Seroprevalence and genomic divergence of circulating strains of feline immunodeficiency virus among Felidae and Hyaenidae species

Feline immunodeficiency virus (FIV) infects numerous wild and domestic feline species and is closely related to human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV). Species-specific strains of FIV have been described for domestic cat (Felis catus), puma (Puma concolor), lion (Panthera leo), leopard (Panthera pardus), and Pallas' cat (Otocolobus manul). Here, we employ a three-antigen Western blot screening (domestic cat, puma, and lion FIV antigens) and PCR analysis to survey worldwide prevalence, distribution, and genomic differentiation of FIV based on 3,055 specimens from 35 Felidae and 3 Hyaenidae species. Although FIV infects a wide variety of host species, it is confirmed to be endemic in free-ranging populations of nine Felidae and one Hyaenidae species. These include the large African carnivores (lion, leopard, cheetah, and spotted hyena), where FIV is widely distributed in multiple populations; most of the South American felids (puma, jaguar, ocelot, margay, Geoffroy's cat, and tigrina), which maintain a lower FIV-positive level throughout their range; and two Asian species, the Pallas' cat, which has a species-specific strain of FIV, and the leopard cat, which has a domestic cat FIV strain in one population. Phylogenetic analysis of FIV proviral sequence demonstrates that most species for which FIV is endemic harbor monophyletic, genetically distinct species-specific FIV strains, suggesting that FIV transfer between cat species has occurred in the past but is quite infrequent today.     

Application of assisted reproduction for population management in felids: the potential and reality for conservation of small cats

Assisted reproductive technology (ART), using the primary applied tools of AI, ET, and sperm and embryo cryopreservation, has been promoted over the past decades for its potential to conserve endangered wildlife, including felids. However, if the goal is efficient, consistent production of viable offspring for population management, then the 'potential' of ART has yet to become 'reality' for any non-domestic cat species. For the five small-sized felids (i.e., Brazilian ocelot, fishing cat, Pallas' cat, Arabian sand cat, black-footed cat) managed by Species Survival Plans (SSPs) in North American zoos, achieving this potential may be an absolute necessity if genetically viable captive populations are to be maintained into the next century. Modeling programs suggest that current SSP populations are not sustainable without periodic introduction of new founders and improved demographic parameters, including longer generation intervals and larger population sizes. ART provides the means to address each of these management challenges. In each small cat SSP species, fecal hormone metabolite assays and seminal analysis have proven useful for characterizing basal reproductive parameters, a necessary prerequisite to developing ART. Of the five SSP species, ART has been used to produce living offspring only in the ocelot, including after AI with frozen-thawed spermatozoa and following transfer of frozen-thawed IVF embryos. The true efficacy of these techniques, however, is still unknown. To improve the applicability of ART for population management, priorities for immediate research include further investigation of ovarian stimulation protocols, sperm and embryo cryopreservation methods, embryo culture systems, and fetal and neonatal viability following ART.     

Ovarian control for assisted reproduction in the domestic cat and wild felids

Of the 37 felid species, all but the domestic cat are classified as threatened with extinction in all or part of their native range. Additionally, the domestic cat is a valuable model for human biomedical research. Propagating some wild felids as well as domestic cat populations serving as human models is a major challenge primarily due to difficulties in transporting animals between facilities to ensure the pairing of genetically matched individuals, behavioral incompatibility between pairs and low fertility. Artificial insemination (AI) and in vitro fertilization/embryo transfer (IVF/ET) are powerful tools for helping manage rare populations. Developing successful assisted reproductive techniques requires knowledge of the female reproductive cycle and precise control of ovarian activity. Successful ovarian stimulation for AI and IVF/ET has been achieved in at least one-third of all cat species. However, sensitivity to a given gonadotropin treatment appears highly species-specific, and poor responses are common, particularly in felid species that exhibit spontaneous ovulations. Furthermore, current gonadotropin regimens have been demonstrated to perturb female reproductive function often leading to reduced fertility. Overall, ovarian response to exogenous hormonal stimulation has been highly variable, and pregnancy success after AI or IVF/ET remains low (<20%) in most species. Therefore, there is an immediate need to develop improved regimens that would allow more predictable ovarian responses in felids. We contend that recent research involving the use of progestins to control the ovary prior to gonadotropin stimulation shows promise for providing consistent ovarian stimulation in felids.     

