Biocultural key species: an assembly of biotic resources with biocultural importance


 Background

The cultural importance assigned to biodiversity is a complex subject, its study has been developed from ethnobotany and ethnomicology, mainly. A new proposal to address cultural importance is from the biocultural key species. Therefore, integrating information on the knowledge and use of various biological groups, the species with the greatest cultural relevance were selected.
Methods

An index (BKSI: Biocultural Key Species Index) was integrated, which assesses the relevance based on general attributes associated with fauna, flora and funga. The study was carried out in the Náhuatl community called El Barco, Lolotla; in the Huastec Hidalguense region. Field work was carried out for two years (2018–2019) with 24 field trips. Percentage ethnographic method combined with snowball (10% of the population) were applied; and as the ethnographic tool multiple free listings (n = 50) were used.
Results

In total of 335 species associated to 537 traditional names in Spanish and indigenous language (Náhuatl) are reported, that belongs to different biological groups (fungi and plants; fish, amphibians, reptiles, birds and mammals). The biocultural relevance degree was categorized respect to the obtained value in the index (BKSI); a representative set of each biological group was selected, being those with the highest biocultural relevance.
Conclusions

It is proposed that these species constitute a useful tool in the application of programs that promote the conservation of diversity from a biocultural approach; they may even promote the proper use of resources or biological restoration.

relatively new trend that proposes the comprehensive recognition and conservation of socioecological relationships and biodiversity [25][26].
Combining the different terms to define and name this type of species, it is proposed to use the term biocultural key species [20]. Based on the aforementioned conceptual proposals, we define them as: "those species that function as icons and can constitute cultural bases at different scales (local, regional or national), have a prominent place in cultural roles or domains (anthropocentric categories), can be represented by a species, but generally it is a set or assembly; because you can have representative species of different taxonomic ranges; and they are strongly related at the cognitive and pragmatic level on certain spatio-temporal scales. They must maintain the species/ethnospecies relationship as a real ethnobiological entity, understood as the correlation between taxonomic identification (species) and its cultural correspondent, which is generally equivalent to its traditional name or cultural assignment".
Cultural importance is a very complex subject from which we are far from understanding how it works, due to its complexity and nature that varies depending on the cosmovision, the local biota, beliefs, education, technological access, level of development of the communities, infrastructure, access to public health, economic activity, commerce, religion, uses and customs, among multiple variables; of people from the same place and the dynamics with their environment. However, the methodological approach that ethnobiology proposes for its understanding is a tool that brings us closer to its approach. For this reason, in this work the term of cultural importance is replaced by biocultural relevance, being understood as the value that a human group assigns to a species/ethnospecies or a set of these.
The methodological approach of cultural importance from ethnobiology helps to select species at a quantitative level important for a certain place and human group. Therefore, based on the traditional methodological conjugation and the new concepts, an index can be designed that provides a metric for its identification and selection. Based on a case study carried out in the Huastec area, in the state of Hidalgo, Mexico (with the native group Náhuatl), the known, named and used biodiversity was documented, a general attribute index was designed for all biological groups (fungi and plants; fish, amphibians, reptiles, birds and mammals) integrated by some already proposed sub-indexes and complemented with some that were designed; the index was applied and the set of biodiversity of greatest biocultural relevance was quantitatively determined. The index includes five variables, which are: frequency of mention by rank-abundance (FMR-A), average mention order (AMO), richness of traditional names (RTN), value of total uses/parts used (VTU/PU) and origin of the species (O). The present work contributes to the topic of cultural relevance and biocultural key species, making an integration between both concepts and proposing a standard and simple metric that provides a quick (quantitative) approach to the selection of species/ethnospecies more relevant at biocultural level.

