Genetic Mixing Research Articles

Searchlight trapping reveals seasonal cross-ocean migration of fall armyworm over the South China Sea

The fall armyworm (FAW), Spodoptera frugiperda, is a migratory noctuid pest that has recently invaded eastern Asia. From 2017 up till 2020, searchlight trapping was used to assess the extent of FAW migration across the South China Sea. Molecular and morphology-based identification confirmed that FAW made its first appearance on Yongxing Island on 11 April 2019, with most trapped individuals belonging to the S. frugiperda “corn-strain”. Carbon isotope analysis further showed that FAW moths originated from C4 host plants, while trajectory analyses revealed that migratory S. frugiperda adults are able to cross the South China Sea and enter mainland China. This long-distance migration process plausibly results in frequent genetic mixing between domestic FAW populations and those of neighboring Southeast Asian countries. Overall, this work provides unique insights into FAW migration across eastern Asia and ultimately can help advance pest forecasting, risk assessment and area-wide pest management.

A continuum of genetic mixing for conservation management along the (mal)adaptation spectrum: A comment on Hoffmann et al.

When restoring gene flow for conservation management, genetic variation should be viewed along a continuum of genetic divergence between donor and recipient populations. On the one hand, maintaining local adaptation (low divergence between donors and recipients) can enhance conservation success in the short term. On the other hand, reducing local adaptation in the short term by increasing genetic diversity (high divergence between some donors and recipients) might have better long‐term success in the face of changing environmental conditions. Both Hoffman et al. (2020) and a paper we previously published in a Special Issue on Maladaptation in Applied Conservation (Derry et al., 2019) provide frameworks and syntheses for how best to apply conservation strategies in light of genetic variation and adaptation. A key difference between these two studies was that whereas Derry et al. (2019) performed a quantitative meta‐analysis, Hoffman et al. (2020) relied on case studies and theoretical considerations, yielding slightly different conclusions. We here provide a summary of the two studies and contrast of the main similarities and differences between them, while highlighting terminology used to describe and explain main concepts.

Hamilton’s rule, gradual evolution, and the optimal (feedback) control of phenotypically plastic traits

Most traits expressed by organisms, such as gene expression profiles, developmental trajectories, behavioural sequences and reaction norms are function-valued traits (colloquially “phenotypically plastic traits”), since they vary across an individual’s age and in response to various internal and/or external factors (state variables). Furthermore, most organisms live in populations subject to limited genetic mixing and are thus likely to interact with their relatives. We here formalise selection on genetically determined function-valued traits of individuals interacting in a group-structured population, by deriving the marginal version of Hamilton’s rule for function-valued traits. This rule simultaneously gives a condition for the invasion of an initially rare mutant function-valued trait and its ultimate fixation in the population (invasion thus implies substitution). Hamilton’s rule thus underlies the gradual evolution of function-valued traits and gives rise to necessary first-order conditions for their uninvadability (evolutionary stability). We develop a novel analysis using optimal control theory and differential game theory, to simultaneously characterise and compare the first-order conditions of (i) open-loop traits – functions of time (or age) only, and (ii) closed-loop (state-feedback) traits – functions of both time and state variables. We show that closed-loop traits can be represented as the simpler open-loop traits when individuals do not interact or when they interact with clonal relatives. Our analysis delineates the role of state-dependence and interdependence between individuals for trait evolution, which has implications to both life-history theory and social evolution.

