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Different Body Sizes (different + body_size)
Selected AbstractsAdaptive significance of food income in European snakes: body size is related to prey energeticsBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2010MARCO A. L. ZUFFI Feeding strategies and diet patterns have been extensively investigated in vertebrates and, more specifically, in snakes. Although it has been hypothesized that prey species may differ in terms of energy content, almost no theoretical or practical study has been carried out to determine actual nutritional values of the common prey types of wild snakes. Our model taxa were a selection of widely distributed and well known European snake species, which have all been studied in depth: approximately 76% of their diet is composed of mammals, reptiles, and insects. We therefore selected a single model species for each of these categories and proceeded with the analyses. Nutritional values were determined using a standard procedure: lizards and mice were richer in proteins than insects (crickets); insects and mice were richer in lipids than lizards, and mice and crickets have a higher energy content than lizards; lizards were rich in ashes. We then applied our experimental results to a selected sample of European terrestrial snakes (11 populations, ten species, seven genera, two families) characterized by different body size (50,160 cm total length) and reproductive strategies (oviparous versus viviparous), aiming to correlate these parameters with patterns of energy income. A direct relationship was found between body mass/body length ratio (BCI, body condition index) and meal energetics: the higher the BCI, the higher was the metabolic requirement, whereas BCI was independent of species or of reproductive system effect. Large-sized snakes thus need a highly diversified and more energy-rich diet than smaller snakes, supporting previous hypotheses. The simple applicability of this method could be of valuable support in further comparative research work, reducing experimental costs and stimulating further ecological, behavioural, and, possibly, phylogenetic comparisons. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 307,317. [source] Spatial distribution of the Japanese common squid, Todarodes pacificus, during its northward migration in the western North Pacific OceanFISHERIES OCEANOGRAPHY, Issue 2 2006ATSUSHI KAWABATA Abstract The spatial distribution of Todarodes pacificus in and near the Kuroshio/Oyashio Transition Zone during its northward migration was examined by comparative surveys using two types of mid-water trawl net and supplementary squid jigging from June to July 2000. The vertical and horizontal distribution patterns varied for different body sizes in relation to the oceanographic structure. Todarodes pacificus of 1,20 cm dorsal mantle length (ML) were widely distributed from the coastal waters of Japan to near 162°E longitude, probably due to transport by the Kuroshio Extension (KE). Todarodes pacificus smaller than 10 cm ML were mainly distributed in temperate surface layers at sea surface temperatures (SSTs) >15°C near the KE meander probably because of their poor tolerance to lower temperatures and limited swimming ability. Squid of 10,15 cm ML were distributed in the offshore waters of 10,15°C SST and in the coastal waters of northern Honshu, and underwent diel vertical migrations between the sea surface at night and deeper layers during the daytime. Squid larger than 15 cm ML were distributed in the coastal feeding grounds of northern Honshu and Hokkaido until they began their southward spawning migration. They also underwent diel vertical migrations, but remained deeper at night than the squid of 10,15 cm ML; this migration pattern closely matched that of their main prey such as euphausiids. We concluded that as T. pacificus grow, they shift their distribution range from the temperate surface layer around the KE toward the colder deeper layers, above 5°C, in the Oyashio and coastal areas. [source] Small and large anemonefishes can coexist using the same patchy resources on a coral reef, before habitat destructionJOURNAL OF ANIMAL ECOLOGY, Issue 5 2002Akihisa Hattori Summary 1According to meta-population models, a superior competitor and a superior disperser can coexist in a patchy environment. The two anemonefishes, a large aggressive Amphiprion clarkii Bennett and a small less-aggressive A. perideraion Bleeker, use the same host anemone Heteractis crispa Ehrenberg on a coral reef, Okinawa, Japan, where most of the hosts disappeared after the coral bleaching in 1998. Their microhabitat (host) use and coexistence, and the quality and quantity of microhabitats were investigated in 1988, 1989, 1999 and 2000 on the coral reef. Their interspecific interaction was also examined. 2Before the habitat destruction, the two species coexisted. Although A. clarkii was behaviourally dominant over A. perideraion in a cohabiting group, A. perideraion was a superior competitor in terms of site displacement, because A. perideraion could displace a microhabitat. Adult A. clarkii emigrated from a cohabiting group probably due to the high cost of interactions with adult A. perideraion . Although it is easier to defend a small area for a larger species, sharing a host with adult A. perideraion may not pay for A. clarkii because A. clarkii needs a larger area. 3A. clarkii was not only a superior disperser, which was able to find a vacated host, but also a pioneer species that was able to use newly settled small hosts. Larval A. clarkii settled on such a small host because they were able to move to larger hosts for future reproduction, while A. perideraion did not settle on a small host because of low mobility after settlement. Microhabitat (host) with various sizes might have promoted their coexistence. 