Our goals here are to: (1) assess the generality of one aspect of the island rule - the progressive trend towards decrease in size in larger species - for fossil carnivores on islands; (2) offer ...causal explanations for this pattern and deviations from it - as far as fossil carnivores are concerned; and (3) estimate the speed of this trend. Oceanic and oceanic-like islands world-wide. Body size estimates of fossil insular carnivores and of their phylogenetically closest mainland relative were obtained from our own data and the published literature. Our dataset consisted of 18 species from nine islands world-wide. These data were used to test whether the body size of fossil insular carnivores varies as a function of body size of the mainland species in combination with characteristics of the island ecosystem. Dwarfism was observed in two canid species. Moderate decrease in body mass was observed in one hyena species. Gigantism was observed in one otter species. Moderate body mass increase was observed in two otter species, one galictine mustelid and perhaps one canid. Negligible or no change in body mass at all was observed in five otter species, three galictine mustelids and one genet. Size changes in teeth do not lag behind in comparison to skeletal elements in the dwarfed canids. The evolutionary speed of dwarfism in a canid lineage is low. Size change in fossil terrestrial insular carnivores was constrained by certain ecological conditions, especially the availability of prey of appropriate body size. When such alternative prey was not available, the carnivores retained their mainland size. The impact of competitive carnivores seems negligible. The case of (semi-)aquatic carnivores is much less clear. The species that maintained their ancestral body mass may have changed their diet, as is evidenced by their dentition. Among the otters, one case of significant size increase was observed, perhaps best explained as being due to it entering the niche of an obligate aquatic otter. Dwarfism was not observed in otters. The island rule seems to apply to fossil carnivores, but with exceptions. The dependency of the island rule on resource availability is emphasized by the present study.
Helminthological studies of carnivores in Central Black Earth Nature Reserve (Kursk region) are carried out. High degree of infection of carnivores with hel-minthes is determined. Helminth eggs have ...been detected in 98 % of animal fecal samples. More often eggs of cestodes, nematodes Capillariidae, Tosascaris leoni-na, Uncinaria stenocephala, trematodes Alaria alata have been found. In 94,1 % of foxes a mixed infection caused by A. alata, Capillaria spp., T. leonina, Toxocara sp., U. stenocephala and cestodes has been determined. Carnivores of martens fam-ily were infected with Capillaria spp. and cestodes. 4,9 % of foxes were infected with one helminth species. The most common helminthes in carnivores are Capil-laria spp. High density of carnivores in nature reserve may cause widespread hel-minthosis.
Study into the effect of vitamins A and E on total and differential leukocyte count, as well as morphometric parameters of lymphocytes in three carnivorous species—dark brown American mink (
Neovison ...vison
, Mustelidae), blue fox (
Vulpes lagopus,
Canidae), and silver fox (
V. vulpes,
Canidae)—was conducted. The highest white blood cells count (WBC count) and the largest surface area of lymphocytes and their nuclei in the peripheral blood were observed in mink, while the lowest indices were found in silver fox. Additional supplementation with vitamins A and E for 14 days had no effect on the WBC and differential leukocyte count, except for silver foxes receiving vitamin E, in which a decrease in relative eosinophils and monocytes content was observed. The action of vitamins was mainly manifested in changes in the lymphocytes’ morphometric parameters. The addition of vitamin A into the diet of mink and silver fox and vitamin E into only mink’s diet led to an increase in the surface area of lymphocytes and, in some cases, their nuclei, which was accompanied by a rise in the cytoplasm size in mink cells. In blue fox, on the contrary, both vitamins induced a decrease in the surface area of the lymphocytes and their nuclei. The observed changes may be associated with the immunomodulatory effects of vitamins A and E of the studied species of carnivorous mammals, while the found differences may be associated with features of the morphologic and functional organization of lymphocytes and the immune status.
Seed dispersal by animals is a key interaction, with effects on the population ecology and evolution of many plant lineages. Despite the fact that infrequent seed dispersers can potentially provide ...important services to plant populations, little attention has been paid so far to scarce mutualists. We assessed different aspects of quantity and quality of seed dispersal from fruit removal to seed germination in the Iberian pear, Pyrus bourgaeana, finding that fruit consumers markedly differed in the nature of their interaction with the tree. Whereas the abundant rodents, rabbits, and deer damaged all seeds eaten, the uncommon carnivores badger and fox and the abundant boars dispersed a large fraction of ingested seeds as viable propagules, acting as legitimate seed dispersers. Despite low rates of visitation by badgers to fruiting trees, they transported more viable seeds than the abundant boars, due to better seed treatment and a higher feeding rate on pears. Seed dispersal by all 3 legitimate dispersers, especially the badger, enhanced post-dispersal P. bourgaeana seed survival, supporting the “escape” predation hypothesis. Pyrus bourgaeana showed relatively high frequencies of visits by a myriad of frugivores; however, it relied on the dispersal service provided by an infrequent carnivore, the badger, rather than on those provided by the abundant mammalian herbivores. Therefore, under some circumstances, uncommon animal counterparts play major roles in their mutualistic interactions with flowering plants. Nomenclature: Váldes et al., 2007.
