Species living in distinct habitats often experience unique ecological selective pressures, which can drive phenotypic divergence. However, how ecophenotypic patterns are affected by allometric trends and trait integration levels is less well understood. Here we evaluate the role of allometry in shaping body size and body form diversity in Pristurus geckos utilizing differing habitats. We found that patterns of allometry and integration in body form were distinct in species with different habitat preferences, with ground-dwelling Pristurus displaying the most divergent allometric trend and high levels of integration. There was also strong concordance between intraspecific allometry across individuals and evolutionary allometry among species, revealing that differences in body form among individuals were predictive of evolutionary changes across the phylogeny at macroevolutionary scales. This suggested that phenotypic evolution occurred along allometric lines of least resistance, with allometric trajectories imposing a strong influence on the magnitude and direction of size and shape changes across the phylogeny. When viewed in phylomorphospace, the largest rock-dwelling species were most similar to the smallest ground-dwelling species, and vice versa. Thus, in Pristurus, phenotypic evolution along the differing habitat-based allometric trajectories resulted in similar body forms at differing body sizes in distinct ecological habitats., This work was funded in part by PGC2018-098290-B-I00 (Ministerio de Ciencia, Innovación y Universidades/Agencia Estatal de Investigación/FEDER, UE) and PID2021-128901NB-I00 (MCIN/AEI/10.13039/501100011033 and by European Regional Development Fund, a way of making Europe), Spain to S.C. H.T.C. is supported by a “Juan de la Cierva—Formación” postdoctoral fellowship (FJC2021-046832-I). I.M. was funded by the Alexander von Humboldt Foundation through a Humboldt Research Fellowship, and partially funded by the project PID2022-138275NB-I00 granted by FEDER/Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación. A.T. is supported by the “la Caixa” doctoral fellowship program (LCF/BQ/DR20/11790007). G.R. was funded by an FPI grant from the Ministerio de Ciencia, Innovación y Universidades, Spain (PRE2019-088729). B.B.C. was funded by an FPU grant from Ministerio de Ciencia, Innovación y Universidades, Spain (FPU18/04742). D.C.A. was funded in part by the National Science Foundation Grant (DBI-1902511)., Peer reviewed

An important part of the ecological evolution of many lineages consists of adaptations to new diets as climate and available resources changed. In this study, we inferred when squirrels adapted morphologically to new diets by analyzing data from both extant and extinct species. We relied on the relationship between tooth morphology in extant squirrels and their dietary preferences to infer the diets of extinct species. To achieve this, we employed two approaches, namely geometric morphometrics and Elliptic Fourier analyses, to measure the outline of the fourth lower premolar (p4) in occlusal view. We then used both datasets to infer the diets of extinct species. Additionally, we used phylogenetic comparative methods on extant data to explore the evolution of diet and tooth size, identifying potential drivers of squirrel morphological evolution in the context of past climatic changes. Our findings indicate that the morphology of squirrel teeth has been maintained through the evolutionary history of most lineages, but that it also has changed in some lineages as a result of adaptations to particularly demanding diets, sometimes mediated by climatic factors, which have played a crucial role in shaping tooth morphology. Furthermore, we demonstrated that both geometric morphometrics and Elliptic Fourier analyses can yield a similar percentage of correct classifications and congruent dietary inferences. This study provides valuable insights into the macroevolutionary changes in squirrels and provides further evidence of the usefulness of tooth morphology for inferring the diets of extinct mammalian species., We are grateful to all the curators of the collections that granted access to the specimens studied in this work: Darrin Lunde for allowing us access to the extant Sciuridae collection at the National Museum of Natural History (Washington, DC, USA); Marisa Surovy, Sara Ketelsen, Eleanor Hoeger for providing access to the extant mammal collection at the American Museum of Natural History (New York, USA); Jin Meng and Judy Galkin for the palaeontological collection of the American Museum of Natural History (New York, USA) and Christiane Funk for the Mammal Collection of the Museum für Naturkunde (Berlin, Germany). We also thank Robert S. Voss and Maria Rios for their assistance in obtaining a 2018 Collection Study Grant from the American Museum of Natural History (AMNH, Richard Gilder Graduate School).

We thank Transmitting Science and lecturers Julien Claude (School of Evolutionary Sciences, Montpellier, France) and Julien Clavel (CNRS, France) for the courses “Geometric Morphometrics in R" and “Modeling and Analysis of Multivariate Trait Evolution Using mvMORPH” who contributed to the development of this work.

We thank Violeta Menéndez González for her help in automating data labelling, and Guillermo Navalón and Fernando Blanco for fruitful discussions during the development of this work.

