Core-periphery structure of a medicinal botanical system in Uruguay

Abstract

Background

Human evolution has granted upon an individual’s cognitive mechanisms necessary for remembering experiences, vital for both survival and reproduction. These experiences manifest into cultural traits, influencing human culture, particularly in healthcare and maintenance. Studies regarding medicinal plants and treatments are integral to the study of the medical botanical system. Pharmacopeias highlight the prevalence of specific species widely used, aligning with the “consensus within diversity theory” in evolutionary ethnobiology. Within the framework of this theory, we reflect on the results we’ve achieved in a priority area recognized by UNESCO for its biocultural significance, both locally and regionally.

Methods

This study integrated network analysis and qualitative methods to examine the botanical medical system of “Parque Regional Quebradas del Norte” in Rivera, Uruguay.

Results

Study results demonstrate a core-periphery structure, with a strongly interconnected core resistant to fragmentation, ensuring structural stability. Additionally, the presence of peripheral nodes throughout the system was identified, enhancing the resilience of the botanical medicinal system against potential disturbances.

Conclusion

The core species renowned for their versatility and multiple medicinal uses, treating less severe ailments effectively. Additionally, core plants serve as prototypes for innovations. Their extinction poses a threat to the system’s resilience. Conversely, peripheral plants, though vulnerable, offer possibilities for therapeutic innovations. In the face of environmental change, conservation efforts should prioritize species that are vulnerable to extinction, particularly within the core. Simultaneously, preserving knowledge associated with peripheral plants presents a bicultural conservation strategy, ensuring the botanical system’s robustness among evolving ecological conditions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13002-024-00739-z.

Introduction

Throughout the course of adaptation, humans have developed cognitive processes to confront the difficulties presented by nature. As a result, natural selection has played a crucial role in shaping individuals’ psychological structure, enabling them to remember experiences and enhance their ability to survive. Sensations and perceptions are naturally interpreted to create a response to difficult and stimulating environments [1–4]. Nairne and Pandeirada [3] propose that experiences are generationally remembered, integrated into an adaptive memory system. It has been documented that cultural features respond to situations of risk, partner preference, illness prevention, healing processes and illness therapies [5–9]. These cultural traits are transmitted within a population through various pathways or mechanisms of knowledge diffusion: (a) from parents to children (vertical); (b) among peers of the same generation (horizontal); (c) between generations, excluding the parenteral route (oblique); (d) from a prestigious individual or a means of communication to many individuals in a group (one-to-many); (e) from the elderly to the younger individuals in a population (many-to-one) [10, 11]. Furthermore, according to Berkes [12], cultural traits can be interpreted as “products of generations of intelligent reflection tested in the rigorous laboratory of survival, whose persistence is evidence of their power.” However, the prevalence of a cultural trait in a population can either remain stable or change dramatically over time, depending on the type of information, transmission mechanisms, population size and the environmental context [4, 9, 13]. These can be classified as cultural norms (e.g., continuous cultural traits), knowledge about resources, techniques and tools (e.g., quantitative cultural traits) and cultural innovations (e.g., novel cultural traits) [6, 14, 15]. The body of knowledge about plants and treatments used for a therapeutic purpose constitutes a quantitative cultural trait [6, 14, 15]. If this trait were preserved in human adaptive memory, it could potentially enhance the population’s quality of life [1–3]. In this context, the structure, function, type and frequency of trait transmission could have a vital role [1, 6, 16–18]. The collection of medicinal plants, related treatments, and knowledgeable users can be regarded as the primary components of a medical botanical system within a community [5, 19].

Patterns related to the selection of medicinal plants in pharmacopoeias have shown a marked prevalence of certain botanical families. This convergence phenomena in usage are attributed to the action of some factors alone or acting in combination: (i) the presence of prominent organoleptic characteristics [16, 17, 20–22], (ii) being associated with a doctrine of signatures [23], (iii) therapeutic effectiveness [24, 25], (iv) environmental availability and accessibility [26].