4After the habitat destruction, the superior competitor A. perideraion went extinct locally due probably to lack of small host utilization ability. The present study implies that the difference in body size between the two competitors plays an important role in their coexistence, because species with different body sizes can have different mobility and require different amounts of resources. [source] Effects of marine reserve age on fish populations: a global meta-analysisJOURNAL OF APPLIED ECOLOGY, Issue 4 2009Philip P. Molloy Summary 1. ,Marine reserves are widely used for conservation and fisheries management. However, there is debate surrounding the speed of population recovery inside reserves and how recovery differs among species. Here, we determine how reserve effectiveness in enhancing fish density changes with reserve age. We also examine how the effects of protection vary between fished and non-fished species and among species of different body sizes, which we use as a proxy for life history and ecology. 2. ,We meta-analysed over 1000 ratios of fish densities (inside : outside reserves) taken from reserves of 1,26 years old from around the world. 3. ,Overall, older reserves were more effective than younger reserves, with fish densities increasing within reserves by ,5% per annum relative to unprotected areas. Reserves older than 15 years consistently harboured more fish compared with unprotected areas; younger reserves were less reliably effective. 4. ,Large, fished species responded strongly and positively to protection in old (>15 years) and, unexpectedly, in new and young (,10 years) reserves. Small, fished species and non-fished species of all sizes showed weaker responses to protection that did not vary predictably with reserve age. 5. ,We expected large fish to respond more slowly to protection than smaller species. We also expected small species to decline after large fish had recovered (i.e. trophic cascades). Neither prediction was supported. 6. , Synthesis and applications. Our meta-analyses demonstrate that, globally, old reserves are more effective than young reserves at increasing fish densities. Our results imply that reserves should be maintained for up to 15 years following establishment, even if they initially appear ineffective. If protection is maintained for long enough, fish densities within reserves will recover and such benefits will be particularly pronounced for large, locally fished species. [source] Pre-dispersal acorn predation in mixed oak forests: interspecific differences are driven by the interplay among seed phenology, seed size and predator sizeJOURNAL OF ECOLOGY, Issue 6 2009Josep M. Espelta Summary 1.,Pre-dispersal seed predation (PSP) often occurs in multi-host,predator systems (e.g. several plant species exposed to a common array of granivorous insects). However, whether the interaction among seed phenology, seed size and predator size accounts for interspecific differences in PSP remains elusive. 2.,We studied PSP in a mixed-oak forest with two oaks (the larger-seeded Quercus humilis and the smaller-seeded Q. ilex), both depredated by two acorn weevils (the smaller Curculio glandium and the larger C. elephas). We intensively monitored acorn production and infestation phenology and we identified the weevil species depredating acorns by means of DNA taxonomy. 3.,The minimum acorn size required for infestation was lower for C. glandium than for C. elephas, in accordance with their different body sizes. This resulted in an earlier infestation phenology in C. glandium and the ability of this species to infest both smaller and larger acorns. Above a minimum acorn size threshold, no selection for larger acorns by weevils was observed. 4.,Initial acorn crop size was similar in the two oaks. Nonetheless, the earlier acorn phenology and the production of larger acorns in Q. humilis favoured the earlier infestation by C. glandium and the predation by both small and large weevils. Smaller acorns of Q. ilex almost excluded infestation by the larger C. elephas. 5.,Although larger acorns of Q. humilis could better survive infestation (preserve the embryo), higher PSP in this species finally resulted in a lower mature acorn crop size than in Q. ilex. 6.,Synthesis. In a multi-host,predator system, smaller-seeded species may benefit from a reduced PSP because they exclude larger granivorous insects, but also by means of a ,free-rider effect', if larger-seeded heterospecifics earlier reach a critical size to be depredated. These results also highlight the benefits of a small body size in granivorous insects to depredate seeds earlier and to forage on a wider range of seed sizes. Whether the advantage of ,being small' in this antagonistic plant,animal interaction is offset by other processes, or whether it results in a pressure towards seed and insect size reduction, deserves further attention. [source] Water temperature fluctuations and territoriality in the intertidal zone: two possible explanations for the elevational distribution of body size in Graus nigraJOURNAL OF FISH BIOLOGY, Issue 2 2002C. E. Hernández On the central coast of Chile, distribution of body size in Graus nigra varied with tidal pool height. With