Evaluation of the degree of mycophilia-mycophobia among highland and lowland inhabitants from Chiapas, Mexico

Fieldwork was carried out in two regions of the State of Chiapas, Mexico: Los Altos de Chiapas (Highlands) and Lacandon Rainforest (Lowlands) (Figure 2). The Lacandon rainforest is a region with altitudes ranging between 0 and 1200 m a.s.l., with a warm humid climate and evergreen or sub-evergreen rainforest [23]. Due to human activity, the original vegetation has been transformed to grasslands and “acahuales” in different succession degrees. The region is integrated by 14 municipalities with a total population of 713,944 [24]. In this region there are three native indigenous groups: Lacandon, Ch’ol and Tseltal, as well as diverse mestizo groups and migrant indigenous groups mainly represented by Tseltal from the highlands and Mam. Indigenous population represents 62% of the total population. Men and women have a balanced proportion approaching 50% [24].

Chiapas Highlands is a mountainous region with altitudes between 1200 and 2700 m a.s.l. It has a temperate climate and a vegetation of pine-oak, pine-oak-liquidambar, and cloud forest, as well as large plantation areas [25]. The region includes 19 municipalities with a total population of 671,170. 49% of the indigenous populations are speakers of Tsotsil, Tseltal, Tojolabal, and Chuj. The proportion of men and women is balanced [24].

In all Chiapas, around 20 000 species of mushrooms are estimated to be present; only 2% of them have been registered [16]. There are no studies documenting the richness of mushrooms in each ecological region in detail, however the richness of the highlands is presumed to outstrip that of the lowlands in a 3 to 1 proportion (Cifuentes com. pers.). Furthermore, in the highlands ectomycorrhizal mushrooms with large and fleshy fruit bodies are more common while in the lowlands, smaller, leathery, saprobial mushrooms are more frequent. Different studies have demonstrated the great quantity of recognized and used species and explored how these organisms fit into peoples’ worldview, the naming and classification of species, the ethnomycological knowledge they have built around them, and the uses they give them [15, 16]. There are cognitive similitudes registered among inhabitants of both regions: the logic behind the naming and classification of mushrooms, the knowledge about their biology and ecology, and their usefulness (edible, medicinal, ludic, ornamental, and recreational). Notwithstanding such similarities, there are marked differences among ecological regions, such as the number of species consumed −24 in the highlands and only 11 in the lowlands–. With regard to toxic species, there is no systematic study recording their identity or number in each ecological region; however, it seems all the species considered as deathly have been registered exclusively in the highlands due to the mycorrhizal association between them and Pinus spp. and Quercus spp.

To evaluate the degree of mycophilia-mycophobia in the study area, a method for gathering and analyzing information was designed. Based on literature and previous fieldwork, nine important cultural domains describing the attitude of a person toward mushrooms were identified: 1) knowledge and use of edible species [3, 16, 26‐30]; 2) knowledge of toxic species [19, 31]; 3) knowledge of species without cultural importance [5]; 4) worldview or “Imago mundi”; that is, the way people explains their universe, its origin and order, and how humans participate in that order [19, 32]; 5) multiple use of mushroom species, not only edible [33]; 6) presence of specialists in mushroom picking [34]; 7) ethnoecological knowledge [18, 32, 35]; 8) transmission of ethnomycological knowledge [36]; and 9) perceived importance of mushrooms as a group of organisms [5]. Through these domains, 19 indicators were selected to describe the general attitude of a person toward mushrooms (Table 1). A structured interview including one question per indicator plus sociocultural information (ethnicity, occupation, origin, community and ecological region) was constructed (see Additional file 1). Answers were codified with a value of 1 when the answer was equivalent to a positive attitude, 0.5 when it corresponded to a neutral attitude and 0 when the answer was equivalent to a negative attitude. The Mycophilia-Mycophobia Index (MMI) value was calculated by adding the score obtained for each indicator, so that each interviewee had a MMI value between 0 (mycophobia maximum) and 19 (mycophilia maximum).

Fieldwork was designed to record the variation between highlands and lowlands. Random samples of the people were obtained from different towns. Ten communities were selected in each ecological region according to their size, ethnical groups, and dialectal variants (Table 1). In each town, individuals over 15 years of age were interviewed. Interviewees were chosen in a random way using maps of housing for each community, totaling 115 interviewees in the lowlands and 106 in the highlands (221 in both ecological regions) (Table 2). Non-structured and semi structured interviews were also carried out [37] to clarify the context of the local reality and the ideas expressed by the interviewees. All interviews –structured, non-structured and semi structured –were carried out in the houses of the interviewed, having previously agreed on a convenient time for them. Interviewers were careful not to let visiting times interfere with a random selection of the sample. Responses to the interviews were written down; for structured interviews pre-established formats were used (see Additional file 1) and the rest of the interviews were registered in field diaries.

To analyze the relation between ecological region, sociocultural factors, and positive, neutral, or negative attitudes, we followed two procedures. First, we analyzed the 19 indicators separately through χ² tests to determine which indicators presented significant differences between ecological regions. Second, to explore whether populations form groups based on ecological region or other sociocultural variables, multivariate techniques were used. Each indicator was a trait to evaluate (qualitative, three states) and an average of interviewees was calculated to obtain a relative value of each indicator per community. A distance matrix was calculated using the method of average taxonomic distance. With these values a Cluster Analysis by Complete Linkage method and a Principal Coordinates Analysis (PCO) were carried out in NTSYS (Numerical Taxonomy and Multivariate Analysis System) ver. 2.11x for PC [38].

