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opencc-zeroDec 2014View details →

Data from: Iterative adaptive radiations of fossil canids show no evidence for diversity-dependent trait evolution

A long-standing hypothesis in adaptive radiation theory is that ecological opportunity constrains rates of phenotypic evolution, generating a burst of morphological disparity early in clade history. Empirical support for the early burst model is rare in comparative data, however. One possible reason for this lack of support is that most phylogenetic tests have focused on extant clades, neglecting information from fossil taxa. Here, I test for the expected signature of adaptive radiation using the outstanding 40-My fossil record of North American canids. Models implying time- and diversity-dependent rates of morphological evolution are strongly rejected for two ecologically important traits, body size and grinding area of the molar teeth. Instead, Ornstein–Uhlenbeck processes implying repeated, and sometimes rapid, attraction to distinct dietary adaptive peaks receive substantial support. Diversity-dependent rates of morphological evolution seem uncommon in clades, such as canids, that exhibit a pattern of replicated adaptive radiation. Instead, these clades might best be thought of as deterministic radiations in constrained Simpsonian subzones of a major adaptive zone. Support for adaptive peak models may be diagnostic of subzonal radiations. It remains to be seen whether early burst or ecological opportunity models can explain broader adaptive radiations, such as the evolution of higher taxa.

opencc-zeroDec 2010View details →

Data from: Do convergent ecomorphs evolve through convergent morphological pathways? Cranial shape evolution in fossil hyaenids and borophagine canids (Carnivora, Mammalia)

Cases of convergent evolution, particularly within ecomorphological contexts, are instructive in identifying universally adaptive morphological features across clades. Tracing of evolutionary pathways by which ecomorphological convergence takes place can further reveal mechanisms of adaptation, which may be strongly influenced by phylogeny. Ecomorphologies of carnivorous mammals represent some of the most outstanding cases of convergent evolution in the Cenozoic radiation of mammals. This study examined patterns of cranial shape change in the dog (Canidae) and hyena (Hyaenidae) families, in order to compare the evolutionary pathways that led to the independent specialization of bone-cracking hypercarnivores within each clade. Geometric morphometrics analyses of cranial shape in fossil hyaenids and borophagine canids provided evidence for deep-time convergence in morphological pathways toward the independent evolution of derived bone-crackers. Both clades contained stem members with plesiomorphic generalist/omnivore cranial shapes, which evolved into doglike species along parallel pathways of shape change. The evolution of specialized bone-crackers from these doglike forms, however, continued under the constraint of a full cheek dentition and restriction on rostrum length reduction in canids, but not hyaenids. Functionally, phylogenetic constraint may have limited borophagine canids to crack bones principally with their carnassial instead of the third premolar as in hyaenids, but other cranial shape changes associated with durophagy nevertheless evolved in parallel in the two lineages. Size allometry was not a major factor in cranial shape evolution in either lineage, supporting the interpretation of functional demands as drivers for the observed convergence. The comparison between borophagines and hyaenids showed that differential effects of alternative functional "solutions" that arise during morphological evolution may be multiplied with processes of the "macroevolutionary ratchet" already in place to further limit the evolutionary pathways available to specialized lineages.

opencc-zeroDec 2016View details →

Data from: Rediscovering a forgotten canid species

Background: The African wolf, for which we herein recognise Canis lupaster Hemprich and Ehrenberg, 1832 (Symbolae Physicae quae ex Itinere Africam Borealem er Asoam Occidentalem Decas Secunda. Berlin, 1833) as the valid species name (we consider the older name Canis anthus Cuvier, 1820 [Le Chacal de Sénégal, Femelle. In: Geoffroy St.-Hilaire E, Cuvier F, editors. Histoire Naturelle des Mammifères Paris, A. Belin, 1820] a nomen dubium), is a medium-sized canid with wolf-like characters. Because of phenotypic similarity, specimens of African wolf have long been assigned to golden jackal (Canis aureus Linnaeus, 1758 [Systema Naturae per Regna Tria Naturae, Secundum Classes, Ordines, Genera, Species, cum Characteribus, Differentiis, Synonymis, Locis. Tomus I. Editio decima, reformata, 1758]). Results: Here we provide, through rigorous morphological analysis, a species description for this taxonomically overlooked species. Through molecular sequencing we assess its distribution in Africa, which remains uncertain due to confusion regarding possible co-occurrence with the Eurasian golden jackal. Canis lupaster differs from all other Canis spp. including the golden jackal in its cranial morphology, while phylogenetically it shows close affinity to the Holarctic grey wolf (Canis lupus Linnaeus, 1758 [Systema Naturae per Regna Tria Naturae, Secundum Classes, Ordines, Genera, Species, cum Characteribus, Differentiis, Synonymis, Locis. Tomus I. Editio decima, reformata, 1758]). All sequences generated during this study clustered with African wolf specimens, consistent with previous data for the species. Conclusions: We suggest that the estimated current geographic range of golden jackal in Africa represents the African wolf range. Further research is needed in eastern Egypt, where a hybrid zone between Eurasian golden jackal and African wolf may exist. Our results highlight the need for improved studies of geographic range and population surveys for the taxon, which is classified as 'least concern' by the IUCN due to its erroneous identification as golden jackal. As a species exclusively distributed in Africa, investigations of the biology and threats to African wolf are needed.

opennotspecifiedAug 2011View details →

Distribution. Llamas are found at 3800-5000 m above sea level in the Central Andes, from C Peru to W Bolivia and N Argentina. Llama distribution reached its apex during the expansion of the Inca Empire (1470-1532 ap), when pack trains were used to carry supplies for the royal armies to S Colombia and C Chile. Although originally indigenous and endemic to South America, Llamas have now been exported to countries around the world as a companion animal, featured in livestock shows, used for trekking and backpacking, cottage industry and home use ofits wool, and in North America increasingly utilized as a guard animal for protecting sheep and goats from canid predators. in Camelidae

Distribution. Llamas are found at 3800-5000 m above sea level in the Central Andes, from C Peru to W Bolivia and N Argentina. Llama distribution reached its apex during the expansion of the Inca Empire (1470-1532 ap), when pack trains were used to carry supplies for the royal armies to S Colombia and C Chile. Although originally indigenous and endemic to South America, Llamas have now been exported to countries around the world as a companion animal, featured in livestock shows, used for trekking and backpacking, cottage industry and home use ofits wool, and in North America increasingly utilized as a guard animal for protecting sheep and goats from canid predators.

