Abstract The viability and phenotypes of wild populations can be affected by hybridization with domesticated and/or feral conspecifics. These impacts can be quantified with increasing precision using emerging genomic and bioinformatic tools—raising concerns about the genetic makeup of contemporary wild, non-domesticated gene pools. Research and policy surrounding the wild forms of domestic species are primarily focussed on mammals and fishes, leaving abundant and ecologically significant taxa underexplored. Here, we review current knowledge of the patterns and consequences of wild–domestic–feral admixture on the wild counterparts of domesticated birds. First, we summarize the available information regarding conspecific wild populations of domesticated avian species—finding both genome-wide and more compartmentalized impacts of admixture. We synthesize this literature to illustrate how admixture can impact fitness and phenotypes, and we summarize the factors which can impact the extent of introgression. Last, we identify priority areas to stimulate necessary research and conservation activities. Specifically, we suggest priorities for research into domesticated birds’ wild counterparts to (1) deepen our understanding of patterns of wild–domestic–feral introgression, (2) identify the mechanisms underpinning the recruitment of domestic or feral alleles into wild populations, (3) increase awareness of the potential positive and negative consequences of such introgression, and (4) develop effective conservation strategies to maintain genetically distinctive wild-type avian populations.

Recent work indicates that feralisation is not a simple reversal of domestication, and therefore raises questions about the predictability of evolution across replicated feral populations. In the present study we compare genes and traits of two independently established feral populations of chickens (Gallus gallus) that inhabit archipelagos within the Pacific and Atlantic regions to test for evolutionary parallelism and/or divergence. We find that feral populations from each region are genetically closer to one another than other domestic breeds, despite their geographical isolation and divergent colonisation histories. Next, we used genome scans to identify genomic regions selected during feralisation (selective sweeps) in two independently feral populations from Bermuda and Hawaii. Three selective sweep regions (each identified by multiple detection methods) were shared between feral populations, and this overlap is inconsistent with a null model in which selection targets are randomly distributed throughout the genome. In the case of the Bermudian population, many of the genes present within the selective sweeps were either not annotated or of unknown function. Of the nine genes that were identifiable, five were related to behaviour, with the remaining genes involved in bone metabolism, eye development and the immune system. Our findings suggest that a subset of feralisation loci (i.e. genomic targets of recent selection in feral populations) are shared across independently established populations, raising the possibility that feralisation involves some degree of parallelism or convergence and the potential for a shared feralisation 'syndrome'.

Phenotypic change plays diverse roles in species’ colonization, but most invasion studies target single species. To compare ecomorphological changes among co-invading species with overlapping niches, we examined three lizards on the island of O‘ahu (Anolis carolinensis, A. sagrei, Phelsuma laticauda). Using specimens from three decades of unfolding invasions obtained through museum collections and contemporary field work, we quantified shifts in three traits: snout vent length (SVL), forelimb-, and hindlimb-length (limb lengths relative to SVL). We hypothesized that competition among these three species has led to ecological shifts that will be detectable through morphological change. Overall, we found that unique patterns of phenotypic change were both species-specific and sex-specific within species: (1) male A. sagrei, female A. carolinensis, and male P. laticauda increased in SVL and (2) relative hindlimb length increased in female A. carolinensis since the 1980s. The observed changes involve traits that may be consequential to invasion dynamics. This study illustrates how museum- and field-based research can be integrated to document nuanced temporal patterns in the phenotypes of co-invading species that share similar niches in native ranges, raising questions about the underlying process(es) driving species- and sex-specific change in co-invaded systems.

Chickens are believed to have inhabited the Hawaiian island of Kauai since the first human migrations around 1200AD, but numbers have peaked since the tropical storms Iniki and Iwa in the 1980s and 1990s that destroyed almost all the chicken coops on the island and released large numbers of domestic chickens into the wild. Previous studies have shown these now feral chickens are an admixed population between Red Junglefowl (RJF) and domestic chickens. Here, using genetic haplotypic data, we estimate the time of the admixture event between the feral population on the island and the RJF to 1981 (1976–1995), coinciding with the timings of storm Iwa and Iniki. Analysis of genetic structure reveals a greater similarity between individuals inhabiting the northern and western part of the island to RJF than individuals from the eastern part of the island. These results point to the possibility of introgression events between feral chickens and the wild chickens in areas surrounding the Koke’e State Park and the Alaka’i plateau, posited as two of the major RJF reservoirs in the island. Furthermore, we have inferred haplotype blocks from pooled data to determine the most plausible source of the feral population. We identify a clear contribution from RJF and layer chickens of the White Leghorn (WL) breed. This work provides independent confirmation of the traditional hypothesis surrounding the origin of the feral populations and draws attention to the possibility of introgression of domestic alleles into the wild reservoir.

