Major Patterns (major + pattern)

Distribution by Scientific Domains

Selected Abstracts

Historical biogeography of scarabaeine dung beetles

Adrian L. V. Davis
Abstract Aim, (1) To review briefly global biogeographical patterns in dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae), a group whose evolutionary history has been dominated by ecological specialization to vertebrate dung in warmer climates. (2) To develop hypotheses accounting for the evolution of these patterns. Location, Six principal biogeographical regions: Palaearctic, Oriental, Afrotropical, Australasia, Neotropical, Nearctic and five outlying islands or island groups harbouring endemic genera: Caribbean, Madagascar, Mauritius, New Caledonia, New Zealand. Methods, Major patterns of tribal, generic and species distribution are investigated using cluster analysis, ordination, parsimony analysis of endemism and track analysis. Attempts are made to resolve biogeographical patterns with findings in the fields of plate tectonics, fossil and evolutionary history, plus phylogeny of both mammals and dung beetles. Results, Because of conflict between published findings, it is uncertain at what point in time density of dinosaur dung, mammal dung or both became sufficiently great to select for specialized habits in dung beetles. However, biogeographical evidence would suggest a Mesozoic origin followed by further taxonomic radiation during the Cenozoic, possibly in response to the increasing size and diversity of mammalian dung types in South America and Afro-Eurasia. Proportional generic distribution in fourteen tribes and subtribes showed four principal biogeographical patterns: (1) southerly biased Gondwanaland distribution, (2) Americas or (3) Madagascar endemism, and (4) northerly biased, Afro-Eurasian-centred distribution with limited numbers of genera also widespread in other regions. Proportional composition of faunas in eleven geographical regions indicated three principal distributional centres, East Gondwanaland fragments, Afro-Eurasia and the Americas. These patterns probably result from three principal long-term range expansion and vicariance events (Mesozoic: Gondwanaland interchange and fragmentation, Cenozoic: Afro-Eurasian/Nearctic interchange and the Great American interchange). It is suggested that old vicariance caused by the Mesozoic fragmentation of Gondwanaland leads to a high degree of regional endemism at generic or tribal level across one or more Gondwanaland tracks. In contrast, it is suggested that the more recent Cenozoic range expansions occurred primarily towards northern regions leading to endemism primarily at species level. These Cenozoic radiations were facilitated by the re-linking of continents, either because of tectonic plate movements (Africa to Eurasia in Miocene), climatically induced sea-level change (Afro-Eurasia to Nearctic in Miocene and Pleistocene), or similar coupled with orogenics (Nearctic to Neotropical in Pliocene). Speciation has followed vicariance either because of climatic change or physical barrier development. These recent range expansions probably occurred principally along an Afro-Eurasian land track to the Nearctic and Neotropical and an Americas land track northwards from the Neotropics to the Nearctic, with limited dispersal from Eurasia to Australia, probably across a sea barrier. This accounts for the overall, spatially constrained, biogeographical pattern comprising large numbers of species-poor genera endemic to a single biogeographical region and fewer more species-rich genera, many of which show wider biogeographical distributions. In most southerly regions (Australasia, Madagascar, Neotropical), faunal composition and generic endemism is primarily dominated by elements with Gondwanaland ancestry, which is consistent with the Gondwanaland origin claimed for Scarabaeinae. In Afro-Eurasia (Palaearctic, Oriental, Afrotropical), generic endemism of monophyletically derived Afro-Eurasian and widespread lineages is centred in the Afrotropical region and faunal composition is numerically dominated by Afro-Eurasian and widespread elements. In the Nearctic region, the fauna is jointly dominated by widespread elements, derived from Afro-Eurasia, and Gondwanaland and Americas elements derived from the Neotropical region. Main conclusions, Global biogeographical patterns in scarabaeine dung beetles primarily result from Mesozoic and Cenozoic range expansion events followed by vicariance, although recent dispersal to Australia may have occurred across sea barriers. Detailed phylogenetics research is required to provide data to support dispersal/vicariance hypotheses. [source]

Do Characteristics of Parental Child Homicide in Sweden Fit Evolutionary Predictions?