Study area
The Huastec belongs to the historical Mesoamerican region [27]; culturally it is characterized by the confluence of various indigenous groups [28]; being Náhuatl the majority group [29].
The Huastec has a rugged topography derived from its geological formation, with elevations ranging from sea level to over 2,000 meters above sea level; which directly influences a variation of climates and high biological diversity [30]. The community of El Barco, Lolotla,

Field work and species taxonomic identification
The community of El Barco was visited for two years (January 2018 to December 2019) with a total of 24 field trips. The criteria of selection were by their type of vegetation, geographic location, degree of cover vegetation, roads to access the community and a high percentage of speakers of the indigenous language (Náhuatl, [32]). The project was previously presented to local authorities and approved through a community assembly for its development. Also, free informed consent was obtained prior at each interview (International Society of  Nahuas. The region is predominant for its warm-humid climate. The ethnographic method (percentage) was interviewing more than 10% (n= 50) of the local population [35], and the selection of the informants was by the snowball technique [36], with an age range of 17 to 80 years old. Ethnobiological information was collected using the multiple free listing ethnographic tool [37][38], which included questions focused on documenting which animals, fungi and plants they knew, the common or local name assigned to them in Spanish and Náhuatl, what use they had, and to be used, what part of the specimen was used.
The biological material was processed and identified depending on the taxonomic group, in general there were: a) specimen collections for fungi and plants, b) specimens or parts of animals donated by informants, c) specimen photographs, d) visual stimuli (use of field guides or posters with recognized species [34], e) association of traditional nomenclature with ethnobiological information in the area and f) published regional taxonomic lists.

Data analysis
The data were ordered in databases (spreadsheets of Excel) for each biological groups separately. Crustaceans and molluscs were included in the fish database as they were considered river fauna; the other biological groups are natural. The information in each database included: species, traditional names (Spanish/Náhuatl), categories of use and parts used. Ordinal matrices independent of the databases were too designed for each of the biological groups [55].

BKSI: Biocultural Key Species Index
This index is designed based on other methodological proposals [9][10][11][12][13]. It is made up of five subscripts that are: a) MFR-A= Mention Frequency by Rank-Abundance, AMO= Average Order Mention, RTN= Richness Names Traditional, VUT/PU= Value Total Uses and Parts Used, and O= Species Origin; adding the correction factor (CF) of Amorozo and Gély [56] to each subscript in which the relation is included: informants-ethnographic sample (n/N).

Mention Frequency by Rank-Abundance
It expresses the positive responses given for an i species in a sample of informants like Pieroni [12] or Garibay-Orijel et al. [13]. However, the frequency, that is, the possibility of finding a resource in daily life, may reflect its abundance in an ecosystem [9]; maintaining the relationship between abundant and rare species. Being necessary to evaluate this relationship, represented by pi = proportional abundance of species i, that is, the number of individuals of i species divided by the total number of individuals in the sample, which is known as the adjusted sample size [57]. − = * * Where: f= i species frequency; ∑f= summation of frequencies in the sample

Average Mention Order
It is obtained starting from the organization of the data in ordinal matrices proposed by Ryan et al. [55], where it is assumed that the mentioned species is random in a sample and all are represented in the sample (at least once); it acquires values close to zero when the mentions of species i are few or one, therefore, the higher the value obtained, the greater proportion of representation of the i species in the sample. Their analysis is based on value assignation to the ordering of the mentions for all species.

Where:
Osp i = value assigned to positions for the i species Osp n = sum of rankings in the sample CF= correction factor, that is, the proportion between the number of informants who mention i species over the total number of informants (n/N)

Richness Names Traditional
Following the basic principles of traditional classification [1,2] the richness of traditional names was estimated from the number of names assigned to an i species, considering the greatest number of linguistic variants. First, the nomenclatural relationship (NR), was determined under the concepts of equity, proportionality, synonymy and homonymy; these last two mentioned by Freire and Pauly [58]. Equity is understood as the assignment of a traditional name to an i species (1:1); proportionality as the association of more than one traditional name to more than one i species (>1:>1); synonymy is the ratio of more than one traditional name to an i species (>1:1); and homonymy is equal to a traditional name associated with various taxa (1:>1; e.g. Table 1).
On the other hand, based on the meaning of traditional names, as an indication of their cultural relevance, the value of linguistic interpretation (VIL) was obtained. Determining the nomenclatural category to which the name refers according to its meaning, these categories were assigned an arbitrary value. In general, four nomenclatural categories were identified, therefore, the value of linguistic interpretation depends on the number of categories identified, which ranges from 0.25 to 1 (