I.M. was funded by a predoctoral fellowship from the Complutense University of Madrid (CT27/16-CT28/16) and two travel grants (EB40/17 and EB14/19) from the same institution to visit museum collections. I.M. received a research grant from the American Museum of Natural History (AMNH) to visit the collections in 2018. I.M. is currently funded by the Alexander von Humboldt Foundation through a Humboldt Postdoctoral Fellowship. P.M.C.R. was funded by a predoctoral fellowship from the Complutense University of Madrid (CT42/18-CT43/18). HT-C is supported by a “Juan de la Cierva - Formación” postdoctoral fellowship (FJC2021-046832-I) funded by MCIN/AEI/10.13039/501100011033 and by the European Union Next Generation EU/PRTR. This is a contribution of the Research Group Team UCM-910607 on the Evolution of Cenozoic Mammals and Continental Palaeoenvironments of UCM. This work was partly supported by the projects PID2022-138275NB-I00 and PID2020-116220GB-I00 granted by FEDER/Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación., Peer reviewed

The resource-use hypothesis proposed by Elisabeth S. Vrba suggests that lineages display varying tendencies toward generalism or specialization in biome occupancy, with a tendency towards the accumulation of specialists due to their higher rate of speciation through vicariance. It also posits differences in biome occupancy patterns driven by the environmental characteristics of biomes, with a higher presence of biome specialist species in biomes that are placed in the extremes of the global climatic gradients. Here, we tested this hypothesis in turtles, a very ancient and morphologically stable lineage, representing a remarkable diversity with 357 species, many of which are threatened with extinction. We analyzed the resource-use hypothesis in a phylogenetic context within the Testudines lineage. For this purpose, a presence/absence matrix was compiled for all species across all 10 terrestrial biomes. Their distribution across biomes was contrasted with 10,000 Monte Carlo simulations. The relationship between diversification rates and both the biomic specialization index and the biomes occupied by specialists species was evaluated. The results demonstrate strong consistency with Vrba`s hypothesis, revealing a higher number of biome specialist species than expected by chance, with a significant accumulation of species in tropical ecosystems. These trends also were observed for ecological groups (terrestrial and freshwater species). In addition, higher diversification rates were observed for biome specialist species, although the particular biome occupied did not significantly influence their diversification rates., The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work is a collaborative contribution by the Research Group in Ecology and Biodiversity Conservation (ECOBIO) and their research team in Paleobiology, Ecology and Evolution (PaleoEco) from the Santiago de Cali University (USC), funded by research project 313-6211223588 from the General Research Directorate (DGI) and under calls 01 and 09 2024. the Palaeoclimatology, Macroecology and Macroevolution of Vertebrates (PMMV) research team from the Complutense University of Madrid as a part of the research group UCM 910607 on Evolution of Cenozoic Mammals and Continental Paleoenvironments (partially funded by projects PID2020-116220GB-I00 and PID2022-138275NB-I00 from the Spanish Ministry of Science, Innovation and Universities), and the MAPAS Lab project from the University of Vigo (funded by the ERC grant agreement 947921 from the European Research Council under the European Union’s Horizon 2020 research and innovation programme)., Peer reviewed

Bone weathering constitutes a highly informative and commonly studied variable in taphonomic analyses. Vertebrate paleontologists, zoo-archeologists and forensic anthropologists have used weathering as a taphonomic clock to ascertain the exposure time of a bone assemblage before burial. Given that climatic conditions largely govern the weathering process, it is essential to investigate the effects of weathering across various climatic settings. This study analyzes the bone weathering process at Doñana National Park (Spain), a Mediterranean climate area. In 2018, we set an experiment in which four bones, three tibias and one skull, belonging to the main ungulates from Doñana (red deer, fallow deer, horse and wild boar) were placed in an enclosure and exposed to the natural environmental conditions. We present here results after almost 6 years of exposure. Over the study period, the most exposed area of the bones reached weathering stages 1 and 2, an intermediate progression between semi-arid tropical savannas, where weathering stages were initially described, and temperate and colder climates. By the final observation, the tibia of the horse, the heaviest taxon in our study, only has reached weathering stage 1, so our study agrees with previous studies in that the rate of weathering differs across body size, being slower in larger animals. The skull of Sus scrofa stands out for exhibiting modifications that differ from those observed in the tibias, probably due to the different structural anatomy of this bone. We have characterized the local meteorological conditions throughout the experiment and the soil composition as they might play a role in the weathering progression. This research constitutes a first attempt to calibrate the weathering scale in a Mediterranean climatic context, a setting that contains abundant and important fossil assemblages but that lacks bone weathering calibration., Funding was provided by MSCA-700196 project (European Union’s Horizon 2020) and PID2022-138275NB-I00 project (Spanish Government)., Peer reviewed