The core-periphery structure

The organization in a core-periphery structure demonstrates the tendency of the medical botanical system to form a specific group of plants mostly used by the majority of users. From the perspective of evolutionary ethnobiology and cultural evolution, it can be associated with the “consensus within diversity theory” (see also [27]) and “cultural attraction theory” (see, e.g., [4]) [5]. Moving to a more specific perspective, regarding medical botanical systems in particular, it is termed “core kit” [18, 28, 29], “ensemble” [30, 31], or “plant complexes” [32]. Concerning the process of incorporating new plants, according to some theories, it is interpreted as an event that allows expanding the “stock” of therapeutic possibilities [18]. It has been proposed that the phenotype and organoleptic characteristics of frequently used plants (i.e., the core) would serve as prototypes for the incorporation of new plants into the medicinal system [18, 32–34]. In summary, the integration of new plants would be incorporated by connecting them to the core, and their few connections with the rest of the system would place them in a peripheral location, resulting in less widespread transmission of knowledge [16–18, 22, 27, 31, 35]. Finally, this pattern of medicinal system growth is consistent with a core-periphery structure reported in other natural systems [36–40].

To describe and explain this phenomenon, we propose a methodological approach using network analysis. This approach is based on graph theory and provides a relevant framework for understanding complex systems in general [41, 42] and ethnobotanical knowledge systems in particular [35, 43, 44]. An advantage of the methodological approach is its ability to describe and explain network data through abstract models, enabling the representation of a complex reality [41, 42, 45] and visualizing how individuals engage with natural resources to identify patterns of interaction [35, 46]. Furthermore, this approach provides a valuable tool for ethnographic studies seeking to unravel this complexity [47].

In this way, network analysis enables the detection of patterns in complex systems by representing a wide range of natural phenomena, such as interaction networks [41]. This approach has allowed us to reveal the presence of a core-periphery structure in a medical botanical system. This is composed of a basic set or “Kit” of medicinal plants that form a structural core [18, 27, 31, 35, 48]. Furthermore, this phenomenon of organizing interactions around a structural core is widely recognized in various complex systems [36–40]. In addition, this has allowed us to understand the determinants of agent cohesion and dispersion in an interaction network, as well as their effects on system functioning [36]. From a network theory and analytical perspective, the existence of a core corresponds to a group of nodes strongly interconnected with each other, which cannot be easily fragmented or divided, thus providing structural stability. The stability of the core also promotes the stability of peripheral nodes and, consequently, the overall system [36–40].

Medical botanical systems can be analyzed as graphs represented in a matrix where the rows contain the plants and the columns contain knowledgeable users [35, 43, 49, 50]. And particularly, medicinal plants can be related to the users as well as the diseases or therapeutic objectives associated with them [44]. This suggests, from the theory of complex networks, there are strong reasons to expect core-periphery assemblies in ethnobotany and it is noteworthy that ethnobotanical theory itself has predicted this pattern [18, 21, 31, 43]. Furthermore, the presence of a core structure is related to the system’s stability and its ability to withstand disturbances, ensuring the population’s health [38]. This property becomes particularly relevant when considering the erosion processes reported in traditional knowledge systems experienced by some populations [44, 51, 52]. Thus discovering a structure that provides stability could contribute to biocultural conservation goals [53].

Our hypothesis suggests that adaptive memory preserves quantitative cultural traits, such as those associated with a select group of beneficial medicinal plants present in medical botanical systems, which contribute to safeguard and improve population quality of life. These plants have been identified by most users, establishing a consensus core. By reaffirming the information that is circulating among users, the consensus in usage ensures that it is transmitted culturally and strengthens the system in the face of possible disturbance scenarios. From this hypothesis, we predict first: medicinal botanical systems present a “basic kit” of plants that is visualized as a structural core; second: core plants are more resistant and third: the versatility of uses is associated with belonging in the structural core, with prioritization of knowledge transmission, and therefore, with the conservation of their use.

