No abstract

Land-use and climate change are affecting the abundance and distribution of species. The Trans-Mexican Volcanic Belt (TMVB) is a very diverse region due to geological history, geographic position and climate, however, is one of the most disturbed regions in Mexico. Reptiles are particularly sensitive to environmental changes due to their low dispersal capacity and thermal ecology. In this study, we define the environmental niche (a part of it; considering climatic, topographic and land use variables) and potential distribution (present and future) of the five Thamnophis species present in TMVB. To do so, we used the maximum entropy modelling software (MAXENT). First, we modeled to select the most important variables to explain the distribution of each species, then we modeled again only with the most important variables and projected these models to the future (year 2050) considering a middle-moderate climate change scenario (rcp45) and the land use and vegetation variables for year 2050, generated with Land Change Modeler based on the land use change occurred between years 2002 and 2011. We also calculated niche overlap between species in environmental space for the present and the future. Percentage of arid vegetation was a negative important variable for all the species and minimum temperature of the coldest month was selected as an important variable in four of the five species. Distance to Abies forest had a high percentage of contribution for T. scalaris and T. scaliger distribution. We found that all Thamnophis species will experience reductions in their distribution ranges in the TMVB in the future, however, for the whole country, the distribution of T. melanogaster seems to increase in the future. T. scalaris is the species that will suffer the biggest reduction in its distribution; the fact that this species is limited by high temperatures and that cannot shift its distribution upward, as it is already distributed in the highest elevations, can be the cause of this dramatic decline. We found a reduction in niche overlap between species in the future, which means a reduction in the PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.3476v1 | CC BY 4.0 Open Access | rec Running title: Niche modeling of TMVB garter snakes. Abstract: 1 2 3 4 5 6 7 8 9 10 11 12 13 PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.3476v1 | CC BY 4.0 Open Access | rec Land-use and climate change are affecting the abundance and distribution of species. The Trans-Mexican Volcanic Melt (TMVM) is a very diverse region due to geological history, geographic position and climate, however, is one of the most disturbed regions in Mexico. Reptiles are particularly sensitive to environmental changes due to their low dispersal capacity and thermal ecology. In this study, we define the environmental niche (a part of it; considering climatic, topographic and land use variables) and potential distribution (present and future) of the five Thamnophis species present in TMVM. To do so, we used the maximum entropy modelling softwa...

Laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) is a microanalytical tool especially suitable for providing fast and precise U‐Pb geochronological results on zircon grains. A new 193 nm excimer laser adapted to a micromachining workstation, equipped with a newly designed two‐volume ablation cell and coupled with a quadrupole ICP‐MS, is presented here. The system was tuned routinely to achieve sensitivities in the range of 3000 cps/μg g−1 for 238U (< 2% RSD), with a 34 μm spot size, at 5 Hz and ∼ 8 J cm−2, while ablating the NIST SRM 612 glass reference material. The system was capable of providing fast (< 1.5 minutes each analysis) and precise (generally < 1.5% 1s errors) 206Pb/238U zircon ages. The ages of widely used reference material zircons (Plesovice, 337 Ma; Temora, 416 Ma; R33, 418 Ma; Sri Lanka, 564 Ma; 91500, 1065 Ma) could be precisely matched, with an accuracy on isotopic ratios that ranged from ∼ 2 to ∼ 6%, depending on the homogeneity of the natural reference materials.

No abstract

[1] The magmatic record of the easternmost part of the Trans-Mexican Volcanic Belt elucidates how temporal changes in subduction parameters influence convergent margin volcanism. In the Palma Sola massif, three phases of magmatic rocks with distinct chemical characteristics were emplaced in a relatively short time span (17 Ma): Miocene calc-alkaline plutons, latest Miocene-Pleistocene alkaline plateau basalts, and Quaternary calc-alkaline cinder cones. Plutons have arc-like trace element patterns (Ba/Nb = 16-101), and their Sr, Nd, and Pb isotopic compositions become more ''depleted'' with increasing SiO 2 contents. Their Pb isotopes are bracketed by the subducted sediments and Pacific mid-ocean ridge basalts (MORB), requiring the participation of an unradiogenic component that mixes with a sediment contribution. High Sr/Y and Gd/Yb ratios in the least radiogenic pluton might indicate a melt coming from the subducted MORB. Trace element patterns of the plateau basalts show moderate or negligible subduction contributions (Ba/Nb = 6-31). Rocks without subduction signatures are similar to ocean island basalts, indicating melting of an enriched mantle wedge. The plateau basalts form an array in 206 Pb/ by an essentially flat subduction angle that favored melting of the subducted oceanic crust. Slab rollback in the Pliocene allowed melting of deeper portions of the wedge by the injection of dehydrated sediment melts. In the Quaternary, an even steeper subduction angle provided negligible slab contributions to the Palma Sola region, and upper crustal contamination largely controls the petrogenesis.