Modern Tendencies In The Ethnic Relations Of Kuramas

The article highlights the issues, such as Kurama ethnicity ( or “ethnic group of Kuramas”), which is involved in the Uzbek nation, its ethnic composition, the identity sense of the Kuramas in terms of unity of the people, the attitude to the Uzbek national unity and transformational processes. Corresponding issues are presented as material for ongoing scientific analysis based on field materials and, where appropriate, scientific and popular literature data. The core meaning of the term “kurama” is explined by the fact that this ethnic group is of the polycomponent. To be specific, it is feasable to promote the idea that the genetic composition of Kuramas has a common root with Karluk, Kipchak and Oguz ethnicities, since the period of Turkish commonality. Subsequently, after the end of the Turkish commonality and the formation of independent Turkic fraternal nations, the ethnic union of the Uzbek, Turkmen, Kyrgyz and Kazakh peoples began in Central Asia. In particular, the main core of the Uzbek nation began with the Karluk branch, while the Uyghur ethnos grew in the same process with the Uzbek ethnic genesis, and the subsequent stages of development in the border areas were independent. However, the bond of historical ties between the two branches has not been ripped up. The article also analyses the issues of genetic memory of Kuramin residents of different villages along the streams of mountain and rivers. Thus, a survey conducted among the residents of Lashkarak Sai shows that the older generation practically began to forget the tribal origins of not only individual families, but also the entire group of residents of the compact community of the village. As for the inhabitants of Ertashsay, which originates from the Karakush peak, dividing the Tianshan mountain ranges into Chatkal and Kurama, they partly associate themselves with the traditional 92 Uzbek tribes. However, this information of Ertashsay residents is contraindicated for data on the genetic mixing of the Kuramis, consisting of Uzbek-Kazakh-Kyrgyz components. Our observations on the formation of the names of certain groups of Kuramins are interesting. Thus, the inhabitants of a number of villages, who have retained the memory of family ties in the past, are now known by various nicknames given to them from other villages. For example, Ezma top (chatty), Kal topi (bald), Zhanghirok topi (bells), Pulat topi (steelworkers), Toq topi (fed), etc. In addition, some groups of Kuraminians got their names from their place of residence: Kuramin residents Kurboz, Badrangi, Chelenovul, Ajir ovul, Samguron ovul, Guldirama soy, Kara kishlak, Soyogzi, etc. In general, in the ethno-cultural situation of the Kuramin people, there is a gradual tendency to smooth out the previously stable traditional forms of life, social relations and purely Kuramin rituals and customs, which merge with the general Uzbek ones, since the Kuramin people mostly identify themselves as Uzbeks.

Seed Shadows of Northern Pigtailed Macaques within a Degraded Forest Fragment, Thailand

Research Highlights: Frugivores able to disperse large seeds over large distances are indispensable for seedling recruitment, colonization and regeneration of tropical forests. Understanding their effectiveness as seed dispersal agents in degraded habitat is becoming a pressing issue because of escalating anthropogenic disturbance. Although of paramount importance in the matter, animal behaviour’s influence on seed shadows (i.e., seed deposition pattern of a plant population) is difficult to evaluate by direct observations. Background and Objectives: We illustrated a modeling approach of seed shadows incorporating field-collected data on a troop of northern pigtailed macaques (Macaca leonina) inhabiting a degraded forest fragment in Thailand, by implementing a mechanistic model of seed deposition with random components. Materials and Methods: We parameterized the mechanistic model of seed deposition with macaque feeding behavior (i.e., consumed fruit species, seed treatments), gut and cheek pouch retention time, location of feeding and sleeping sites, monthly photoperiod and movement patterns based on monthly native fruit availability using Hidden Markov models (HMM). Results: We found that northern pigtailed macaques dispersed at least 5.5% of the seeds into plantation forests, with a majority of medium- to large-seeded species across large distances (mean > 500 m, maximum range of 2300 m), promoting genetic mixing and colonization of plantation forests. Additionally, the macaques produced complementary seed shadows, with a sparse distribution of seeds spat out locally (mean >50 m, maximum range of 870 m) that probably ensures seedling recruitment of the immediate plant populations. Conclusions: Macaques’ large dispersal distance reliability is often underestimated and overlooked; however, their behavioral flexibility places them among the last remaining dispersers of large seeds in disturbed habitats. Our study shows that this taxon is likely to maintain significant seed dispersal services and promote forest regeneration in degraded forest fragments.

Genetic mixing for population management: From genetic rescue to provenancing.