Finally, the objectives of this study contribute to applied ethnobiology in biocultural conservation by embracing the theory of “consensus within diversity” [27], as summarized by Ferreira Júnior et al. [18], and demonstrated in various ethnobotanical research (e.g., [21, 31, 35]). To achieve this, we use theoretical framework and network methodology within a unique biocultural setting, such as the “Parque Regional Quebradas del Norte” in Rivera, Uruguay. We aim to elucidate some aspects of the intricate interactions between individuals and medicinal botanical resources comprising the medicinal botanical system. The identification of overarching patterns, such as the core-periphery structure, facilitates a deeper comprehension of the factors that influence botanical resource selection and utilization.

Materials and methods

Study area

In 2011, a total of 110,882 hectares within the Department of Rivera (55° 33′ 2.74″ W; 30° 54′ 19.22″ S), Uruguay, were designated as the “UNESCO Biosphere Reserve”, known as the “Parque Regional Quebradas del Norte”. This expansive area encompasses the localities of Rivera city, Tranqueras, Minas de Corrales, and Valle del Lunarejo, the latter is the central area of the biosphere reserve (Fig. 1). Moreover, it has a warm subtropical climate corresponding to category ‘Cfa’ according to the Köppen-Geiger classification [54, 55]. Renowned for its vast network of rivers, the reserve creates an ecosystem mosaic that includes a wide variety of tree species and grasslands dominated by the Poaceae, Fabaceae, Orchidaceae, and Asteraceae families [56]. Recognized for its significance in conservation, the reserve also seeks to maintain rural communities’ cultural heritage, particularly important practices associated with the ‘gaucho’ figure. Additionally, Uruguay is notable for its rural communities and people, who are known as ‘descendants of the ships’ and whose ancestry is mostly derived from waves of european migration and the african slave trade. Furthermore, as noted by Bonilla et al. [57], this population combines elements of various prehispanic cultures, which were originally made up of native groups belonging to the macroethnicity Charrúa/Guenoa and then later by the Guaraníes [58], resulting in a pluricultural context [59]. This trait is most pronounced in the northern regions of Uruguay, where the Department of Rivera, home to almost 100,000 people, is an example of this biocultural diversity [60]. Currently, over a quarter of the people residing in the rural area of Rivera engage in agricultural activities on family farms of less than 40 hectares, operating with limited investment resources. Production units sell their products directly in nearby populated centers. Given the need for investment in infrastructure, technical knowledge, and market access, this activity is primarily conceived for self-consumption and surplus sales, with limited capitalization achievements [61].

Fig. 1.

Location of Uruguay in South America. Map of Uruguay, Department of Rivera, and the main localities comprising the study area, highlighting the central area of the “Bioma Pampa-Quebradas del Norte Biosphere Reserve’s”

Ethnobotanical data collection

Ethnobotanical prospecting began in 2012, aiming to engage with community members who possess knowledge (i.e., local experts) in medicinal plants. Using these references, snowball sampling was employed to identify and interview forty-four participants, 17 men and 27 women, with an average age of 78 years [62]. Additionally, the snowball methodology determined the sample size, as it starts with an initial contact with a local expert, who is endorsed by the community as possessing knowledge. Subsequently, this expert indicates another, and thus all community experts become involved [63]. For all participants, we used semi-structured interviews (see: supplementary interview material) and participant observation method to record local knowledge [63, 72]. All the interviews were recorded generating audio files along with annotations in field notebooks. The interviews were transcribed, and a meticulous interpretation of the interlocutors’ perceptions regarding diseases, treatments, and the plants used (i.e., emic categories) was conducted. This led to building a categorization (i.e., etic categorization) in order to carry out the analyzes [63]. Thus, the 109 ailments mentioned have been categorized into 30 etic categories (e.g., “poor digestion” was categorized as gastrointestinal) (Table 2 supplementary material). Furthermore, the methodological approach adheres to the ethical principles of the International Society of Ethnobiology, which require obtaining informed consent and seeking permission to publish the data [64]. Throughout this study, we have engaged in discussions with each of the participants regarding the “inalienable character” of the information provided by the local population, including the exclusive use of recordings and images for the purposes of this research.