[Aim] Habitat breadth shapes species' responses to environmental change and influences large-scale biodiversity patterns. According to Vrba's resource-use hypothesis, biome specialists (inhabiting a single biome) exhibit higher speciation rates than generalists due to increased population isolation during habitat fragmentation, generally associated with past climate changes, particularly in biomes at extremes of the global climatic gradient. However, the phylogenetic and geographic distribution of biome specialists remains poorly understood. Here, we use squirrels to assess whether: (1) clades accumulate more specialist species than expected by chance, (2) this accumulation is associated with biomes at the extremes of the climatic gradient (tropical rainforest, subtropical desert, steppe and tundra), (3) habitat specialisation relates to geographic patterns of phylogenetic diversity and (4) species-level recent speciation rates., [Location] Global., [Taxon] Squirrels (Sciuridae, Rodentia)., [Methods] We compared observed biome specialisation indices (BSI) of species to MCMC-generated null distributions. We then mapped global patterns of specialist and generalist richness, phylogenetic diversity and recent species-level speciation rates., [Results] Squirrels include more biome specialists than expected under a null model that randomises biome occupancy, supporting the resource-use hypothesis. Tropical rainforests and steppes harboured more specialists than expected, whereas deserts and tundra did not, the latter likely due to their low species richness. Regions with high specialist richness (e.g., Southeast Asia) exhibited lower levels of phylogenetic diversity, consistent with Miocene speciation. In contrast, high recent speciation occurred in Holarctic steppes and South America, likely reflecting Pleistocene glacial radiations and post-Panamanian colonisation, respectively., [Main Conclusions] During periods of climatic change, the origin of new specialist lineages through rapid speciation led to specialist-dominated and phylogenetically clustered faunas, particularly in fragmented biomes. However, recent speciation rates reflect emerging rather than historical diversification hotspots. The Sunda Shelf emerges as a key conservation priority due to its exceptional richness, low phylogenetic diversity and concentration of endemic specialists., This research has been partially supported by the Spanish Ministry of Science and Innovation under projects PGC2018-094955-A-I00, PID2020-116220GB-I00, PID2022-138275NB-I00 and PID2023-151089NB-I00, PID2024-155134NB-I00 and PID2024-155435NB-I00. I.M. was funded by a Humboldt Research Fellowship for postdoctoral researchers from the Alexander von Humboldt Foundation. I.M. and J.L.C. were supported by grant CNS2023–144573 funded by MCIN/AEI/10.13039/501100011033 and by the European Union NextGenerationEU/PRTR (to J.L.C). F.B. was supported by the Open Societal Challenges Programme, The Open University, UK; Grant No OSC30: Modelling Past Climate Changes and Species Extinctions: The Neogene as a Case Study (MoPaCS). S.G. is part of the MAPAS project that has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant agreement No. 947921). S.G. was also supported by a Margarita Salas Postdoctoral Fellowship via the Universidad Complutense of Madrid (CT31/21) and by a Ramón Areces Postdoctoral Fellowship (XXXVII-Ciencias). E.G. and A.Q. are both funded by a predoctoral fellowship from the Universidad Complutense of Madrid (CT58/21-CT59/21)., Peer reviewed

Toxodontidae was an extinct family of South American notoungulates, widely studied systematically, but not so much from an ecological perspective. This work aims to improve the knowledge about variations in diet and habitats of different representatives of this group in the context of biotic and abiotic events throughout the last 20 Myr. The tooth enamel carbon isotope composition (δC) of 7 genera recorded in 11 localities of Central, West and Northeastern Argentina, from the Early Miocene to the Late Pleistocene, was analyzed. The diet of the toxodontids studied in this work ranges from mainly C resources during the Miocene, mixed C-C in the Pliocene, to a significant consumption of C plants during the Pleistocene. Differences in diet during the Late Pleistocene were also recorded, associated with geographic (i.e., Northeastern vs. Central) and temporal (i.e., glacial vs. interglacial periods) variations, evidencing the adaptive capacity of the group under ecological and environmental pressures., This research was financed by the 2022 call of the grant program ‘Ayudas a Jóvenes Investigadores de la Sociedad Española de Paleontología’. DSP is supported by a predoctoral grant PRE2019–089848 from the Ministerio de Ciencia e Innovación (Spain). This work is a contribution of the research group UCM 910607 on Evolution of Cenozoic Mammals and Continental Paleoenvironments and the projects PID2020-116220GB-I00 and PID2022-138275NB-I00 (Ministerio de Ciencia, Innovación y Universidades, Spain), National Geographic-Waitt Foundation #W467-16, Santander Universidades, 21G FCEyN (Facultad de Ciencias Exactas y Naturales, UNLPam, Argentina), PGI 24 H/154 (Secretaría de Ciencia y Tecnología, UNS, Argentina), and PICT 2019-2874 (MINCyT, Argentina).

