Domestication Process Research Articles

Refining the evolutionary tree of the horse Y chromosome

The Y chromosome carries information about the demography of paternal lineages, and thus, can prove invaluable for retracing both the evolutionary trajectory of wild animals and the breeding history of domesticates. In horses, the Y chromosome shows a limited, but highly informative, sequence diversity, supporting the increasing breeding influence of Oriental lineages during the last 1500 years. Here, we augment the primary horse Y-phylogeny, which is currently mainly based on modern horse breeds of economic interest, with haplotypes (HT) segregating in remote horse populations around the world. We analyze target enriched sequencing data of 5 Mb of the Y chromosome from 76 domestic males, together with 89 whole genome sequenced domestic males and five Przewalski’s horses from previous studies. The resulting phylogeny comprises 153 HTs defined by 2966 variants and offers unprecedented resolution into the history of horse paternal lineages. It reveals the presence of a remarkable number of previously unknown haplogroups in Mongolian horses and insular populations. Phylogenetic placement of HTs retrieved from 163 archaeological specimens further indicates that most of the present-day Y-chromosomal variation evolved after the domestication process that started around 4200 years ago in the Western Eurasian steppes. Our comprehensive phylogeny significantly reduces ascertainment bias and constitutes a robust evolutionary framework for analyzing horse population dynamics and diversity.

Genetic differentiation following recent domestication events: A study of farmed Nile tilapia (Oreochromis niloticus) populations.

Nile tilapia (Oreochromis niloticus) is among the most farmed finfish worldwide, distributed across different environmental conditions. Its wide distribution has mainly been facilitated by several breeding programs and widespread dissemination of genetically improved strains. In the first Nile tilapia study exploiting a whole-genome pooled sequencing (Poolseq) approach, we identified the genetic structure and signatures of selection in diverse, farmed Nile tilapia populations, with a particular focus on the GIFT strain, developed in the 1980s, and currently managed by WorldFish (GIFTw). We also investigated important farmed strains from The Philippines and Africa. Using both SNP array data and Poolseq SNPs, we characterized the population structure of these samples. We observed the greatest separation between the Asian and African populations and greater admixture in the Asian populations than in the African ones. We also established that the SNP array data were able to successfully resolve relationships between these diverse Nile tilapia populations. The Poolseq data identified genomic regions with high levels of differentiation (F ST) between GIFTw and the other populations. Gene ontology terms associated with mesoderm development were significantly enriched in the genes located in these regions. A region on chromosome Oni06 was genetically differentiated in pairwise comparisons between GIFTw and all other populations. This region contains genes associated with muscle-related traits and overlaps with a previously published QTL for fillet yield, suggesting that these traits may have been direct targets for selection on GIFT. A nearby region was also identified using XP-EHH to detect genomic differentiation using the SNP array data. Genomic regions with high or extended homozygosity within each population were also identified. This study provides putative genomic landmarks associated with the recent domestication process in several Nile tilapia populations, which could help to inform their genetic management and improvement.

Comparative genomic analysis uncovers candidate genes related with milk production and adaptive traits in goat breeds

During the process of animal domestication, both natural and artificial selection cause variation in allele frequencies among populations. Identifying genomic areas of selection in domestic animals may aid in the detection of genomic areas linked to ecological and economic traits. We studied genomic variation in 140 worldwide goat individuals, including 75 Asian, 30 African and 35 European goats. We further carried out comparative population genomics to detect genomic regions under selection for adaptability to harsh conditions in local Asian ecotypes and also milk production traits in European commercial breeds. In addition, we estimated the genetic distances among 140 goat individuals. The results showed that among all studied goat groups, local breeds from West and South Asia emerged as an independent group. Our search for selection signatures in local goats from West and South Asia revealed candidate genes related to adaptation to hot climate (HSPB6, HSF4, VPS13A and NBEA genes) and immune response (IL7, IL5, IL23A and LRFN5) traits. Furthermore, selection signatures in European commercial goats involved several milk production related genes, such as VPS13C, NCAM2, TMPRSS15, CSN3 and ABCG2. The identified candidate genes could be the fundamental genetic resource for enhancement of goat production and environmental-adaptive traits, and as such they should be used in goat breeding programs to select more efficient breeds.