Features of the participants surveyed.

The participants in the interviews have knowledge of medicinal plants and related therapies. Most of them are low-income people who were raised in rural areas; some came to the city to explore possibilities for employment. Since childhood, the men have assisted their families in identifying and harvesting medicinal plants for resale in local markets and shipment to the city of Montevideo. Currently, they engage in selling medicinal plants by walking with their baskets along the main avenues of Rivera city. On the other hand, women from the area engage in various occupations such as cleaning, cosmetics sales, laundry services, handicraft sales, and elderly care. They supplement their income by selling medicinal plants, which they collect, dry, and package from their gardens. While their primary customers are their neighbors, they also occasionally sell plants at local markets. Additionally, a small number of interlocutors are engaged in agriculture and develop micro-tourism ventures as a complementary activity, where they share their knowledge of medicinal plants with visitors, adding value to the trails of their establishments.

Sample collection for medicinal plants studies

The ethnobotanical reference materials were obtained by soliciting a sample of each specimen from the interlocutors, who also guided the identification and collection of medicinal plants at the specified field sites. We identified the reference material using botanical keys, reference literature, and consulted with specialists [56, 65–67]. Scientific names were validated and updated through consultation with the following databases: [68–70]. Subsequently, reference specimens were deposited in the Herbarium of the National Museum of Natural History of Montevideo (MNHN) (voucher numbers: MVM 23201 to 23345) (also see Castiñeira Latorre et al. [44] for details on ethnographic methodology). Finally, in order to identify the main active compounds of the species in the structural core as well as their primary organoleptic qualities (taste and aroma), we reviewed the research available (Table 3 supplementary material).

Data analysis

Based on this information, an affiliation matrix X was compiled, consisting of interlocutors i (rows of the matrix) and medicinal plants j (columns of the matrix) (see also [44]). The elements x_ij represent the connection between an interlocutor i and a medicinal plant j. Therefore, if a link exists between i and j, the value of x_ij is 1, and if there is no link, x_ij is 0. For the affiliation network, the presence of a core-periphery structure was determined, identifying the species corresponding to each component [40]. Using the “k-cores” function from the R package “sna” (Tools for Social Network Analysis), we identify the core and periphery components in the affiliation network. That is, the k-cores function produces degree-based k-cores and returns a vector of core numbers. By definition, the k-core contains the higher order k + 1-core, while the periphery is defined by nodes in the k-core and not in the k + 1-core. The maximal subgraph is represented by a value $K_{\text{core}}^{max}$ of the largest order k-core, that is called the k-core number of the network, and it corresponds to the innermost core of the network. This subgraph is unique and extracted by iteratively pruning nodes with degree less than k (see Morone et al. [71]). In our analysis we used only the largest of the k-cores, hereafter called “core”, and the rest of nodes that do not occur in the largest core were considered as periphery. With the purpose of assessing the robustness of the components of the affiliation network, both the core and the periphery, and testing the hypothesis that the core of the medicinal system is preserved over time [18], we conducted a computational experiment. This experiment involved the random removal of interlocutors without replacement in the network of interlocutors vs. species of medicinal plants. After each removal, the proportion of plant species remaining within the core and periphery was quantified. Subsequently, the number of uses of medicinal plants (i.e., versatility) corresponding to the core was compared to the uses of medicinal plants corresponding to the periphery. The means were compared using unpaired t-tests. Lastly, a linear regression was employed to determine if more versatile plants are assigned by more interlocutors (i.e., popularity). The open-source R software system [73] was used for all studies. The “bipartite” package (which visualizes bipartite networks and calculates certain ecological indicators), the “sna” package (which offers tools for social network analysis), and the “igraph” package (which offers network analysis and visualization).