Value Total Uses and Parts Used
Based on the different indices to evaluate the use value [10,11,14,59,60], an index was integrated that includes the use value for each i species, associated with the number of parts used for each i species. The number of the categories depends on the biological group, as well as the number of used parts; so, there are different values for animals (mammals, birds, reptiles, amphibians, fish), fungi and plants. Where:

Results
A total of 4,399 mentions of fauna, flora and mycobiota known and / or exploited by the

Mention frequency Rank Abundance
The species that receive the highest values in this sub-index are: a) mammals Pecari tajacu   7, fungi). The similarity between the species in this subscript and in the previous one, is a function of the partial and significant correlation (r =0.6040, p> 0.05) between both metrics (FMR-A and AMO).

Richness Names Traditional
To calculate this subscript, the nomenclatural association types were first identified, where we have that 50% of the recognized species in the sample have an equitable association, that is, the corresponding of a species to its ethnospecies perfectly identified (1:1), 37% have a proportional relationship, more than one traditional name associated with a species (>1:1), which are generally two names, one in Spanish and the other in Náhuatl; 10% have more than one traditional name related to more than one species (>1:>1; synonymy) and 3% have a relation of one name to more than one species (1:>1; homonymy

Value Total Uses and Parts Used
The 90% of total flora, fauna and microbiota species are within any use category, sometimes,

Species Origen
In order to obtain this sub index, the sum of sub index was obtained and added a value of 1 for native species/ethnospecies, while this value of 1 was subtracted for those species identified as introduced or naturalized.

Relationship between sub-indexes
In order to determine the redundancy between the sub-indexes that integrate the BKSI, a indicates that such sub-indexes are independent metrics (Figure 2).

Biocultural Key Species Index
Results  these are also associated with exceptinoal magical proterties, in which if a person performs a ´cleaning´ with these animals, they (users) can obtain the maximum protection possible, that is why many of their parts are used, as well as whole specimens. Finally, the LBR category is the most representative, with 50 species (Figure 3b).  Figure 3f).

