Integration of genomic and ecological methods inform management of an undescribed, yet highly exploited, sardine species.

Assessing genetic diversity within species is key for conservation strategies in the context of human-induced biotic changes. This is important in marine systems, where many species remain undescribed while being overfished, and conflicts between resource-users and conservation agencies are common. Combining niche modelling with population genomics can contribute to resolving those conflicts by identifying management units and understanding how past climatic cycles resulted in current patterns of genetic diversity.

Assessment of Wild Rocket ( (L.) DC.) Germplasm Accessions by NGS Identified SSR and SNP Markers.

Rocket is the common designation for two baby-leaf salad crops of the Brassicaceae family: Eruca sativa (L.) Cav., usually referred to as annual garden rocket, and Diplotaxis tenuifolia (L.

Out of Asia? Expansion of Eurasian Lyme borreliosis causing genospecies display unique evolutionary trajectories.

Vector-borne pathogens exist in obligate transmission cycles between vector and reservoir host species. Host and vector shifts can lead to geographic expansion of infectious agents and the emergence of new diseases in susceptible individuals. Three bacterial genospecies (Borrelia afzelii, Borrelia bavariensis, and Borrelia garinii) predominantly utilize two distinct tick species as vectors in Asia (Ixodes persulcatus) and Europe (Ixodes ricinus).

Extensive introgression at late stages of species formation: Insights from grasshopper hybrid zones.

The process of species formation is characterized by the accumulation of multiple reproductive barriers. The evolution of hybrid male sterility, or Haldane's rule, typically characterizes later stages of species formation, when reproductive isolation is strongest. Yet, understanding how quickly reproductive barriers evolve and their consequences for maintaining genetic boundaries between emerging species remains a challenging task because it requires studying taxa that hybridize in nature.

Transcriptomic data reveals nuclear-mitochondrial discordance in Gomphocerinae grasshoppers (Insecta: Orthoptera: Acrididae).

The phylogeny of many groups of Orthoptera remains poorly understood. Previous phylogenetic studies largely restricted to few mitochondrial markers found many species in the grasshopper subfamily Gomphocerinae to be para- or polyphyletic, presumably because of incomplete lineage sorting and ongoing hybridization between putatively young lineages. Resolving the phylogeny of the Chorthippus biguttulus species complex is important because many morphologically cryptic species occupy overlapping ranges across Eurasia and serve important ecological functions.

A lizard with two tales: What diversification within Sceloporus occidentalis teaches us about species formation.

In 1859, Charles Darwin proposed that species are not fundamentally different from subspecies or the varieties from which they evolve. A century later, Dobzhansky (1958) suggested that many such lineages are ephemeral and are likely to reverse differentiation through introgression (Figure 1a); only a few evolve complete reproductive isolation and persist in sympatry. In this issue of Molecular Ecology, Bouzid et al.

Genomic methods reveal independent demographic histories despite strong morphological conservatism in fish species.

Human overexploitation of natural resources has placed conservation and management as one of the most pressing challenges in modern societies, especially in regards to highly vulnerable marine ecosystems. In this context, cryptic species are particularly challenging to conserve because they are hard to distinguish based on morphology alone, and thus it is often unclear how many species coexist in sympatry, what are their phylogenetic relationships and their demographic history. We answer these questions using morphologically similar species of the genus Mugil that are sympatric in the largest coastal Marine Protected Area in the Tropical Southwestern Atlantic marine province.

Recovery from hybrid breakdown reveals a complex genetic architecture of mitonuclear incompatibilities.

Reproductive isolation is often achieved when genes that are neutral or beneficial in their genomic background become functionally incompatible in a foreign genomic background, causing inviability, sterility or other forms of low fitness in hybrids. Recent studies suggest that mitonuclear interactions are among the initial incompatibilities to evolve at early stages of population divergence across taxa. Yet, the genomic architecture of mitonuclear incompatibilities has rarely been elucidated.