Results

A core-periphery structure was identified in the affiliation network. The maximal subgraph is represented by a value $K_{\text{core}}^{max}$ = 8 (Fig. 2, Table 1 supplementary material). Thirty-three of the 159 medicinal species comprise the core structure (Fig. 2, Table 1 supplementary material). This result is consistent with the first prediction of the hypothesis. The result of the removal experiment is consistent with the second prediction of the hypothesis and shows that the proportion of species that remain in the system is always higher in the core than in the periphery of the network (Fig. 3). With the removal of two interlocutors, 52% of the species are maintained in the core and 12% in the periphery. In this sense, with only 10 interlocutors, 100% of the core species and 50% of the periphery species are maintained. Regarding the third prediction of the hypothesis, it is observed that the plants in the core have a higher cumulative number of uses mentioned by interlocutors, in comparison to the plants in the periphery (${\overline{X}}_{\text{core}}$ = 20.88 vs. ${\overline{X}}_{\text{periphery}}$ = 3.89; t[12, 33] = 7.9; p < 0.001; Fig. 4). When exploring the relationship between popularity and versatility, a positive linear relationship was detected between the number of assigned uses and the number of interlocutors (F_{[1, 157]}  = 1225; r² = 0.89; p < 0.0001; Fig. 5). Finally, all species in the structural core exhibit organoleptic properties (aroma and taste), related to the presence of essential oils, phenolic compounds, and alkaloids (see Table 3, supplementary material).

Fig. 2.

The Bioma Pampa-Quebradas del Norte Biosphere Reserve’s ethnobotanical network, showing the species list that represents the core structure, links between interlocutors and medicinal plants, and a core-periphery structure

Fig. 3.

Experiments of removal. The percentage of core network species as a function of interlocutors count is shown by the dotted line, while the solid line shows the relationship with periphery species

Fig. 4.

Box plot shows the mean, standard deviations, and outliers of the number of uses for each species defined by core and periphery analysis

Fig. 5.

Correlation between the number of assigned uses and the number of interlocutors. Each point represents a medicinal species (n = 159)

Discussion

Through analyzing the biological [37, 39, 40, 73–75] and social [46, 47, 76–78] networks structures, we investigated the relationships between different concepts in network theorys [41, 42, 79]. Our results, which showed a core-periphery structure within the medicinal botanical system, were consistent with the fundamental ideas of ethnobotanical [18, 21, 31, 35, 80, 81], particularly with the “consensus within diversity” theory [18, 21, 27, 31, 35]. As it has been observed, most people agree to use a particular group of plants, within a wider range of medicinal plants. In Uruguay, other ethnobotanical studies conducted near our research area show a higher frequency of use for medicinal plants that are part of the structural core, which supports our results [82]. Moreover, a quantitative review of medicinal plants in the Patagonian Andes reports “a common body of botanical knowledge, called the Mapuche pharmacopoeia” [22]. In addition, these observations have also been highlighted for food botanical resources, such as the diversity of ethnospecies of “yuca” (Manihot esculenta) in rural communities [35].

