Past and present taxonomy of theLiolaemus lineomaculatussection (Liolaemidae): is the morphological arrangement hypothesis valid?

Tracing evolutionary trajectories in the presence of gene flow in South American temperate lizards (Squamata: Liolaemus kingii group)

Evolutionary processes behind lineage divergence often involve multidimensional differentiation. However, in the context of recent divergences, the signals exhibited by each dimension may not converge. In such scenarios, incomplete lineage sorting, gene flow, and scarce phenotypic differentiation are pervasive. Here, we integrated genomic (RAD loci of 90 individuals), phenotypic (linear and geometric traits of 823 and 411 individuals, respectively), spatial, and climatic data to reconstruct the evolutionary history of a speciation continuum of liolaemid lizards (Liolaemus kingii group). Specifically, we (a) inferred the population structure of the group and contrasted it with the phenotypic variability; (b) assessed the role of postdivergence gene flow in shaping phylogeographic and phenotypic patterns; and (c) explored ecogeographic drivers of diversification across time and space. We inferred eight genomic clusters exhibiting leaky genetic borders coincident with geographic transitions. We also found evidence of postdivergence gene flow resulting in transgressive phenotypic evolution in one species. Predicted ancestral niches unveiled suitable areas in southern and eastern Patagonia during glacial and interglacial periods. Our study underscores integrating different data and model-based approaches to determine the underlying causes of diversification, a challenge faced in the study of recently diverged groups. We also highlight Liolaemus as a model system for phylogeographic and broader evolutionary studies.

Description of the neuroanatomy of the brachial plexus in South American lizards. Phylogenetic implications

Few studies considered the anatomy of the nerve plexuses and musculature associated with them in ectothermic sauropsids. Based on differentiated Sudan Black B staining and conventional dissections, we describe the neuroanatomy of the brachial plexus, its main associated nerves, and muscles. For that, representatives of the genera Diplolaemus, Liolaemus, Phymaturus, and Tropidurus were selected. Based on this, potentially useful characters for phylogenetic analysis were described. Our results show that the brachial plexus can be formed by four, five, or six nerve branches. The brachial flexor trunk, circumflex, interosseous, median, radial, subscapulocoracoid, supracoracoid, and ulnar nerves were identified. Regarding the muscles innervated by the main nerves, the following muscles were identified: biceps brachii, deltoideus scapularis, latissimus dorsi, levator scapulae, pectoralis, serratus thoracis, trapezius, triceps longus caudalis, and triceps longus lateralis. Phylogenetic analyzes revealed 31 potential synapomorphies. There exists evidence that neuroanatomy studies in a phylogenetic context could provide useful information helping to elucidate the relationships between taxonomic groups.

Complex Patterns of Diversification in the Gray Zone of Speciation: Model-Based Approaches Applied to Patagonian Liolaemid Lizards (Squamata: Liolaemus kingii clade)

In this study we detangled the evolutionary history of the Patagonian lizard clade Liolaemus kingii, coupling dense geographic sampling and novel computational analytical approaches. We analyzed nuclear and mitochondrial data (restriction site-associated DNA sequencing and cytochrome b) to hypothesize and evaluate species limits, phylogenetic relationships, and demographic histories. We complemented these analyses with posterior predictive simulations to assess the fit of the genomic data to the multispecies coalescent model. We also employed a novel approach to time-calibrate a phylogenetic network. Our results show several instances of mito-nuclear discordance and consistent support for a reticulated history, supporting the view that the complex evolutionary history of the kingii clade is characterized by extensive gene flow and rapid diversification events. We discuss our findings in the contexts of the "gray zone" of speciation, phylogeographic patterns in the Patagonian region, and taxonomic outcomes. [Model adequacy; multispecies coalescent; multispecies network coalescent; phylogenomics; species delimitation.].

A new lizard species of the Liolaemus kingii group (Squamata: Liolaemidae) from northwestern Chubut province (Argentina)

We describe Liolaemus attenboroughi sp. nov., a lizard distributed in the northwestern Patagonian Steppe of Chubut province (Argentina) previously confused with L. kingii (Bell 1843). Recent studies based on molecular evidence supports its evolutionary independence. Here we provide a morphological diagnosis of this lineage, comparisons between three molecular species delimitation methods, and an updated phylogeny of the L. kingii group. Based on current knowledge of its distribution, this new species is allopatric with geographically close species of the L. kingii group.

Filling Linnean shortfalls increases endemicity patterns: conservation and biogeographical implications for the extreme case of Liolaemus (Liolaemidae, Squamata) species

Linnean shortfalls, or the discrepancy between formally described species and the number of existing species, imply noteworthy biodiversity conservation constraints. The case of Argentinian reptiles is unique in this context. The genus Liolaemus represents ~60% of the Argentine reptile fauna and has a current species description rate of 3.25 spp./year, leading to a significant increase in the number of known species. Filling Linnean shortfalls within this genus has revealed an extraordinary recent evolutionary radiation that strongly modifies the spatial accumulation patterns of richness and endemism, mainly in the Patagonian steppe and Monte ecoregions of Argentina. Thus, while 40 years ago none of the studied species was considered endemic at the ecoregional level, today the genus represents an essential element to define the southernmost terrestrial ecoregions of the world. Furthermore, the remarkable decrease in the average extent of occurrence (EOO) of Liolaemus species implies an increased extinction risk in light of threats caused by humans. Based on the thresholds for the IUCN Red List B1 criteria, and 11 well-studied clades of Liolaemus, we show that, while in 1980 87% of the described species would not qualify as threatened based on EOO, today 80% of the species have an EOO smaller than 20 000 km2. Therefore, they may qualify as threatened based on the B1 EOO thresholds, which demonstrates the importance of the recent increase of knowledge regarding the taxonomy, systematics and genetics of the group.

