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Among evolutionary trends shaping phenotypic diversity over macroevolutionary scales, CREA (CRaniofacial Evolutionary Allometry) describes a tendency, among closely related species, for the smaller-sized of the group to have proportionally shorter rostra and larger braincases. Here, we used a phylogenetically broad cranial dataset, 3D geometric morphometrics, and phylogenetic comparative methods to assess the validity and strength of CREA in extinct and living felids. To test for the influence of biomechanical constraints, we quantified the impact of relative canine height on cranial shape evolution. Our results provided support to CREA at the family level. Yet, whereas felines support the rule, big cats, like Pantherinae and Machairodontinae, conform weakly if not at all with CREA predictions. Our findings suggest that Machairodontinae constitute one of the first well-supported exceptions to this biological rule currently known, probably in response to the biomechanical demands and developmental changes linked with their peculiar rostral adaptations. Our results suggest that the acquisition of extreme features concerning biomechanics, evo-devo constraints, and/or ecology is likely to be associated with peculiar patterns of morphological evolution, determining potential exceptions to common biological rules, for instance, by inducing variations in common patterns of evolutionary integration due to heterochronic changes under ratchet-like evolution.

Pantherine felids (‘big cats’) include the largest living cats, apex predators in their respective ecosystems. They are also the earliest diverging living cat lineage, and thus are important for understanding the evolution of all subsequent felid groups. Although the oldest pantherine fossils occur in Africa, molecular phylogenies point to Asia as their region of origin. This paradox cannot be reconciled using current knowledge, mainly because early big cat fossils are exceedingly rare and fragmentary. Here, we report the discovery of a fossil pantherine from the Tibetan Himalaya, with an age of Late Miocene–Early Pliocene, replacing African records as the oldest pantherine. A ‘total evidence’ phylogenetic analysis of pantherines indicates that the new cat is closely related to the snow leopard and exhibits intermediate characteristics on the evolutionary line to the largest cats. Historical biogeographic models provide robust support for the Asian origin of pantherines. The combined analyses indicate that 75% of the divergence events in the pantherine lineage extended back to the Miocene, up to 7 Myr earlier than previously estimated. The deeper evolutionary origin of big cats revealed by the new fossils and analyses indicate a close association between Tibetan Plateau uplift and diversification of the earliest living cats.

As apex predators, felids (Felidae) face unresolved phylogenetic controversies due to their recent rapid speciation and remarkable morphological conservatism. Previous studies, often relying on a limited number of genetic markers, were constrained by insufficient data and conflicting phylogenetic signals, leaving these disputes unresolved. Therefore, establishing a robust phylogenetic framework based on larger-scale genomic data is crucial. This study integrated complete mitogenomes from 37 species representing all major felid genera to characterize genomic diversity, selection pressures, and phylogenetic relationships. Results revealed conserved gene content and arrangement patterns but significant intergenic variation in nucleotide composition, with the light-strand encoded ND6 exhibiting pronounced strand-specific bias. Nucleotide diversity was highest in ND4L (Pi = 0.132) and ATP6 (Pi = 0.131), suggesting their utility as novel markers for species delimitation and population studies. Selection pressure analysis indicated strong purifying selection on cytochrome oxidase subunits (e.g., COX1 Ka/Ks = 0.00327) but relaxed constraints on ATP8 (Ka/Ks = 0.12304). Phylogenies reconstructed from the complete 13PCGs + 2rRNAs dataset (showing high congruence between maximum likelihood and Bayesian methods) clearly delineated Felidae into two primary clades (Pantherinae and Felinae), confirming monophyly of all genera and positioning Neofelis nebulosa as the basal lineage within Pantherinae. Crucially, exclusion of ND6 (12PCGs + 2rRNAs) yielded topologies congruent with the complete 13PCGs + 2rRNAs dataset, whereas single-gene or limited multi-gene datasets produced inconsistent trees (particularly at genus-level nodes). This demonstrates that near-complete mitogenomic data (≥12PCGs + 2rRNAs) are essential for reconstructing robust felid phylogenetic frameworks. Our study provides insights into carnivoran mitogenome evolution.