Using PGFM (13,14-dihydro-15-keto-prostaglandin F2α) as a non-invasive pregnancy marker for felids

Understanding the complex endocrine interactions that control reproduction in felids is essential for captive breeding management. The most important demand is a quick and reliable pregnancy diagnosis. However, the occurrence of pseudopregnancies in felids complicates matters. We investigated whether the fecal prostaglandin metabolite (PGFM) recently suggested for pregnancy diagnosis in the lynx is suitable for all felid species. We found that increased levels of PGFM during the last trimester indicate pregnancy in seven of the eight main lineages of the carnivore family Felidae. PGFM levels in a sand cat (domestic cat lineage) were basal at mating and remained so until Day 40 post-mating. Day 41 marked the beginning of a distinct increase culminating in peak levels of 6.5 μg/g before parturition and decreasing again to baseline thereafter. Similar pregnancy profiles were obtained from the domestic cat, the leopard cat, the lynx, the ocelot and the caracal lineage, whereas in pseudopregnant individuals (sand cat, Iberian and Eurasian lynx) fecal PGFM remained at basal levels. In pregnant cheetahs (puma lineage) PGFM increased above basal following day ∼48 peaking before pregnancy but remained at baseline in pseudopregnant females. Discrepancies existed in the Panthera lineage. While Chinese leopard, Sumatran tiger, and the black panther showed marked increases of PGFM during the last weeks of pregnancy, only moderate increases in PGFM levels were found in the Indochinese tiger and the Persian leopard. Altogether, PGFM as tool for pregnancy diagnosis has been proven to be useful in breeding management of felids.     

Resolution of recent radiations within three evolutionary lineages of felidae using mitochondrial restriction fragment length polymorphism variation

Patterns of mitochondrial restriction fragment length polymorphism (RFLP) variation were used to resolve more recent relationships among the species of the Felidae ocelot lineage, domestic cat lineage, and pantherine lineage. Twenty-five of 28 restriction enzymes revealed site variation in at least 1 of 21 cat species. The ocelot lineage was resolved into three separate sistertaxa groups: Geoffroy's cat (Oncifelis geoffroyi) and kodkod (O. guigna), ocelot (Leopardus pardalis) and margay (L. wiedii), and pampas cat (Lynchailurus colocolo) and most of the tigrina samples (Leopardus tigrina). Within the domestic cat lineage, domestic cat (Felis catus), European wild cat (F. silvestris), and African wild cat (F. libyca) formed a monophyletic trichotomy, which was joined with sand cat (F. margarita) to a common ancestor. Jungle cat (F. chaus) and black-footed cat (F. nigripes) mtDNAs diverged earlier than those of the other domestic cat lineage species and are less closely related. Within the pantherine lineage, phylogenetic analysis identified two distinct groups, uniting lion (P. leo) with leopard (P. pardus) and tiger (P. tigris) with snow leopard (P. uncia).To whom correspondence should be addressed.     

Molecular Phylogeny of Mitochondrial Cytochrome b and 12S rRNA Sequences in the Felidae: Ocelot and Domestic Cat Lineages

Molecular phylogeny of the cat family Felidae is derived using two mitochondrial genes, cytochrome b and 12S rRNA. Phylogenetic methods of weighted maximum parsimony and minimum evolution estimated by neighbor-joining are employed to reconstruct topologies among 20 extant felid species. Sequence analyses of 363 bp of cytochrome b and 376 bp of the 12S rRNA genes yielded average pair-wise similarity values between felids ranging from 94 to 99% and from 85 to 99%, respectively. Phylogenetic reconstruction supports more recent, intralineage associations but fails to completely resolve interlineage relationships. Both genes produce a monophyletic group ofFelisspecies but vary in the placement of the pallas cat. The ocelot lineage represents an early divergence within the Felidae, with strong associations between ocelot and margay, Geoffroy's cat and kodkod, and pampas cat and tigrina. Implications of the relative recency of felid evolution, presence of ancestral polymorphisms, and influence of outgroups in placement of the topological root are discussed.     

Rescue and maturation in vitro of follicular oocytes collected from nondomestic felid species.