An integrative approach to address species limits in the southernmost members of the Liolaemus kingii group (Squamata: Liolaemini)

Recent conceptual and methodological advances have enabled an increasing number of studies to address the problem of species delimitation in a comprehensive manner. This is of particular interest in cases of species whose divergence times are recent and/or effective population sizes are large, where the conclusions obtained from a single source of evidence may lead to erroneous estimations of true species numbers or incorrect assignment of individuals to species. Iguanian lizards of the Liolaemus kingii group (13 species) comprise an important component of the endemic fauna of Patagonia. The southernmost species of this group (namely L. baguali, L. escarchadosi, L. sarmientoi, and L. tari) show widely overlapping distributions across southern Patagonia, also, their phylogenetic relationships are ambiguous and species boundaries have not been explicitly tested. Here we use a comprehensive approach to assess species limits through the use of molecular and morphological information (mitochondrial cytb, nuclear sequences collected by ddRADseq, and linear, meristic and landmark-based morphometrics). We found support for the current taxonomy given that the different analyses recognized the nominal species (4 entities), also a candidate species was supported by mitochondrial and morphological data. In addition, we detected signs of admixture between some of the species. Our results indicate that the L. kingii group can serve as a model system in studies of diversification accompanied by hybridization in nature, which in turn might have been promoted by past climatic oscillations and generalist morphologies. We emphasize the importance of using multiple lines of evidence in order to solve evolutionary stories, and minimizing potential erroneous results that may arise when relying on a single source of information.

Phylogenomic data resolve higher-level relationships within South American Liolaemus lizards

Phylogenomic approaches now generate hundreds of loci representative of the whole genome that can be used for phylogenetic analyses. The South American lizard genus Liolaemus is the most species-rich vertebrate radiation from temperate zones (more than 265 described species), yet most higher-level phylogenetic relationships within Liolaemus remain poorly resolved. In this study, we used 584 nuclear loci collected using targeted sequenced capture to estimate the phylogenetic relationships among 26 species representing the two subgenera within Liolaemus (Eulaemus + Liolaemus), and all major groups within Eulaemus. Previous molecular and morphological-based phylogenetic analyses of Eulaemus based on a limited number of characters resolved few higher-level relationships, although one point of agreement is that the early divergence within Eulaemus corresponds to the lineomaculatus section, followed by the diversification of eight main clades that are strongly supported and recognized. Liolaemus probably experienced relatively rapid divergences during parts of its evolutionary history, and a phylogenomic approach was used to resolve the relationships among the major groups. The new analyses presented here support the division of Liolaemus into two subgenera, and resolve relationships among many of the major clades of Eulaemus with strong support. A Bayesian divergence dating analysis using 44 protein-coding genes provides an estimation of the split of the two Liolaemus subgenera of approximately 19,7 ma (95% HPD = 16,94-23,04), while diversification within Eulaemus started at 15,05 ma (95% HPD = 12,94 - 17,59) among the L. lineomaculatus and the L. montanus series by Mid Miocene. A novel phylogenetic network analyses for SNP data identified two hybridizing edges among different groups of Eulaemus at different points in time. Having a solid phylogenetic hypothesis of the main Eulaemus clades opens new opportunities to test a variety of macroevolutionary questions for this unique radiation.

Unravelling interspecific relationships among highland lizards: first phylogenetic hypothesis using total evidence of the Liolaemus montanus group (Iguania: Liolaemidae)

The South American lizard genus Liolaemus comprises > 260 species, of which > 60 are recognized as members of the Liolaemus montanus group, distributed throughout the Andes in central Peru, Bolivia, Chile and central Argentina. Despite its great morphological diversity and complex taxonomic history, a robust phylogenetic estimate is still lacking for this group. Here, we study the morphological and molecular diversity of the L. montanus group and present the most complete quantitative phylogenetic hypothesis for the group to date. Our phylogeny includes 103 terminal taxa, of which 91 are members of the L. montanus group (58 are assigned to available species and 33 are of uncertain taxonomic status). Our matrix includes 306 morphological and ecological characters and 3057 molecular characters. Morphological characters include 48 continuous and 258 discrete characters, of which 70% (216) are new to the literature. The molecular characters represent five mitochondrial markers. We performed three analyses: a morphology-only matrix, a molecular-only matrix and a matrix including both morphological and molecular characters (total evidence hypothesis). Our total evidence hypothesis recovered the L. montanus group as monophyletic and included ≥ 12 major clades, revealing an unexpectedly complex phylogeny.

Reptiles of Chubut province, Argentina: richness, diversity, conservation status and geographic distribution maps

An accurate estimation of species and population geographic ranges is essential for species-focused studies and conservation and management plans. Knowledge of the geographic distributions of reptiles from Patagonian Argentina is in general limited and dispersed over manuscripts from a wide variety of topics. We completed an extensive review of reptile species of central Patagonia (Argentina) based on information from a wide variety of sources. We compiled and checked geographic distribution records from published literature and museum records, including extensive new data from the LJAMM-CNP (CENPAT-CONICET) herpetological collection. Our results show that there are 52 taxa recorded for this region and the highest species richness was seen in the families Liolaemidae and Dipsadidae with 31 and 10 species, respectively. The Patagónica was the phytogeographic province most diverse in species and Phymaturus was the genus of conservation concern most strongly associated with it. We present a detailed species list with geographical information, richness species, diversity analyses with comparisons across phytogeographical provinces, conservation status, taxonomic comments and distribution maps for all of these taxa.