Animal and plant species around the world are being challenged by the deleterious effects of inbreeding, loss of genetic diversity, and maladaptation due to widespread habitat destruction and rapid climate change. In many cases, interventions will likely be needed to safeguard populations and species and to maintain functioning ecosystems. Strategies aimed at initiating, reinstating, or enhancing patterns of gene flow via the deliberate movement of genotypes around the environment are generating growing interest with broad applications in conservation and environmental management. These diverse strategies go by various names ranging from genetic or evolutionary rescue to provenancing and genetic resurrection. Our aim here is to provide some clarification around terminology and to how these strategies are connected and linked to underlying genetic processes. We draw on case studies from the literature and outline mechanisms that underlie how the various strategies aim to increase species fitness and impact the wider community. We argue that understanding mechanisms leading to species decline and community impact is a key to successful implementation of these strategies. We emphasize the need to consider the nature of source and recipient populations, as well as associated risks and trade‐offs for the various strategies. This overview highlights where strategies are likely to have potential at population, species, and ecosystem scales, but also where they should probably not be attempted depending on the overall aims of the intervention. We advocate an approach where short‐ and long‐term strategies are integrated into a decision framework that also considers nongenetic aspects of management.

Complementarity increases production in genetic mixture of loblolly pine (Pinus taeda L.) throughout planted range

AbstractIncreased genotypic diversity has been associated with increased biomass production in short‐rotation tree species. Increasing the genotypic diversity of loblolly pine (Pinus taeda L.) in an attempt to increase productivity has not been extensively studied nor tested operationally or over long durations (i.e., >7 yr). We used genetically mixed and pure rows of loblolly pine growing throughout its planted range—Virginia, North Carolina, and Brazil—to test the effects of genetic mixing on volume production. There were no significant effects of mixing rows compared to pure rows on uniformity or mortality. Under intensive silviculture, individual trees planted in mixed rows had approximately 7% greater volume than those in the pure rows (estimate = 0.015 m3/tree ± 0.006) in the final year of measurement—year 8 for Brazil and year 10 for North Carolina and Virginia. Scaling the increase in individual stem volume under mixed rows and intensive silviculture to 1235 stems ha−1 would equate to an additional 1.85 m3·ha−1·yr−1 in mean annual increment. Measuring the net biodiversity effect, our data suggest the positive growth response is driven by complementarity and not selection, meaning both genetic entries tend to grow larger when grown together. Additional trials are necessary to test the effects of mixing rows across large plots and to assess whether this increase is sustained throughout the rotation. If this increasing trend were to hold for intensively managed plantations, strategically mixing rows to increase productivity could be a valuable addition to an intensively managed plantation requiring relatively little added operational consideration to implement.

Post-release genetic assessment of two congeneric weed biological control agents

Introductions of biological control agents are unique field experiments to examine the response of novel organisms to new environments. Post-release monitoring is particularly challenging where closely related and morphologically similar biological control agents have been released. Two closely-related phytophagous weevils, Larinus minutus and L. obtusus, were introduced as biological control agents for two major rangeland weeds, diffuse knapweed, Centaurea diffusa and spotted knapweed, C. stoebe subsp. micranthos in North America. The release of the Larinus species coincided with a decline in C. diffusa abundance in many areas. However, it was not clear whether both species of Larinus had become established as they are morphologically very similar. We asked: (1) Could genetic markers be used to identify both the weevil species? (2) Do both weevil species attack both knapweed species in Canada? (3) Are the levels of genetic diversity of the introduced populations of the weevils similar to those of a European source population? (4) Is genetic mixing between the weevil species occurring? Both microsatellite and CO1 mtDNA markers distinguish between the two weevil species. Larinus obtusus was only found on spotted knapweed, while L. minutus was more widely distributed and attacked both weed species. The relatively large initial introductions of weevils to British Columbia (4,300 L. minutus and 5,500 L. obtusus) together with rapid population growth and frequent redistribution among sites has been sufficient to maintain levels of genetic diversity. Results from small samples showed that haplotype, nucleotide diversity and allelic richness of the introduced populations were comparable to those of a European population. We found no evidence for hybridization in the introduced populations.