OsMADS17 simultaneously increases grain number and grain weight in rice

During the processes of rice domestication and improvement, a trade-off effect between grain number and grain weight was a major obstacle for increasing yield. Here, we identify a critical gene COG1, encoding the transcription factor OsMADS17, with a 65-bp deletion in the 5′ untranslated region (5′ UTR) presented in cultivated rice increasing grain number and grain weight simultaneously through decreasing mRNA translation efficiency. OsMADS17 controls grain yield by regulating multiple genes and that the interaction with one of them, OsAP2-39, has been characterized. Besides, the expression of OsMADS17 is regulated by OsMADS1 directly. It indicates that OsMADS1-OsMADS17-OsAP2-39 participates in the regulatory network controlling grain yield, and downregulation of OsMADS17 or OsAP2-39 expression can further improve grain yield by simultaneously increasing grain number and grain weight. Our findings provide insights into understanding the molecular basis co-regulating rice yield-related traits, and offer a strategy for breeding higher-yielding rice varieties.

Morphometrics of waterlogged archaeological seeds give new insights into the domestication and spread of Papaver somniferum L. in Western Europe.

Domesticated opium poppy Papaver somniferum L. subsp. somniferum probably originated in the Western Mediterranean from its possible wild progenitor, Papaver somniferum L. subsp. setigerum and spread to other European regions. Seeds of opium poppy have been identified in different European regions since the Early Neolithic (from the 6th millennium cal. BC onwards) period. However, until recently, the absence of morphological identification criteria has prevented the discrimination between wild and domestic morphotypes. New morphometric approaches to distinguish modern subspecies have been proven to be applicable to waterlogged archaeological remains, opening the possibility of understanding the process of domestication of the plant in both time and space. This paper applies seed outline analyses, namely elliptic Fourier transforms, combined with size and number of cells to archaeological waterlogged Papaver seeds throughout the Neolithic period in the NW Mediterranean and the surroundings of the Alps. Furthermore, one example from the Late Bronze Age (LBA) was added to see what kind of differences appeared during the >1000 years between the end of the Neolithic and the LBA. The aim of the study is to classify the archaeological seeds as domestic or wild morphotypes and observe morphometric changes in connection to geographical and chronological patterns that can explain the spread and domestication process(es) of this important crop. A total of 295 archaeological seeds coming from 10 waterlogged sites dating between 5300-2300 cal. BC (Neolithic), and one LBA site dating to 1070 cal. BC were analysed. The results indicate the presence of seeds, similar to the wild morphotype, in the Mediterranean sites and larger seeds, similar to the domestic morphotype, in the regions surrounding the Alps. The number of cells mainly increased during the Late Neolithic (3300 to 2300 cal. BC) and, finally, in the Late Bronze Age (ca. 1050-800 cal. BC), larger, morphologically domesticated seeds are clearly predominant. A change in the shape of the seeds is only clearly visible in the LBA material. Altogether our results suggest that opium poppy seeds show no sign of domestication in the early periods of the Neolithic, despite the fact that the plant was very probably already cultivated at that time in the western Mediterranean region.

Environment as a limiting factor of the historical global spread of mungbean.

While the domestication process has been investigated in many crops, the detailed route of cultivation range expansion and factors governing this process received relatively little attention. Here using mungbean (Vigna radiata var. radiata) as a test case, we investigated the genomes of more than one thousand accessions to illustrate climatic adaptation's role in dictating the unique routes of cultivation range expansion. Despite the geographical proximity between South and Central Asia, genetic evidence suggests mungbean cultivation first spread from South Asia to Southeast, East, and finally reached Central Asia. Combining evidence from demographic inference, climatic niche modeling, plant morphology, and records from ancient Chinese sources, we showed that the specific route was shaped by the unique combinations of climatic constraints and farmer practices across Asia, which imposed divergent selection favoring higher yield in the south but short-season and more drought-tolerant accessions in the north. Our results suggest that mungbean did not radiate from the domestication center as expected purely under human activity, but instead the spread of mungbean cultivation is highly constrained by climatic adaptation, echoing the idea that human commensals are more difficult to spread through the south-north axis of continents.