The potential for rescuing immature oocytes from the ovaries of females of rare felid species which die or undergo medical ovariohysterectomy was evaluated. Ovaries were recovered from 13 species representing 35 individuals in good-to-poor health. Although the majority of females were 10 yr of age or older and in fair-to-poor health, a total of 846 oocytes were recovered of which 608 (71.9%) were classified as fair-to-excellent quality. One hundred of these oocytes were used for initial maturation classification and as parthogenetic controls. Overall, of the 508 fair-to-excellent quality oocytes placed in culture, 164 (32.3%) matured to metaphase II in vitro. For species in which 3 or more individuals yielded oocytes, mean oocyte maturation rates were as follows: 36.2%, tiger; 27.9% leopard; and 8.3%, cheetah. In vitro insemination of oocytes resulted in fertilization (2 polar bodies, 2 pronuclei, or cleavage) rates of 9.1% to 28.6% (leopard) using homologous fresh spermatozoa and 4.0% (lion) to 40.0% (puma) using homologous frozen-thawed spermatozoa. Inseminations using heterologous (domestic cat) spermatozoa also resulted in fertilized oocytes in the tiger, leopard, snow leopard, puma, serval, and Geoffroy's cat (range in fertilization rate, 5.0% for leopard to 46.2% for puma). Cleaved embryos resulted from the insemination of leopard oocytes with homologous sperm (n = 1 embryo) and puma oocytes with domestic cat sperm (n = 3 embryos). These results demonstrate that immature ovarian oocytes from rare felid species can be stimulated to mature in vitro despite an excision-to-culture interval as long as 36 h.(ABSTRACT TRUNCATED AT 250 WORDS)     

Directional selection in the evolution of elongated upper canines in clouded leopards and sabre‐toothed cats

Extremely developed or specialized traits such as the elongated upper canines of extinct sabre‐toothed cats are often not analogous to those of any extant species, which limits our understanding of their evolutionary cause. However, an extant species may have undergone directional selection for a similar extreme phenotype. Among living felids, the clouded leopard, Neofelis nebulosa, has exceptionally long upper canines for its body size. We hypothesized that directional selection generated the elongated upper canines of clouded leopards in a manner similar to the process in extinct sabre‐toothed cats. To test this, we developed an approach that compared the effect of directional selection among lineages in a phylogeny using a simulation of trait evolution and approximate Bayesian computation. This approach was applied to analyse the evolution of upper canine length in the Felidae phylogeny. Our analyses consistently showed directional selection favouring longer upper canines in the clouded leopard lineage and a lineage leading to the sabre‐toothed cat with the longest upper canines, Smilodon. Most of our analyses detected an effect of directional selection for longer upper canines in the lineage leading to another sabre‐toothed cat, Homotherium, although this selection may have occurred exclusively in the primitive species. In all the analyses, the clouded leopard and Smilodon lineages showed comparable directional selection. This implies that clouded leopards share a selection advantage with sabre‐toothed cats in having elongated upper canines.     

A MOLECULAR PHYLOGENY OF THE FELIDAE: IMMUNOLOGICAL DISTANCE

The phylogenetic distances between 34 of the 37 extant species of Felidae were estimated using albumin immunological distances (AID). Albumins from ten cat species were used to prepare antisera in rabbits. A consensus phylogeny was constructed from a matrix of reciprocal AID measurements using four distinct phylogenetic algorithms. A series of one-way measurements using the ten index antisera and those 24 species for which albumins were available (but antisera were not), permitted addition of these “species' limbs” to the previously derived phylogenetic trees. The major conclusions of the derived topology were: 1) the earliest branch of the feline radiation occurred approximately 12 million years B.P. and led to the small South American cats (ocelot, margay, Geoffroy's cat, etc.); 2) the second branching occurred 8-10 million years B.P. and included the close relatives of the domestic cat (wildcats, jungle cat, sand cat, and black-footed cat) plus Pallas's cat; 3) the third lineage which began to radiate 4-6 million years B.P. was the pantherine lineage, which included several early branches (cheetah, serval, clouded leopard, golden cats, and puma) and a very recent (2 million years B.P.) split between the lynxes and the modern great cats (Panthera). The topology of the Felidae derived from albumin immunological distance is highly consistent with the karyological disposition of these species, as well as with the fossil record of this family. Because of the recent divergence of this group, the presented data set and the derived topology contain certain unresolved phylogenetic relationships which are so indicated.     

