共查询到20条相似文献,搜索用时 15 毫秒
1.
J.‐F. LEMAÎTRE S. A. RAMM R. A. BARTON P. STOCKLEY 《Journal of evolutionary biology》2009,22(11):2215-2221
The ‘expensive tissue hypothesis’ predicts a size trade‐off between the brain and other energetically costly organs. A specific version of this hypothesis, the ‘expensive sexual tissue hypothesis’, argues that selection for larger testes under sperm competition constrains brain size evolution. We show here that there is no general evolutionary trade‐off between brain and testis mass in mammals. The predicted negative relationship between these traits is not found for rodents, ungulates, primates, carnivores, or across combined mammalian orders, and neither does total brain mass vary according to the level of sperm competition as determined by mating system classifications. Although we are able to confirm previous reports of a negative relationship between brain and testis mass in echolocating bats, our results suggest that mating system may be a better predictor of brain size in this group. We conclude that the expensive sexual tissue hypothesis accounts for little or none of the variance in brain size in mammals, and suggest that a broader framework is required to understand the costs of brain size evolution and how these are met. 相似文献
2.
M. V. Ugryumov 《Russian Journal of Developmental Biology》2009,40(1):14-22
The main prerequisite for organism’s viability is the maintenance of the internal environment despite changes in the external environment, which is provided by the neuroendocrine control system. The key unit in this system is hypothalamus exerting endocrine effects on certain peripheral organs and anterior pituitary. Physiologically active substances of neuronal origin enter blood vessels in the neurohemal parts of hypothalamus where no blood-brain barrier exists. In other parts of the adult brain, the arrival of physiologically active substances is blocked by the blood-brain barrier. According to the generally accepted concept, the neuroendocrine system formation in ontogeny starts with the maturation of peripheral endocrine glands, which initially function autonomously and then are controlled by the anterior pituitary. The brain is engaged in neuroendocrine control after its maturation completes, which results in a closed control system typical of adult mammals. Since neurons start to secrete physiologically active substances soon after their formation and long before interneuronal connections are formed, these cells are thought to have an effect on brain development as inducers. Considering that there is no blood-brain barrier during this period, we proposed the hypothesis that the developing brain functions as a multipotent endocrine organ. This means that tens of physiologically active substances arrive from the brain to the systemic circulation and have an endocrine effect on the whole body development. Dopamine, serotonin, and gonadotropin-releasing hormone were selected as marker physiologically active substances of cerebral origin to test this hypothesis. In adult animals, they act as neurotransmitters or neuromodulators transmitting information from neuron to neuron as well as neurohormones arriving from the hypothalamus with portal blood to the anterior pituitary. Perinatal rats—before the blood-brain barrier is formed—proved to have equally high concentration of dopamine, serotonin, and gonadotropin-releasing hormone in the systemic circulation as in the adult portal system. After the brain-blood barrier is formed, the blood concentration of dopamine and gonadotropin-releasing hormone drops to zero, which indirectly confirms their cerebral origin. Moreover, the decrease in the blood concentration of dopamine, serotonin, and gonadotropin-releasing hormone before the brain-blood barrier formation after the microsurgical disruption of neurons that synthesize them or inhibition of dopamine and serotonin synthesis in the brain directly confirm their cerebral origin. Before the blood-brain barrier formation, dopamine, serotonin, gonadotropin-releasing hormone, and likely many other physiologically active substances of cerebral origin can have endocrine effects on peripheral target organs—anterior pituitary, gonads, kidney, heart, blood vessels, and the proper brain. Although the period of brain functioning as an endocrine organ is not long, it is crucial for the body development since physiologically active substances exert irreversible effects on the targets as morphogenetic factors during this period. Thus, the developing brain from the neuron formation to the establishment of the blood-brain barrier functions as a multipotent endocrine organ participating in endocrine control of the whole body development. 相似文献
3.