The analysis of stable isotopes in fossil mammals is useful for reconstructing paleoenvironmental and paleoecological conditions, but has been rarely applied to the Neogene of South America. In this study, we perform an integrative analysis (including U–Pb zircon dates and mammalian stable isotopes data) for the Late Miocene–Early Pliocene of central Argentina. We provide radioisotopic ages for some classic fossiliferous localities in this region, including an age of 9.7 ± 0.3 Ma for Arroyo Chasicó and 4.5 ± 0.2 Ma for Farola Monte Hermoso, and address the interval covering the Chasicoan (Late Miocene), Huayquerian (Late Miocene–Early Pliocene), and Montehermosan (Early Pliocene) stages/ages. In the Chasicoan Stage/Age, taxa with mixed C<inf>3</inf>–C<inf>4</inf> diets are recorded, suggesting the existence of favorable conditions for the C<inf>4</inf> photosynthetic pathway before its full expansion. However, taxa represented across most of the Huayquerian Stage/Age show a preference for C<inf>3</inf>–based diets, which changes in the latest Huayquerian–Montehermosan stages/ages when an increase in the percentage of C<inf>4</inf> plants in the diet of notoungulates, rodents, and xenarthrans is recorded, coinciding with the global expansion of C<inf>4</inf> plants. For the first time, the dietary behavior of two South American endemic sparassodont metatherians (Lycopsis and Thylacosmilus) has been evaluated from using stable isotope; analysis of these hypercarnivores show differences in δ¹³C values, suggesting prey partitioning, partly due to the difference in body size. The fossiliferous sites studied, and the new isotopic and chronological information obtained, provide more detailed paleoecological and paleoenvironmental contexts for the Argentine Pampas during the last stages of the isolation of South America and the first pulses of the Great Biotic American Interchange. In addition, the new ages allow to better adjust the arrival of the first Holarctic immigrants in the region., This research was financed by PGC2018–094955–A–I00, PID2020-
116220GB-I00 and PID2022-138275NB-I00 projects (Ministerio de
Ciencia e Innovacion, ´ Spain), 13G and 21G projects (Facultad de Ciencias Exactas y Naturales, UNLPam, Argentina), PGI 24H/154 project
(Secretaría de Ciencia y Tecnología, UNS, Argentina). DSP acknowledges a predoctoral grant PRE2019–089848 (Ministerio de Ciencia e
Innovacion, ´ Spain). LD benefited from National Geographic–Waitt
Foundation grant #W467–16, a Santander Universidades grant, and a
Complutense–del Amo grant. We thank P. L. Koch (University of California Santa Cruz, USA) for access to his laboratory, D. Andreasen
(University of California Santa Cruz, USA) for assistance with stable
isotope analysis and M. Zarate ´ (UNLPAM, Argentina) for his help in the
collection of zircon samples in La Pampa. AEM and RLT were granted
with two U–Pb zircon datings from the 2021 - 2022 LA. TE. Andes -
CONICET funding. We are indebted to M. Reguero (Museo de La Plata,
Argentina), N. Sanchez ´ (Museo Municipal de Ciencias Naturales Vicente
di Martino, Argentina) and R. Caputo (Museo Municipal de Ciencias
Naturales Carlos Darwin, Argentina) for enabling collection access. This
is a contribution of the research group UCM 910607 on Evolution of
Cenozoic Mammals and Continental Palaeoenvironments. Thanks are
also extended to Dr. Falcon-Lang and four anonymous reviewers, whose
comments and suggestions help to improve this paper; and J. Fern´
andez
Pindado for all his help., Peer reviewed