Toxoplasma gondii is a common parasite that infects warm-blooded animals and influences host physiology. T. gondii is known to target the host's central nervous system, affecting circulating levels of steroid hormones, fear-related behaviors, and health, although these effects appear to vary among host taxa. Here, we investigated the relationship between T. gondii infection and levels of plasma testosterone and cortisol within a wild population of spotted hyenas (Crocutacrocuta, n = 109). In our analyses, we accounted for age and sex via stratified regression analyses. We detected a negative association between circulating plasma testosterone and T. gondii infection among female cubs and subadults as well as adult male hyenas. We found no associations between T. gondii infection and cortisol in any age class or sex group of hyenas. Our work adds to a growing body of literature by characterizing the relationship between T. gondii infection and physiology in a novel host in its natural habitat. In a broader context, our findings indicate that responses to infection vary with characteristics of the host and point to a clear need for additional studies and priorities for future work that include diverse taxa and ecological settings.

Abstract Phenotypic change plays diverse and crucial roles in biotic invasion, but most studies of invasions focus on individual species. To compare ecomorphological changes among co-invading species with overlapping native niches, we examined three lizards on the island of O‘ahu: (Anolis carolinensis, A. sagrei, Phelsuma laticauda). Using specimens from three decades of unfolding invasions obtained from museum collections and the field, we quantified temporal shifts in three ecologically relevant traits: snout vent length (SVL), forelimb-, and hindlimb-length (limb lengths relative to SVL). We found unique patterns of phenotypic change in each species as well as sex-specific changes within species: 1) both anole species increased in SVL since the 1980s, 2) forelimb length increased in Phelsuma females and in both sexes in A. carolinensis, and 3) relative hindlimb length increased in Phelsuma (both sexes) and decreased in A. sagrei (both sexes). The observed changes involve ecomorphological traits that are feasibly consequential to invasion dynamics. Our study illustrates how museum- and field-based research can be integrated to document nuanced temporal patterns in the phenotypes of co-invading species that share similar niches in their native ranges; it also raises important questions about the underlying process(es) driving species- and sex-specific change in co-invaded systems.

Recent work indicating that feralisation is not a simple reversal of domestication has raised questions about the predictability of evolutionary change across replicated feral populations. In the present study we compare genes and traits of two independently feral populations of chickens (G. gallus) inhabiting archipelagos in Pacific and Atlantic regions to test for evolutionary parallelism and/or divergence. First, we confirm purported differences in these two populations’ ancestries are corroborated by genetic and phenotypic analyses. Indeed, whereas Pacific (Kauaii) chickens recently outcrossed with wild relatives, our genetic data from Atlantic (Bermuda) chickens is more consistent with solely domestic origins encompassing diverse G. gallus breeds. Next we used genome scans to contrast the targets of feralisation (selective sweeps) between the two independently feral populations. Two sweep loci were shared between these focal populations and this overlap is inconsistent with a null model in which selection targets are randomly distributed throughout the genome. The larger set of sweep loci from the two feral genepools were also found to govern traits that were heavily modified during G. gallus’ domestication (e.g. the nervous system and behaviour, metabolism, and reproduction). Assessment of SNPs using allelic differences and SNP annotation led to candidate SNPs for further investigation for five of the genes present. Our findings suggest that a subset of feralisation loci are shared across independently-established populations, raising the possibility that feralisation involves some degree of parallelism or convergence, though a clearer understanding of possible ‘feralisation syndromes’ will require elucidating genotype-phenotype relationships in any populations being compared.

Wastewater was screened for the presence of functionally significant mutations in SARS-CoV-2 associated with emerging variants of concern (VOC) by ddPCR, and results accorded with sequencing of clinical samples from the same region. We propose that PCR-based screening of wastewater can provide a powerful tool for rapid and inexpensive screening of large population segments for VOC-associated mutations and can hone complementary sampling and sequencing of direct (human) test material to track emerging VOC.