The mammalian centromere-associated protein B (CENP-B) shares significant sequence similarity with 3 proteins in fission yeast (Abp1, Cbh1, and Cbh2) that also bind centromeres and have essential function for chromosome segregation and centromeric heterochromatin formation. Each of these proteins displays extensive sequence similarity with pogo-like transposases, which have been previously identified in the genomes of various insects and vertebrates, in the protozoan Entamoeba and in plants. Based on this distribution, it has been proposed that the mammalian and fission yeast centromeric proteins are derived from "domesticated" pogo-like transposons. Here we took advantage of the vast amount of sequence information that has become recently available for a wide range of fungal and animal species to investigate the origin of the mammalian CENP-B and yeast CENP-B-like genes. A highly conserved ortholog of CENP-B was detected in 31 species of mammals, including opossum and platypus, but was absent from all nonmammalian species represented in the databases. Similarly, no ortholog of the fission yeast centromeric proteins was identified in any of the various fungal genomes currently available. In contrast, we discovered a plethora of novel pogo-like transposons in diverse invertebrates and vertebrates and in several filamentous fungi. Phylogenetic analysis revealed that the mammalian and fission yeast CENP-B proteins fall into 2 distinct monophyletic clades, each of which includes a different set of pogo-like transposons. These results are most parsimoniously explained by independent domestication events of pogo-like transposases into centromeric proteins in the mammalian and fission yeast lineages, a case of "convergent domestication." These findings highlight the propensity of transposases to give rise to new host proteins and the potential of transposons as sources of genetic innovation. 相似文献
4.
The evolution of the social brain: anthropoid primates contrast with other vertebrates 总被引:1,自引:0,他引:1
The social brain hypothesis argues that large brains have arisen over evolutionary time as a response to the social and ecological conflicts inherent in group living. We test predictions arising from the hypothesis using comparative data from birds and four mammalian orders (Carnivora, Artiodactyla, Chiroptera and Primates) and show that, across all non-primate taxa, relative brain size is principally related to pairbonding, but with enduring stable relationships in primates. We argue that this reflects the cognitive demands of the behavioural coordination and synchrony that is necessary to maintain stable pairbonded relationships. However, primates differ from the other taxa in that they also exhibit a strong effect of group size on brain size. We use data from two behavioural indices of social intensity (enduring bonds between group members and time devoted to social activities) to show that primate relationships differ significantly from those of other taxa. We suggest that, among vertebrates in general, pairbonding represents a qualitative shift from loose aggregations of individuals to complex negotiated relationships, and that these bonded relationships have been generalized to all social partners in only a few taxa (such as anthropoid primates). 相似文献
5.
Boniface O. Oindo 《African Journal of Ecology》2002,40(3):267-275
Species are by definition different from each other. This fact favours ranking rather than additive indices. However, ecologists have measured species diversity in terms of species richness, or by combining species richness with the relative abundance of species within an area. Both methods raise problems: species richness treats all species equally, while relative abundance is not a fixed property of species but varies widely temporally and spatially, and requires a massive sampling effort. The functional aspect of species diversity measurement may be strengthened by incorporating differences between species such as body size as a component of diversity. An index of diversity derived from a measure of variation in body size among species is proposed for large grazing mammals. The proposed diversity index related positively to species abundance, indicating that the use of body size as a surrogate for diversity is adequate. Because the proposed index is based on presence or absence data, the expensive and time consuming counting of individuals per species in each sampling unit is not necessary. 相似文献
6.
Boddy AM McGowen MR Sherwood CC Grossman LI Goodman M Wildman DE 《Journal of evolutionary biology》2012,25(5):981-994
There is a well-established allometric relationship between brain and body mass in mammals. Deviation of relatively increased brain size from this pattern appears to coincide with enhanced cognitive abilities. To examine whether there is a phylogenetic structure to such episodes of changes in encephalization across mammals, we used phylogenetic techniques to analyse brain mass, body mass and encephalization quotient (EQ) among 630 extant mammalian species. Among all mammals, anthropoid primates and odontocete cetaceans have significantly greater variance in EQ, suggesting that evolutionary constraints that result in a strict correlation between brain and body mass have independently become relaxed. Moreover, ancestral state reconstructions of absolute brain mass, body mass and EQ revealed patterns of increase and decrease in EQ within anthropoid primates and cetaceans. We propose both neutral drift and selective factors may have played a role in the evolution of brain-body allometry. 相似文献
7.