Cats under cover: Habitat models indicate a high dependency on woodlands by Atlantic Forest felids

Four Neotropical small and medium felids—the ocelot, jaguarundi, margay, and southern tiger cat—have overlapping geographic distributions in the endangered Atlantic Forest. Local studies show that these felids avoid areas with high human impact, but the three smaller ones use human‐modified areas more frequently than do ocelots. To understand how landscape changes affect the habitat distribution of these four felids in the Atlantic Forest of Argentina, we used maximum entropy models to analyze the effect of environmental and anthropogenic factors. We estimated niche breadth and overlap among these felids. The conversion of the native forest to land uses without trees was the most important variable that determined the habitat distribution of the four species. For all four species, the optimal habitat covered about 1/3 of the study area and corresponds mainly to the native forest areas. Nearly 50% of these areas had some level of protection. The niche width was higher for the small felids than for ocelots. Niche overlap was high for all species pairs, but higher among the small felids and lower for each of these with the ocelot. The four felids were negatively affected by native forest loss, with ocelots being more sensitive than the smaller felids. The conversion of unprotected forest areas to other types of land uses would imply a greater habitat loss for these felids. The protection of current remnants of Atlantic Forest in Argentina is important for the long‐term conservation of the four felids. Abstract in Spanish is available with online material.     

Phylogenetic reconstruction of South American felids defined by protein electrophoresis

Phylogenetic associations among six closely related South American felid species were defined by changes in protein-encoding gene loci. We analyzed proteins isolated from skin fibroblasts using two-dimensional electrophoresis and allozymes extracted from blood cells. Genotypes were determined for multiple individuals of ocelot, margay, tigrina, Geoffroy's cat, kodkod, and pampas cat at 548 loci resolved by two-dimensional electrophoresis and 44 allozyme loci. Phenograms were constructed using the methods of Fitch-Margoliash and neighbor-joining on a matrix of Nei's unbiased genetic distances for all pairs of species. Results of a relative-rate test indicate changes in two-dimensional electrophoresis data are constant among all South American felids with respect to a hyena outgroup. Allelic frequencies were transformed to discrete character states for maximum parsimony analysis. Phylogenetic reconstruction indicates a major split occurred approximately 5–6 million years ago, leading to three groups within the ocelot lineage. The earliest divergence led to Leopardus tigrina, followed by a split between an ancestor of an unresolved trichotomy of three species (Oncifelis guigna, O. geoffroyi, and Lynchaduris colocolo) and a recent common ancestor of Leopardus pardalis and L. wiedii. The results suggest that modern South American felids are monophyletic and evolved rapidly after the formation of the Panama land bridge between North and South America.Correspondence to: J. Pecon Slattery     

Sabertooth characters in the clouded leopard (Neofelis nebulosa Griffiths 1821)

The clouded leopard (Neofelis nebulosa) is an unusual medium-sized felid whose ecology in the wild is poorly known. Mainly famous for its large canines, it has often been an overlooked taxon in analyses of felid morphology and systematics or has proven aberrant and difficult to interpret. In this article I report on a number of unusual features in the clouded leopard skull hitherto considered characteristic of sabertooth felids exclusively, and, accordingly, universally believed to be absent in extant felids. The skull morphology of the clouded leopard sets it apart from other extant felids, and in a number of respects it approaches the morphology of primitive sabertooths. This indicates convergence of several characters in machairodontine felids and the clouded leopard, mainly as adaptations for attaining a large gape. This raises doubts about the characters hitherto considered as distinguishing sabertoothed from nonsabertoothed predators, and since no evidence at present suggests a different functional killing and feeding ecology in Neofelis, regardless of its unusual skull morphology, also whether primitive sabertoothed felids were functionally similar to advanced forms such as Homotherium, Megantereon, or Smilodon.     

Comparative endocrinology of domestic and nondomestic felids

The ability to track gonadal and adrenal activity via hormones is key to optimizing health and reproduction. Through decades of study, a great deal has been learned about the biology of female domestic cats, including endocrine function. More recently, comparative endocrine studies have greatly expanded our knowledge base of nondomestic felids as well. The latter has been possible largely through the development of noninvasive fecal steroid metabolite analysis techniques, which currently is the method of choice for monitoring endocrine function in wildlife species, including felids. It now is well-recognized that a range in endocrine patterns exists among Felidae, with many traits and mechanisms being uncommon, if not unique. There is a high degree of variability in the type of ovulation (spontaneous versus induced) expressed across the taxon. Even within species, some individuals exhibit ovulation that is only induced, whereas others ovulate spontaneously as well. Steroid metabolism also differs in that metabolites are excreted almost exclusively in feces, with very little steroid found in urine. Across species there are marked differences in seasonal and social influences on reproduction, adrenal responses to husbandry practices, and ovarian responses to assisted reproductive procedures. This means that developing strategies to improve health and reproduction of felids must be done on a species by species basis. This paper summarizes current knowledge on the reproductive endocrinology of female domestic and nondomestic cats, and describes how the rapidly growing endocrine database is aiding ex situ management efforts.     

