Rate of change for the thermal adapted inversions in Drosophila subobscura Abstract The changes of chromosomal inversion polymorphism composition of Drosophila subobscura in samples from Apatin (Serbia) were studied in a 24-years interval (1994–2018). The variation was significant for all autosomes and directional, increasing the inversions considered as ‘warm’, whereas those reported as ‘cold’ decreased. Furthermore, the Chromosomal Thermal Index (CTI), which allows studying the thermal adaptation of the whole karyotype increased significantly in that period of time. These results were in agreement with the indicators of global warming in Apatin: a trend to increase of the mean, maximum and minimum (this latter even significant) temperatures, and an erratic pattern of rainfall (also usual in global warming). The deviations from the Wright–Fisher model of genetic drift were used to consider the possible effect of migration or selection as evolutionary factors responsible for the change in inversion frequencies. To quantify approximately the rate of change in the frequencies, for each kind of inversions (‘cold’, ‘warm’ and ‘non-thermal adapted’), the difference in frequency between the Apatin samples obtained in 1994 and 2018 was computed and then it was divided by the number of years elapsed. This rate was always higher (from twice as many as thirty times more depending on the autosome) for thermal adapted inversions (‘cold’ or ‘warm’) than the ‘non-thermal’ adapted. From this study, it could be concluded that the chromosomal inversions of D. subobscura could change (in composition and frequencies) in a predictable direction and a rather ‘rapid’ rhythm to adapt to the global warming scenario.

Genome-wide identification, phylogenetic and expression analysis of the maize HECT E3 ubiquitin ligase genes Abstract HECT (homologous to the E6AP carboxyl terminus) ubiquitin ligase genes (E3s) are enzymes with diverse functions influencing plant growth, development, and responses to abiotic stresses. However, there is relatively little information available regarding the maize HECT E3 gene family. In the present study, 12 maize HECT E3 genes (ZmUPL1 to ZmUPL12) were identified at the whole-genome level. The phylogenetic relationships, structures, and expression levels of the maize HECT E3 genes were then analyzed. On the basis of the constructed maximum likelihood phylogenetic tree, the HECT E3 genes were divided into six groups. The quantitative real-time polymerase chain reaction assay results revealed that all of the maize ZmUPL genes were expressed in most of the examined tissues and were responsive to three abiotic stresses. Considered together, the study results may provide a useful foundation for future investigations of maize stress-tolerance genes as well as functional analyses of the E3 enzymes in diverse agriculturally important crop species.

Genetic variability and effective population size in Hymenaea stigonocarpa (Fabaceae) germplasm collection: tools for breeding programs and genetic conservation Abstract The conservation of plant genetic resources is essential for breeding programs. Regarding the native species of the Brazilian Cerrado biome, many studies have demonstrated their high potential for use in both medicines and foods. Hymenaea stigonocarpa, a tree with wide occurrence in the Cerrado, has economic importance, and due its extractive use, the establishment of a breeding program is relevant for sustainable use and conservation. Thus, the first germplasm collection of the species was installed at the Federal University of Goiás (UFG). To know the magnitude of genetic variability and how it was distributed in the collection, 353 individuals, distributed in 119 families from 24 subpopulations collected in the Cerrado biome, were genotyped using capillary electrophoresis. Nine pairs of microsatellite markers were genotyped. The UFG germplasm collection showed a high level of genetic diversity (mean \(\bar{H}e\) = 0.554) at the evaluated loci. By Analysis of Molecular Variance (AMOVA), a significant genetic structure was detected (θP = 0.152, p < 0.01), which was expected since the subpopulations that originated the germplasm collection were collected in geographically distant locations. In addition, the germplasm collection had a population effective size of 54.9 and presented an allelic representation of 79.89% compared to 32 natural subpopulations. These results demonstrate that the germplasm collection preserves a high genetic diversity of H. stigonocarpa with a population effective size considered sufficient for the conduction of a breeding program.

The complete chloroplast genomes of two species in threatened monocot genus Caldesia in China Abstract Caldesia is a genus in the family Alismataceae mainly found in the tropical and temperate regions of the Northern hemisphere. In China, two species, Caldesia parnassifolia, and Caldesia grandis are recorded as critically endangered in sporadic regions. Available protection of the genetic resource of these threatened species has been impeded due to limited genomic information. Here, we sequence the whole chloroplast (cp) genome of the two Caldesia species using high throughput sequencing technology. The whole cp genomes of C. parnassifolia and C. grandis were 167,647 bp and 168,500 bp, respectively with a typical quadripartite structure. There were 115 unique genes with 81 protein-coding genes, 31 tRNA genes, and four rRNA genes. Both species showed a GC content of 37.1%. A duplication of two tRNA genes and a ~ 6 kb inversion region in the LSC was noted in both species. Mononucleotide simple sequence repeats (SSRs) A/T were most abundant for both Caldesia species. High nucleotide variability was recorded in ycf1 gene and trnK-UUU/rps16 intergenic spacer region. All RNA editing conversions were C–U in 23 and 24 protein-coding genes for C. parnassifolia and C. grandis, respectively. Phylogenetic analysis placed both Caldesia species as sister to Sagittaria lichuanensis. This study will be useful for further evolutionary, systematic researches and conservation of the genus Caldesia.