断乳是哺乳动物早期生活中最重要的事件。早期断乳不仅仅是幼体从吃奶到独立取食的一个过渡,由早期断乳引起的母性剥夺或社会隔离是一种强应激,会破坏母子联系,并且对幼体以后的行为和神经化学系统有持久的影响,如母性行为和社会玩耍行为减少、攻击行为和焦虑水平增加、认知水平降低、日节律行为失常、影响脑的发育和神经修饰、对应激源更加敏感、应激神经内分泌反应增强等。早期断乳使HPA轴功能破坏,干扰了脑、行为和神经内分泌的发育及调节机制,导致了动物机能失调或对环境不当地适应。因此,哺乳期幼体所处的社会环境至关重要,哺乳提供的不仅是乳汁,还有更为重要的母性联系和母性抚育,应避免不适当的早期断乳。由早期断乳引发行为改变的神经生物学机制值得深入研究。 相似文献
8.
A. E. Spotorno J. C. Marín G. Manríquez J. P. Valladares E. Rico & C. Rivas 《Journal of Zoology》2006,270(1):57-62
To test whether there are differences between living lineages of domestic guinea pigs Cavia porcellus , we studied 118 specimens from six breeds collected along six Andean countries as well as 15 from the wild cavy species ( Cavia tschudii ). The mean weight and body length of 15 adult wild cavies (295±31 g, 242±8.3 mm) were significantly smaller than 25 creole guinea pigs from Bolivia and Chile (639±157 g, 287±23.7 mm, respectively). Eighteen laboratory/pet guinea pigs (including the English Pirbright breed) were also smaller (900±173 g, 308±21 mm) than 25 improved ones from Peru (Tamborada breed, 1241±75.4 g, 317±12 mm) and Ecuador (Auqui breed, 1138±65.5 g, 307±8 mm). Similar size increases appeared in the first axis of a principal component analysis of six skeletal measurements, recovering 84% of total variation. Phylogenetic and haplotype analyses of complete cytochrome b gene sequences consistently joined all 22 domestic individuals (13 shared unambiguous substitutions, 100% bootstrap in 1000 replicates), probably from a single first ancient domestication in the western Andes. Six laboratory/pet sequences were also joined within a common branch (six shared substitutions, 96% bootstrap), probably from a documented European second phase. By contrast, those from improved Auqui joined a northern creole subgroup (one shared substitution, 84% bootstrap), and those from Nativa and improved Tamborada clustered together and with a southern creole subgroup (four shared substitutions, 86% bootstrap); this suggests at least two independent modern events during a more complex third phase, producing two improved guinea pigs selected for size and meat. Cavia tschudii sequences showed some unexpected geographic variation. 相似文献
9.
Juha J. Saarinen Alison G. Boyer James H. Brown Daniel P. Costa S. K. Morgan Ernest Alistair R. Evans Mikael Fortelius John L. Gittleman Marcus J. Hamilton Larisa E. Harding Kari Lintulaakso S. Kathleen Lyons Jordan G. Okie Richard M. Sibly Patrick R. Stephens Jessica Theodor Mark D. Uhen Felisa A. Smith 《Proceedings. Biological sciences / The Royal Society》2014,281(1784)
There is accumulating evidence that macroevolutionary patterns of mammal evolution during the Cenozoic follow similar trajectories on different continents. This would suggest that such patterns are strongly determined by global abiotic factors, such as climate, or by basic eco-evolutionary processes such as filling of niches by specialization. The similarity of pattern would be expected to extend to the history of individual clades. Here, we investigate the temporal distribution of maximum size observed within individual orders globally and on separate continents. While the maximum size of individual orders of large land mammals show differences and comprise several families, the times at which orders reach their maximum size over time show strong congruence, peaking in the Middle Eocene, the Oligocene and the Plio-Pleistocene. The Eocene peak occurs when global temperature and land mammal diversity are high and is best explained as a result of niche expansion rather than abiotic forcing. Since the Eocene, there is a significant correlation between maximum size frequency and global temperature proxy. The Oligocene peak is not statistically significant and may in part be due to sampling issues. The peak in the Plio-Pleistocene occurs when global temperature and land mammal diversity are low, it is statistically the most robust one and it is best explained by global cooling. We conclude that the macroevolutionary patterns observed are a result of the interplay between eco-evolutionary processes and abiotic forcing. 相似文献
10.
