Species distribution models (SDM) are widely used in diverse research areas because of their simple data requirements and application versatility. However, SDM outcomes are sensitive to data input and methodological choices. Such sensitivity and diverse applications mean that flexibility is necessary to create SDMs with tailored protocols for a given set of data and model use. We introduce the r package flexsdm for supporting flexible species distribution modelling workflows. flexsdm functions and their arguments serve as building blocks to construct a specific modelling protocol for user's needs. The main flexsdm features are modelling flexibility, integration with other modelling tools, simplicity of the objects returned and function speed. As an illustration, we used flexsdm to define a complete workflow for California red fir Abies magnifica. This package provides modelling flexibility by incorporating comprehensive tools structured in three steps: (a) The Pre‐modelling functions that prepare input, for example, sampling bias correction, sampling pseudo‐absences and background points, data partitioning, and reducing collinearity in predictors. (b) The Modelling functions allow fitting and evaluating different modelling approaches, including individual algorithms, tuned models, ensembles of small models and ensemble models. (c) The Post‐modelling functions include tools related to models' predictions, interpolation and overprediction correction. Because flexsdm comprises a large part of the SDM process, from outlier detection to overprediction correction, flexsdm users can delineate partial or complete workflows based on the combination functions to meet specific modelling needs.
A new species of lizard genus Homonota from southern Buenos Aires Province, Argentina is described. Homonota wil-liamsii sp. nov. was previously considered as part of the H. darwinii species, but differs by a combination of charactersfrom the nominal species and from other species of the genus. Its geographic distribution is restricted to an isolated mountain system not connected with other habitats suitable for Homonota darwinii
Color polymorphisms in general and melanism in particular have been the focus of many evolutionary adaptation studies. In lizards of the genus Liolaemus Wiegmann, 1834, patterns of melanism have been poorly studied, although they have been used as diagnostic characters for identifying and describing new species. We investigated the relationships between melanism, body size, sex, and time in a population of Rawson Lizard (Liolaemus xanthoviridis Cei and Scolaro, 1980) with extensive ventral melanism. The study took place in Bahía Isla Escondida, Chubut (Argentina), during three summer seasons (2012 to 2014). We tagged each individual, recorded body measurements and sex, and took ventral photographs to estimate the proportion of melanism. Our results showed that ventral melanism increased over time as each individual increased its snout–vent length (SVL). Body size explained 44% of the variation in melanism and males were more melanistic than females. Previous comparative studies of lizards in this species group showed no relationship between melanism and different taxonomic units or with thermal functionality. Here, we present evidence suggesting that melanism might be a character with an ontogenetic origin that is strongly associated with sex and body size. This pattern could be shared among species of this group of lizards, and even more importantly, it may be related to variable selection forces occurring throughout ontogeny.
It has long been considered sufficient a single method or only a descriptive diagnosis to propose a new species. Recently, many works have proposed new theoretical paradigms to consider multiple sources of evidence to support the hypothesis of new taxa within an integrative approach. Despite this, many new described species continue to be merely descriptive and without any reproducible statistical analysis to support these descriptions. We tested whether five species described as members of a species complex of the lizard genus Liolaemus from Patagonia, can be differentiated based on classical morphometric analyses and ecological niche modeling. Individuals were sampled from their type localities. Our results showed that the univariate tests and Principal Component Analyses (PCA) were more accurate to differentiate species compared to the Linear Discriminant Analyses (LDA). However, there were almost no morphometric differences between two of the analyzed species. Major differences were found in bioclimatic variables of four of the species through Maxent ENMs and PCA using the original worldclim variables. Our results partially support the hypothesis that species can be differentiated by classical morphometric analyses, and found a strong support for the hypothesis that these taxa can be differentiated through their bioclimatic niches. These two approaches based on repeatable statistical basis, can supplement qualitative descriptive diagnoses of new species of the genus Liolaemus.
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