Episodic positive diversifying selection on key immune system genes in major avian lineages Abstract The major histocompatibility complex (MHC) of the adaptive immune system and the toll-like receptor (TLR) family of the innate immune system are involved in the detection of foreign invaders, and thus are subject to parasite-driven molecular evolution. Herein, we tested for macroevolutionary signatures of selection in these gene families within and among all three major clades of birds (Paleognathae, Galloanserae, and Neoaves). We characterized evolutionary relationships of representative immune genes (Mhc1 and Tlr2b) and a control gene (ubiquitin, Ubb), using a relatively large and phylogenetically diverse set of species with complete coding sequences (34 orthologous loci for Mhc1, 29 for Tlr2b, and 37 for Ubb). Episodic positive diversifying selection was found in the gene-wide phylogenies of the two immune genes, as well as at specific sites within each gene (8.5% of codon sites in Mhc1 and 2.7% in Tlr2b), but not in the control gene (Ubb). We found 20% of lineages under episodic diversifying selection in Mhc1 versus 9.1% in Tlr2b. For Mhc1, selection was relaxed in the Galloanserae and intensified in the Neoaves relative to the other clades, but no differences were detected among clades in the Tlr2b gene. In summary, we provide evidence of episodic positive diversifying selection in key immune genes and demonstrate differential strengths of selection within Class Aves, with the adaptive gene showing an increased divergence and evolutionary rate over the innate gene, contributing to the growing understanding of vertebrate immune gene evolution.

MITF: an evolutionarily conserved transcription factor in the sea urchin Paracentrotus lividus Abstract Microphthalmia-associated transcription factor (MITF) is a member of MYC superfamily, associated with melanocyte cells, as it was discovered in depigmented mice. However, over the last years it was found to be involved in many cellular signaling pathways, among which oncogenesis, osteoclast differentiation, and stress response. In mammals, Mitf gene mutations can cause diverse syndromes affecting pigmentation of eyes or skin, bone defects and melanomas. As MITF protein homologs were also found in some invertebrates, we have isolated and characterized the MITF cDNAs from the sea urchin Paracentrotus lividus, referred to as Pl-Mitf. The in silico study of the secondary and tertiary structure of Pl-Mitf protein showed high conserved regions mostly lying in the DNA binding domain. To understand the degree of evolutionary conservation of MITF, a phylogenetic analysis was performed comparing the Pl-Mitf deduced protein with proteins from different animal species. Moreover, the analysis of temporal and spatial expression pattern of Pl-Mitf mRNA showed that it was expressed from the onset of gastrulation of the sea urchin embryo to the pluteus larva, specifically in primary mesenchymes cells (PMCs), the sea urchin skeletogenic cells, and in the forming archenteron, the larval gut precursor. In silico protein–protein interactions analysis was used to understand the association of MITF with other proteins. Our results put in evidence the conservation of the MITF protein among vertebrates and invertebrates and may provide new perspectives on the pathways underlying sea urchin development, even if further functional analyses are needed.

Late flowering in F 1 hybrid rice brought about by the complementary effect of quantitative trait loci Abstract Late flowering sometimes occurs in F1 hybrids between rice varieties (Oryza sativa L.), although the parental varieties show similar days-to-flowering (DTF). The genetic architecture prompting the occurrence of such late flowering is poorly understood. To clarify the genetic architecture of late flowering in F1 hybrids from a cross between rice varieties, ‘Koshihikari’ and ‘IR64’, we performed quantitative trait locus (QTL) analysis using an F2 population (selfed progeny of an F1 plant), in which heterozygous genotypes should segregate in a certain proportion in a Mendelian manner. The QTL analysis detected three significant QTLs. At one QTL (putatively Heading date 1), the ‘Koshihikari’ allele increased DTF, and at the other two QTLs (putatively Heading date 6 and Oryza sativa Pseudo-Response Regulator 37/Heading date 2), the ‘IR64’ alleles increased DTF. All alleles at these three QTLs showed partial dominance. The combination of the QTLs explained 82.2% of the total phenotypic variance of DTF in the F2 population, with contribution from epistasis between QTLs. There was no difference between DTFs of F1 hybrids and heterozygous genotypes for the three QTLs. Our results demonstrated that the complementary effects accompanied by epistasis of at least three QTLs were responsible for late flowering in F1 hybrids.