Discussion
The present study was focused on evaluating the biocultural relevance of known and used fauna, flora and microbiota species from a Náhuatl community at the Hidalgo Huastec region, Mexico ( Figure 4). In general, the studies focused on evaluating cultural importance have dealt with specific biological groups with own features, e.g. edible plants [12], medical important plants [62], economically important plants [14] or edible fungi [13]; which has allowed to recognize cultural importance in a particular way. In this study, by including several biological groups (plants and fungi; mammals, birds, reptiles, amphibians and fish) it was possible to interpret in an overall manner the biocultural relevance as a function of known and used biodiversity. It has been observed that the variables integrating the BKSI act in an impartial way on the biological groups, that is, these confer the same weight or consideration to either one or other group, independently of the species numbers for each; variation in the index values depend on the granted features for each species (e.g. frequency of mentions per biological group, as well as count of traditional names, uses and parts used; and there is not any biological group more relevant than the others, therefore the structure of natural ecosystems for this indigenous group operate as a whole. It has been found that some biological groups are comprised of a high richness but some do not, this depends directly on the biological characeristics of each group, however, even though some are more diverse than others, it does not necessarily means that they have a higher biocultural relevance, for example, although plants display a higher species with respect to fungi, the latter are not less relevant than plants, both groups are evenly known and employed; as usual, ethnobotany studies report a high species that are known and used in distinct ways [3], which follows the same pattern as this present work. Regarding fungi there are studies in different zones of the country that report a considerable number of known and employe species [63][64][65], in this work there is a report of three species complexes (Cantharellus spp., Pleurotus spp., Auricularia spp.), possibly because many fungi species do not have any use, but the few species are known by most of the inhabitants and the types of use are uniform; besides these are the species recognized and utilized at tropical regions [66]. There are other phenomenon that indicate that species richness is not related to biocultural relevance, e.g. for mammals there is a report of approximately 150 species for this zone [67], in this study the report is of only 31 species, which has to do with species that are not identified at detail culturally, as it is the case for bats (Chiroptera) and mice (Rodentia), where many species simply integrate one ethnospecies; another example is seen for birds, in which species from the Torquilidae are assigned with the same traditional name (´colibrí/huitzltil´).
Cultural importance must be evaluated from different parameters that include cultural domain diversity; since the metrics used in enthnobiology, only encloses a fraction of what it belongs to something more inclusive. It must be considered that species can become more or less relevant through the adaptive processes or their participation within the distinct cultural domains or anthropocentric categories, which involve a whole series of social or cultural practices [19]. Therefore, species that obtain the maximum and high relevance values, must be those that have an important role in religion, myths, arts, rituals, politics, science, economy, customs, language, etc. [17][18][19][20]. The index used here is merely integrated by five sub-inexes that cover a small fraction of all cultural domains but provide a close look to the cognitive, perceptual and employment of biotic resources aspects. RNT is a variable of the cultural domain of the language, besides is a primary cognitive construction form, it is worth mentioning that this is the first parameter that attemps to measure this cultural aspect, integrating several nomenclatural relations, following and complementing the bases proposed by Freire & Pauly [58]; and the VTU/PU includes in a general manner several cultural domains that can be: food source, medicinal, economical, religious, artistic and ritual; therefore, this sub-index provides a practical cultural value [14].
Meanwhile the species origin (O) is an assignment to subtract relevance to introduced species that frequently are important economically, which does not necessarily mean that these are important culturally. mentions that in an ethnobiological study there are species widely mentioned and others not so much, that can be a reflection of its ecological status; however that is about a relationship between species that can be more mentioned than others; this can possibly or not reflect such ecological role of a species i, what is truly appropriate to consider is that such relation between abundant species and rare (as it is done in ecology), thus, an adjustment has been made to the MFR-A sub-index by employing the abundance range curve formula [57], obtaining the proportion of most abundant and rare species in this way, consequently frequency of mentions per abundance range (MFR-A).
In the AMO sub-index, there has been a methodological problem identifie, which has to do directly with the data origins; the premise of this sub-index is that the mentions of the ethnotaxa or species in a list area randomized, and the higher the sample (informant number) and the number of times species i is mentioned, a higher average number will result for species i; technically, if two ethnotaxa or species are mentioned the same amount of times but in distinct positions, the predominant of one of the two, is that which has been mentioned in the last spots, due to a growing value assignment. This sub-index was not able to be corrected, despite trying diverse adjustments, because of this, it was decided that by doing a minor adjustment, that allows for lowering the final value and as a result to reduce the overestimation of species i.
Based on the basic principles of traditional classification [1,2] a sub-index that allows for measuring richness of names was designed, implementing a series of concepts, which makes this sub-index subjective [9, 12,13]. This subscript assesses the role that biotic resources play within language [17,19,20]. Being the first subscript of this nature, and provides a quantitative value (by the number of traditional names assigned to species i) and subjective [9,12,13] when the values are weighted. which corresponds to the linguistic interpretation of each traditional name.
The cultural importance has been strongly operated from the methodological proposal of use value [10, 11, 14 16], where Reyes-García et al. [14] indicates that his is a way to measure active knowledge of a species i. The sub-index (VTU/PU) integrates both the uses given for a species i, as well as the employed parts of such species.

