Ancient DNA reveals differences in behaviour and sociality between brown bears and extinct cave bears

Ancient DNA studies have revolutionized the study of extinct species and populations, providing insights on phylogeny, phylogeography, admixture and demographic history. However, inferences on behaviour and sociality have been far less frequent. Here, we investigate the complete mitochondrial genomes of extinct Late Pleistocene cave bears and middle Holocene brown bears that each inhabited multiple geographically proximate caves in northern Spain. In cave bears, we find that, although most caves were occupied simultaneously, each cave almost exclusively contains a unique lineage of closely related haplotypes. This remarkable pattern suggests extreme fidelity to their birth site in cave bears, best described as homing behaviour, and that cave bears formed stable maternal social groups at least for hibernation. In contrast, brown bears do not show any strong association of mitochondrial lineage and cave, suggesting that these two closely related species differed in aspects of their behaviour and sociality. This difference is likely to have contributed to cave bear extinction, which occurred at a time in which competition for caves between bears and humans was likely intense and the ability to rapidly colonize new hibernation sites would have been crucial for the survival of a species so dependent on caves for hibernation as cave bears. Our study demonstrates the potential of ancient DNA to uncover patterns of behaviour and sociality in ancient species and populations, even those that went extinct many tens of thousands of years ago

Desgaste dentario e ingestión de partículas minerales en osos actuales y extintos del Norte de España

[Abstract] The dental morphology of the cave bear Ursus spelaeus (Rosenmuller & Heinroth, 1794) indicates its specialisation as a vegetation eater. Although vegetal matter plays also an important role in the diet of most living bears, the dental wear exhibited by cave bears differs qualitatively from that seen in brown bears even on gross inspection. The diet of the extant brown bear Ursus arctos (Linnaeus, 1758) is well known from present-day stu-dies involving direct observation as well as scat analysis. The ingestion of tubers and other gritty foods has repeatedly been suggested as the cause for the extreme wear observed on cave bear teeth. In this work we seek to analyse the modes and degrees of enamel-wear in brown and cave bears from Northern Spain with the objective of shedding some light on the cave bear diet as regards to grit ingestion. We examine the incidence of gross wear features and enamel micro-fractures on the bear molars, and from this it is concluded that the cave bears analysed here did not ingest gritty foods and seemed to avoid putting into their mouth any object at all soiled with gritty dirt

Hominid exploitation of the environment and cave bear populations:the case of Ursus spelaeus Rosenmuller-Heinroth in Amutxate cave (Aralar, Navarra-Spain)

Cave bears (Ursus deningeri and U. spelaeus) and hominids (Homo heidelbergensis, H. neanderthalensis, and H. sapiens) were potential competitors for environmental resources (subterranean and open air). Here, we examined the age at death of cave bear (Ursus spelaeus Rosenmuller-Heinroth) specimens from Amutxate cave in order to shed light on the effect of resource sharing between cave bears and hominids. After studying dental wear of the deciduous and permanent dentitions, the ontogenetic development of mandibles, and incremental layers of cement (annuli), we defined five age groups differentiated by marked development and size gaps. Our findings indicate that after hibernating, bears abandoned the den, thereby leaving the subterranean environment (caves) free for temporary hominid occupation—this would explain the subtle traces of hominid presence in many dens. However, a simple calculation based on age at death of subadult and adult cave bear specimens in Amutxate cave, extrapolated to the whole cave area, showed that the area surrounding this cave hosted bears for at least 9,000 years. This length of habitation, quite similar to the time-span derived from amino acid racemization and electron spin resonance, indicates that bear populations in the Amutxate cave constituted a serious constraint for hominid exploitation of the environment

Fossil Population Structure and Mortality of the Cave Bear From the Mokrica Cave (North Slovenia)