Thus, employing network analysis methods, the reflections based on extensive ethnobotanical surveys agree with the core-periphery structure observed in this study [18, 28–32]. If the center-periphery structure is supported, the question arises: What might be the possible reasons for consensus on the core species? Suppose our adaptive memory is selective and has limitations in recalling the vast diversity of medicinal plants available. Our results indicate that some species are used more frequently than others, suggesting that the selection of medicinal plants is not a random process [1–3]. We observed how the core integrates herbaceous species (e.g., Baccharis trimera, B. articulata) and shrubs (e.g., Schinus molle, Blepharocalyx salicifolius, Scutia buxifolia) that are native and widely available in the environment, along with native species with limited availability (e.g., Stenachaenium sp.) and adventitious species that thrive under human intervention (e.g., Rosmarinus officinalis). This reaffirms an active selection behavior, which can be shaped by the environment (e.g., resource availability) but not determined by it [19, 83]. In addition, probably certain characteristics of plants such as aroma and flavor, considered organoleptic properties, contribute as mnemonic resources to remember prototype plants [16]. These prototype plants include traits that make them identifiable as medicinal, such as organoleptic properties that serve as memory aids, making it easier to remember them and directing research toward other, related plants [16, 17]. Especially in early learning (i.e., childhood and youth), these mnemonic resources aid in the organization and anchoring of complex information [2, 3]. These prototype plants are powerfully linked to the ideas of health by their aroma and flavor [21, 22]. Most of the plants in the core have at least one of these organoleptic properties: bitter taste and aroma, which are connected to the concentrations of phenolic, aromatic and alkaloids compounds [84, 85].

However, a limitation of the present study is that we have not investigated other characteristics that could be relevant for integration into the core [18]. In this context, Bennett [23] highlights the significance of the mnemonic resource associated with the doctrine of signatures, in which individuals recognize the therapeutic value of plants based on specific morphological characteristics. Despite receiving numerous criticisms (see Bennett [23]), there are studies that demonstrate significant correlations between morphology and cultural attributes associated with use [21]. Hilgert [31] showed sociocultural illnesses associated with the breaking of taboos and supernatural elements, where medicinal plants act as a vehicle for the curative procedures practiced by traditional healers. In summary, although most of the plants within the core exhibit distinctive organoleptic characteristics associated with their use and effectiveness, potentially making them the most suitable models for experimentation (according to Leonti [17]), it is still necessary to consider a perspective that addresses other cultural aspects.

Contributions to biocultural conservation

The phenomenon of loss of traditional knowledge is widely documented in the literature [51, 80, 86] and is linked to many factors, including the decline of the rural population, whose contact with natural resources is first-hand, the migration or death of traditional knowledge holders (shamans, elders) and the extinction of species [18]. These combined factors are evident in rural areas of Uruguay, where older people move to cities in search of basic services and take their traditional knowledge with them [61]. Furthermore, changes in the agricultural production matrix modify natural habitats, which contributes to the extinction of several species [87]. In this work, we report to a medical botanical system that presents a core-periphery structure, where the core is resistant to the loss of interlocutors (i.e., erosion or loss of traditional knowledge) and plants (i.e., local extinction of species). Therefore, the basic kit of medicinal plants is preserved and resistant to disturbances in a medical botanical system with this structure (see, e.g., [18]). According to the preserved nature of medicinal knowledge within the core plants, it is expected that these plants are prioritized in the transmission of ethnobotanical knowledge through a combination of various mechanisms (e.g., vertical, horizontal, radial, and oblique) [10, 11, 88]. In addition, it is observed that there is a similar proportion of native and adventitious plants, which is expected in multicultural societies [89, 90]. As has been observed, core knowledge is the most widespread and develops through a gradual accumulation of information over generations, providing the medical system with resilience against knowledge loss. This suggests the existence of a cultural heritage that combines indigenous knowledge (e.g., native plants) with the knowledge of the first immigrants who populated the countryside (e.g., adventitious plants) [57, 58]. According to Ferreira Júnior et al. [18], peripheral plants have the ability to persist throughout the system, serving as a reservoir or “stock” of information. Periphery plants could act as therapeutic inventions in reaction to new illnesses [1, 9, 91].

