Diaz, M. A. | Search bioRxiv

bioRxiv2026

Statistical invisibility of working equids in Mexico: Dissecting the gap between global diagnostics and official data (1970-2022).

BackgroundWorking equids are fundamental to the socioeconomic structure of Mexicos small-scale agricultural sector, which accounts for 71.2% of the countrys active Agricultural Production Units (APUs). Despite their critical role in human rural livelihoods, food security, and sustainable development, these animals face systemic "statistical invisibility" within national and international productive frameworks. This study evaluates the long-term population dynamics and geographical distribution of working equids to analyze their current status amidst agricultural modernization. MethodsA retrospective analysis was conducted using national census data from 1970 to 2022 provided by the National Institute of Statistics, Geography, and Informatics (INEGI). Population trends for horses, donkeys, and mules were calculated using the Average Annual Variation Rate (AAVR). The severity of population declines was classified according to an adaptation of the International Union for Conservation of Nature (IUCN) criteria. Finally, national census records from INEGI, Agri-food and Fisheries Information Service (SIAP) and The Ministry of Agriculture and Rural Development (SADER) were contrasted with FAOSTAT database estimates to identify reporting discrepancies. ResultsBetween 1970 and 2022, the total equine population in Mexico decreased by 76.5%, falling from 6.8 to 1.6 million. However, a "paradox of modernization" was identified: while total numbers plummeted, the proportion of equids used specifically for work reached a historical peak of 81% in 2022, effectively having doubled from the 44% recorded in 2007. While donkeys and mules have suffered drastic total reductions (87% and 88%, respectively), working horses experienced a resilient 37% recovery between 2007 and 2022 (+3.71% AAVR). Furthermore, a staggering 710.8% discrepancy was found between national census data and FAOSTAT estimates, representing an overestimation of 11.3 million animals in international records. ConclusionsThe persistence and recent recovery of working equids reflect a "resilience of necessity" for approximately 500,000 APUs that depend exclusively on animal traction and packing due to economic constraints and complex topography. These findings challenge the narrative of total agricultural mechanization and highlight an urgent need for evidence-based public policies that address the statistical invisibility of working equids as indispensable drivers of rural sustainability and food security.

scientific communication and education↗

bioRxiv2020

Exploring the boundaries of microbial habitability in soil

Microbes are widely assumed to be capable of colonizing even the most challenging terrestrial surface environments on Earth given enough time. We would not expect to find surface soils uninhabited by microbes as soils typically harbor diverse microbial communities and viable microbes have been detected in soils exposed to even the most inhospitable conditions. However, if uninhabited soils do exist, we might expect to find them in Antarctica. We analyzed 204 ice-free soils collected from across a remote valley in the Transantarctic Mountains (84 - 85{degrees}S, 174 - 177{degrees}W) and were able to identify a potential limit of microbial habitability. While most of the soils we tested contained diverse microbial communities, with fungi being particularly ubiquitous, microbes could not be detected in many of the driest, higher elevation soils - results that were confirmed using cultivation-dependent, cultivation-independent, and metabolic assays. While we cannot confirm that this subset of soils is completely sterile and devoid of microbial life, our results do show that microbial habitability and activity can be restricted by near-continuous exposure to cold, dry, and salty conditions, establishing the environmental conditions that constrain habitability in terrestrial surface environments. Constant exposure to these conditions for thousands of years has generated uninhabited surface soil environments, with either no detectable microbes or conditions which are not suitable to sustain microbial activity. Such uninhabited soils are unlikely to be unique to the studied region with this work challenging expectations about where microbes might, or might not, be able to thrive on Earth and other planets. Significance StatementCertain surface soils in Antarctica have remained effectively uninhabited due to a near-continuous exposure to cold-dry-salty conditions. This is an unexpected result because soils, even those in hyper-arid deserts, typically contain detectable microorganisms. Additionally, the prevalence of fungi at the colder, drier, higher elevation sites suggests that certain fungi may in fact be better adapted than bacteria or archaea to some of the most challenging soil environments on Earth.

ecology↗