Genetic analysis and QTL mapping of domestication-related traits in chili pepper (Capsicum annuum L.).

Chili pepper (Capsicum annuum L.) is one of the oldest and most phenotypically diverse pre-Columbian crops of the Americas. Despite the abundance of genetic resources, the use of wild germplasm and landraces in chili pepper breeding is limited. A better understanding of the evolutionary history in chili peppers, particularly in the context of traits of agronomic interest, can contribute to future improvement and conservation of genetic resources. In this study, an F2:3 mapping population derived from a cross between a C. annuum wild accession (Chiltepin) and a cultivated variety (Puya) was used to identify genomic regions associated with 19 domestication and agronomic traits. A genetic map was constructed consisting of 1023 single nucleotide polymorphism (SNP) markers clustered into 12 linkage groups and spanning a total of 1,263.87cM. A reciprocal translocation that differentiates the domesticated genome from its wild ancestor and other related species was identified between chromosomes 1 and 8. Quantitative trait locus (QTL) analysis detected 20 marker-trait associations for 13 phenotypes, from which 14 corresponded to previously identified loci, and six were novel genomic regions related to previously unexplored domestication-syndrome traits, including form of unripe fruit, seedlessness, deciduous fruit, and growth habit. Our results revealed that the genetic architecture of Capsicum domestication is similar to other domesticated species with few loci with large effects, the presence of QTLs clusters in different genomic regions, and the predominance of domesticated recessive alleles. Our analysis indicates the domestication process in chili pepper has also had an effect on traits not directly related to the domestication syndrome. The information obtained in this study provides a more complete understanding of the genetic basis of Capsicum domestication that can potentially guide strategies for the exploitation of wild alleles.

Major genetic locus with pleiotropismdetermined seed-related traits in cultivated and wild soybeans.

Here, a novel pleiotropic QTL qSS14 simultaneously regulating four seed size traits and two consistently detected QTLs qSW17 and qSLW02 were identified across multiple years. Seed-related traits were the key agronomic traits that have been artificially selected during the domestication of wild soybean. Identifying the genetic loci and genes that regulate seed size could clarify the genetic variations in seed-related traits and provide novel insights into high-yield soybean breeding. In this study, we used a high-density genetic map constructed by F10 RIL populations from a cross between Glycine max and Glycine soja to detect additive QTLs for seven seed-related traits over the last three years. As a result, we identified one novel pleiotropic QTL, qSS14, that simultaneously controlled four seed size traits (100-seed weight, seed length, seed width, and seed thickness) and two consistently detected QTLs, qSW17, and qSLW02, in multiple years of phenotypic data. Furthermore, we predicted two, two and three candidate genes within these three critical loci based on the parental resequencing data and gene function annotations. And the relative expression of four candidate genes GLYMA_14G155100, GLYMA_17G061000, GLYMA_02G273100, and GLYMA_02G273300 showed significant differences among parents and the extreme materials through qRT-PCR analysis. These findings could facilitate the determination of beneficial genes in wild soybean and contribute to our understanding of the soybean domestication process.

4500 years of morphological diversification in Western Europe wild boars (Sus scrofa) and the consequences of the Neolithic transition

Evolutionary biologists have recently solicited archaeologists to help document and understand the morphological evolution of animals in response to human activities and, more generally, to help reconstruct the history and significance of the anthropogenic impact on worldwide ecosystems. Artificial selection associated with domestication is the best-known example of a major anthropogenic morphological evolution preserved in the archaeological record. However, the impact of the domestication process and dispersal on the morphological evolution of animals has been far less explored. To fill this gap, we focused on 4500 years of evolution in Western Europe Sus scrofa, covering the Neolithic transition ‒ a major anthropogenic ecological disturbance involving landscape modification and the translocation of domestic mammals. Using geometric morphometrics on key phenotypic markers preserved in the archaeological record, associated with isotopic studies, we explored how, and in response to which cultural drivers, the Neolithic niche construction has influenced the morphological evolution of Western European wild boars (Sus scrofa scrofa). The decoupling of size and shape components from bone morphological variation has facilitated the identification of several processes of phenotypic diversification of Sus s. scrofa in response to human behaviour during the Neolithic transition in Western Europe.