To evaluate which ecological and sociocultural factors better explain the distribution of different attitudes toward mushrooms in the human population we built several models using the beta probability-density function [39]. This distribution was chosen because the attitude towards mushrooms may be either a dichotomic (mycophiles-mycophobes) or gradual variable. The beta distribution is extremely flexible, and may assume a wide range of shapes, from an extremely bimodal form with two peaks at extreme MMI values (as it would be expected if mycophilia and mycophobia were mutually exclusive) to one single bell-shaped curve in which most members of a population have intermediate MMI values (as would be expected if the attitude towards mushrooms were a continuous variable). Each model consisted of one or more beta distributions that described the probability density of observing an individual with a given MMI in a population within an ecological region or having certain sociocultural attribute. In total, we produced eleven models by fitting through maximum likelihood a beta distribution to different subsets of the MMI values sampled: a) Null model: The probability of sampling a person with any given MMI value is independent of the ecological region and sociocultural variables; b) Single-factor models: In these, different probability distributions were fitted to data according to either ecological region (highlands-lowlands), occupation (peasant-non peasant: where peasants are defined as people whose occupations put them in direct contact or usage of the natural spaces, such as those in land cultivation, stockbreeding, extraction of forest resources, forest rangers, or people involved in the development of productive projects in rural communities. Non-peasants are defined as people whose occupation does not require such contact, like people working in commerce, transportation, and public service, to name a few), ethnicity (indigenous-mestizo: where indigenous are defined as those who recognize themselves as such and speak an indigenous language and mestizos are defined as those speaking Spanish as a first language), gender (man-woman), or origin (native-migrant); c) Two-factor models with ecological region: In all of these models, the probability distribution of MMI was assumed to depend on the ecological region and one of the sociocultural factors (e.g., ecological region and gender, ecological region and ethnicity, etc.); and d) Two-factor sociocultural model: This model included the joint effect of occupation and ethnicity on MMI, and was chosen because there is a vast amount of literature that points out that these two factors are the most important ones in determining the relationship between people and natural resources [21].

The 11 models were then compared with the Akaike Information Criterion (AIC) [40]. This procedure allows for organizing the hypotheses (expressed as models) into a hierarchy that formally indicates the evidence supporting each one, allowing one to select the best among the competing models. If any model has an AIC value two units lower than another, it is concluded that the former is better supported by the data. If the difference in AIC values is smaller than two units, both models have similar support and it is impossible to select one over the other [40].

There was a significantly greater frequency (χ² tests, p < 0.05) of positive attitudes in the highlands regarding recognition and morphology of toxic species (items 2.1 and 2.2 in the structured interview) and presence of specialists (6.1). In contrast, lowlands showed significantly more positive attitudes towards species without cultural significance (3.1) and mushrooms as a group (9.1), as well as more frequent neutral or negative attitudes in terms of myths (4.1) and ethnoecological knowledge of the relation between mushrooms and animals (7.2). No significant differences were found for the 12 indicators related to knowledge and use of edible mushrooms, knowledge of mushroom’s role in the ecosystem, knowledge transmission, percieved importance of mushrooms, and the existence of non-alimentary uses (Figure 3).

Except for the indicator related to attitude toward species without cultural significance (3.1) in the highlands, and the one related to presence of non-alimentary use (5.1) for both ecological regions, indicators in both ecological regions show that most people have positive attitudes and knowledge (Figure 3) of mushrooms.

The classification analysis found two large groups, each comprising both highland and lowland communities (Figure 4). The PCO analysis suggests the apparent formation of two groups. With the exception of Palenque and San Antonio, the highland communities do not mix with the lowlands (Figure 5). The most important indicators were items 5.1, 4.1, and 3.1 of the interview, that is, in the communities on the upper left quadrant of the graph there were more people aware of non-alimentary uses and tales and myths including mushrooms, and with a positive attitude towards species without cultural significance. However, positive values along the second principal coordinate axis correspond to communities mainly from the highlands that were characterized by a greater fear of species without cultural significance. Lowland communities with negative second PCO values included more people without knowledge of the morphology of toxic species or the relationships between animals and mushrooms, and which have less mushroom specialists in their communities.

Contrary to what would be expected if mycophilia-micophobia were mutually exclusive, all the fitted probability distributions were bell-shaped. This means that that there is a greater probability of finding people with intermediate degrees of mycophilia-mycophobia than extreme mycophobes or mycophiles. However, an overall trend towards moderate to high mycophilia was observed in the entire population (Figure 6e). The model that was best supported by the data included occupation and ethnicity, while the remaining models would be discarded as they all have much lower AIC values (Table 3). Indigenous peasants had the highest degree of mycophilia, followed by mestizo peasants and indigenous non-peasants, which had similar attitudes among themselves. Mestizo non-peasants had the lowest degree of mycophilia in the studied population (Figure 6a).

All the models that accounted for the remaining sociocultural factors had a greater support than the null model, suggesting that gender and origin also determine the degree of mycophilia (Table 3). Men and natives were more mycophilic than women and migrants, respectively (Figure 6b-c).

Models in which ecological region and sociocultural variables interacted received the same or less support than the models with the respective sociocultural variables alone. Also, the null model had a similar support as the model with ecological region, making them indiscernible (Table 3). The MMI values in highlands and lowlands are quite similar, and thus resemble the distribution fitted for the null model (Figure 6d-e). Thus, all evidence points to sociocultural differences among populations (particularly regarding occupation and ethnicity) as better explanatory factors of mycophilia-mycophobia than ecological region.