The fossil population structure of the cave bear from the Mokrica cave was evaluated to provide new data concerning the behaviour and mortality of this extinct species. Age at death was estimated for 128 different individuals by analysing cementum increments, root formation and crown wear of left M1 teeth. After the frequency distribution of specimens through one-year intervals, the mortality trends can be estimated for various lifetime periods, and interpreted in accordance with data for present-day bears. The original death assemblage was presumably juvenile-dominated. Extremely fragile molars of less than 6 month old cubs did not get preserved. Yearlings are the most numerous age class in the fossil population from the Mokrica cave. Mortality drastically dropped after cave bears survived their first hibernation in the second winter. The lowest mortality rate was observed in the 9-15 years age group, when cave bears would be expected to be in their prime. The oldest age recorded by cementum analysis is approximately 30 years, which indicates that the maximum life span was similar to present-day bears. Study of dental tissues shows that the mortality in the cave was seasonally restricted – the majority of deaths in the cave occured during winter and in early spring. Sex structure of the fossil population has been studied on the sample of 750 canines. The significantly higher proportion of males in the group of older juveniles and subadults could be explained by the fact that the weaning period is more critical for males also in present-day bears. In young adults and prime adults the mortality was presumably higher in females. The sex structure of adult bears, especially in the sample of older individuals, indicates that the Mokrica cave was used as winter den mostly by solitary males

Heavy reliance on plants for Romanian cave bears evidenced by amino acid nitrogen isotope analysis

Heavy reliance on plants is rare in Carnivora and mostly limited to relatively small species in subtropical settings. The feeding behaviors of extinct cave bears living during Pleistocene cold periods at middle latitudes have been intensely studied using various approaches including isotopic analyses of fossil collagen. In contrast to cave bears from all other regions in Europe, some individuals from Romania show exceptionally high δ15N values that might be indicative of meat consumption. Herbivory on plants with high δ15N values cannot be ruled out based on this method, however. Here we apply an approach using the δ15N values of individual amino acids from collagen that offsets the baseline δ15N variation among environments. The analysis yielded strong signals of reliance on plants for Romanian cave bears based on the δ15N values of glutamate and phenylalanine. These results could suggest that the high variability in bulk collagen δ15N values observed among cave bears in Romania reflects niche partitioning but in a general trophic context of herbivory

Cueva Coro Tracito (Tella Sin, Huesca) el primer yacimiento de alta montaña español de Ursus spelaeus Ros-Hein. Nota preliminar.

In this paper we present the first results of metrical analysis of premolar and molar lengths and metacarpal length and width of Ursus spelaeus Ros.-Hein. from Coro Tracito cave, the first cave bear high mountain site in Spain. According to their dental dentition size the Coro Tracito bears can be grouped into de the ?normal sized? cave bears of Spain. Their slender metacarpal bones place them between into the ?small paw? cave bear group. The lower dentine aspartic acid razemization ratios allowd us to date the Coro Tracito cave bear population as a tardy population that probably inhabited the area at the 3 Oxigen Stage Episode

THE GENUS URSUS IN EURASIA: DISPERSAL EVENTS AND STRATIGRAPHICAL SIGNIFICANCE

On the basis of the results of former studies by the present authors five main groups of bears are recognized: Ursus gr. minimus - thibetanus (black bears), Ursus gr. etruscus (etruscan bears), Ursus gr. arctos (brown bears), Ursus gr. deningei - spelaeus (cave bears) and Ursus gr. maritimus (white bears). Black bears seem to have disappeared from Europe during the Late Pliocene, immigrated again at the beginning of the Middle Pleistocene, and definitively died out in Europe at the beginning of the Late Pleistocene. Etruscan bears occur more or less contemporaneously in the southern areas of Europe and Asia during the Late Pliocene. The Asian branch apparently became extinct at the end of this period, while the European stock survived, giving rise to more advanced representatives during the Early Pleistocene. Brown bears seem to have originated in Asia. This group dispersed widely in holoarctic areas diversifying into a great number of varieties. They reached Europe presumably at the very end of the Early Pleistocene. The arrival of brown bears in Europe is a crucial event, which approximately coincides with the great faunal turnover which marks the Early-Middle Pleistocene transition. Brown bears replaced the etruscan bears, typical of the Villafranchian faunal assemblages, and gave rise to the cave bear line. Cave bears were very successful in Europe during the Middle and Late Pleistocene and disappeared at the end of the last glaciation or even at the very beginning of the Holocene. White bears presumably originated from northern Eurasian brown bear populations during the Late Pleistocene

