Interlinked population dynamic and evolutionary responses to spatial and seasonal environmental variation, stemming from interactions and feedbacks among phenotypic variation, genetic variation, selection and demography, could generate complex eco-evolutionary dynamics that span temporal and spatial scales. Partially migratory metapopulations (PMMPs), featuring sequential seasonal sympatry and allopatry of different sets of resident and seasonally migrant individuals, have clear potential for such eco-evolutionary outcomes. This is because ongoing evolution of reversible seasonal migration affects spatio-seasonal population dynamics and densities, which could in turn shape forms and magnitudes of selection on migration, causing feedbacks on evolution. However, key environmental and genetic conditions that maintain migratory polymorphisms, and resulting eco-evolutionary dynamics of PMMPs given stochastic environmental variation and strong spatially restricted seasonal perturbations, have not been characterized. We built a general individual-based model that tracks eco-evolutionary dynamics in PMMPs inhabiting spatially structured and seasonally varying landscapes, with seasonal migration formulated as a quantitative genetic threshold trait. Simulations showed that such genetic architectures and landscape structures, which are common in nature, readily produce stable partially migratory systems given diverse regimes of environmental variation. Partial migration is maintained whenever sites differ in non-breeding season suitability, defined as variation in density-dependence, causing 'ideal free' non-breeding distributions where residents and migrants occur with frequencies generating similar survival probabilities. Further, bet-hedging can cause stable partial migration without any fixed differences in non-breeding season density-dependence among sites and even without density-dependence at all, given sufficiently large stochastic environmental fluctuations among sites and years. Importantly, major local non-breeding season mortality events, as could result from extreme climatic events, generate eco-evolutionary dynamics that ripple out to affect breeding and non-breeding season space use of subpopulations throughout the PMMP, on both short and longer timeframes. These effects result from spatially divergent selection on the occurrence and destination of migration. Our model thus shows how changing partial seasonal migration acts as a key mediator of eco-evolutionary dynamics in (meta)populations occupying spatially and seasonally varying environments. It thereby initiates new steps towards predicting responses of natural partially migratory populations to ongoing changes in spatio-seasonal patterns of environmental variation.

The distribution and intensity of tick-borne disease (TBD) transmission events across Europe are increasing in response to changes in climate, land use and host populations. Understanding how changing environmental factors drive seasonal tick population dynamics is critical for predicting the public health impacts of TBDs. Here, we develop an environmentally driven system of stage-structured delay-differential equations to predict the population dynamics of Ixodes ricinus, the primary vector of human TBDs in Europe. We validate the model against data from 77 tick populations in 20 European countries, finding that 55% of the variation observed in the population dynamics of nymphs can be attributed to the effects of climatic variation. Over the last 40 years, we predict a climate change-induced increase in tick abundance and seasonal activity in northern Europe, and commensurate decreases across southern Europe, which should be accounted for in national health policy and climate change adaptation plans.

ABSTRACT Parasites can impose substantial fitness costs on hosts, yet infection intensity varies markedly among individuals and across life stages. Age‐related variation in parasite burden may reflect shifts in behaviour or physiology that alter exposure and susceptibility, or arise from selective disappearance of heavily infected individuals. Distinguishing between these processes is essential for understanding the ecological and evolutionary consequences of parasitism in wild populations. Age at first reproduction (AFR) is a fundamental life‐history trait that shapes lifelong infection dynamics through trade‐offs between reproductive investment, somatic maintenance, immune defence and survival. Because reproductive investment and timing often differ between sexes, age at first reproduction may generate sex‐specific infection trajectories across adulthood, yet whether early‐life reproductive strategies are linked to adult parasite dynamics in a sex‐specific manner remains largely unexplored. Using 10 years of individual‐based monitoring in European shags (Gulosus aristotelis), we tested whether age at first reproduction predicts within‐individual changes in gastrointestinal nematode burden across adulthood and whether these trajectories differ between sexes. Parasite burdens were quantified by repeated endoscopy, and a within‐subject centring approach was used to separate within‐ from between‐individual age effects and explicitly account for selective disappearance. Age at first reproduction predicted sex‐specific infection trajectories in male but not female shags. Early‐ and modal‐recruiting males showed within‐individual declines in parasite burden with age, whereas late‐recruiting males exhibited progressive increases. A marginal trend in early‐recruiting males suggests possible selective disappearance in this group. Females showed consistent within‐individual declines regardless of age at first reproduction, with no evidence of selective disappearance. These findings provide the first evidence that age at first reproduction is associated with sex‐specific parasite infection trajectories in a long‐lived bird, revealing how early‐life reproductive strategies are linked to adult host–parasite dynamics. Integrating life‐history variation with longitudinal, within‐individual approaches exposes mechanisms that cross‐sectional analyses cannot detect and highlights the population‐level consequences of sex‐specific infection trajectories.