the objective of determining whether environmental temperature is one of the possible causes which explains the observed distribution pattern, two behavioural responses were analysed during an experimental period of increasing water temperature: number of opercular movements (an indirect measure of energy expenditure) and activity levels. The interactions of temperature × time and body size × time had a significant effect on the number of opercular movements. At low temperatures (13,15° C), large fish reached a maximum number of opercular movements, while small fish reached a maximum only at high temperatures (23,25° C). The interaction temperature × time had a significant effect on activity levels of different body sizes. In general, large fish appeared to be less active than small fish, however, at very high temperatures (24,26° C) all individuals increased their activity levels. These data indicate that small fish are acclimatized to live in a wider range of temperatures (13,23° C), and, for fish of all body sizes, the highest temperatures (23,26° C) probably constitute a suboptimal microhabitat. Strong territoriality was observed, with large individuals displacing smaller individuals. These data suggest that temperature is an important factor in explaining why large individuals are not present in high tidal pools (high temperatures), whereas territoriality explains why small individuals are not in low tidal pools (habitat of large individuals). [source] Support for a metapopulation structure among mammalsMAMMAL REVIEW, Issue 3 2009PIETER I. OLIVIER ABSTRACT 1The metapopulation metaphor is increasingly used to explain the spatial dynamics of animal populations. However, metapopulation structure is difficult to identify in long-lived species that are widely distributed in stochastic environments, where they can resist extinctions. The literature on mammals may not provide supporting evidence for classic metapopulation dynamics, which call for the availability of discrete habitat patches, asynchrony in local population dynamics, evidence for extinction and colonization processes, and dispersal between local populations. 2Empirical evidence for metapopulation structure among mammals may exist when applying more lenient criteria. To meet these criteria, mammals should live in landscapes as discrete local breeding populations, and their demography should be asynchronous. 3We examined the literature for empirical evidence in support of the classical criteria set by Hanski (1999), and for the more lenient subset of criteria proposed by Elmhagen & Angerbjörn (2001). We suggest circumstances where metapopulation theory could be important in understanding population processes in mammals of different body sizes. 4The patchy distribution of large (>100 kg) mammals and dispersal often motivate inferences in support of a metapopulation structure. Published studies seldom address the full suite of classical criteria. However, studies on small mammals are more likely to record classic metapopulation criteria than those on large mammals. The slow turnover rate that is typical for medium-sized and large mammals apparently makes it difficult to identify a metapopulation structure during studies of short duration. 5To identify a metapopulation structure, studies should combine the criteria set by Hanski (1999) and Elmhagen & Angerbjörn (2001). Mammals frequently live in fragmented landscapes, and processes involved in the maintenance of a metapopulation structure should be considered in conservation planning and management. [source] Hindlimb adaptations in Ourayia and Chipetaia, relatively large-bodied omomyine primates from the Middle Eocene of UtahAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2006Rachel H. Dunn Abstract North American omomyids represent a tremendous Eocene radiation of primates exhibiting a wide range of body sizes and dietary patterns. Despite this adaptive diversity, relatively little is known of the postcranial specializations of the group. Here we describe hindlimb and foot bones of Ourayia uintensis and Chipetaia lamporea that were recovered from the Uinta B member (early Uintan Land Mammal Age), Uinta Formation, Utah. These specimens provide insights into the evolution of postcranial adaptations across different body sizes and dietary guilds within the Eocene primate radiation. Body mass estimates based on talar measurements indicate that Ourayia uintensis and Chipetaia lamporea weighed about 1,500,2,000 g and 500,700 g, respectively. Skeletal elements recovered for Ourayia include the talus, navicular, entocuneiform, first metatarsal, and proximal tibia; bones of Chipetaia include the talus, navicular, entocuneiform, and proximal femur. Both genera had opposable grasping big toes, as indicated by the saddle-shaped joint between the entocuneiform and first metatarsal. Both taxa were arboreal leapers, as indicated by a consistent assemblage of characters in all represented bones, most notably the somewhat elongated naviculars, the high and distinct trochlear crests of the talus, the posteriorly oriented tibial plateau (Ourayia), and the cylindrical head of the femur (Chipetaia). The closest resemblances to Ourayia and Chipetaia are found among the Bridger omomyines, Omomys and Hemiacodon. The results of our comparisons suggest that the later, larger, more herbivorous omomyines from Utah retained a skeletal structure characteristic of earlier, smaller North American omomyids. Am J Phys Anthropol, 2006. © 2006 Wiley-Liss, Inc. [source] | |||||||||||||