泰国Khao Yai国家公园豹猫和云豹的生态和保护

于1997年10月到1999年10月在泰国KhaoYai国家公园对两种同域分布的物种（即豹猫和云豹）进行了研究。使用带诱饵的陷阱捕捉了这些动物,进行麻醉,确定了性别、年龄,并戴上了无线电项圈,对6只雌性豹猫和4只雄性豹猫进行了1—18个月的无线电追踪。豹猫在干旱季节的利用区域大于雨季,雄性利用的区域大于雌性。在夜间和晨昏时节,豹猫活动增加,但是并没有节律性活动。所有豹猫个体在旱季和雨季的活动都相似,但雄性个体的白天活动多于雌性。豹猫的行走距离有性别差异但是没有季节差异;其食物以鼠类为主。分别对1只雌性云豹和1只雄性云豹进行了17个月和7个月的无线电追踪,雌性个体的活动面积为39．4km^2,而雄性个体活动面积为42．2km^2,核心区都是2．9km2。云豹对半绿林的使用大于其它类型的植被,在晨昏和夜间的活动增加,其活动无节律。     

Sympatric Asian felid phylogeography reveals a major Indochinese–Sundaic divergence

The dynamic geological and climatological history of Southeast Asia has spawned a complex array of ecosystems and 12 of the 37 known cat species, making it the most felid‐rich region in the world. To examine the evolutionary histories of these poorly studied fauna, we compared phylogeography of six species (leopard cat Prionailurus bengalensis, fishing cat P. viverrinus, Asiatic golden cat Pardofelis temminckii, marbled cat P. marmorata, tiger Panthera tigris and leopard P. pardus) by sequencing over 5 kb of DNA each from 445 specimens at multiple loci of mtDNA, Y and X chromosomes. All species except the leopard displayed significant phylogenetic partitions between Indochina and Sundaland, with the central Thai–Malay Peninsula serving as the biogeographic boundary. Concordant mtDNA and nuclear DNA genealogies revealed deep Indochinese–Sundaic divergences around 2 MYA in both P. bengalensis and P. marmorata comparable to previously described interspecific distances within Felidae. The divergence coincided with serial sea level rises during the late Pliocene and early Pleistocene, and was probably reinforced by repeated isolation events associated with environmental changes throughout the Pleistocene. Indochinese–Sundaic differentiations within P. tigris and P. temminckii were more recent at 72–108 and 250–1570 kya, respectively. Overall, these results illuminate unexpected, deep vicariance events in Southeast Asian felids and provide compelling evidence of species‐level distinction between the Indochinese and Sundaic populations in the leopard cat and marbled cat. Broader sampling and further molecular and morphometric analyses of these species will be instrumental in defining conservation units and effectively preserving Southeast Asian biodiversity.     

Learning from the past to prepare for the future: felids face continued threat from declining prey

Many contemporary species of large‐felids (≥ 15 kg) feed upon prey that are endangered, raising concern that prey population declines (defaunation) will further threaten felids. We assess the threat that defaunation presents by investigating a late Quaternary (LQ), ‘present‐natural’ counterfactual scenario. Our present‐natural counterfactual is based on predicted ranges of mammals today in the absence of any impacts of modern humans Homo sapiens through time. Data from our present‐natural counterfactual are used to understand firstly how megafauna extinction has impacted felid communities to date and secondly to quantify the threat to large‐felid communities posed by further declines in prey richness in the future. Our purpose is to identify imminent risks to biodiversity conservation and their cascading consequences and, specifically, to indicate the importance of preserving prey diversity. We pursue two lines of enquiry; first, we test whether the loss of prey species richness is a potential cause of large‐felid extinction and range loss. Second, we explore what can be learnt from the large‐scale large‐mammal LQ losses, particularly in the Americas and Europe, to assess the threat any further decline in prey species presents to large‐felids today, particularly in Africa and Asia. Large‐felid species richness was considerably greater under our present‐natural counterfactual scenario compared to the current reality. In total, 86% of cells recorded at least one additional felid species in our present‐natural counterfactual, and up to 4–5 more large‐felid species in 10% of the cells. A significant positive correlation was recorded between the number of prey species lost and the number of large‐felid species lost from a cell. Extant felids most at risk include lion and Sunda clouded leopard, as well as leopard and cheetah in parts of their range. Our results draw attention to the continuation of a trend of megafauna decline that began with the emergence of hominins in the Pleistocene.     