The form, magnitude and temporal dynamics of selection on phenotypic plasticity will fundamentally shape eco-evolutionary responses to environmental variation, but such attributes have not been fully conceptualized or quantified in nature. We provide a general framework that conceptualizes the dynamics of selection on phenotypic plasticity in labile dichotomous traits, which commonly shape behaviour and life history. Specifically, we highlight distinctions between selection on expressed plasticity and selection on resulting phenotypes, effects of phenotypic switches in opposite directions, and the full selection dynamics emerging across temporal sequences of environmental conditions. To enact this framework, we quantified selection on early-life plasticity in the ecologically critical trait of seasonal migration versus residence, by fitting a novel multi-state model to spatio-seasonal resighting data from 13 newly fledged cohorts of partially migratory European shags (Gulosus aristotelis). We demonstrate strong and consistent directional selection against early-life plasticity, manifested as substantially lower juvenile survival after phenotypic switches from resident to migrant, but not after reverse switches from migrant to resident. Yet, evident short-term costs translated into weaker and fluctuating selection on plasticity given sequences of phenotypes expressed throughout initial months. We thereby reveal how complex forms of selection against early-life plasticity can arise yet be rapidly attenuated in nature.

Life-history traits expressed in early life can exhibit considerable among-cohort variation, which could substantially affect population age-structure and dynamics if initial variation persists into later life-stages. Yet, initial among-cohort variation could be reinforced, rapidly dissipated, or else completely reshaped by dynamic combinations of age-specific phenotypic plasticity and selective disappearance acting within and among cohorts. However, such effects have not been comprehensively quantified for any trait, precluding full prediction of the form and implications of phenotypic dynamics, and emerging age-specific life-history variation, in varying environments. We provide a framework for conceptualising phenotypic change resulting from joint and interacting effects of cohort-specific and age-specific plasticity and selective disappearance. We implement this framework by quantifying overall early-life age-specific phenotypic change (or stasis), and dissecting underlying dynamics of plasticity and selection, for the ecologically critical life-history trait of seasonal migration versus residence. We achieve this by fitting multi-state models to extensive multi-year ring-resighting data from 9358 colour-ringed European shags (Gulosus aristotelis) from 11 cohorts in a partially migratory population. The overall cross-cohort mean proportion of migrants versus residents remained approximately constant across the four winters following fledging, implying no overall change in the degree of seasonal migration with age. This stasis was underlain by consistently high cross-year individual phenotypic repeatability, and by average plasticity towards residence that was counter-acted by average selective disappearance of sub-adult residents. However, these cross-cohort means obscured substantial among-cohort variation in the initial degree of partial migration, and in subsequent joint effects of plasticity and selective disappearance. Here, plasticity and selection were not systematically associated within or across cohorts or ages, but rather reinforced versus counter-acted each other at different times, thereby reshaping the pattern of among-cohort variation in partial migration across ages. These results demonstrate that an absence of overall age-specific change in a key life-history trait, seasonal migration versus residence, obscures substantial underlying variation in both early-life plasticity and selective disappearance, generating complex phenotypic dynamics within individual cohorts. Standard cross-cohort analyses may therefore inadequately predict future spatio-seasonal dynamics, since novel age-specific life-histories could readily emerge given changing environmental drivers of plasticity and selection.