Discriminating dietary behaviour between wild and domestic goats using dental microwear texture: first results from a modern reference set and early Neolithic goat exploitation in the southern Levant

Current evidence supports the idea that animal domestication occurred in multiple loci and at different time periods throughout the Near East rather than according to a single origin. In this scenario, the southern Levant is being increasingly considered as another presumed primary centre of goat domestication, alongside eastern Anatolia and the Zagros. Assessing the status (i.e. wild or domestic) of this animal in this region, however, is hampered by the difficulty of morphologically distinguishing domestic goats from their wild relatives. Diet reconstruction is a powerful approach to address this issue since the feeding of managed animals is partially controlled by their owners, unlike free-ranging wild populations. For the first time, we propose to contribute to this question through dental microwear texture analysis (DMTA) using confocal microscopy.Characterising how the dietary behaviour of extant wild and domestic goats is reflected in DMTA is critical. For this purpose, we constructed a reference collection composed of three wild goat species (19 Capra pyrenaica from the southern Iberian Peninsula, 12 Capra ibex from the Alps and 12 Capra nubiana from the Near East) and 15 domestic goats (Capra hircus) reared in an extensive system in Mediterranean scrubland areas.The preliminary results indicate that DMTA allows discrimination of the groups of extant goats. The results obtained were used to characterise the palaeodiet of 16 goats (Capra format aegagrus) from two key Early and Middle Pre-Pottery Neolithic B sites in the southern Levant: Kharaysin (Zarqa, Jordan, ca. 8800-7500 cal BC) and Qarassa (As-Suweyda, Syria, 8700-8200 cal BCE). The higher variability in archaeological goats could be an indicator of controlled feedings. It could also support the hypothesis about diverse and experimental management systems at the first steps of animal domestication.This paper shows the potential of this tool to address the process of early animal domestication. Following this initial work, the reference collection will include a broader spectrum of livestock management strategies and the archaeological corpus will be expanded through new samples during upcoming excavations and the integration of additional sites.

Comparative Genomics Study between High and Low Laying Goose Breeds Reveals the Important Role of ESR1 in Laying Ability

The low egg production of goose greatly limits the development of the industry. China possesses the most abundant goose breeds resources. In this study, genome resequencing data of swan goose (Anser cygnoides) and domesticated high and low laying goose breeds (Anser cygnoides domestiation) were used to identify key genes related to egg laying ability in geese and verify their functions. Selective sweep analyses revealed 416 genes that were specifically selected during the domestication process from swan geese to high laying geese. Furthermore, SNPs and Indels markers were used in GWAS analyses between high and low laying breed geese. The results showed that RTCB, BPIFC, SYN3, SYNE1, VIP, and ESR1 may be related to the differences in laying ability of geese. Notably, only ESR1 was identified simultaneously by GWAS and selective sweep analysis. The genotype of Indelchr3:54429172, located downstream of ESR1, was confirmed to affect the expression of ESR1 in the ovarian stroma and showed significant correlation with body weight at first egg and laying frequency of geese. CCK-8, EdU, and flow cytometry confirmed that ESR1 can promote the apoptosis of goose pre-hierarchical follicles ganulosa cells (phGCs) and inhibit their proliferation. Combined with transcriptome data, it was found ESR1 involved in the function of goose phGCs may be related to MAPK and TGF-beta signaling pathways. Overall, our study used genomic information from different goose breeds to identify an indel located in the downstream of ESR1 associated with goose laying ability. The main pathways and biological processes of ESR1 involved in the regulation of goose laying ability were identified by cell biology and transcriptomics methods. These results are helpful to further understand the laying ability characteristics of goose and improve the egg production of geese.