Background Olfactory stimulation is an often overlooked method of environmental enrichment for cats in captivity. The best known example of olfactory enrichment is the use of catnip, a plant that can cause an apparently euphoric reaction in domestic cats and most of the Pantherinae . It has long been known that some domestic cats and most tigers do not respond to catnip. Although many anecdotes exist of other plants with similar effects, data are lacking about the number of cats that respond to these plants, and if cats that do not respond to catnip respond to any of them. Furthermore, much is still unknown about which chemicals in these plants cause this response. Methods We tested catnip, silver vine, Tatarian honeysuckle and valerian root on 100 domestic cats and observed their response. Each cat was offered all four plant materials and a control, multiple times. Catnip and silver vine also were offered to nine tigers. The plant materials were analyzed by gas chromatography coupled with mass spectrometry to quantify concentrations of compounds believed to exert stimulating effects on cats. Results Nearly all domestic cats responded positively to olfactory enrichment. In agreement with previous studies, one out of every three cats did not respond to catnip. Almost 80% of the domestic cats responded to silver vine and about 50% to Tatarian honeysuckle and valerian root. Although cats predominantly responded to fruit galls of the silver vine plant, some also responded positively to its wood. Of the cats that did not respond to catnip, almost 75% did respond to silver vine and about one out of three to Tatarian honeysuckle. Unlike domestic cats, tigers were either not interested in silver vine or responded disapprovingly. The amount of nepetalactone was highest in catnip and only present at marginal levels in the other plants. Silver vine contained the highest concentrations of all other compounds tested. Conclusions Olfactory enrichment for cats may have great potential. Silver vine powder from dried fruit galls and catnip were most popular among domestic cats. Silver vine and Tatarian honeysuckle appear to be good alternatives to catnip for domestic cats that do not respond to catnip.

Among adults of closely related species, a trend in craniofacial evolutionary allometry (CREA) for larger taxa to be long-faced and smaller ones to have paedomorphic aspects, such as proportionally smaller snouts and larger braincases, has been demonstrated in some mammals and two bird lineages. Nevertheless, whether this may represent a ‘rule’ with few exceptions is still an open question. In this context, Felidae is a particularly interesting family to study because, although its members are short-faced, previous research did suggest relative facial elongation in larger living representatives. Using geometric morphometrics, based on two sets of anatomical landmarks, and traditional morphometrics, for comparing relative lengths of the palate and basicranium, we performed a series of standard and comparative allometric regressions in the Felidae and its two subfamilies. All analyses consistently supported the CREA pattern, with only one minor exception in the geometric morphometric analysis of Pantherinae: the genus Neofelis . With its unusually long canines, Neofelis species seem to have a relatively narrow cranium and long face, despite being smaller than other big cats. In spite of this, overall, our findings strengthen the possibility that the CREA pattern might indeed be a ‘rule’ among mammals, raising questions on the processes behind it and suggesting future directions for its study.

The bony labyrinth (inner ear) of mammals reveals systematic as well as morphofunctional information. However, detailed knowledge of bony labyrinth morphology and ontogeny in Pantherinae, that comprise some of the most iconic mammals, is still pending. Hence, we present the first comparative description of the bony labyrinth in all extant species of Panthera and Neofelis some of which are represented by several postnatal stages; particular focus is set on Panthera leo . Our study is based on µCT scans and virtual 3D reconstructions and accompanied by selected morphometric measurements. Even though quite similar in morphology, both genera as well as their species can be distinguished by several features, e.g., shape and relative size of the semicircular canals and presence or absence of an osseous secondary crus commune. In case of the latter, P. pardus shows some intraspecific variation. We also traced the reduction of the fossa subarcuata during ontogeny in P. leo which conforms with previous studies. Negative allometry of the bony labyrinth in relation to skull basal length can be observed during ontogeny as demonstrated by P. leo as well as between different sized species. Although not correlated with the length of the cochlear canal, the number of cochlear turns is higher in captive non-adult P. leo and P. tigris , but lower in adult captive P. pardus . If these intraspecific differences are related to captivity or represent an ontogenetic pattern, needs to be evaluated in future studies based on larger samples.