Parasites are a fundamental component of wild animal populations, often inducing sub-lethal chronic effects that impact host fitness and demography. However, the factors determining variation in infection burden are often poorly understood in wild systems. Environmental conditions can determine exposure to infection and the resources required to respond, but exhibit strong temporal variation. As environmental conditions are predicted to become more variable, it is crucial to understand how these conditions shape burden to predict the downstream effects on host populations. Early-life conditions can shape responses to infection, potentially leading to delayed effects of environmental variation on fitness. The extent to which these are mediated by resources and later-life conditions remains unclear and may vary between the sexes, who often differ in exposure risk and resource requirements. Here, we examine how differences in hatching and breeding conditions influence parasite burden throughout life. We utilise data from a long-term population study of European shags (Gulosus aristotelis) on the Isle of May, Scotland, in which there is substantial variation in the timing of breeding within and between years, and nematode parasite burden can be measured in vivo using endoscopy. We show that adult parasite burden is influenced by seasonal and annual differences in current and early life conditions, but different patterns were observed in adult males and females. Burdens increased across the season in chicks and adult females but not in adult males. Instead, early life effects better explained burden in adult males, with those hatching later and in productive years displaying lower burdens. This suggests that early life may shape behaviour, immunity, or physiological development, impacting subsequent infection. Our findings reveal complex temporal effects on parasitism in species breeding in fluctuating environments. Incorporating seasonal and sex-specific responses to parasitism is crucial to understanding how predicted environmental shifts could impact disease dynamics.

In iteroparous, socially monogamous species, individuals vary in the extent of mate fidelity across breeding attempts, often with important fitness consequences. Numerous studies have demonstrated intrinsic drivers of mate fidelity, notably previous breeding success and parental age. Environmental conditions may also influence mate fidelity, and the habitat-mediated hypothesis predicts that fidelity will be lower when environmental conditions are poor. However, limited testing of this hypothesis has been undertaken in longitudinal studies of single populations. Furthermore, studies have mainly focused on environmental conditions during the breeding season, yet conditions prior to breeding may be important for mate fidelity because this is a critical period for pair bond formation. We investigated the effects of prebreeding environmental conditions (onshore wind component and sea surface temperature) on mate fidelity over a 20-year period in the socially monogamous, iteroparous, long-lived marine bird, the European shag, Gulosus aristotelis. Average fidelity rate varied three-to four-fold between years. Mate fidelity was affected by prebreeding environmental conditions, being lower when onshore winds were more prevalent and sea surface temperature was higher. However, mate fidelity was more strongly affected by intrinsic factors, with higher rates when breeding success in the previous attempt and population density were higher, and among older females and middle-aged males. We found that mate fidelity affected timing of breeding, with faithful pairs laying earlier, and early laying pairs bred more successfully, but there was no independent effect of mate fidelity on breeding success. Our results support the habitat-mediated hypothesis whereby prebreeding environmental conditions affect individual pairing decisions. Given environmental conditions are predicted to change globally, further investigation of their impact on aspects of social behaviour in a range of species is warranted. Crown Copyright (c) 2025 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour. This is an open access article under the CC BY license (http://creativecommons.org/licenses/ by/4.0/).

Arguably, the most fundamental question in population ecology is what drives patterns in the abundance of populations? Small rodents exhibiting regular multiannual cycles in abundance have long been a test bed for addressing this question. The prevailing orthodoxy, the predation hypothesis, contends that nonmigratory, specialist predators are necessary, and specialist and generalist predators, combined, are both necessary and sufficient, for causing population cycles. Thus, variations in survival, from predation, are the key drivers of the cycles. However, this, and other competing theories, have hitherto lacked supportive demographic evidence and hence a solid evidential foundation. Here, we provide such evidence, analyzing 10 y of monthly data from a cyclic field vole population. We find, contrary to the prevailing orthodoxy, that recruitment, not survival, varied substantially from phase to phase in the cycles, made the major contribution to variations in population growth rate, and had cycle-phase-specific negative delayed density dependence. These results, their consistency with what is known from other systems, and the weak demographic foundations of the predation hypothesis, together suggest recruitment, specifically breeding-season length, not predation, as the cycles' driving force. They therefore suggest that re-evaluation of the importance of the various determinants of population abundances, more generally, may be necessary.