Inferring boundaries among fish species of the new world silversides (Atherinopsidae; genus Odontesthes ): new evidences of incipient speciation between marine and brackish populations of Odontesthes argentinensis Abstract Species of new world silversides (Actinopterygii; Atherinopsidae; genus Odontesthes) possess economic relevance, biological interest and ecological importance. In the present paper we: (A) investigate the molecular diversity in marine species of Odontesthes from the South West Atlantic Ocean (SWAO), and analyse their interspecific relationships and divergence by means of DNA Barcoding, including its freshwater congeners, as well. (B) Explore the suitability of DNA Barcoding to analyse the diversity and distribution of haplotypes in Odontesthes argentinensis, the only well documented marine species from the SWAO that exhibit putative estuarine and marine populations. Molecular analysis revealed 100% of agreement between morphological identification and molecular identity. Odontesthes argentinensis, Odontesthes platensis, Odontesthes smitti, Odontesthes nigricans and Odontesthes incisa were assigned to five different barcode index numbers (BINs). Maximum-likelihood analysis showed that all marine species of Odontesthes clustered separately in a unique monophyletic phylogroup, comprising five well defined haplogroups, with genetic divergence between groups ranging from 2.75 to 7.11%. The genetic analysis including freshwater congeners showed that O. incisa clustered alone occupying a basal position. The Fst pairwise comparisons within O. argentinensis support the existence of three population groups: one conformed by Mar Chiquita Lagoon (MCh) specimens, and the others by Mar del Plata/Mar Chiquita coast and San Blas Bay coastal specimens, respectively. The AMOVA showed significant overall differentiation (Fst = 0.238; p = 0.00001) for the entire data set. The previous/present evidence is discussed, and strongly suggests that incipient speciation is occurring in O. argentinensis argentinean populations, and specimens from MCh would be considered at present as the leading candidate of a marine to freshwater incipient speciation event.

Genetic diversity of the Sichuan snub-nosed monkey ( Rhinopithecus roxellana ) in Shennongjia National Park, China using RAD-seq analyses Abstract The Sichuan snub-nosed monkey (Rhinopithecus roxellana) is an endangered species endemic to China, where the smallest population resides in Shennongjia National Park, Hubei Province. In this study, the genetic diversity of the Sichuan snub-nosed monkeys from two areas, Qianjiaping (QJP) and Dalongtan (DLT) in Shennongjia National Park was evaluated using single nucleotide polymorphisms (SNPs) data derived from restriction site-associated DNA sequencing (RAD-seq). A total of 41,260 SNP loci were found in 29 Sichuan snub-nosed monkey individuals. The genome-wide nucleotide diversity (π) of the Shennongjia population was 0.001842. The genetic differentiation (FST) between the QJP and DLT subpopulations was 0.034. The heterozygosity of individuals from QJP was 0.3475 ± 0.03696 and 0.3148 ± 0.03501 for individuals from DLT. Although the DLT and QJP subpopulations did not show significant genetic differences, genetic differentiation between the two subpopulations was confirmed using Bayesian cluster analysis, neighbor-joining trees and principal component analysis. These results suggest that the Shennongjia population of Sichuan snub-nosed monkey has relatively low genetic diversity at the genomic level. The little genetic differentiation noted between the DLT and QJP subpopulations likely due to natural and anthropogenic barriers which may exacerbate loss of genetic diversity of this endangered subpopulation.

Molecular-genetic diversity of the endangered Dalmatian barbelgudgeon, Aulopyge huegelii from the Buško Blato reservoir Abstract A number of studies investigating different aspects of IUCN endangered species, Aulopyge huegelii Heckel, 1843 (Dalmatian barbelgudgeon) biology have been conducted, but data on molecular genetics are lacking. The goal of this survey was to assess the genetic structure of the A. huegelii population from the Buško Blato reservoir, based on four mitochondrial DNA regions and five microsatellite loci. Excluding cytochrome b, more than one haplotype has been detected in all sequenced mtDNA regions, most of which had not been previously described. A total of seven composite haplotypes were detected. Nucleotide diversity was relatively low for all coding genes but slightly higher for the control region. Microsatellite analysis revealed a relatively high value of major allele frequency, lower values of observed and expected heterozygosity, as well as a moderately reduced number of alleles and genotypes in three of the five observed loci. Although with a clear trend of decline, the level of genetic diversity is still sufficient to ensure the subsistence of the population if the stressors are removed. Otherwise, the loss of heterozygosity will continue, possibly to the point of a complete eradication of the Dalmatian barbelgudgeon from the Buško Blato reservoir.