The study presents the status and diversity of major histocompatibility complex (MHC) class I genes in the Far Eastern leopard ( Panthera pardus orientalis ). 20 alleles of MHC genes were obtained from 11 samples in total, 19 alleles were described for the first time for the species. A high diversity of alleles is shown at the level of individuals as well as at the population level. Comparison of MHC gene polymorphism in leopard subspecies showed that the genetic diversity of the Far Eastern leopard is not lower and even possibly higher, than observed of the African and Indian subspecies. The high allelic diversity of the Far Eastern leopard genes is supported by the positive selection affecting on the antigen-binding region of the protein product they encrypt. It is concluded that the low abundance of the Far Eastern leopard has not yet led to irreparable losses in the genetic potential of the population.

The cat family Felidae is one of the most successful carnivore lineages today. However, the study of the evolution of acoustic communication between felids remains a challenge due to the lack of fossils, the limited availability of audio recordings because of their largely solitary and secretive behavior, and the underdevelopment of computational models and methods needed to address acoustic evolutionary questions. This study is a first attempt at developing a machine learning-based approach to the classification of felid calls as well as the identification of acoustic features that distinguish felid call types and species from one another. A felid call dataset was developed by extracting audio clips from diverse sources. The audio clips were manually annotated for call type and species. Due to the limited availability of samples, this study focused on the Pantherinae subfamily. Time-frequency features were then extracted from the Pantherinae dataset. Finally, several classification algorithms were applied to the resulting data. We achieved 91% accuracy for this Pantherinae call type classification. For the species classification, we obtained 86% accuracy. We also obtained the most predictive features for each of the classifications performed. These features can inform future research into the evolutionary acoustic analysis of the felid group. Competing Interest Statement The authors have declared no competing interest.

The jaguar (Panthera onca) is the most relevant predator in South America and an endangered species in Argentina. Therefore genomic, evolutionary and functional studies of this species are strategic to gain biological insights and support conservation efforts. With the advent of sequencing advances the study of relevant character species evolution has to be revisited. Recent comparative genomic analysis revealed a long history of hybridization among extant big cats, which indicates an absence of inter-specific isolation barriers. We aimed to uncover the molecular basis of this inter-species crossing and the evolution of the functional capacities of pantherine gamete interaction Zona Pellucida proteins (ZP) and JUNO. Hi-C long-range sequencing and chromosome-resolved jaguar genome assembly was used to resolve ZP genes loci and reconstruct the evolutionary history of these proteins. Exploring sequence variability in more that 30 Carnivora species, Feliforme and Caniforme sister groups show significant differences in average sequence identity for all studied proteins except ZP4, always showing Caniformes as a more diverse group than Feliformes. Molecular evolution of ZP subunits involved in sperm-recognition, ZP3 and ZP2, showed similar phylogenetic histories, displaying signatures of positive selection among Carnivores and Caniformes, but not among Pantherines or Feliformes. On the other hand, structural cross-linking ZP subunits, ZP1 and ZP4, displayed a different evolutionary history. The fusion protein IZUMO1R was found to be highly conserved in all studied phylogenetic groups. These results strengthen the idea that ZPs are proteins more related to specific-specificity isolation than IZUMO1R, which is specialized in fusion events. Altogether, our findings indicate that sperm-oocyte interaction and fusion proteins lack the degree of diversification necessary to establish a prezygotic reproductive isolation barrier between pantherines, which would explain observed reticulated patterns of evolution in this clade. Competing Interest Statement The authors have declared no competing interest.