The Pattern of Genetic Variation, Survival and Growth in the Abies alba Mill. Population within the Introgression Zone of Two Refugial Lineages in the Carpathians

Background and Objectives: The contact zones of different refugial lineages, where mixing of genetic backgrounds leads to new gene combinations or pre-adaptations, represent hotspots of genetic diversity. The aim of the study was to compare patterns in the genetic structure of the Abies alba Mill. population in the Eastern and Western Carpathians (Eastern Europe) within the introgression zone of two refugial lineages and the growth response of provenances located in a gradient of pollen-mediated gene fluxes. Materials and Methods: The mitochondrial nad5-4 marker and five polymorphic microsatellite nuclear markers (nSSR) were analyzed in 56 subpopulations from Romania, Ukraine, Slovakia and Poland. The survival rate and height growth up to an age of 15 years were compared for 33 subpopulations, forming a distance gradient between 170 and 470 km from the meeting zone of the refugial lineages. Results: The results of the analysis of molecular variance indicated that 8.2% of the total genetic variation is attributable to the between-subpopulation level and 1.7% to the between-lineage level. The pollen-mediated influence of the eastern lineage was detectable at a distance of at least 300 km in the western direction. Eastern provenances with origin sites closer to the meeting zone of the refugial lineages were characterized by lower survival rate and lower heights (about 8% lower than the average tree height) compared to subpopulations from the central and western part of the studied region. Conclusions: Pollen-mediated gene flow between lineages appears to have been sufficient to cause a significant change in phenotypic traits related to tree growth. Subpopulations from the central and western parts of the studied region are better adapted to current climatic conditions. Nonetheless, given the increasing aridity of the regional climate, a safe guideline is to increase genetic mixing.

Abstracts of the 1st Webinar of the SFDP (17 November 2020)

Research Highlights: Frugivores able to disperse large seeds over large distances are indispensable for seedling recruitment, colonization and regeneration of tropical forests. Understanding their effectiveness as seed dispersal agents in degraded habitat is becoming a pressing issue because of escalating anthropogenic disturbance. Although of paramount importance in the matter, animal behaviour’s influence on seed shadows (i.e., seed deposition pattern of a plant population) is difficult to evaluate by direct observations. Background and Objectives: We illustrated a modeling approach of seed shadows incorporating field-collected data on a troop of northern pigtailed macaques (Macaca leonina) inhabiting a degraded forest fragment in Thailand, by implementing a mechanistic model of seed deposition with random components. Materials and Methods: We parameterized the mechanistic model of seed deposition with macaque feeding behavior (i.e., consumed fruit species, seed treatments), gut and cheek pouch retention time, location of feeding and sleeping sites, monthly photoperiod and movement patterns based on monthly native fruit availability using Hidden Markov models (HMM). Results: We found that northern pigtailed macaques dispersed at least 5.5% of the seeds into plantation forests, with a majority of medium- to large-seeded species across large distances (mean > 500 m, maximum range of 2300 m), promoting genetic mixing and colonization of plantation forests. Additionally, the macaques produced complementary seed shadows, with a sparse distribution of seeds spat out locally (mean >50 m, maximum range of 870 m) that probably ensures seedling recruitment of the immediate plant populations. Conclusions: Macaques’ large dispersal distance reliability is often underestimated and overlooked; however, their behavioral flexibility places them among the last remaining dispersers of large seeds in disturbed habitats. Our study shows that this taxon is likely to maintain significant seed dispersal services and promote forest regeneration in degraded forest fragments.

Bayi Tabung Dalam Tinjauan Hukum Islam (Analisis Maqashid Syari’ah)

<p><em>In every era, there are always social phenomena that arise, and Islamic law has covered and answered them for their legal position. One of the examples of the phenomena is IVF (In Vitro Fertilization), which is an artificial insemination as a shortcut to get children by bringing together sperm cells and egg cells outside the body which are then inserted into the mother's womb, so they can grow into a fetus as usual pregnancy. In this IVF process, there are likely to be 5 parties involved, namely: husband, wife, sperm donor, ovum donor and uterine mother. If there is a third party besides wife and husband involved in the process of IVF, there will be indications of genetic mixing in the fetus.</em></p><p><em>IVF with a system without any third party involvement (sperm and ovum from husband and wife) by transferring into the womb of the wife is permissible and the baby is the descendant of his parents. However, if there is involvement of a third party, it is prohibited. IVF In the concept of Maqashid Shari'ah is one of the media that contributes in realizing 1. Hifdzu ad-din (protecting religion), 2. Hifdzu an-nafs (protecting souls), 3. Hifdzu al-aql (protecting the mind), 4. Hifdzu al-mal (protecting property), 5. Hifdzu an-nasab (protecting descendants). However, IVF is more dominant and looks more transparent in the aspect of Hifdzu an-nasab (protecting desdendants).</em></p>

Antagonistic species interaction drives selection for sex in a predator-prey system.