Connor RC 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2007,362(1480):587-602
Bottlenose dolphins in Shark Bay, Australia, live in a large, unbounded society with a fission-fusion grouping pattern. Potential cognitive demands include the need to develop social strategies involving the recognition of a large number of individuals and their relationships with others. Patterns of alliance affiliation among males may be more complex than are currently known for any non-human, with individuals participating in 2-3 levels of shifting alliances. Males mediate alliance relationships with gentle contact behaviours such as petting, but synchrony also plays an important role in affiliative interactions. In general, selection for social intelligence in the context of shifting alliances will depend on the extent to which there are strategic options and risk. Extreme brain size evolution may have occurred more than once in the toothed whales, reaching peaks in the dolphin family and the sperm whale. All three 'peaks' of large brain size evolution in mammals (odontocetes, humans and elephants) shared a common selective environment: extreme mutual dependence based on external threats from predators or conspecific groups. In this context, social competition, and consequently selection for greater cognitive abilities and large brain size, was intense. 相似文献
11.
Humans stand out among the apes by having both an extremely large brain and a relatively high reproductive output, which has been proposed to be a consequence of cooperative breeding. Here, we test for general correlates of allomaternal care in a broad sample of 445 mammal species, by examining life history traits, brain size, and different helping behaviors, such as provisioning, carrying, huddling or protecting the offspring and the mother. As predicted from an energetic-cost perspective, a positive correlation between brain size and the amount of help by non-mothers is found among mammalian clades as a whole and within most groups, especially carnivores, with the notable exception of primates. In the latter group, the presence of energy subsidies during breeding instead resulted in increased fertility, up to the extreme of twinning in callitrichids, as well as a more altricial state at birth. In conclusion, humans exhibit a combination of the pattern found in provisioning carnivores, and the enhanced fertility shown by cooperatively breeding primates. Our comparative results provide support for the notion that cooperative breeding allowed early humans to sidestep the generally existing trade-off between brain size and reproductive output, and suggest an alternative explanation to the controversial ‘obstetrical dilemma’-argument for the relatively altricial state of human neonates at birth. 相似文献
12.
A new look at the scaling of size in mammalian eyes 总被引:1,自引:0,他引:1
R. F. Burton 《Journal of Zoology》2006,269(2):225-232
13.
Taiwan is a mountainous island off the coast of the Asian continent. The island is located on the continental shelf and rises to an elevation of nearly 4000 m. It became an island approximately 4 million years ago and has been connected to the continent more than once since its emergence. Therefore, the elevational zonation of two Taiwanese pairs of congeners in the rodent genera Apodemus and Niviventer can be explained by one of two competing hypotheses. One hypothesis assumes that speciation of the two congeners occurred in situ after an ancestral species migrated from the continent. In contrast, the second hypothesis argues the zonation resulted from separate incursion events during the connections. The phylogenetic analyses, which are based on electrophoretic allozyme data, reject the first of these hypotheses. Furthermore, genetic population structure and gene flow of three species of Taiwanese rodents (Apodemus semotus, Niviventer culturatus and Microtus kikuchii) are studied in relation to their patterns of elevational distribution. The genetic structure of A. semotus and N. culturatus, which have extensive elevational distribution, is rather homogeneous and no genie discontinuity or cline in allele frequency was detected. Gene flow among subpopulations for these two species is rather substantial; therefore, the potential isolating effect imposed by deep river valleys is minimal. Conversely, isolation of populations of M. kikuchii on different mountaintops is quite complete as mirrored by the high level of genie differentiation and low gene flow. 相似文献
14.
Renata Pardini 《Biodiversity and Conservation》2004,13(13):2567-2586
Recent studies on the effects of tropical forest fragmentation indicate that fragmented landscapes are complex and heterogeneous systems influenced by factors other than the size or degree of isolation of forest remnants: of particular importance are the quality of the matrix and the edge-induced habitat changes. In order to investigate the influence of these factors, small mammals were surveyed in 36 sites in the landscape of Una, a region that encompasses some of the last and largest Atlantic Forest remnants in northeastern Brazil. Six sites were distributed on each of six landscape components – the interiors and edges of small remnants, the interiors and edges of large remnants, and the most common forested habitats found in the matrix. The survey comprised 46,656 trap-nights and yielded 1725 individuals of 20 species of rodents and marsupials. Results revealed: an increase in beta-diversity caused by fragmentation; the contrasting effects of the altered forested habitats of the matrix, which harbor both forest and disturbance-adapted species; a greater importance of edge effect than of patch size to the observed changes in small mammal community in remnants; an association among terrestrial forest species and among arboreal forest species in terms of the distribution and abundance in the Una mosaic; and a distinctive vulnerability of these two groups of species to fragmentation. Results emphasize the biological importance and conservation value of both fragmented landscapes and small remnants in the Atlantic Forest, as well as the importance of management techniques to control and attenuate edge effects. 相似文献
15.