Herbivory Damage Increased VOCs in Wild Relatives of Murtilla Plants Compared to Their First Offspring

Murtilla (Ugni molinae) is a shrub native to Chile that has undergone an incipient domestication process aimed at increasing its productivity. The reduction in intrinsic chemical defenses due to the domestication process has resulted in a decrease in the plant's ability to defend itself against mechanical or insect damage. In response to this damage, plants release volatile organic compounds (VOCs) as a means of defense. To understand how domestication has impacted the production of VOCs in the first offspring of murtilla, we hypothesized that their levels would be reduced due to the induction of mechanical and herbivore damage. To test this hypothesis, we collected VOCs from four offspring ecotypes and three wild relatives of murtilla. We induced mechanical and herbivore damage in the plants and then enclosed them in a glass chamber, where we captured the VOCs. We identified 12 compounds using GC-MS. Our results showed that wild relative ecotypes had a higher VOC release rate of 624.6 µg/cm2/day. Herbivore damage was the treatment that produced the highest release of VOCs, with 439.3 µg/cm2/day in wild relatives. These findings suggest that herbivory triggers defenses through the emission of VOCs, and that domestication has influenced the production of these compounds in murtilla. Overall, this study contributes to bridging the gap in the incipient domestication history of murtilla and highlights the importance of considering the impact of domestication on a plant's chemical defenses.

The construction and analysis of wax gourd pangenome uncover fruit quality-related and resistance genes

Large-scale resequencing studies in wax gourd have generated a large data resource and mined many selection signals and candidate genes. In this study, we constructed the first pangenome of wax gourd based on resequencing data and obtained 316 Mb novel contigs containing 996 novel genes. A pan-genome-wide gene present/absent variations analysis of 25,188 genes identified 2154 genes as variable genes. Analysis of gene present/absent variations selection between wild accessions, landraces, and cultivar accessions revealed that many genes, including resistance genes, were lost during the process of domestication and improvement. The 22 resistance gene analogs identified in non-reference contigs are complementary to the 642 resistance gene analogs on the reference genome. Genome-wide association studies of gene present/absent variations with fruit weight, fruit length, fruit diameter, and fruit thickness of wax gourd identified five phenotypic-related candidate genes. Pan-genome-wide identification of NAC, WRKY and HSF gene family identified 7 novel genes. In conclusion, this study provides a more complete sequence and genes of the wax gourd genome and identifies new selected genes as well as phenotypically related candidate genes through a series of analyses, as well as provides an abundant resource and research reference for breeding and gene function studies in the wax gourd.

Being a Dog: A Review of the Domestication Process

The process of canine domestication represents certainly one of the most interesting questions that evolutionary biology aims to address. A "multiphase" view of this process is now accepted, with a first phase during which different groups of wolves were attracted by the anthropogenic niche and a second phase characterized by the gradual establishment of mutual relationships between wolves and humans. Here, we provide a review of dog (Canis familiaris) domestication, highlighting the ecological differences between dogs and wolves, analyzing the molecular mechanisms which seem to have influenced the affiliative behaviors first observed in Belyaev's foxes, and describing the genetics of ancient European dogs. Then, we focus on three Mediterranean peninsulas (Balkan, Iberian and Italian), which together represent the main geographic area for studying canine domestication dynamics, as it has shaped the current genetic variability of dog populations, and where a well-defined European genetic structure was pinpointed through the analysis of uniparental genetic markers and their phylogeny.

Horse domestication as a multi-centered, multi-stage process: Botai and the role of specialized Eneolithic horse pastoralism in the development of human-equine relationships