The evolutionary maintenance of sexual reproduction has long challenged biologists as the majority of species reproduce sexually despite inherent costs. Providing a general explanation for the evolutionary success of sex has thus proven difficult and resulted in numerous hypotheses. A leading hypothesis suggests that antagonistic species interaction can generate conditions selecting for increased sex due to the production of rare or novel genotypes that are beneficial for rapid adaptation to recurrent environmental change brought on by antagonism. To test this ecology-based hypothesis, we conducted experimental evolution in a predator (rotifer)-prey (algal) system by using continuous cultures to track predator-prey dynamics and in situ rates of sex in the prey over time and within replicated experimental populations. Overall, we found that predator-mediated fluctuating selection for competitive versus defended prey resulted in higher rates of genetic mixing in the prey. More specifically, our results showed that fluctuating population sizes of predator and prey, coupled with a trade-off in the prey, drove the sort of recurrent environmental change that could provide a benefit to sex in the prey, despite inherent costs. We end with a discussion of potential population genetic mechanisms underlying increased selection for sex in this system, based on our application of a general theoretical framework for measuring the effects of sex over time, and interpreting how these effects can lead to inferences about the conditions selecting for or against sexual reproduction in a system with antagonistic species interaction.

Puzzling out plant reproduction by haploid induction for innovations in plant breeding.

Mixing maternal and paternal genomes in embryos is not only responsible for the evolutionary success of sexual reproduction, but is also a cornerstone of plant breeding. However, once an interesting gene combination is obtained, further genetic mixing is problematic. To rapidly fix genetic information, doubled haploid plants can be produced: haploid embryos having solely the genetic information from one parent are allowed to develop, and chromosome doubling generates fully homozygous plants. A powerful path to the production of doubled haploids is based on haploid inducer lines. A simple cross between a haploid inducer line and the line with gene combinations to be fixed will trigger haploid embryo development. However, the exact mechanism behind in planta haploid induction remains an enduring mystery. The recent discoveries of molecular actors triggering haploid induction in the maize crop and the model Arabidopsis thaliana pinpoint an essential role of processes related to gamete development, gamete interactions and genome stability. These findings enabled translation of haploid induction capacity to other crops as well as the use of haploid inducer lines to deliver genome editing machinery into various crop varieties. These recent advances not only hold promise for the next generations of plant breeding strategies, but they also provide a deeper insight into the fundamental bases of sexual reproduction in plants.

In silico bacteria evolve robust cooperation via complex quorum-sensing strategies

Many species of bacteria collectively sense and respond to their social and physical environment via ‘quorum sensing’ (QS), a communication system controlling extracellular cooperative traits. Despite detailed understanding of the mechanisms of signal production and response, there remains considerable debate over the functional role(s) of QS: in short, what is it for? Experimental studies have found support for diverse functional roles: density sensing, mass-transfer sensing, genotype sensing, etc. While consistent with theory, these results cannot separate whether these functions were drivers of QS adaption, or simply artifacts or ‘spandrels’ of systems shaped by distinct ecological pressures. The challenge of separating spandrels from drivers of adaptation is particularly hard to address using extant bacterial species with poorly understood current ecologies (let alone their ecological histories). To understand the relationship between defined ecological challenges and trajectories of QS evolution, we used an agent-based simulation modeling approach. Given genetic mixing, our simulations produce behaviors that recapitulate features of diverse microbial QS systems, including coercive (high signal/low response) and generalized reciprocity (signal auto-regulation) strategists — that separately and in combination contribute to QS-dependent resilience of QS-controlled cooperation in the face of diverse cheats. We contrast our in silico results given defined ecological challenges with bacterial QS architectures that have evolved under largely unknown ecological contexts, highlighting the critical role of genetic constraints in shaping the shorter term (experimental evolution) dynamics of QS. More broadly, we see experimental evolution of digital organisms as a complementary tool in the search to understand the emergence of complex QS architectures and functions.