Since rodent fossils are preserved in many low- and high-latitude archaeological and paleontological sites from a wide variety of environments, their associations are a commonly useful proxy for inferring past local climate and environmental conditions. Such a frequent and widespread geographic distribution can help us to better understand past climate evolution by providing access to high spatiotemporal resolution at large geographical scales. The aim of this paper is to develop an approach to generate continental-scale temperature maps based on rodent associations and to assess their reliability compared to state-of-the-art general circulation models (GCMs). We used the Bioclimatic Analysis, based on fossil and modern rodent associations, to infer climate zone distribution and local temperatures (mean annual temperature, mean temperature of the warmest month and mean temperature of the coldest month), at the Western Palearctic (Europe, Middle East and North Africa) for six different periods: the Last Glacial Maximum (LGM), Heinrich Stadial, Bølling, Allerød, Younger Dryas and present-day conditions. The Bioclimatic Analysis is combined with a spatial generalized linear mixed model to interpolate these surface temperatures across the Western Palearctic. We show that the spatial patterns in mean annual temperature and mean temperature of the warmest and coldest months are very similar between our interpolations and GCMs for both present-day and LGM conditions, but the rodent-based approach provides slightly cooler LGM estimations in western Europe and warmer ones in eastern Europe. Throughout the Late Glacial oscillations, the rodent-based model infers globally small variations in mean annual temperature and mean temperature of the warmest months and slightly larger changes in mean temperature of the coldest months. Nonetheless, some events show weak but significant regional variations depending of the events and the climate variable. For instance, the most important shifts in mean annual temperature between the Allerød and Younger Dryas are observed in northwestern regions. Northeastern regions, on the other hand, experienced relatively stable mean annual temperature, although they did experience considerable warming of the warmest month and cooling of the coldest month. Minor discrepancies appear between GCMs and the rodent-based model, the latter showing colder temperature in northwestern Europe and hence a differential west-east gradient in ice-sheet influence. Our results demonstrate that rodent associations are robust proxies for reconstructing and regionalizing past temperatures at broad scales, offering a readily reproducible approach to be reimplemented in future studies incorporating new rodent data., Ministerio de Ciencia e Innovación (España); Ministerio de Universidades (España); European Union Center (US); Universidad Complutense de Madrid; Fundación Ramón Areces; Alexander von Humboldt Foundation; Biogéosciences laboratory

Background: Species richness increases gradually as latitude decreases, however, the explanation for this phenomenon remains unclear. Ecological hypotheses suggest that greater niche diversity in tropical biomes may facilitate the coexistence of a larger number of species. The close relationship between species morphology and ecology can lead to a greater morphological disparity in tropical biomes. Methods: In this study, we used 2D geometric morphometric techniques on the ventral view of the cranium of flying squirrels (Pteromyini, Sciuridae) to determine the relationship between diet and cranial morphology and to evaluate if morphological disparity is higher in tropical biomes. Results: The results show that diet has a significant impact on cranial shape and size, with large, wide and robust crania in folivorous and generalist species, while frugivorous species tend towards smaller and narrower crania, and nucivorous have a wide variability. This suggests that biomes with more available dietary niches would show greater morphological disparity. However, we found no statistical differences in shape and size disparity among biomes or between observed and simulated disparity based on species richness. Conclusions: Our results show that there are not disparity differences between tropical and temperate biomes, even when temperate biomes are less rich than tropical ones, suggesting that the quantity of available niches may not be the key factor in generating morphological disparity. Instead, it could be the presence of extreme niches that demand specialised adaptations for exploitation, which might be of greater significance. A greater importance of size-changing adaptations would decrease shape disparity in biomes with many niches., This paper is a contribution by the research group UCM 910607 to the
PGC2018-094955-A-I00, PID2020-116220GB-I00 and PID2022-138275NB-I00
projects (Spanish Ministry of Science and Innovation).

Stable isotope analysis has become a key tool in paleontology, providing insights into ancient diets, ecosystems, climates, and environmental shifts. Despite the growing importance of isotopic studies in South America, no comprehensive bibliometric review has been conducted until now. This study addresses that gap, analyzing the development of the field over the past thirty years. Our results show a rapidly expanding discipline, especially in the last five years, with increasing publication rates and participation from South American researchers, particularly in Brazil and Argentina. However, the analysis also reveals persistent biases: notably, a strong focus on the Quaternary period, which limits broader evolutionary interpretations. Keyword co-occurrence points to dominant themes such as paleodiet, paleoecology, and megafaunal extinction, while highlighting new trends like ecological niche modeling and nitrogen isotope applications. The co-authorship network reflects high levels of collaboration, particularly with Spain and the United States. A marked gender imbalance in authorship is also evident, calling attention to the need for greater inclusivity. This review emphasizes the importance of addressing taxonomic and temporal gaps, strengthening interdisciplinary and international networks, and promoting equity in order to ensure the continued growth and global relevance of isotopic paleontology in South America., This research was financed by PID2022-138275NB-I00 project (Ministerio de Ciencia e Innovación, Spain), PGI 24 H/154 (Secretaría de Ciencia y Tecnología, Universidad Nacional del Sur, Argentina). DSP acknowledges a predoctoral grant PRE2019–089848 (Ministerio de Ciencia e Innovación, Spain). This is a contribution of the research group UCM 910607 on the Evolution of Cenozoic Mammals and Continental Paleoenvironments., Peer reviewed

