Diversity and Novelty of Venom Peptides in Vermivorous Cone Snails, Subgenus (Gastropoda: Mollusca).

A large majority of cone snails (a species in the genus ) are vermivorous (worm-hunting), but the diversity and bioactivity of their venom peptides remain largely unexplored. In this study, we report the first venom gland transcriptomes from two species in the clade, and , and a new transcriptome from a specimen collected in the Philippines. From the set of assembled sequences, a total of 225 , 121 , and 168 putative peptide toxin transcripts were identified, which were assigned to 27 canonical gene superfamilies in and 24 in and in .

Reduced Parallel Gene Expression Evolution With Increasing Genetic Divergence-A Hallmark of Polygenic Adaptation.

Parallel evolution, the repeated evolution of similar traits in independent lineages, is a topic of considerable interest in evolutionary biology. Although previous studies have focused on the parallelism of phenotypic traits and their underlying genetic basis, the extent of parallelism at the level of gene expression across different levels of genetic divergence is not yet fully understood. This study investigates the evolution of gene expression in replicate Drosophila populations exposed to the same novel environment at three divergence levels: within a population, between populations and between species.

A high throughput method for egg size measurement in Drosophila.

Life-history traits are used as proxies of fitness in insects including Drosophila. Egg size is an adaptive and ecologically important trait potentially with genetic variation across different populations. However, the low throughput of manual measurement of egg size has hampered the widespread use of this trait in evolutionary biology and population genetics.

Author Correction: Polygenic adaptation: a unifying framework to understand positive selection.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Polygenic adaptation: a unifying framework to understand positive selection.

Most adaption processes have a polygenic genetic basis, but even with the recent explosive growth of genomic data we are still lacking a unified framework describing the dynamics of selected alleles. Building on recent theoretical and empirical work we introduce the concept of adaptive architecture, which extends the genetic architecture of an adaptive trait by factors influencing its adaptive potential and population genetic principles. Because adaptation can be typically achieved by many different combinations of adaptive alleles (redundancy), we describe how two characteristics - heterogeneity among loci and non-parallelism between replicated populations - are hallmarks for the characterization of polygenic adaptation in evolving populations.

Neuronal Function and Dopamine Signaling Evolve at High Temperature in Drosophila.

Neuronal activity is temperature sensitive and affects behavioral traits important for individual fitness, such as locomotion and courtship. Yet, we do not know enough about the evolutionary response of neuronal phenotypes in new temperature environments. Here, we use long-term experimental evolution of Drosophila simulans populations exposed to novel temperature regimes.

Distinct Patterns of Selective Sweep and Polygenic Adaptation in Evolve and Resequence Studies.

In molecular population genetics, adaptation is typically thought to occur via selective sweeps, where targets of selection have independent effects on the phenotype and rise to fixation, whereas in quantitative genetics, many loci contribute to the phenotype and subtle frequency changes occur at many loci during polygenic adaptation. The sweep model makes specific predictions about frequency changes of beneficial alleles and many test statistics have been developed to detect such selection signatures. Despite polygenic adaptation is probably the prevalent mode of adaptation, because of the traditional focus on the phenotype, we are lacking a solid understanding of the similarities and differences of selection signatures under the two models.

Rapid sex-specific adaptation to high temperature in .

The pervasive occurrence of sexual dimorphism demonstrates different adaptive strategies of males and females. While different reproductive strategies of the two sexes are well-characterized, very little is known about differential functional requirements of males and females in their natural habitats. Here, we study the impact environmental change on the selection response in both sexes.

Shifting the paradigm in Evolve and Resequence studies: From analysis of single nucleotide polymorphisms to selected haplotype blocks.

For almost a decade the combination of whole genome sequencing with experimental evolution (Evolve and Resequence, E&R; Turner, Stewart, Fields, Rice, & Tarone, ) has been used to study adaptation in outcrossing organisms. However, complications caused by inversions and hitchhiking variants have prevented this powerful approach from living up to its potential. In this issue of Molecular Ecology, Michalak, Kang, Schou, Garner, and Loeschke (), provide an important step ahead by using a population of Drosophila melanogaster devoid of segregating inversions to identify the genetic basis of resistance to five environmental stressors.

Genetic redundancy fuels polygenic adaptation in Drosophila.

The genetic architecture of adaptive traits is of key importance to predict evolutionary responses. Most adaptive traits are polygenic-i.e.

A 24 h Age Difference Causes Twice as Much Gene Expression Divergence as 100 Generations of Adaptation to a Novel Environment.

Gene expression profiling is one of the most reliable high-throughput phenotyping methods, allowing researchers to quantify the transcript abundance of expressed genes. Because many biotic and abiotic factors influence gene expression, it is recommended to control them as tightly as possible. Here, we show that a 24 h age difference of females that were subjected to RNA sequencing (RNA-Seq) five and six days after eclosure resulted in more than 2000 differentially expressed genes.

High-throughput fecundity measurements in Drosophila.

Fecundity is probably the most frequently studied fitness component in Drosophila. Nevertheless, currently used methods to measure fecundity are not well-suited for large-scale experiments, with many populations being assayed in parallel. Here we present a standardized pipeline to measure fecundity in many Drosophila population samples with substantially reduced hand on times.

: A Species with Improved Resolution in Evolve and Resequence Studies.

The combination of experimental evolution with high-throughput sequencing of pooled individuals-, evolve and resequence (E&R)-is a powerful approach to study adaptation from standing genetic variation under controlled, replicated conditions. Nevertheless, E&R studies in have frequently resulted in inordinate numbers of candidate SNPs, particularly for complex traits. Here, we contrast the genomic signature of adaptation following ∼60 generations in a novel hot environment for and For , the regions carrying putatively selected loci were far more distinct, and thus harbored fewer false positives, than those in We propose that species without segregating inversions and higher recombination rates, such as , are better suited for E&R studies that aim to characterize the genetic variants underlying the adaptive response.

Characterization of the complete mitochondrial genome of Conus tribblei Walls, 1977.

The genus Conus sensu lato consists of 500-700 species. However, the mitochondrial genomes of only few species have been fully sequenced and reported so far. In this study, the complete mitochondrial genome of Conus tribblei, a member of the poorly known subgenus Splinoconus is sequenced with the mean coverage of 604×.

Structural features of conopeptide genes inferred from partial sequences of the Conus tribblei genome.

The evolvability of venom components (in particular, the gene-encoded peptide toxins) in venomous species serves as an adaptive strategy allowing them to target new prey types or respond to changes in the prey field. The structure, organization, and expression of the venom peptide genes may provide insights into the molecular mechanisms that drive the evolution of such genes. Conus is a particularly interesting group given the high chemical diversity of their venom peptides, and the rapid evolution of the conopeptide-encoding genes.

Comparison of the Venom Peptides and Their Expression in Closely Related Conus Species: Insights into Adaptive Post-speciation Evolution of Conus Exogenomes.

Genes that encode products with exogenous targets, which comprise an organism's "exogenome," typically exhibit high rates of evolution. The genes encoding the venom peptides (conotoxins or conopeptides) in Conus sensu lato exemplify this class of genes. Their rapid diversification has been established and is believed to be linked to the high speciation rate in this genus.

High conopeptide diversity in Conus tribblei revealed through analysis of venom duct transcriptome using two high-throughput sequencing platforms.

The venom of each species of Conus contains different kinds of pharmacologically active peptides which are mostly unique to that species. Collectively, the ~500-700 species of Conus produce a large number of these peptides, perhaps exceeding 140,000 different types in total. To date, however, only a small fraction of this diversity has been characterized via transcriptome sequencing.