Species with high biocultural relevance
Overall, one of the most significant variables to determine the biocultural relevance is the employment given to species, e.g. for fungi there were two use categories, while there were twelve for plants; it is worth mentioning that cultural importance has been originated through the measuring of the associated uses of the species, but not necessarily those showing larger amount of uses are more significant, because there are species that have a specific use and this causes them to be in a preponderant spot within the culture, as well as being considered irreplaceable; e.g. holy cross flower (´flor de la Santa Cruz´, Oncidium sphacelatum), which is used solely and exclusively during May 3 rd , the virgin flower (´flor de la virgen´, Euphorbia pulcherrima), which is used as a decorative element in the Guadalupe Virgin ceremonies during December, or the dead flower (´cempoal/flor de muerto´, Tagetes erecta), which is used in the dead's day festiveness to decorate altars and pantheons. Altogether, these aspects as a whole indicate the cultural rooting.
According to the data from the present research, to determine and try to quantify the cultural importance is sort of complex, it is considered that depending on the type of variables used, is a way to get closer to those species that are important for a particular human group. Given that there are new concepts incorporated it can be considered that the closure is being attained in order to open the guidelines to deepen into the topic, in this case referring to the biocultural key species [17][18][19][20]. It is also noticeable, that there is a wide assemble of species that are important culturally, authors like Rapaport [7], and Descola & Pálsson [8] consider nature to not just being perceived as a subsistence mean, instead more like a sociability mean. To Ellen [18], traditional societies not only coexist with biodiversity, that is, nature is seen as a group of living organisms that have a symbolic use and value integrated in a complex worldview, therefore, species with a higher biocultural relevance cannot operate in an isolated way, instead there are assembles of species.
In regards, the BKSI shows which species are included in different biocultural relevance categories; in the maximum and high biocultural relevance it is considered to allow for finding the most dominant or more relevant species at a cultural level, but taking into account the aforementioned opinions, observations and collections in field, the idea about the biocultural relevance can be supported as it operates on a group of species/ethnospecies, that is also mentioned by Platten & Henfrey [19] by describing the key biocultural species from the anthropologic point of view. It is worth noticing that the importance of species is relative and dynamic, that is, keeps evolving, growing, incorporating and excluding species through time, influenced by economic aspects, climatic changes, resource availability, public policies (health and natural resources protection), migration, commerce and globalization [68].
Starting from the analyzed species assemble ( Figure 3) and taking back the key biocultural species concept [20], it is established that the location of species with a higher biocultural relevance is given from its own nature (biological features) and the inclusion in the different cultural domains, generally integrating a species or ethnospecies assemble, where it does not necessarily state that the higher values species are the most significant in a cultural level.
However, the importance in determining the uses relies in adequate management and exploitation of biodiversity. It has been observed that conservation proposals that are based on this species types are more successful [23] and it encourages biocultural conservation and ancestral knowledge of the useful species.

Conclusion
Through the application of a combination of ethnographic methods, it was possible to collect trustful information by documenting the known, perceived and utilized species by the Nahua people. From there, a methodological proposal of analysis was designed to allow for a significant approach to the species considered to have a higher biocultural relevance to this community from knowledge (MFR-A and AMO), the role of these species in the language (RNT), as well as the diverse employment ways (VTU/PU); which results in a combination of passive and active understanding.
The idea that species that are considered as more relevant at a cultural level is sustained, as they operate in a general way; it is not about isolated species, rather of complexes or assembles; these groups of species are not necessarily related at a biological, ecological or cultural level. Hence, selection of such species depends on various factors that need to be taken into consideration. Identified biological groups are constituted in an independent way, which indicates that there is a recognition, identification and classification of the natural environment for each human group in particular. Besides, there are no biological groups that are more important to another, all of these have the same level of importance within the culture.
It is considered important to highlight the role that key biocultural species can perform, identified as species or ethnospecies complexes or assembles that further display a higher biocultural relevance, constitute elements that these can promote, facilitate and favor the biocultural diversity as a whole. The importance of the understanding of uses and employments of the key biocultural species could aim for the ethnobiological conservation locally, helping to preserve the particular identity of every culture.