One of the potential negative impacts of invasive species is competitive exclusion of native species that have similaror identical ecological niches. Even with extensive knowledge of the similarities ...between the diets and habitats of invasive andnative species, it is difficult to predict the long-term consequences of species interactions over varying spatial and temporalscales with variable resource levels. Here we apply a hierarchical Bayesian model to examine the roles of spatial variations inland use and population densities of the introduced raccoon Procyon lotor and civet Paguma larvata on the population density of the native raccoon dog Nyctereutes procyonoides in the south-eastern Boso Peninsula, central Japan. Our analysis reveals thatintroduced raccoons negatively affect raccoon dog populations. Substantial numbers of native raccoon dogs and the two invasivemammals have been removed by trapping to control damage to crops. Despite these control measures, the invasive raccoonpopulation has increased, which will likely lead to a reduction in the native raccoon dog population. It is thus imperative tomonitor the population trends of native raccoon dogs to conserve this species.
Fatty acid composition of the adipose tissue of six carnivorous mammalian species (European otter Lutra lutra, American mink Mustela vison, European Mink Mustela lutreola, European polecat Mustela ...putorius, stone marten Martes foina and European wild cat Felis silvestris) was studied. These species forage to differing degrees in aquatic and terrestrial food webs. Fatty acid analysis revealed significant differences in polyunsaturated fatty acid composition between species. More specifically, our results underline a gradual significant decrease in the docosahexaenoic acid (DHA)/linoleic acid (LNA) ratio of carnivore species as their dependence on aquatic food webs decreases. In conclusion, the use of the DHA/LNA ratio in long-term studies is proposed as a potential proxy of changes in foraging behaviour of semi-aquatic mammals.
The body mass estimation of several limb bone dimensions (shaft cross‐sectional properties, articular sizes, and bone lengths) were examined using bivariate linear regression analyses. The sample ...included taxonomically and behaviourally diverse small to medium‐sized Recent carnivorans and carnivorous marsupials. All examined limb bone dimensions indicated low errors (percentage standard error of estimate, 8–13) for the body mass estimations. Among them, humeral and femoral shaft properties correlated best with body weight, while limb bone lengths gave larger errors. Both humeral and femoral head dimensions have relatively large individual variations, and distal humeral articular dimensions seem to be influenced more by phylogenetic differences. The regressions based on each locomotor group gave slightly lower errors than those based on the total pooled sample. The results were then applied to hyaenodontid creodonts from the Eocene–Oligocene of North America. The estimated body masses (kg) are: Arfia, 5.4–9.5; Prototomus, <6.0; Pyrocyon, 2.6; Sinopa, 1.3–1.4; Tritemnodon, 7.6–13; Prolimnocyon, 1.6; Thinocyon, 0.7–2.5; Machaeroides, 12; Limnocyon, 7.8– 16; Hyaenodon, 9.1–43. The various limb bone dimensions give different body mass values, but the variation in estimates is smaller compared to those derived from dental or cranial measurements.
Aim In this study we tested the hypothesis that the dispersal success (estimated here as fruit removal rate) of a native shrub species living in the Balearic Archipelago, Cneorum tricoccon L. ...(Cneoraceae), has decreased significantly in those islands where endemic lizards of the genus Podarcis have disappeared. These lizards acted as the main seed dispersers of the plant and became extinct after the introduction of carnivores. At least one of these carnivores, the pine marten (Martes martes L.), is also an important frugivore, consuming the fruits and dispersing the seeds of C. tricoccon and thus allowing the comparison of fruit removal rates between the two groups of vertebrates (lizards and mammals). We further tested the possibility that lizards (in particular, P. pityusensis Boscà) could be exerting selection on seed size. Methods In seven populations from four islands, we monitored fruit removal by either lizards or mammals. The fruits of C. tricoccon do not drop after ripening, remaining attached to the branches for long periods if not removed. In order to test whether lizards might be exerting selection on seed size, we compared seed diameter and weight between defecated and uningested (collected directly from plants) seeds for each of the populations. Results Fruits were removed in significantly greater proportions in those populations where lizards are still present. Data showed that in two of the examined populations in the Pityusic islands, defecated seeds were lighter and smaller than controls suggesting that lizards selected fruits of smaller size than the average of the population. Main conclusions The introduction of carnivores in the Balearics has led to important changes in the population dynamics of many native species. In the larger islands (Mallorca and Menorca), carnivores seemed to have caused the extinction of endemic lizards who acted as the only dispersers of some plants such as C. tricoccon. Pine martens, in particular, are in turn frugivorous and thus can 'replace' to some extent the 'lost' seed dispersers. We hypothesize that besides having decreased fruit removal rates in this shrub, these 'new' dispersers have modified considerably the distribution of the plant on Mallorca island, as the fossil record shows that lizards lived at low altitudes (<500 m a. s. l.) and the plant can be currently found up to 1000 m a. s. l. Furthermore, preliminary data suggest that lizards might be exerting a selective pressure on seed size. If this is true, this pressure might have been released - or counteracted if carnivores select for fruit size as well - after the extinction of lizards from some islands, which would have important ecological consequences for the plant.
The role of carnivorous mammals as seed dispersers of Myrtus communis L. in the Mediterranean environment was studied. Seeds of M. communis were found in faeces of red fox (Vulpes vulpes L.) and ...carnivores from the genus Martes, at four sites on the Tyrrhenic coast of Southern Italy in the period autumn-winter 1993-1995. All the study sites are covered by Mediterranean shrublands with M. communis as one of the dominant species. Content analysis of fox scats showed that fruits of M. communis constitute a relevant component of the diet of these carnivores, although other food categories were also well represented. Further investigations on the effect of mammal digestion on seed germinability showed that carnivores not only moved the seeds away from the mother plant but also enhanced their germinability. This species was known to be bird- and ant-dispersed and the adaptive implications of a multi-vectorial seed dispersal process is discussed.
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