Abstract
Bark beetles are a natural part of coniferous forests. Dendroctonus mexicanus Hopkins is the most widely distributed and most destructive bark beetle in Mexico, colonizing more than 21 pine species. The objectives of this study were to generate ecological niche models for D. mexicanus and three of its most important host species, to evaluate the overlap of climate suitability of the association Dendroctonus–Pinus, and to determine the possible expansion of the bark beetle. We used meticulously cleaned species occurrence records, 15 bioclimatic variables and ‘kuenm’, an R package that uses Maxent as a modeling algorithm. The Dendroctonus–Pinus ecological niches were compared using ordination methods and the kernel density function. We generated 1392 candidate models; not all were statistically significant (α = 0.05). The response type was quadratic; there is a positive correlation between suitability and precipitation, and negative with temperature, the latter determining climatic suitability of the studied species. Indeed, a single variable (Bio 1) contributed 93.9% to the model (Pinus leiophylla Schl. & Cham). The overlap of suitable areas for Dendroctonus–Pinus is 74.95% (P. leiophylla) and on average of 46.66% in ecological niches. It is observed that D. mexicanus begins to expand towards climates not currently occupied by the studied pine species.
Highlights
The conifer species P. leiophylla, P. teocote and P. devoniana were selected because they have the highest percentual incidence of bark beetle D. mexicanus attack in Mexico and are the most susceptible species, with 35.6, 13.9 and 9.4%, respectively [14]
The number of observations is less important than adequately representing species prevalence distributed in the entire geographic and environmental space it occupies [22], for which it is of utmost importance that in SDM and ENM the records comprehend the complete distribution of the species
Not all the models generated in Maxent were statistically significant (α = 0.05)
Summary
Dominated by the genus Pinus, they are especially restricted to mountainous areas, between elevations from 1500 to 4000 m [4], having an affinity for cold temperate climates. These forests contain 49 of the 120 pine species described [5], reaching one of the highest diversities worldwide. The accumulation of greenhouse effect gases in the atmosphere, caused mainly by human activity, has caused an increase of 0.87 ◦ C in the last 10 years [7]. This trend is occurring more rapidly than had been predicted and could have significant effects on adaptations of living organisms
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