Reproductive biology of the 38 extant felid species: a review

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GnRH agonist Lupron (leuprolide acetate) pre-treatments prevent ovulation in response to gonadotropin stimulation in the clouded leopard (Neofelis nebulosa)

In many species, controlling the ovary prior to induction of ovulation improves the success of ovarian response and artificial insemination (AI). We assessed the impact of suppression of estrus with the GnRH agonist, Lupron, on ovarian sensitivity to equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG) in the clouded leopard. Seven female clouded leopards were given two injections of Lupron (3.75 mg IM) 23 d apart, followed 44 d later by eCG and hCG. Daily fecal samples were collected from 60 d before Lupron to 60 d after hCG. Fecal metabolites of estrogen (E) and progesterone (P) were measured by radioimmunoassay. Lupron decreased (P < 0.05) the number of E peaks during Lupron treatment compared to pre-Lupron. All females had baseline E and six of seven (86%) had nadir P on day of eCG. Exogenous gonadotropins induced E elevations in all females. However, mean E in the gonadotropin-provoked estrus was decreased (P < 0.05) compared to pre-Lupron estrous periods. Only one of seven (14%) females ovulated after eCG/hCG. In conclusion, estrous cycle control with Lupron resulted in predictable ovarian suppression prior to gonadotropin stimulation but altered ovarian sensitivity by an as yet unknown mechanism so that ovulation was inhibited, even when using a proven exogenous gonadotropin protocol.     

Comparison of several types of enrichment for captive felids

Enrichment can increase the complexity of the captive environment and possibly enhance captive animals' well‐being by stimulating active behaviors and reducing stereotypical behaviors commonly seen in zoo felids. In this study, three different enrichment items were added to outdoor enclosures of felids at the Montgomery Zoo to test their effects on activity levels and stereotypic pacing. Bones, frozen fish, and spices (cinnamon, chili powder, and cumin) were presented over a 3‐month period to six species of felids: cheetah, cougar, jaguar, lion, ocelot, and tiger. Proportion of time spent engaging in active behaviors and stereotypic pacing were compared before, during, and after treatments. All treatments resulted in a significant increase in activity level from baseline (bones: +15.59%; frozen fish: +35.7%; spices: +12.38%). Effects of enrichment items on activity levels were not sustained 7 days after removal. Proportion of time spent pacing significantly decreased during presentation of spices (?21.25%) and frozen fish (?26.58%), but not with the addition of bones. However, only the effect of frozen fish on stereotypic behavior was sustained 7 days after removal of the enrichment item. In conclusion, bones, spices, and frozen fish are inexpensive and easy‐to‐administer enrichment items that may be used to increase active behaviors of captive felids. Zoo Biol 26:371–381, 2007. © 2007 Wiley‐Liss, Inc.     

Canine morphology in the larger Felidae: implications for feeding ecology

Canine morphology is analysed at seven intervals along the crown in both anteroposterior and lateromedial perspective in seven species of large felids. The puma and the snow leopard have stout, rather conical canines, whereas those of lions, jaguars, and tigers bear substantial resemblance to each other, reflecting their phylogenetic relationships, and are less conical and large. The canines of the leopard are intermediate in morphology between those of the other species, probably reflecting its more generalized diet. The clouded leopard has very large and blade-like canines, which are different from the other analysed species. Canine bending strengths to estimated bite forces appear to differs less among the species than morphology, indicating that the evolution of canines has been constricted with respect to their strength in failure, probably owing to their being equally important for species fitness. However, the clouded leopard again stands out, having a high estimated bite force and rather weak canines in bending about the anteroposterior as well as lateromedial planes compared to the other species. Canine morphology to some extent reflects differences in killing mode, but also appears to be related to the phylogeny. The marked divergence of the clouded leopard is presently not understood.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 91 , 573–592.