Cave of La Chěnelaz (Hostias, Ain, France). The large Mammals of the layer 6b

More than 3600 remains of large Mammals have been discovered in layer 6b of the cave of La Chenelaz, about 33\u27000 years ago. The identified taxa belong to the orders of Insectivora, Carnivora, Lagomorpha, Rodentia, Perissodactyla and Artiodactyla. The Carnivora are the most numerous with 38% of the remains. At this time, the cave was occupied by bears (cave bears mainly and brown bears) which hibernated there. Alternatively, it was a lair for hyaenas and wolves, who raised their cubs there and brought their preys (Perissodactyla and Artiodactyla mainly), and smaller Carnivora like the red fox or the pine marten. Many of the studied species indicate a warm and woody climate. Some remains belong to the porcupine. The genus Hystrix is present in Europe during the Pleistocene but is always scarce. No trace of human occupation was discovered in layer 6b

Microwear and isotopic analyses on cave bear remains from Toll Cave reveal both short-term and longterm dietary habits

Dietary habits of the extinct Ursus spelaeus have always been a controversial topic in paleontologicalvstudies. In this work, we investigate carbon and nitrogen values in the bone collagen and dental microwear of U. spelaeus specimens recovered in Level 4 from Toll Cave (Moià, Catalonia, NE Iberian Peninsula). These remains have been dated to > 49,000 14C BP. The ability of both proxies to provide data on the diet of U. spelaeus at different times in the life-history (isotopes: average diet of life; microwear: last days/weeks before death), allows us to generate high-resolution and complementary data. Our results show lower values (δ13C & δ15N) in cave bears than in strict herbivores (i.e. Cervus elaphus) recovered from the same level of Toll Cave. On the other hand, 12 lower molars (m1) were analysed through low-magnification microwear technique. The cave bears from Toll Cave show a microwear pattern like that of extant bears with omnivorous and carnivorous diets. These data are discussed in the framework of all available data in Europe and add new information about the plasticity of the dietary habits of this species at the southern latitudes of Europe during Late Pleistocene periods

Paleozoological stable isotope data for modern management of historically extirpated Missouri black bears (Ursus americanus)

Title from PDF of title page (University of Missouri--Columbia, viewed on Aug. 20, 2010).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Thesis advisor: Dr. R. Lee Lyman.M.A. University of Missouri--Columbia 2010.Human population growth and intensification of resource extraction during the 19th century changed the American landscape. Deforestation, residential sprawl and hunting activities impacted the behavior and sometimes the existence of native species. By the early 1900s, North American black bears (Ursus americanus) were extirpated from Missouri. Modern efforts to restore this species to the region are guided by the assumption that extant extra-local black bear ecology accurately depicts native Missouri ursid ecology. Paleozoological data provide the only means to test this assumption. Stable carbon and nitrogen isotope analysis of skeletal remains of ten late Holocene black bears from Lawson Cave in central Missouri reveals three aspects of native black bear diet: 1) Lawson Cave black bears are isotopically distinct from herbivores and carnivores; 2) There is no clear trend in black bear diet over the past 600 years; and 3) Lawson Cave black bear diet is not significantly different from that of modern black bears. Native Missouri black bears, as reflected by the Lawson Cave ursids, are no different from extralocal modern black bears in terms of diet. Therefore, these ecological data can be applied to future management and conservation planning regarding Missouri black bears by indicating appropriate regions (which can support the resource-use habits of black bears) for relocation programs.Includes bibliographical references