Our findings indicate that the plants which make up the core structure are the most well-known to the population (i.e., popular) and are attributed a higher number of treatments for various diseases (i.e., versatile plants). This allows us to interpret that versatility is an important characteristic for inclusion in the core structure. A similar pattern has been reported for communities in northeastern Brazil [92]. This trend could be explained by the presence of various secondary metabolites in some plants, which could be related to their action on a variety of therapeutic targets [92]. Therefore, plants used for a specific treatment without adverse health effects are perceived by populations as safe plants, facilitating greater experimentation and use for a wider range of treatments over time [18]. Furthermore, a relationship has been found between the severity of diseases and their associated treatments [9], as well as the maintenance of this information in adaptive memory. These findings confirm results obtained from the core structure, where popular medicinal plant therapies are used to treat frequent less severe ailments [91] and are maintained in the disturbance scenarios. Even though there are regular hospital rounds in the rural Rivera area and access to industrialized drugs, locals choose to treat their illnesses with a combination of official medical practices and the traditional medicinal plant system. In this context, the medicinal botanical system is primarily used to treat mild illnesses.

The plants included in the core are mostly utilized to treat disorders of the kidneys and digestive system (e.g., Equisetum giganteum, Matricaria recutita), enhance blood circulation (e.g., Scutia buxifolia). Moreover, many diseases are linked to the typical Uruguayan rural diet, which is high in calories and saturated fats and mostly consists of sheep and cattle meat. Yet, for a comprehensive interpretation of the phenomenon, future considerations should include information on disease prevalence and culturally perceived effectiveness [53, 93].

Finally, we explored a region with high priority for biocultural conservation (sensu Gavin et al. [94]) employing an interdisciplinary approach that integrated various fields of knowledge, including ethnographic, ecological and network analysis [43]. Our goal was to investigate the concept of “consensus within diversity” as proposed by Barrett [27] and further developed by Ferreira Júnior et al. [18]. The outcomes of this investigation provide valuable insights for developing strategies that prioritize efforts and underscore the urgency of preserving prototype plants within the core as well as potential innovations within the periphery of medicinal botanical systems. On one hand, core plants act as prototypes for other potential species, and their loss by extinction could significantly affect the system’s resilience. On the other hand, peripheral plants are highly vulnerable but may offer possibilities for therapeutic innovations, especially in the face of changing scenarios. Addressing this dilemma could benefit from an examination of medicinal treatments associated with core and peripheral plants, taking into consideration disease prevalence within medicinal botanical systems. In view of social and environmental change, the information on the structure of the botanical medical system (i.e., core and periphery) can guide strategies for the conservation of biocultural heritage. In this sense, it could be suggested that conservation efforts should be concentrated on vulnerable to extinction species mainly of the core and on people’s knowledge from the peripheral plants as a biocultural conservation strategy (sensu Gavin et al. [9]).

Conclusion

This contribution shows the interactions between components of biodiversity and culture in the context of medicinal botanical systems in an area of relevance for biocultural conservation in Uruguay and the region. Through the analysis of biological and social networks, we have confirmed the existence of a core-periphery structure within this system, highlighting the presence of a core of widely used medicinal plants and a periphery that acts as a reservoir of information and potential source of therapeutic innovation.

Our findings support the theory of “consensus within diversity”, demonstrating how the majority of people agree on the use of a specific set of plants within a wide range of options. Additionally, we have reported how certain organoleptic characteristics, such as aroma and taste, influence the selection and memorization of prototype medicinal plants.

In terms of biocultural conservation, our study emphasizes the importance of protecting the central species of the medicinal botanical system, which act as fundamental pillars of community health and resilience to environmental and social disturbances.

Author contributions

EC designed the article and drafted the main text with the assistance of AB and AC. EC conducted field studies and various stages of research, obtaining results, including outreach activities in communities. AB and AC performed network analyses. All authors have read and approved the current manuscript version.

Funding

This work was partially funded by the foreign postgraduate Scholarship Program of the Agencia Nacional de Investigación e Innovación (ANII), Uruguay (Grant No. POS_EXT_2013_1_13495).

Availability of data and materials

All data used in this review can be found in the additional files.

Declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.