We present a genome assembly from an individual female Gulosus aristotelis, previously known as Phalacrocorax aristotelis, (the European shag; Chordata; Aves; Pelecaniformes; Phalacrocoracidae). The genome sequence is 1,279.1 megabases in length. Most of the assembly is scaffolded into 36 chromosomal pseudomolecules, including the Z and W sex chromosomes. Gene annotation of this assembly on Ensembl identified 16,474 protein coding genes. The mitochondrial genome has also been assembled and is 18.61 kilobases in length.

There is increasing research interest in bio or socio-cultural approaches in the context of infectious disease challenges, predicated on the notion that addressing health inequities in poor and marginalised populations requires nuanced, place-based understanding of the burden and impacts of health problems and associated factors determining health status and outcomes. Yet, to date, there is no systematic synthesis of how extant studies have used a biocultural approach to characterise social vulnerability in the context of zoonoses affecting humans, especially in low-and middle-income countries (LMICs). We conducted a scoping review of the scientific literature that have applied biocultural approaches within zoonoses research from LMICs. In total 43 studies were reviewed mostly from Africa (n = 24), followed by Asia (n = 12) and Latin America (n = 1). Ebola virus disease (n = 13) was the topmost disease of research interest, with reported studies mostly led by authors affiliated to Global North higher education institutions (particularly in the USA). Overall, the review showed that place-based differences and cultural systems are important determinants of vulnerability to many reported disease hazards across LMIC settings. Biocultural approaches are not holistically considered within zoonoses research and largely inclined towards the ‘cultural’ (n = 38) relative to the ‘biological’ (n = 5) aspect that influenced place-based resource use and health decision-making. The top three biocultural categories used were: livelihood practices, beliefs and knowledge systems. Twenty-five social vulnerability indicators (categorised into 6 components) were identified of which at-risk population demography (e.g. children, % of adults), education and socioeconomic status were commonly reported. Altogether, the review highlights the untapped potential of bio-culturally-informed research in advancing granular, place-based understanding of the complex socioecological, political and cultural factors that can lead to differences in disease vulnerabilities and capacities of different populations to adapt.

Kyasanur forest disease virus (KFDV) is a tick-borne flavivirus causing debilitating and potentially fatal disease in people in the Western Ghats region of India. The transmission cycle is complex, involving multiple vector and host species, but there are significant gaps in ecological knowledge. Empirical data on pathogen-vector-host interactions and incrimination have not been updated since the last century, despite significant local changes in land use and the expansion of KFD to new areas. Mathematical models predict that transovarial transmission, whereby adult female ticks pass KFDV infections to their offspring, plays an important role in the persistence of KFD, but this has not been shown in the wild. Here we set out to establish whether transovarial transmission of KFDV was occurring under natural field conditions by assessing whether host-seeking larvae were positive for KFDV. Ticks were sampled by dragging and flagging across a broad range of habitats within the agro-forest matrix at 49 sites in two districts: Shivamogga, Karnataka and Wayanad, Kerala (September 2018-March 2019), and larvae were tested for KFDV by PCR. In total, larval ticks from 7 of the 49 sites sampled tested positive for KFDV, indicating that transovarial transmission is occurring. Of the 13 KFDV-positive larval samples, 3 came from around houses and gardens, 5 from crops (3 from harvested rice paddy and 2 from areca plantation), 1 from teak plantation and 4 (2 from 1 transect) from forests. Five different tick species were found to have KFDV-positive larvae: Haemaphysalis spinigera, H. bispinosa, Rhipicephalus annulatus, R. microplus and an unidentifiable species of Haemaphysalis (no close match in GenBank). Our empirical confirmation of transovarial transmission has important implications for understanding and predicting KFD dynamics, suggesting that ticks may act as a reservoir for KFDV. Moreover, small mammals and cattle may play crucial roles in transmission if small mammals are the main hosts for larvae infected via transovarial transmission, and cattle support large numbers of infected female adult ticks. This first report of transovarial transmission of KFDV, and within a hitherto undescribed range of vectors and habitats, will help disease managers improve KFD surveillance and mitigation strategies, ultimately leading to communities becoming more resilient to the risk of this tick-transmitted disease.