Toxoplasma gondii is hypothesized to manipulate the behavior of warm-blooded hosts to promote trophic transmission into the parasite's definitive feline hosts. A key prediction of this hypothesis is that T. gondii infections of non-feline hosts are associated with costly behavior toward T. gondii's definitive hosts; however, this effect has not been documented in any of the parasite's diverse wild hosts during naturally occurring interactions with felines. Here, three decades of field observations reveal that T. gondii-infected hyena cubs approach lions more closely than uninfected peers and have higher rates of lion mortality. We discuss these results in light of 1) the possibility that hyena boldness represents an extended phenotype of the parasite, and 2) alternative scenarios in which T. gondii has not undergone selection to manipulate behavior in host hyenas. Both cases remain plausible and have important ramifications for T. gondii's impacts on host behavior and fitness in the wild. The parasite causing toxoplasmosis can manipulate prey to behave in ways that promote transmission to the parasite's definitive feline hosts. The first study consistent with this extended phenotype in the wild finds that infected hyena cubs approach lions more closely than uninfected peers and have higher rates of lion mortality.

There is growing interest in the alteration of host behaviors by parasites, yet crucial gaps remain in our understanding of its ecological and evolutionary significance. Here, we present the first evidence that the enhanced boldness of infected intermediate hosts of Toxoplasma gondii can increase their risk of mortality by the parasite’s definitive feline hosts. In a long-term study of hyenas in Kenya’s Masai Mara region, we found that 65% of hyenas were seropositive for T. gondii in ELISA IgG assays. Seropositive hyenas approached lions more closely than uninfected counterparts, and also showed longer latencies to approach a simulated conspecific territorial intruder. Lastly, although not significant, the ratio of mortalities caused by lions (vs. other sources) was higher for hyenas that were infected by T. gondii. These results accord with a long-standing hypothesis that the manipulation of host boldness and/or ailurophilia evolved to enhance disease transmission. Since hyenas are rarely consumed by lions, however, elevating their boldness toward lions may not be adaptive for T. gondii. Instead, it may reflect “collateral manipulation” that evolved to influence homologous mechanisms underlying behaviors of alternative hosts (e.g. rodents). This model is often invoked to explain T. gondii’s many effects in humans, but is virtually unexplored in natural settings. For T. gondii, these effects could feasibly impact both behavior and fitness in a vast array, and significant proportion, of earth’s mammals and birds. In addition to characterizing behavioral covariates of infection, we examined spatial and temporal patterns of T. gondii prevalence within the Mara landscape. Contrary to our predictions, disease prevalence did not differ 1) at a protected vs. disturbed locality, or 2) over three decades of increasing human activity within the disturbed locality.

Toxoplasma gondii is widely reported to manipulate the behavior of its non-definitive hosts in ways that promote lethal interactions with the parasite’s definitive feline hosts. Nonetheless, there is a lack of data on the association between T. gondii infection and costly behavioral interactions with felids in nature. Here, we report that three decades of field observations reveal T. gondii infected hyena cubs approach lions more closely than uninfected peers and have higher rates of lion mortality. Our findings support the hypothesis that T. gondii’s manipulation of host boldness is an extended phenotype that promotes parasite transmission from intermediate hosts to feline predators. While upregulating hyena boldness toward lions might achieve this, it may also reflect a collateral influence of manipulative traits that evolved in other hosts (e.g., rodents). In either case, our findings corroborate the potential impacts of a globally distributed and generalist parasite ( T. gondii ) on fitness-related interaction with felids in a wild host. One Sentence Summary Wild hyenas infected with the parasite T. gondii show evidence of costly behavioral manipulation when interacting with lions.

The postdoctoral workforce comprises a growing proportion of the science, technology, engineering and mathematics (STEM) community, and plays a vital role in advancing science. Postdoc professional development, however, remains rooted in outdated realities. We propose enhancements to postdoc-centred policies and practices to better align this career stage with contemporary job markets and work life. By facilitating productivity, wellness and career advancement, the proposed changes will benefit all stakeholders in postdoc success—including research teams, institutions, professional societies and the scientific community as a whole. To catalyse reform, we outline recommendations for (1) skills-based training tailored to the current career landscape, and (2) supportive policies and tools outlined in postdoc handbooks. We also invite the ecology and evolution community to lead further progressive reform.