Quantitative reconstructions of terrestrial seasonality remain limited despite their relevance for understanding past climate–ecosystem interactions. Here, we investigate seasonal hydroclimatic and ecological variability across the Vallesian Crisis in the Iberian Peninsula using serial δ18O and δ13C analyses of Hipparion tooth enamel. We analyzed 11 sets of serial enamel samples from 10 different molars and 1 premolar, totalling 141 samples from two fossil sites spanning the MN9–MN10 interval: Los Valles de Fuentidueña (Duero Basin; ∼9.6 Ma, MN9) and Batallones-10 (Madrid Basin; ∼9.1 Ma, MN10). All individuals display well-defined sinusoidal δ18O profiles, indicating seasonal fluctuations in ingested meteoric water and corroborating good preservation of the isotopic signal. Compared to MN9, Hipparion from Batallones-10 exhibits higher δ18O values and markedly broader intra-tooth δ18O ranges, pointing to an intensification of seasonality by ∼9.1 Ma in the central Iberian basins. This pattern is consistent with enhanced evaporation and increased seasonal contrasts in temperature and/or hydrology during the late Vallesian. In contrast, δ13C values from both localities indicate diets dominated by C3 vegetation, with limited seasonal variability and no evidence for C4 resource consumption. Isotopic niche metrics suggest a broader dispersion of isotopic space at Batallones-10, although this trend should be interpreted cautiously due to uneven sample sizes. Overall, our results provide new quantitative evidence for the establishment of stronger seasonality in inland southwestern Europe during the Vallesian Crisis and highlight the utility of serial enamel isotope analyses for resolving fine-scale paleoenvironmental change during episodes of faunal turnover.

Species living in distinct habitats often experience unique ecological selective pressures, which can drive phenotypic divergence. However, how ecophenotypic patterns are affected by allometric trends and trait integration levels is less well understood. Here we evaluate the role of allometry in shaping body size and body form diversity in Pristurus geckos utilizing differing habitats. We found that patterns of allometry and integration in body form were distinct in species with different habitat preferences, with ground-dwelling Pristurus displaying the most divergent allometric trend and high levels of integration. There was also strong concordance between intraspecific allometry across individuals and evolutionary allometry among species, revealing that differences in body form among individuals were predictive of evolutionary changes across the phylogeny at macroevolutionary scales. This suggested that phenotypic evolution occurred along allometric lines of least resistance, with allometric trajectories imposing a strong influence on the magnitude and direction of size and shape changes across the phylogeny. When viewed in phylomorphospace, the largest rock-dwelling species were most similar to the smallest ground-dwelling species, and vice versa. Thus, in Pristurus, phenotypic evolution along the differing habitat-based allometric trajectories resulted in similar body forms at differing body sizes in distinct ecological habitats.

Aim: Habitat breadth shapes species' responses to environmental change and influences large-­ scale biodiversity patterns. According to Vrba's resource-­use hypothesis, biome specialists (inhabiting a single biome) exhibit higher speciation rates than generalists due to increased population isolation during habitat fragmentation, generally associated with past climate changes, particularly in biomes at extremes of the global climatic gradient. However, the phylogenetic and geographic distribution of biome specialists remains poorly understood. Here, we use squirrels to assess whether: (1) clades accumulate more specialist species than expected by chance, (2) this accumulation is associated with biomes at the extremes of the climatic gradient (tropical rainforest, subtropical desert, steppe and tundra), (3) habitat specialisation relates to geographic patterns of phylogenetic diversity and (4) species-­ level recent speciation rates.
Location: Global.
Taxon: Squirrels (Sciuridae, Rodentia).
Methods: We compared observed biome specialisation indices (BSI) of species to MCMC-­generated null distributions. We then mapped global patterns of specialist and generalist richness, phylogenetic diversity and recent species-­ level speciation rates.
Results: Squirrels include more biome specialists than expected under a null model that randomises biome occupancy, supporting the resource-­use hypothesis. Tropical rainforests and steppes harboured more specialists than expected, whereas deserts and tundra did not, the latter likely due to their low species richness. Regions with high specialist richness (e.g., Southeast Asia) exhibited lower levels of phylogenetic diversity, consistent with Miocene speciation. In contrast, high recent speciation occurred in Holarctic steppes and South America, likely reflecting Pleistocene glacial radiations and post-­ Panamanian colonisation, respectively.
Main Conclusions: During periods of climatic change, the origin of new specialist lineages through rapid speciation led to specialist-­dominated and phylogenetically clustered faunas, particularly in fragmented biomes. However, recent speciation rates reflect emerging rather than historical diversification hotspots. The Sunda Shelf emerges as a key conservation priority due to its exceptional richness, low phylogenetic diversity and concentration of endemic specialists.