We present a genome assembly from an individual female Gulosus aristotelis, previously known as Phalacrocorax aristotelis, (the European shag; Chordata; Aves; Pelecaniformes; Phalacrocoracidae). The genome sequence is 1,279.1 megabases in length. Most of the assembly is scaffolded into 36 chromosomal pseudomolecules, including the Z and W sex chromosomes. Gene annotation of this assembly on Ensembl identified 16,474 protein coding genes. The mitochondrial genome has also been assembled and is 18.61 kilobases in length.

Theory predicts that high population density leads to more strongly connected spatial and social networks, but how local density drives individuals' positions within their networks is unclear. This gap reduces our ability to understand and predict density-dependent processes. Here we show that density drives greater network connectedness at the scale of individuals within wild animal populations. Across 36 datasets of spatial and social behaviour in >58,000 individual animals, spanning 30 species of fish, reptiles, birds, mammals and insects, 80% of systems exhibit strong positive relationships between local density and network centrality. However, >80% of relationships are nonlinear and 75% are shallower at higher values, indicating saturating trends that probably emerge as a result of demographic and behavioural processes that counteract density's effects. These are stronger and less saturating in spatial compared with social networks, as individuals become disproportionately spatially connected rather than socially connected at higher densities. Consequently, ecological processes that depend on spatial connections are probably more density dependent than those involving social interactions. These findings suggest fundamental scaling rules governing animal social dynamics, which could help to predict network structures in novel systems.

Emerging infectious diseases are of major concern to animal and human health. Recent emergence of high pathogenicity avian influenza virus (HPAIV) (H5N1 clade 2.3.4.4b) led to substantial global mortality across a range of host species. Co-occurring species showed marked differences in mortality, generating an urgent need for better epidemiological understanding within affected populations. We therefore tested for antibodies, indicative of previous exposure and recovery, and for active viral infection in apparently healthy individuals (n = 350) across five co-occurring seabird species on the Isle of May, Scotland, during 2023, following H5N1 HPAIV associated mortality in the preceding summer. Antibody prevalence to AIV subtypes varied substantially between species, ranging from 1.1% in European shags (Gulosus aristotelis) (to H5) to 78.7% in black-legged kittiwakes (Rissa tridactyla) (to H16 or both H13 and H16), and between 31 and 41% for three auk species (H5, H16 or both). At least 20.4% of auks had antibodies to an as yet unidentified subtype, suggesting further subtypes circulating in the population. We found low levels of active, but asymptomatic, AIV infection in individuals (1.6–4.5%), but excluded this as H5N1. Our results emphasise the importance of testing healthy individuals to understand the prevalence of co-circulating AIV subtypes in wild populations, and the potential for future reassortment events which could alter virus behaviour and impact.

Understanding the maintenance and dynamics of phenotypic polymorphisms requires unpicking key ecological mechanisms shaping the fitness costs and benefits of expressing alternative phenotypes, generating selection. Seasonal migration versus year-round residence expressed in partially migratory populations represents one common polymorphism that can experience strong selection through differential reproductive success. Yet, key hypothesised pathways that could generate such selection remain to be empirically tested. One hypothesis is that migratory tactics affect subsequent reproductive success through carry-over effects on breeding site retention and resulting breeding dispersal. By remaining in breeding areas all year round, residents could retain their preferred breeding site between years, and consequently have higher reproductive success. Conversely, migrants that escape harsh non-breeding season conditions could return in better condition, with high resource holding potential, and outcompete residents to retain their site. Such effects could further depend on migration timing and vary between years. Yet, such pathways have not been quantified, precluding empirical parameterisation of partial migration theory. We used 4 years of breeding and non-breeding season data from partially migratory European shags (Gulosus aristotelis) to test whether the three most frequent migratory tactics in this population (full resident, early migrant departing soon after breeding, and late migrant departing in late autumn) differed in their breeding site retention; whether site retention predicted reproductive success; and hence whether effects of migratory tactic on reproductive success were explicable through site retention. Overall, residents were much more likely to retain their breeding site between years than both early and late migrants, and site retention was associated with increased reproductive success. Yet, these effects varied somewhat among years: late migrants were always least likely to retain their site but had variable relative reproductive success. Path analyses revealed that effects of migratory tactic on reproductive success were only partly attributable to breeding site retention. These results indicate that multiple mechanisms underlie reproductive selection on migratory tactics, potentially contributing to maintaining behavioural polymorphisms. Yet, the clear associations between migratory tactics and local breeding dispersal reveal that these movements can be strongly interlinked across seasons, shaping overall spatioseasonal dynamics in partially migratory systems.