Selection regimes and population structures can be powerfully changed by domestication and feralization, and these changes can modulate animal fitness in both captive and natural environments. In this review, we synthesize recent studies of these two processes and consider their impacts on organismal and population fitness. Domestication and feralization offer multiple windows into the forms and mechanisms of maladaptation. Firstly, domestic and feral organisms that exhibit suboptimal traits or fitness allow us to identify their underlying causes within tractable research systems. This has facilitated significant progress in our general understandings of genotype-phenotype relationships, fitness trade-offs, and the roles of population structure and artificial selection in shaping domestic and formerly domestic organisms. Additionally, feralization of artificially selected gene variants and organisms can reveal or produce maladaptation in other inhabitants of an invaded biotic community. In these instances, feral animals often show similar fitness advantages to other invasive species, but they are also unique in their capacities to modify natural ecosystems through introductions of artificially selected traits. We conclude with a brief consideration of how emerging technologies such as genome editing could change the tempos, trajectories, and ecological consequences of both domestication and feralization. In addition to providing basic evolutionary insights, our growing understanding of mechanisms through which artificial selection can modulate fitness has diverse and important applications-from enhancing the welfare, sustainability, and efficiency of agroindustry, to mitigating biotic invasions.

Formerly domesticated organisms and artificially selected genes often escape controlled cultivation, but their subsequent evolution is not well studied. In this review, we examine plant and animal feralization through an evolutionary lens, including how natural selection, artificial selection, and gene flow shape feral genomes, traits, and fitness. Available evidence shows that feralization is not a mere reversal of domestication. Instead, it is shaped by the varied and complex histories of feral populations, and by novel selection pressures. To stimulate further insight we outline several future directions. These include testing how 'domestication genes' act in wild settings, studying the brains and behaviors of feral animals, and comparative analyses of feral populations and taxa. This work offers feasible and exciting research opportunities with both theoretical and practical applications.

Tissue samples from 699 birds from three regions of Asia (Myanmar, India, and South Korea) were screened for evidence of infection by avian parasites in the genera Plasmodium and Haemoproteus. Samples were collected from November 1994 to October 2004. We identified 241 infected birds (34.0%). Base-on-sequence data for the cytochrome b gene from 221 positive samples, 34 distinct lineages of Plasmodium, and 41 of Haemoproteus were detected. Parasite diversity was highest in Myanmar followed by India and South Korea. Parasite prevalence differed among regions but not among host families. There were four lineages of Plasmodium and one of Haemoproteus shared between Myanmar and India and only one lineage of Plasmodium shared between Myanmar and South Korea. No lineages were shared between India and South Korea, although an equal number of distinct lineages were recovered from each region. Migratory birds in South Korea and India originate from two different migratory flyways; therefore crosstransmission of parasite lineages may be less likely. India and Myanmar shared more host species and habitat types compared to South Korea. Comparison between low-elevation habitat in India and Myanmar showed a difference in prevalence of haematozoans.

Feralisation is a complex process that occurs when a domestic population is returned to the wild. It impacts species invasion biology, speciation, conservation and hybridisation and can be thought of as the reverse of domestication. Domestication has been an area of intense interest and study ever since Darwin, and useful as a model for evolution and the effects of strong directional selection. Despite domestication being used to identify genes affecting a large number of traits that change with selection, little is known about the genomic changes associated with feralisation. Much of the current work on the genetics of feralisation has focused on the detection of early hybrids (F1 or F2) between wild and domestic populations. Feralisation can lead to large changes in morphology, behaviour and many other traits, with the process of feralisation involving the sudden return of both natural and sexual selection. Such evolutionary forces influence predatory, foraging and mate choice decisions and exert strong effects on once domesticated, now feral, individuals. As such, feralisation provides a unique opportunity to observe the genomic and phenotypic responses to selection from a known (domesticated) standpoint and identify the genes underlying these selective targets. In this review, we summarise what is known in particular regarding the genomics of feralisation, and also the changes that feralisation has induced on brain size and behaviour.

Different factors may modulate the gut microbiota of animals. In any particular environment, diet, genetic factors and human influences can shape the bacterial communities residing in the gastrointestinal tract. Metagenomic approaches have significantly expanded our knowledge on microbiota dynamics inside hosts, yet cultivation and isolation of bacterial members of these complex ecosystems may still be necessary to fully understand interactions between bacterial communities and their host. A dual approach, involving culture-independent and -dependent techniques, was used here to decipher the microbiota communities that inhabit the gastro intestinal tract of free-range, broiler and feral chickens. In silico analysis revealed the presence of a core microbiota that is typical of those animals that live in different geographical areas and that have limited contact with humans. Anthropic influences guide the metabolic potential and the presence of antibiotic resistance genes of these different bacterial communities. Culturomics attempts, based on different cultivation conditions, were applied to reconstruct in vitro the microbiota of feral chickens. A unique strain collection representing members of the four major phyla of the poultry microbiota was assembled, including bacterial strains that are not typically retrieved from the chicken gut.