For over a decade there has been general, but not universal, consensus that the earliest known evidence for horse husbandry was at Eneolithic Botai, Kazakhstan, circa 3,500 BCE. Recent ancient genomic analyses, however, indicate that Botai is not the source of modern domestic horse stock (DOM2 lineage), but is instead related to the Przewalski clade of horses. DOM2 appears to instead to have emerged in early Bronze Age (mid 3rd Mill. BCE) in the Pontic-Caspian steppe, and spread quickly replacing other horse lineages after approximately 2,000 BCE. Whilst the specific evidence for earlier husbandry at Botai is not diminished by this evidence, it has broken the consensus regarding the early stages of horse domestication, with some now viewing it as a later event. This paper argues that domestication is rarely an event, but instead a process that is ongoing. The case is made for a “prey pathway” initial phase of domestication in multiple localities during the Eneolithic, which was based around local subsistence pastoralist niche construction. This took different forms due to the presence or absence of ruminant domestic stock in the Eastern European or Central Asian steppes, respectively. Whilst “push” factors likely played a part in the development of horse specialist pastoralism at Botai, it is suggested that “pull” factors accelerated the spread of DOM2 lineages, replacing others, in the later Bronze Age. The DOM2 spread was principally driven, not by local subsistence needs, but wider social, economic and military desirability of equestrianism. The long-term process of horse domestication continues in modernity with major breed changes caused first by the post-medieval agricultural revolution and, more currently, the desire for sporting achievement.

Domesticating Vigna stipulacea: Chromosome-Level genome assembly reveals VsPSAT1 as a candidate gene decreasing hard-seededness.

To increase food production under the challenges presented by global climate change, the concept of de novo domestication-utilizing stress-tolerant wild species as new crops-has recently gained considerable attention. We had previously identified mutants with desired domestication traits in a mutagenized population of the legume Vigna stipulacea Kuntze (minni payaru) as a pilot for de novo domestication. Given that there are multiple stress-tolerant wild legume species, it is important to establish efficient domestication processes using reverse genetics and identify the genes responsible for domestication traits. In this study, we identified VsPSAT1 as the candidate gene responsible for decreased hard-seededness, using a Vigna stipulacea isi2 mutant that takes up water from the lens groove. Scanning electron microscopy and computed tomography revealed that the isi2 mutant has lesser honeycomb-like wax sealing the lens groove than the wild-type, and takes up water from the lens groove. We also identified the pleiotropic effects of the isi2 mutant: accelerating leaf senescence, increasing seed size, and decreasing numbers of seeds per pod. While doing so, we produced a V. stipulacea whole-genome assembly of 441 Mbp in 11 chromosomes and 30,963 annotated protein-coding sequences. This study highlights the importance of wild legumes, especially those of the genus Vigna with pre-existing tolerance to biotic and abiotic stresses, for global food security during climate change.

Historical aspects of carp domestication and breeding

Common carp (Cyprinus carpio L.) is one of the most widely cultivated fish species in the world. According to FAO, in 2020, it ranked 4th in the global production of aquaculture products. When growing carp all over the world, both natural reservoirs and pond farms, trucks and industrial complexes of cage farms, UZS and others are used. In a number of countries, there is a traditional extensive production of carp in large ponds and natural reservoirs for recreational purposes. There are systems of ponds and reservoirs, the design and original construction of which in many cases date back hundreds of years, representing managed landscapes. This sector of aquaculture brings significant social and cultural dividends, at the same time, carp breeding is often criticized as an anthropogenic factor in the eutrophication of inland freshwater reservoirs. Currently, the process of domestication and the ways of settlement of this species have become the subject of close attention of many researchers. As with some other domestic animals, even the original habitat of the carp is subject to a number of doubts, and the place and time of the appearance of the mirror morph remains a mystery. The purpose of this review was to study the historical aspects and trends of carp domestication in the world, to identify the main time intervals of domestication and breeding, modern methods of working with carp and possible prospects for the development of carp farming in the world. In addition, the main theories of the origin and initial distribution of the species are considered.

