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.

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.