Historical isolation facilitates species radiation by sexual selection: Insights from Chorthippus grasshoppers.

Theoretical and empirical studies have shown that species radiations are facilitated when a trait under divergent natural selection is also involved in sexual selection. It is yet unclear how quick and effective radiations are where assortative mating is unrelated to the ecological environment and primarily results from sexual selection. We address this question using sympatric grasshopper species of the genus Chorthippus, which have evolved strong behavioural isolation while lacking noticeable ecomorphological divergence.

Adaptation to a latitudinal thermal gradient within a widespread copepod species: the contributions of genetic divergence and phenotypic plasticity.

Understanding how populations adapt to heterogeneous thermal regimes is essential for comprehending how latitudinal gradients in species diversification are formed, and how taxa will respond to ongoing climate change. Adaptation can occur by innate genetic factors, by phenotypic plasticity, or by a combination of both mechanisms. Yet, the relative contribution of such mechanisms to large-scale latitudinal gradients of thermal tolerance across conspecific populations remains unclear.

Population Structure of the Rockpool Blenny Entomacrodus vomerinus Shows Source-Sink Dynamics among Ecoregions in the Tropical Southwestern Atlantic.

The Tropical Southwestern Atlantic is characterized by prominent ecosystems with large-scale oceanographic complexity. Yet, the evolutionary processes underlying genetic differentiation and connectivity in this region remain largely unknown. Entomacrodus vomerinus (Valenciennes, 1836) is a demersal fish with planktonic larvae endemic to this marine province, inhabiting shallow tidal pools in continental and oceanic reef environments.

Next-generation biology: Sequencing and data analysis approaches for non-model organisms.

As sequencing technologies become more affordable, it is now realistic to propose studying the evolutionary history of virtually any organism on a genomic scale. However, when dealing with non-model organisms it is not always easy to choose the best approach given a specific biological question, a limited budget, and challenging sample material. Furthermore, although recent advances in technology offer unprecedented opportunities for research in non-model organisms, they also demand unprecedented awareness from the researcher regarding the assumptions and limitations of each method.

Transcriptome-wide patterns of divergence during allopatric evolution.

Recent studies have revealed repeated patterns of genomic divergence associated with species formation. Such patterns suggest that natural selection tends to target a set of available genes, but is also indicative that closely related taxa share evolutionary constraints that limit genetic variability. Studying patterns of genomic divergence among populations within the same species may shed light on the underlying evolutionary processes.

Hybridization during altitudinal range shifts: nuclear introgression leads to extensive cyto-nuclear discordance in the fire salamander.

Ecological models predict that, in the face of climate change, taxa occupying steep altitudinal gradients will shift their distributions, leading to the contraction or extinction of the high-elevation (cold-adapted) taxa. However, hybridization between ecomorphologically divergent taxa commonly occurs in nature and may lead to alternative evolutionary outcomes, such as genetic merger or gene flow at specific genes. We evaluate this hypothesis by studying patterns of divergence and gene flow across three replicate contact zones between high- and low-elevation ecomorphs of the fire salamander (Salamandra salamandra) that have experienced altitudinal range shifts over the current postglacial period.

Ring species as demonstrations of the continuum of species formation.

In the mid-20th century, Ernst Mayr (1942) and Theodosius Dobzhansky (1958) championed the significance of 'circular overlaps' or 'ring species' as the perfect demonstration of the gradual nature of species formation. As an ancestral species expands its range, wrapping around a geographic barrier, derived taxa within the ring display interactions typical of populations, such as genetic and morphological intergradation, while overlapping taxa at the terminus of the ring behave largely as sympatric, reproductively isolated species. Are ring species extremely rare or are they just difficult to detect? What conditions favour their formation? Modelling studies have attempted to address these knowledge gaps by estimating the biological parameters that result in stable ring species (Martins et al.