Orchid conservation: from theory to practice.

Given the exceptional diversity of orchids (26 000+ species), improving strategies for the conservation of orchids will benefit a vast number of taxa. Furthermore, with rapidly increasing numbers of endangered orchids and low success rates in orchid conservation translocation programmes worldwide, it is evident that our progress in understanding the biology of orchids is not yet translating into widespread effective conservation. We highlight unusual aspects of the reproductive biology of orchids that can have important consequences for conservation programmes, such as specialization of pollination systems, low fruit set but high seed production, and the potential for long-distance seed dispersal. Further, we discuss the importance of their reliance on mycorrhizal fungi for germination, including quantifying the incidence of specialized versus generalized mycorrhizal associations in orchids. In light of leading conservation theory and the biology of orchids, we provide recommendations for improving population management and translocation programmes. Major gains in orchid conservation can be achieved by incorporating knowledge of ecological interactions, for both generalist and specialist species. For example, habitat management can be tailored to maintain pollinator populations and conservation translocation sites selected based on confirmed availability of pollinators. Similarly, use of efficacious mycorrhizal fungi in propagation will increase the value of ex situ collections and likely increase the success of conservation translocations. Given the low genetic differentiation between populations of many orchids, experimental genetic mixing is an option to increase fitness of small populations, although caution is needed where cytotypes or floral ecotypes are present. Combining demographic data and field experiments will provide knowledge to enhance management and translocation success. Finally, high per-fruit fecundity means that orchids offer powerful but overlooked opportunities to propagate plants for experiments aimed at improving conservation outcomes. Given the predictions of ongoing environmental change, experimental approaches also offer effective ways to build more resilient populations.

Global Transmission, Spatial Segregation, and Recombination Determine the Long-Term Evolution and Epidemiology of Bovine Coronaviruses.

Bovine coronavirus (BCoV) is widespread in cattle and wild ruminant populations throughout the world. The virus causes neonatal calf diarrhea and winter dysentery in adult cattle, as well as upper and lower respiratory tract infection in young cattle. We isolated and deep sequenced whole genomes of BCoV from calves with respiratory distress in the south–west of France and conducted a comparative genome analysis using globally collected BCoV sequences to provide insights into the genomic characteristics, evolutionary origins, and global diversity of BCoV. Molecular clock analyses allowed us to estimate that the BCoV ancestor emerged in the 1940s, and that two geographically distinct lineages diverged from the 1960s–1970s. A recombination event in the spike gene (breakpoint at nt 1100) may be at the origin of the genetic divergence sixty years ago. Little evidence of genetic mixing between the spatially segregated lineages was found, suggesting that BCoV genetic diversity is a result of a global transmission pathway that occurred during the last century. However, we found variation in evolution rates between the European and non-European lineages indicating differences in virus ecology.

Bacterial Transformation Buffers Environmental Fluctuations through the Reversible Integration of Mobile Genetic Elements.

Horizontal gene transfer (HGT) promotes the spread of genes within bacterial communities. Among the HGT mechanisms, natural transformation stands out as being encoded by the bacterial core genome. Natural transformation is often viewed as a way to acquire new genes and to generate genetic mixing within bacterial populations. Another recently proposed function is the curing of bacterial genomes of their infectious parasitic mobile genetic elements (MGEs). Here, we propose that these seemingly opposing theoretical points of view can be unified. Although costly for bacterial cells, MGEs can carry functions that are at points in time beneficial to bacteria under stressful conditions (e.g., antibiotic resistance genes). Using computational modeling, we show that, in stochastic environments, an intermediate transformation rate maximizes bacterial fitness by allowing the reversible integration of MGEs carrying resistance genes, although these MGEs are costly for host cell replication. Based on this dual function (MGE acquisition and removal), transformation would be a key mechanism for stabilizing the bacterial genome in the long term, and this would explain its striking conservation.IMPORTANCE Natural transformation is the acquisition, controlled by bacteria, of extracellular DNA and is one of the most common mechanisms of horizontal gene transfer, promoting the spread of resistance genes. However, its evolutionary function remains elusive, and two main roles have been proposed: (i) the new gene acquisition and genetic mixing within bacterial populations and (ii) the removal of infectious parasitic mobile genetic elements (MGEs). While the first one promotes genetic diversification, the other one promotes the removal of foreign DNA and thus genome stability, making these two functions apparently antagonistic. Using a computational model, we show that intermediate transformation rates, commonly observed in bacteria, allow the acquisition then removal of MGEs. The transient acquisition of costly MGEs with resistance genes maximizes bacterial fitness in environments with stochastic stress exposure. Thus, transformation would ensure both a strong dynamic of the bacterial genome in the short term and its long-term stabilization.