Eco-evolutionary responses to environmentally induced selection fundamentally depend on magnitudes of genetic variation underlying traits that facilitate population persistence. Additive genetic variances and associated heritabilities can vary across environmental conditions, especially for labile phenotypic traits expressed through early life. However, short-term seasonal dynamics of genetic variances are rarely quantified in wild populations, precluding inference on eco-evolutionary outcomes in seasonally dynamic systems. This limitation applies to seasonal migration versus residence, constituting one key trait where rapid microevolution could rescue partially migratory populations from changing seasonal environments. We fitted novel quantitative genetic 'capture-recapture animal models' to multi-generational pedigree and year-round resighting data from 11 cohorts of European shags (Gulosus aristotelis), to estimate season-specific additive genetic variances in liabilities to migrate, and in resulting expression of migration, in juveniles' first autumn and winter. We demonstrate non-negligible genetic variation underlying early-life migration, with twice as large additive genetic variances and heritabilities in autumn than winter. Since early-life survival selection on migration typically occurs in winter, highest genetic variation and strongest selection are seasonally desynchronized. Our results reveal complex within- and among-year dynamics of early-life genetic and phenotypic variation, demonstrating that adequate inference of eco-evolutionary outcomes requires quantifying microevolutionary potential on appropriate scales and seasonal timeframes.

1. Population dynamic and eco-evolutionary responses to environmental variation and change fundamentally depend on combinations of within- and among-cohort variation in the phenotypic expression of key life-history traits, and on corresponding variation in selection on those traits. Specifically, in partially migratory populations, spatio-seasonal dynamics depend on the degree of adaptive phenotypic expression of seasonal migration versus residence, where more individuals migrate when selection favours migration. 2. Opportunity for adaptive (or, conversely, maladaptive) expression could be particularly substantial in early life, through the initial development of migration versus residence. However, within- and among-cohort dynamics of early-life migration, and of associated survival selection, have not been quantified in any system, preventing any inference on adaptive early-life expression. Such analyses have been precluded because data on seasonal movements and survival of sufficient young individuals, across multiple cohorts, have not been collected. 3. We undertook extensive year-round field resightings of 9359 colour-ringed juvenile European shags Gulosus aristotelis from 11 successive cohorts in a partially migratory population. We fitted Bayesian multi-state capture-mark-recapture models to quantify early-life variation in migration versus residence and associated survival across short temporal occasions through each cohort's first year from fledging, thereby quantifying the degree of adaptive phenotypic expression of migration within and across years. 4. All cohorts were substantially partially migratory, but the degree and timing of migration varied considerably within and among cohorts. Episodes of strong survival selection on migration versus residence occurred both on short timeframes within years, and cumulatively across entire first years, generating instances of instantaneous and cumulative net selection that would be obscured at coarser temporal resolutions. Further, the magnitude and direction of selection varied among years, generating strong fluctuating survival selection on early-life migration across cohorts, as rarely evidenced in nature. Yet, the degree of migration did not strongly covary with the direction of selection, indicating limited early-life adaptive phenotypic expression. 5. These results reveal how dynamic early-life expression of and selection on a key life-history trait, seasonal migration, can emerge across seasonal, annual, and multi-year timeframes, yet be substantially decoupled. This restricts the potential for adaptive phenotypic, microevolutionary, and population dynamic responses to changing seasonal environments.