Hybrid dysfunction and physiological compensation in gene expression.

The formation of new species is often a consequence of genetic incompatibilities accumulated between populations during allopatric divergence. When divergent taxa interbreed, these incompatibilities impact physiology and have a direct cost resulting in reduced hybrid fitness. Recent surveys of gene regulation in interspecific hybrids have revealed anomalous expression across large proportions of the genome, with 30-70% of all genes exhibiting transgressive expression (i.

The genomic architecture of population divergence between subspecies of the European rabbit.

The analysis of introgression of genomic regions between divergent populations provides an excellent opportunity to determine the genetic basis of reproductive isolation during the early stages of speciation. However, hybridization and subsequent gene flow must be relatively common in order to localize individual loci that resist introgression. In this study, we used next-generation sequencing to study genome-wide patterns of genetic differentiation between two hybridizing subspecies of rabbits (Oryctolagus cuniculus algirus and O.

Hybridization at an ecotone: ecological and genetic barriers between three Iberian vipers.

The formation of stable genetic boundaries between emerging species is often diagnosed by reduced hybrid fitness relative to parental taxa. This reduced fitness can arise from endogenous and/or exogenous barriers to gene flow. Although detecting exogenous barriers in nature is difficult, we can estimate the role of ecological divergence in driving species boundaries by integrating molecular and ecological niche modelling tools.

Ecological novelty by hybridization: experimental evidence for increased thermal tolerance by transgressive segregation in Tigriopus californicus.

Early generations of hybrids can express both genetic incompatibilities and phenotypic novelty. Insights into whether these conflicting interactions between intrinsic and extrinsic selection persist after a few generations of recombination require experimental studies. To address this question, we use interpopulation crosses and recombinant inbred lines (RILs) of the copepod Tigriopus californicus, and focus on two traits that are relevant for the diversification of this species: survivorship during development and tolerance to thermal stress.

Conservation of avian germplasm by xenogeneic transplantation of spermatogonia from sexually mature donors.

Approximately 12.5% of all 9,920 extant bird species in the world are threatened with extinction, and yet conservation efforts through natural breeding of captive species continue to encounter difficulties. However, sperm cryopreservation and artificial insemination offer potential benefits over natural breeding, but their applicability is still limited in nondomestic species.

Ring distributions leading to species formation: a global topographic analysis of geographic barriers associated with ring species.

Background: In the mid 20th century, Ernst Mayr and Theodosius Dobzhansky championed the significance of circular overlaps or ring species as the perfect demonstration of speciation, yet in the over 50 years since, only a handful of such taxa are known. We developed a topographic model to evaluate whether the geographic barriers that favor processes leading to ring species are common or rare, and to predict where other candidate ring barriers might be found.

Results: Of the 952,147 geographic barriers identified on the planet, only about 1% are topographically similar to barriers associated with known ring taxa, with most of the likely candidates occurring in under-studied parts of the world (for example, marine environments, tropical latitudes).

RAD51 plays a crucial role in halting cell death program induced by ionizing radiation in bovine oocytes.

Reproductive health of humans and animals exposed to daily irradiants from solar/cosmic particles remains largely understudied. We evaluated the sensitivities of bovine and mouse oocytes to bombardment by krypton-78 (1 Gy) or ultraviolet B (UV-B; 100 microjoules). Mouse oocytes responded to irradiation by undergoing massive activation of caspases, rapid loss of energy without cytochrome-c release, and subsequent necrotic death.

Predictors for reproductive isolation in a ring species complex following genetic and ecological divergence.

Background: Reproductive isolation (RI) is widely accepted as an important "check point" in the diversification process, since it defines irreversible evolutionary trajectories. Much less consensus exists about the processes that might drive RI. Here, we employ a formal quantitative analysis of genetic interactions at several stages of divergence within the ring species complex Ensatina eschscholtzii in order to assess the relative contribution of genetic and ecological divergence for the development of RI.