDV lineages. We estimate that, after an initial introduction out of China, the United States acted as an important source of PEDV introductions into Japan, Korea, China and Mexico. Live swine trade also explains the dispersal of PEDV on a global scale. Given the increasingly global trade of live swine, our findings have important implications for designing prevention and containment measures to combat a wide range of livestock coronaviruses.

We studied the inheritance of RAPD fragments in haploid and diploid tissues of eight parents and 80 diploid controlled F1 progeny of Pinus sylvestris (L.). Most fragments detected in the diploid tissue of parents were also present in their haploid macrogametophytes. All fragments observed in the parents were found in the progeny. Individual fragments amplified by a single primer were observed in unrelated trees suggesting that primer competition is not likely to cause 'epistatic' effects on RAPD polymorphism. Segregation of all variable fragments observed in haploid and diploid materials fitted the proportions expected for a dominant Mendelian trait. The segregating fragments were either present or absent confirming the dominant character of RAPD variation reported in most previous studies. None of the fragments detected in this study appeared to originate from uniparentally inherited cytoplasmic DNA. Our present results provide additional support for the usefulness of RAPD fragments as genetic markers. Nevertheless, the few differences observed between haploid and diploid tissues with respect to some fragments emphasize the need for inheritance studies preceding the use of RAPD fragments as genetic markers.

Premise: Plants have evolved different ecological strategies in response to environmental challenges, and a higher lability of such strategies is more common in plant groups that adapt to various niches. Crassula (Crassulaceae), occurring in varied mesic to xeric habitats, exhibits a remarkable diversity of life-forms. However, whether any particular life-form trait has shaped species diversification in Crassula has remained unexplored. This study aims to investigate diversification patterns within Crassula and identify potential links to its life-form evolution. Methods: A phylogenetic tree of 140 Crassula taxa was reconstructed using plastid and nuclear loci and dated based on the nuclear DNA information only. We reconstructed ancestral life-form characters to estimate the evolutionary trends of ecophysiological change, and subsequently estimated net diversification rates. Multiple diversification models were applied to examine the association between certain life-forms and net diversification rates. Results: Our findings confirm a radiation within Crassula in the last 10 million years. A configuration of net diversification rate shifts was detected, which coincides with the emergence of a speciose lineage during the late Miocene. The results of ancestral state reconstruction demonstrate a high lability of life-forms in Crassula, and the traitdependent diversification analyses revealed that the increased diversification is strongly associated with a compact growth form. Conclusions: Transitions between life-forms in Crassula seem to have driven adaptation and shaped diversification of this genus across various habitats. The diversification patterns we inferred are similar to those observed in other major succulent lineages, with the most-speciose clades originating in the late Miocene.

A B S T R A C TAs the outbreaks of COVID-19 in worldwide, coronavirus has once again caught the attention of people. Canine coronavirus is widespread among dog population, and sometimes causes even fatal cases. Here, to characterize the prevalence and evolution of current circulating canine coronavirus (CCoV) strains in China, we collected 213 fecal samples from diarrheic pet dogs between 2018 and 2019. Of the 213 samples, we found 51 (23.94%) were positive for CCoV. Co-infection with canine parvovirus (CPV), canine astrovirus (CaAstV), canine kobuvirus (CaKV), Torque teno canis virus (TTCaV) were ubiquitous existed. Mixed infection of different CCoV subtypes exists extensively. Considering the limited sequences data in recent years, we sequenced 7 nearly complete genomes and 10 complete spike gene. Phylogenetic analysis of spike gene revealed a new subtype CCoV-II Variant and CCoV-IIa was the most prevalent subtype currently circulating. Moreover, we identified strain B906_ZJ_2019 shared 93.24% nucleotide identifies with previous strain A76, and both of them clustered with CCoV-II Variant, which were not well clustered with the known subtypes. Recombination analysis of B906_ZJ_2019 indicated that strain B906_ZJ_2019 may a recombinant variant between CCoV-I and CCoV-II, which is consistent with strain A76. Furthermore, amino acid variations widely existed among current CCoV-IIa strains circulating in China and the classic CCoV-IIa strains, in spite of the unknown functions.In a word, we report a useful information as to the etiology and evolution of canine coronavirus in China based on the available sequences, which is urgent for the devise of future effective disease prevention and control strategies.

Since its first emergence in 1998 in Malaysia, Nipah virus (NiV) has become a great threat to domestic animals and humans. Sporadic outbreaks associated with human‐to‐human transmission caused hundreds of human fatalities. Here, we collected all available NiV sequences and combined phylogenetics, molecular selection, structural biology and receptor analysis to study the emergence and adaptive evolution of NiV. NiV can be divided into two main lineages including the Bangladesh and Malaysia lineages. We formly confirmed a significant association with geography which is probably the result of long‐term evolution of NiV in local bat population. The two NiV lineages differ in many amino acids; one change in the fusion protein might be involved in its activation via binding to the G protein. We also identified adaptive and positively selected sites in many viral proteins. In the receptor‐binding G protein, we found that sites 384, 386 and especially 498 of G protein might modulate receptor‐binding affinity and thus contribute to the host jump from bats to humans via the adaption to bind the human ephrin‐B2 receptor. We also found that site 1645 in the connector domain of L was positive selected and involved in adaptive evolution; this site might add methyl groups to the cap structure present at the 5′‐end of the RNA and thus modulate its activity. This study provides insight to assist the design of early detection methods for NiV to assess its epidemic potential in humans.

Sequence analysis of the mitochondrial coxI gene in eight gymnosperm species revealed a high rate of nonsynonymous nucleotide substitutions with a strong (98%) predominance of C-T substitutions. Further analysis of the corresponding coxI cDNA sequences showed that all the non-synonymous C-T changes in the coxI genomic DNA sequences were eliminated by RNA editing resulting in nearly identical mRNA (amino acid) sequences among the species. Pronounced variation in the number and location of edited sites was found among species. Most species had a relatively large number of edited sites (from 25 to 34). However, no RNA editing of the coxI sequence was found in Gingko biloba or Larix sibirica. The sequence composition of the investigated coxI fragment suggests that the coxI gene in G. biloba and L. sibirica originated from edited mitochondrial coxI transcripts by reverse transcription followed by insertion into the nuclear genome or back into the mitochondrial genome. Our results also demonstrate that where there are a large number of edited sites, RNA editing can accelerate the divergence of nucleotide sequences among species.