Investigating the domestication and early management of reindeer (Rangifer tarandus) in the Sámi archaeological context from teeth geometric morphometrics

For centuries, reindeer herding has been an integral part of the subsistence, lifeways, economy and cosmology of the Sámi of northern Fennoscandia. Despite its importance, the timing and details of early reindeer domestication are still highly debated. Identifying domesticated individuals in the archaeological record remains complicated due to the presence of two interbreeding subspecies in Fennoscandia and a mixed socio-economic organisation by Sámi populations, which was mainly a combination of wild reindeer hunting and small-scale reindeer herding. This study proposes methodological improvement for identifying domestic individuals using 2D landmark and sliding semi-landmark based geometric morphometrics on the isolated lower molars of 389 modern specimens, and 90 teeth from four archaeological sites in Finnish Lapland. Our results indicate that despite the significant impact of wear on overall tooth morphology, our protocol is very useful for identifying subspecies (classification accuracy of the two species is between 78 and 91% depending on the wear class) and understanding the morphological changes induced by the domestication process. We suggest that the morphological variation observable among modern populations has been impacted by recent changes in herding strategies in northern Fennoscandia, and that the archaeological domesticated reindeer populations were relatively different, probably due to selection by the Sámi. This study also highlights the importance of using other direct evidence or contextual archaeological data to better trace the early evidence of a domesticated reindeer economy in northern Fennoscandia, and aid in reconstructing the socio-economic changes in Sámi populations over time.

The use of pigs vocalisation structure to assess the quality of human-pig relationship

Studying human-animal interactions in domestic species and how they affect the establishment of a positive Human-Animal Relationship (HAR) may help us improve animal welfare and better understand the evolution of interspecific interactions associated with the domestication process. Understanding and describing the quality of an HAR requires information on several aspects of the animal biology and emotional states (social, spatial and postural behaviours, physiological and cognitive states). Growing evidence shows that acoustic features of animal vocalisations may be indicators of emotional states. Here, we tested the hypothesis that vocal structure may indicate the quality of HAR. At weaning, 30 piglets were positively handled by an experimenter who talked to and physically interacted with them three times a day, while 30 other piglets only received the contact necessary for proper husbandry. After two weeks, we recorded the behaviours and vocalisations produced in the presence of the static experimenter for 5 min. We repeated this test two weeks later, after a conditioning period during which human presence with additional positive contacts was used as a reward for all piglets. We hypothesized this conditioning period would lead to a positive human-piglet relationship for all piglets. As expected, piglets that were positively handled at weaning expressed a higher attraction toward the experimenter, and, after the conditioning, piglets that were not positively handled at weaning expressed a similar level of attraction than the positively handled ones. Piglets positively handled at weaning produced shorter grunts than the other ones, regardless of the context of recording, which may indicate a more positive affect. During reunions with the static experimenter, a more positive HAR was associated with a decrease in vocal reactivity to human proximity. However, during reunions with the experimenter providing additional positive contacts and over the conditioning, spatial proximity to the human systematically triggered shorter and higher pitched grunts, which may indicate a more positive emotional state. Results first show that changes in vocal structure are consistent with indicators of positive states in the presence of a human. Second, these changes are stronger when the human positively interact with the piglets, supposedly emphasizing a higher positive arousal state during these interactions. We show that vocalisation structure may be a promising indicator of the quality of human-pig relationship.

Floral scent of the Mediterranean fig tree: significant inter-varietal difference but strong conservation of the signal responsible for pollinator attraction

For thousands of years, humans have domesticated different plants by selecting for particular characters, often affecting less-known traits, including the volatile organic compounds (VOCs) emitted by these plants for defense or reproduction. The fig tree Ficus carica has a very wide range of varieties in the Mediterranean region and is selected for its traits affecting fruits, including pollination, but the effect of human-driven diversification on the VOCs emitted by the receptive figs to attract their pollinator (Blastophaga psenes) is not known. In the present study, VOCs from receptive figs of eight varieties in northern Morocco, were collected at different times within the manual pollination period and analyzed by gas chromatography-mass spectrometry. Genetic analyses using microsatellite loci were performed on the same varieties. Despite strong inter-varietal differences in the quantity and relative proportions of all VOCs, the relative proportions of the four pollinator-attractive VOCs showed limited variation among varieties. There was no significant correlation between genetic markers and chemical profiles of the different varieties. While diversification driven by humans has led to differences between varieties in VOC profiles, this paper suggests that throughout the process of domestication and varietal diversification, stabilizing selection has maintained a strong signal favoring pollinator attraction.