Fig. 1 in Composition of the canid auditory bulla and a new look at the evolution of carnivoran entotympanics

Fig. 1 Simplified diagram showing the spatial relations between the 'caudal entotympanic' portion of the auditory bulla (left semicircles) and the principal sinus contributing to the bullar inflation and septal formation in the Aeluroidea (e.g. felids) (a) and Cynoidea (canids) (b). Ventral views of left auditory bulla. Rostral entotympanic is not shown. Dotted lines indicate where the aeluroid septum bullae and cynoid intrabullar septum start to develop. Abbreviations: CES, caudal entotympanic sinus; T, ectotympanic; VES, ventral entotympanic sinus

Fig. 3 Juvenile Canis lupus ZIN O-34160 in Composition of the canid auditory bulla and a new look at the evolution of carnivoran entotympanics

Fig. 3 Juvenile Canis lupus ZIN O-34160 (a) and ZIN O-34158 (b); postero-ventro-medial views of the left (a) and reversed right (b) auditory bullae. Stereophotographs. In ZIN O-34160, all entotympanics are still separate except for the early contacting rostral entotympanic and anterior caudal entotympanic. In ZIN O-34158, the ventral entotympanic is already embraced by the anterior and posterior caudal entotympanics. Abbreviations: AE, anterior caudal entotympanic; AL, alisphenoid; BO, basioccipital; BS, basisphenoid; OC, occipital condyle; P, petrosal; PE, posterior caudal entotympanic; PGP, postglenoid process; POP, paroccipital process; RL, lateral vertical plate of rostral entotympanic; SQ, squamosal; T, ectotympanic; VE, ventral entotympanic. Asterisk indicates an unknown contributor to the lateral wall of the carotid canal; dashed outline denotes the ventral entotympanic borders. Scale bars equal 5 mm

Fig. 4 Juvenile Canis lupus ZIN O-34158 in Composition of the canid auditory bulla and a new look at the evolution of carnivoran entotympanics

Fig. 4 Juvenile Canis lupus ZIN O-34158; postero-ventro-lateral view of the right auditory bulla. Note the distinct suture between the ventral entotympanic and posterior caudal entotympanic. The latter is not yet completely ossified posterodorsally (to form the anterior wall of the stylomastoid foramen) and laterally (to contact the ectotympanic). Abbreviations: AL, alisphenoid; BO, basioccipital; BS, basisphenoid; EO, exoccipital; M, mastoid; P, petrosal; PE, posterior caudal entotympanic; PGP, postglenoid process; POP, paroccipital process; R, rostral entotympanic; SQ, squamosal; T, ectotympanic; TH, tympanohyal; VE, ventral entotympanic. Scale bar equals 5 mm

Fig. 2 in Composition of the canid auditory bulla and a new look at the evolution of carnivoran entotympanics

Fig. 2 Schematic reconstruction of entotympanic ossifications in the canid auditory bulla. a–g Consecutive states within the first five postnatal weeks; posteromedial and slightly ventral views of left auditory bulla (see Fig. 3 for similar aspects of the skull). Non-bullar bones are not shown. Abbreviations: AC, anterior carotid foramen; AD, anterodorsal intrabullar septum; AE, anterior caudal entotympanic; PC, posterior carotid foramen; PD, posterodorsal intrabullar septum; PE, posterior

Fig. 5 in Composition of the canid auditory bulla and a new look at the evolution of carnivoran entotympanics

Fig. 5 Ossification of the medial wall of the carotid canal in juvenile Vulpes vulpes. a ZIN O-9147, postero-ventro-medial view of the right auditory bulla. Note that the medial wall of the carotid canal is still unossified and represented by a semi-transparent film of connective tissue (RM). b NMNHU 1092, ventromedial view of the right auditory bulla. In this slightly older specimen, the rostral entotympanic is completely ossified, but its suture with the anterior caudal entotympanic

opencc-zeroDec 2022View details →

Evolutionary radiation in canids following continental colonizations

Colonization of a new environment may trigger a remarkable radiation process, defined as an accelerated accumulation of species in a short period of time. However, how often colonization events trigger such radiations is still an open question. We studied the worldwide dispersal of the subfamily Caninae to investigate whether the invasion of new continents resulted in a great increase in species diversification. We used a combination of phylogenetic analyses and ancestral area reconstructions to estimate ancestral ranges of 56 extant and extinct species of Caninae, as well as variation in speciation and extinction rates through time and across clades. Our findings indicate that canids experienced a remarkable radiation event when lineages were able to reach Eurasia and South America around 11 million years ago. This large number of species arising in a short period of time suggests that canids experienced ecological opportunity events within the new areas, implying that the differences in the ecological settings between continents, and size variation among Canidae and other carnivores may be responsible for the variation in clade dynamics. We suggest that the advance of grasslands and the new herbivorous fauna that came with it were the major forces responsible for the diversification of wolves in North America. On the other hand, empty niches and the absence of competitors can explain the success of canids in Africa and South America. We argue that interaction with other carnivores probably also affected the diversification dynamics of canids.