16.
Effects of metabolic level on the body size scaling of metabolic rate in birds and mammals 总被引:1,自引:0,他引:1
Glazier DS 《Proceedings. Biological sciences / The Royal Society》2008,275(1641):1405-1410
Metabolic rate is traditionally assumed to scale with body mass to the 3/4-power, but significant deviations from the '3/4-power law' have been observed for several different taxa of animals and plants, and for different physiological states. The recently proposed 'metabolic-level boundaries hypothesis' represents one of the attempts to explain this variation. It predicts that the power (log-log slope) of metabolic scaling relationships should vary between 2/3 and 1, in a systematic way with metabolic level. Here, this hypothesis is tested using data from birds and mammals. As predicted, in both of these independently evolved endothermic taxa, the scaling slope approaches 1 at the lowest and highest metabolic levels (as observed during torpor and strenuous exercise, respectively), whereas it is near 2/3 at intermediate resting and cold-induced metabolic levels. Remarkably, both taxa show similar, approximately U-shaped relationships between the scaling slope and the metabolic (activity) level. These predictable patterns strongly support the view that variation of the scaling slope is not merely noise obscuring the signal of a universal scaling law, but rather is the result of multiple physical constraints whose relative influence depends on the metabolic state of the organisms being analysed. 相似文献
17.
JOHN DAMUTH 《Biological journal of the Linnean Society. Linnean Society of London》1981,15(3):185-193
Harestad & Bunnell (1979) showed that, at least for North American species, home ranges of large herbivorous mammals are relatively larger than we would expect on metabolic grounds, and suggested that the productivity of the environment for mammal species decreases with increasing body size. This interpretation assumes that the number of conspecifics that share an individual's home range is independent of body size. Data presented here show that this is not true for the species in their sample; the home range is shared with an increasing number of conspecifics in larger herbivore species. The productivity of the environment for a species is independent of body size and the area available to an individual for its own use scales approximately as do individual metabolic requirements. These results agree with conclusions based upon the scaling of population density with body mass and illustrate the interrelationship between home range and dietary and social organization trends among mammalian herbivores. Individual home range area is a function of the way in which the local population of a species, not merely an individual, exploits the environment. 相似文献
18.
Ross-Ibarra J 《Genetica》2005,123(1-2):197-204
Plant domestication ranks as one of the most important developments in human history, giving human populations the potential to harness unprecedented quantities of the earths resources. But domestication has also played a more subtle historical role as the foundation of the modern study of evolution and adaptation. Until recently, however, researchers interested in domestication were limited to studying phenotypic changes or the genetics of simple Mendelian traits, when often the characters of most interest – fruit size, yield, height, flowering time, etc. – are quantitative in nature. The goals of this paper are to review some of the recent work on the quantitative genetics of plant domestication, identify some of the common trends found in this literature, and offer some novel interpretations of the data that is currently available. 相似文献
19.
N. E. Basova E. V. Rozengart 《Journal of Evolutionary Biochemistry and Physiology》2009,45(2):211-220
The paper deals with a comparative study of various aspects of reactivity (substrate and inhibitor specificity, sensitivity to action of hydrophobic organophosphorus inhibitors, capability for reactivation) of cholinesterase preparations from brain, erythrocytes, and serum of a group of mammals (human, rabbit, rat, cattle, dog, and cat). It has turned out that at preservation of the species and tissue specificity, catalytic properties of the brain and erythrocyte cholinesterases of the same animal species are very close to each other. 相似文献
20.
The extent of extinctions of mammals on islands 总被引:2,自引:0,他引:2
Many of the world's oceanic and oceanic-like islands possessed endemic mammal faunas before they were colonized by humans. These faunas, unbalanced and impoverished compared to continental faunas, usually lacked large mammalian carnivores. In virtually all cases, the arrival of humans and their domesticants and commensals on these islands is related to the extirpation of large numbers of endemic insular mammals. These extinction events affected at least 27% of autochthonous mammal species on the world's oceanic and oceanic-like islands. This percentage rises the 35% when volant mammals are excluded. This reduction in the natural biodiversity brought about the disappearance of several unique biological types that apparently never existed on the continents. 相似文献