The Genetic Differentiation of Common Toads on UK Farmland: The Effect of Straight-Line (Euclidean) Distance and Isolation by Barriers in a Heterogeneous Environment

Genetic differentiation plays an integral role in species persistence. However, it remains challenging to quantify the ways in which the degree of isolation affects animal populations. The Common Toad (Bufo bufo) is a species of conservation concern, particularly in the UK, where populations have undergone large-scale declines. There are two types of isolation that are relevant to toad population persistence. These are: 1) isolation by distance (IBD), where populations that are further apart become more isolated with time; and 2) isolation by barrier (IBB), where the presence of barriers to movement can isolate populations. Both IBB and IBD are relevant to Common Toad survival, and thus conservation, in fragmented landscapes typical of farmlands. We collected Common Toad genetic material from eight different breeding ponds amongst the rural farmland landscapes of Oxfordshire, England to test the effect of IBD and IBB on toad genetic differentiation. We detected no significant effect of IBD (range 2–22 km between breeding ponds) on Common Toad genetic differentiation at this scale. We did, however, identify a significant and positive relationship between IBB and Common Toad genetic differentiation. Breeding populations were more genetically different with increasing barrier distance. The lack of a relationship between IBD and toad genetic differentiation could suggest that Common Toads are not as philopatric as previously thought, with reduced availability of suitable breeding ponds possibly driving more migrants to disperse greater distances and thereby possibly improving genetic mixing of the metapopulation.

DNA is the key to unlocking our ancient African past

Each region of the world, and the human groups living in them, have unique histories of migration, genetic mixing (admixture) and adaptation that have shaped their past. While archaeology has been of extreme value in elucidating this complex, multifaceted past, the genesis of DNA studies has enriched their story, and now ancient DNA (aDNA) has helped answer even more questions surrounding our prehistory. aDNA offers a unique opportunity to access genetic variation of past populations and enables us to contextualize past populations in present-day genetic variation. By linking the past to the present in this way, we now have a deeper understanding of our prehistory, and how our genetic landscape has changed from the past to the present. However, the study of aDNA is complex and there are various factors that need to be considered to yield successful aDNA results.

Designing Innovative Management for Cultivated Biodiversity: Lessons from a Pioneering Collaboration between French Farmers, Facilitators and Researchers around Participatory Bread Wheat Breeding

The industrialization of farming has significantly threatened cultivated biodiversity. Participatory breeding endeavours to overcome this issue by enabling farmers to select a wide range of crop varieties in different conditions, and to foster genetic mixing through seed exchanges, crosses or mixtures. This necessitates the design of new forms of coordination and organization for the farmers and partners involved. This article reports on an ongoing initiative, aiming to facilitate the participatory design of such forms of coordination and organization. It first outlines the method used (Knowledge–Concept–Proposals or KCP), and how it has been tailored to this highly decentralized context involving politically engaged actors on a quest for autonomy. It then presents the exploratory results of the first two workshops: these include group consolidation, the sharing of heterogeneous knowledge, the generation of innovative ideas, and the elaboration of preliminary projects. Finally, this empirical case is compared with other initiatives supporting the participatory design of natural resource management strategies and tools. Its key original dimensions and benefits are that the workshop protocol is replicable, the data produced can be easily exploited, and it allows for testing hypotheses in the field of design science.