Understanding how species' ecological partitioning functions across biomes is fundamental to macroecology and conservation biology. Here, we examine the global distribution of dietary strategies in terrestrial mammals, focusing on how biome specialization modulates trophic diversity and structure at a broad geographical scale. Using species-level data from over 3600 terrestrial mammal species, we constructed a multivariate dietary space and quantified the area, redundancy, dispersion, uniqueness, and turnover of trophic strategies across ten major biomes. Species were classified as biome specialists, moderate generalists, or extreme generalists based on their biome breadth. By analysing biome specialists and generalists separately, we show that biome specialists tend to exhibit more constrained and compositionally distinct dietary niches in less productive biomes, while generalists, particularly moderate generalists, dominate functional space occupancy in all biomes, even the harsher ones such as tundra and taiga. This highlights how environmental constraints and ecological roles shape trophic strategies at a global scale. Notably, extreme generalists tended to exhibit more carnivorous or insectivorous diets, suggesting a strategy based on mobile predation or opportunism rather than a highly diversified omnivory. Despite these general patterns, highly productive biomes supported the greatest diversity of dietary strategies, with higher functional redundancy and niche packing. Nestedness and turnover analyses revealed that biome specialists diets are often subsets of generalists diets, but with significant compositional shifts across biomes. These findings underscore the dual role of biome generalists as both functional stabilizers and potential limiters of ecological diversity, and highlight the vulnerability of specialist species to global change. Our study offers a mechanistic framework for understanding how dietary strategies interact with environmental filtering, and for identifying functional risks in changing ecosystems.

Understanding how species' ecological partitioning functions across biomes is fundamental to macroecology and conservation biology. Here, we examine the global distribution of dietary strategies in terrestrial mammals, focusing on how biome specialization modulates trophic diversity and structure at a broad geographical scale. Using species‐level data from over 3600 terrestrial mammal species, we constructed a multivariate dietary space and quantified the area, redundancy, dispersion, uniqueness, and turnover of trophic strategies across ten major biomes. Species were classified as biome specialists, moderate generalists, or extreme generalists based on their biome breadth. By analysing biome specialists and generalists separately, we show that biome specialists tend to exhibit more constrained and compositionally distinct dietary niches in less productive biomes, while generalists, particularly moderate generalists, dominate functional space occupancy in all biomes, even the harsher ones such as tundra and taiga. This highlights how environmental constraints and ecological roles shape trophic strategies at a global scale. Notably, extreme generalists tended to exhibit more carnivorous or insectivorous diets, suggesting a strategy based on mobile predation or opportunism rather than a highly diversified omnivory. Despite these general patterns, highly productive biomes supported the greatest diversity of dietary strategies, with higher functional redundancy and niche packing. Nestedness and turnover analyses revealed that biome specialists diets are often subsets of generalists diets, but with significant compositional shifts across biomes. These findings underscore the dual role of biome generalists as both functional stabilizers and potential limiters of ecological diversity, and highlight the vulnerability of specialist species to global change. Our study offers a mechanistic framework for understanding how dietary strategies interact with environmental filtering, and for identifying functional risks in changing ecosystems., Agencia Estatal de Investigación | Ref. PID2021-123202NA-I00, Agencia Estatal de Investigación | Ref. PID2020-116220GB-I00, Agencia Estatal de Investigación | Ref. PID2022-138275NB-I00, Universidade de Vigo, Xunta de Galicia, Universidade de Vigo/CISUG, Ministerio de Universidades | Ref. CT31/21

En este artículo, examinamos el impacto, a menudo pasado por alto, de la menstruación en las experiencias de trabajo de campo en las disciplinas de las ciencias naturales. Realizamos una encuesta transversal a 429 participantes, predominantemente mujeres (86.0%), con una representación limitada de personas no binarias y sin hombres trans, para investigar los desafíos logísticos, sociales y relacionados con la salud que se afrontan durante el trabajo de campo.


La encuesta, que combinó datos cuantitativos y cualitativos, reveló que el 86% de los encuestados ha experimentado la menstruación, y casi la mitad (48%) reportó un dolor menstrual significativo durante el trabajo de campo. Los hallazgos cuantitativos indican que la logística del trabajo de campo rara vez se adapta a las necesidades de salud menstrual: el 85% de los participantes manifestó que los botiquines estándar no incluyen productos de higiene menstrual. Además, los datos cualitativos destacaron dificultades en la comunicación sobre cuestiones menstruales, ya que solo el 30.5% de los encuestados se sintió cómodo discutiendo estos temas con supervisores masculinos, en comparación con el 59.9% con supervisores femeninos.