High population density should drive individuals to more frequently share space and interact, producing better-connected spatial and social networks. Despite this widely-held assumption, it remains unconfirmed how local density generally drives individuals' positions within wild animal networks. We analysed 34 datasets of simultaneous spatial and social behaviour in >55,000 individual animals, spanning 28 species of fish, reptiles, birds, mammals, and insects. >80% of systems exhibited strongly positive relationships between local density and network centrality, providing broad empirical evidence that local density increases connectedness at the individual level. However, >75% of density-connectedness relationships were nonlinear, and density's importance declined at higher values in >70% of systems, signifying saturating effects. Density's effect was much stronger and less saturating for spatial than social networks, suggesting population density drives individuals to become disproportionately spatially connected rather than socially. These findings reveal fundamental trends underlying societal structuring, with widespread behavioural, ecological, and evolutionary implications. ### Competing Interest Statement The authors have declared no competing interest.

BACKGROUND:Traditional medicine (TM) interventions are plausible therapeutic alternatives to conventional medical interventions against emerging and endemic zoonotic diseases, particularly in low-and middle-income countries that may lack resources and infrastructure. Despite the growing popularity in the usage of TM interventions, their clinical safety and effectiveness are still contested within conventional healthcare in many countries. METHODS:We conducted a scoping review of the peer-reviewed literature that synthesises and maps the evidence on TM interventions for the treatment and prevention of zoonoses on the Indian subcontinent. The region, a global hotspot of biodiversity and emerging infections, is characterised by high prevalence of TM use. Based on the scientific literature (mostly case study research, n=l06 studies), our review (1) maps the scope of the literature, (2) synthesises the evidence on the application of TM interventions for zoonoses, and (3) critically reflects on the state of TM and identifies areas for future research focus. RESULTS:The evidence synthesis confirmed widespread usage of TM interventions for zoonoses on the subcontinent, with the majority of research reported from India (n=99 studies, 93.4%), followed by Pakistan (n=3 studies, 2.8%), Bangladesh (n=2 studies, 1.9%), and Sri Lanka (n=1, 0.9%). Most of the reviewed studies reported on ethno-medicinal uses of plant species, primarily for treating dengue (n=20 studies), tuberculosis (n=18 studies), Escherichia coli infection (n=16 studies), lymphatic filariasis and cholera (n=9 apiece). However, the evidence on the safety and effectiveness of these reported TM interventions is limited, indicating that these data are rarely collected and/or shared within the peer-reviewed literature. CONCLUSION:This review thus highlights that, whilst TMs are already being used and could offer more widely accessible interventions against emerging and endemic zoonoses and ectoparasites, there is an urgent need for rigorous clinical testing and validation of the safety and effectiveness of these interventions.

The risk of spillover of zoonotic diseases to humans is changing in response to multiple environmental and societal drivers, particularly in tropical regions where the burden of neglected zoonotic diseases is highest and land use change and forest conversion is occurring most rapidly. Neglected zoonotic diseases can have significant impacts on poor and marginalised populations in low-resource settings but ultimately receive less attention and funding for research and interventions. As such, effective control measures and interventions are often hindered by a limited ecological evidence base, which results in a limited understanding of epidemiologically relevant hosts or vectors and the processes that contribute to the maintenance of pathogens and spillover to humans. Here, we develop a generalisable next generation matrix modelling framework to better understand the transmission processes and hosts that have the greatest contribution to the maintenance of tick-borne diseases with the aim of improving the ecological evidence base and framing future research priorities for tick-borne diseases. Using this model we explore the relative contribution of different host groups and transmission routes to the maintenance of a neglected zoonotic tick-borne disease, Kyasanur Forest Disease Virus (KFD), in multiple habitat types. The results highlight the potential importance of transovarial transmission and small mammals and birds in maintaining this disease. This contradicts previous hypotheses that primates play an important role influencing the distribution of infected ticks. There is also a suggestion that risk could vary across different habitat types but currently more research is needed to evaluate this relationship. In light of these results, we outline the key knowledge gaps for this system and future research priorities that could inform effective interventions and control measures.