Estos hallazgos subrayan importantes lagunas en el apoyo a la salud menstrual durante el trabajo de campo. Sugieren que medidas prácticas —como asegurar la disponibilidad de productos menstruales en los botiquines de primeros auxilios y fomentar un diálogo más abierto sobre la salud menstrual— podrían mejorar el apoyo a las investigadoras que menstrúan. Sin embargo, nuestros resultados también destacan la necesidad de realizar investigaciones adicionales para explorar los factores sistémicos más amplios que subyacen a estos desafíos. En última instancia, abordar estas lagunas podría contribuir a crear un entorno más inclusivo y equitativo para todas las personas dedicadas a la investigación., In this article, we examine the often-overlooked impact of menstruation on fieldwork experiences in natural sciences disciplines.
We conducted a cross-sectional survey of 429 participants, predominantly women (86.0%) with limited non-binary representation and no
transgender men, to investigate the logistical, social, and health-related challenges faced during fieldwork.
The survey, combining quantitative and qualitative data, revealed that 86% of respondents have experienced menstruation, with nearly half
(48%) reporting significant menstrual pain while working in the field. Quantitative findings indicate that fieldwork logistics rarely
accommodate menstrual health needs: 85% of participants reported that standard first aid kits do not include menstrual hygiene products.
Additionally, qualitative data highlighted difficulties in communication about menstrual issues, with only 30.5% of respondents feeling
comfortable discussing these issues with male supervisors, compared to 59.9% with female supervisors.
These findings underscore significant gaps in support for menstrual health during fieldwork. They suggest that practical measures—such
as ensuring menstrual products are available in first aid kits and fostering more open dialogue about menstrual health—could improve
support for menstruating researchers. However, our results also highlight the need for further research to explore the broader systemic
factors underlying these challenges. Ultimately, addressing these gaps may contribute to creating a more inclusive and equitable
environment for all researchers., Alexander von Humboldt Foundation | Ref. HumboldtResearch Fellowship, 2020-2021 Biodiversa+ and Water JPI joint call for research projects | Ref. InterRest project, DeutscheForschungsgemeinschaft (DFG, German Research Foundation | Ref. 491739988, Estonian Research Council, the Spanish Ministry of Science, Innovationand Universities and the Spanish State Investigation Agency | Ref. PCI2022-1329, Ministerio de Universidades | Ref. CT31/21, Agencia Estatal de Investigación | Ref. PID2022-138275NB-I00, Swedish Environmental Protection Agency | Ref. 2022-00027, Agencia Estatal de Investigación | Ref. PCI2022-132941

The resource-use hypothesis proposed by Elisabeth S. Vrba suggests that lineages display varying tendencies toward generalism or specialization in biome occupancy, with a tendency towards the accumulation of specialists due to their higher rate of speciation through vicariance. It also posits differences in biome occupancy patterns driven by the environmental characteristics of biomes, with a higher presence of biome specialist species in biomes that are placed in the extremes of the global climatic gradients. Here, we tested this hypothesis in turtles, a very ancient and morphologically stable lineage, representing a remarkable diversity with 357 species, many of which are threatened with extinction. We analyzed the resource-use hypothesis in a phylogenetic context within the Testudines lineage. For this purpose, a presence/absence matrix was compiled for all species across all 10 terrestrial biomes. Their distribution across biomes was contrasted with 10,000 Monte Carlo simulations. The relationship between diversification rates and both the biomic specialization index and the biomes occupied by specialists species was evaluated. The results demonstrate strong consistency with Vrba`s hypothesis, revealing a higher number of biome specialist species than expected by chance, with a significant accumulation of species in tropical ecosystems. These trends also were observed for ecological groups (terrestrial and freshwater species). In addition, higher diversification rates were observed for biome specialist species, although the particular biome occupied did not significantly influence their diversification rates., Dirección General de Investigaciones of Universidad Santiago de Cali | Ref. DGI-01-2025, Dirección General de Investigaciones of Universidad Santiago de Cali | Ref. 313- 6211223588, Dirección General de Investigaciones of Universidad Santiago de Cali | Ref. DGI-09-2024, Agencia Estatal de Investigación | Ref. PID2020-116220GB-I00, Agencia Estatal de Investigación | Ref. PID2022-138275NB-I00