ETHOLOGY, Issue 11 2007
Johanna Nordlund
Evolutionary models have been used to explain parental child homicide. One idea is that children with low fitness value to their parents will be less loved and cared for and therefore more at risk in conflict situations. It is then important to investigate if conflicts with the children are the major pattern in cases of parental child homicide. The aim of this study is to survey the background circumstances of parental child homicide in Sweden and relate them to the evolutionary model suggested. We more specifically investigate if the homicides occur in conflict situations with the child, the frequency of several victims (including the partner or former partner) and if there are differences in characteristics of homicides between stepparents and genetic parents. Our results show that parental child homicide is a heterogeneous phenomenon, where relatively few cases were the result of a conflict with the child-victims. Instead severe conflicts between parents were the most common circumstance in which children were killed. Many children were victims of an extended suicide, which often included several members of the family. Step-parents were more likely to kill children aggressively in conflicts with them than genetic parents. The complexity of the phenomenon suggests that an evolutionary model based upon a mechanism related to conflicts with the child-victim has limited explanatory value on parental child homicide in general. [source]

Protein chip-based microarray profiling of oxidized low density lipoprotein-treated cells

Sergiy Sukhanov
Abstract Commercially available high-content Ab380 and extensively validated DLM26 homemade protein microarrays were used to profile the effects of the pro-atherogenic molecule, oxidized low density lipoprotein (OxLDL), on human aortic smooth muscle cells. Protein microarrays detected 298 proteins in cell lysates and 54 of these were differentially regulated. Microarray data were validated by immunoblotting for a selected set of up- and down-regulated proteins. The protein microarray data sets were compared with our recent cDNA microarray-based gene expression results in order to characterize the global effect of OxLDL on smooth muscle cell functions. A group of cell-cell interaction molecules was classified as up-regulated by OxLDL, whereas nucleic acid/protein biosynthesis, structural and humoral response proteins/genes were under-expressed in cells treated by OxLDL. These findings reveal the major pattern of OxLDL-induced effects on the human aortic smooth muscle cells functions and also demonstrate that protein chip-based microarrays could be a useful proteomic tool to profile disease-related states of muscle cells. [source]


EVOLUTION, Issue 4 2002
Madalena Branco
Abstract Nested clade analysis was applied to cytochrome b restriction site data previously obtained on 20 natural populations of the European rabbit across the Iberian Peninsula to test the hypothesis of postglacial dispersal from two main refugia, one in the northeast and the other in the southwest. Apart from historical fragmentation that resulted in geographic discontinuity of two distinct mitochondrial DNA (mtDNA) clades A and B, patterns of haplotype genetic variability have been shaped mostly by restricted gene flow via isolation by distance. The distribution of tip versus interior haplotypes suggests that dispersal occurred from both the southwestern and northeastern groups. Dispersal from the southwest had a north and northwest direction, whereas from the northeast it had mostly a western and southern orientation, with subsequent overlap in a southeastern-northwestern axis across the Iberian Peninsula. The analysis of the pairwise mismatch distribution of a 179,181-bp fragment of the mtDNA control region, for seven of those populations, further supports the idea that major patterns of dispersal were in the direction of central Iberia. Additionally, rabbit populations do not show signs of any significant loss of genetic diversity in the recent past, implying that they maintained large population sizes and structure throughout the ice ages. This is congruent with the fact that the Iberian Peninsula was itself a glacial refugium during Quaternary ice ages. Nonetheless, climatic oscillations of this period, although certainly milder than in northern Europe, were sufficient to affect the range distributions of Iberian organisms. [source]

Patterns of variability in the satellite microwave sounding unit temperature record: comparison with surface and reanalysis data

Giovanni Sturaro
Abstract Principal component analysis is applied to global temperature records to study the differences in the patterns of variability between surface and troposphere. Surface, Microwave Sounding Unit (lower troposphere, channel 2 and channel 4) and National Centers for Environmental Prediction,National Center for Atmospheric Research reanalysis thickness data are studied in the common period 1979,2000. The patterns of variability are classified into geographical regions and compared. The series of their time coefficients are correlated to assess the existence of common and significant climate-change signals in the form of climatic trends. The objective is to identify the physical processes determining the records' variations and the differences between the surface and the satellite records that might be related to the discrepancy in their globally averaged trend. Major differences were found in the Tropics, where the surface warming is not paralleled in any other record. The surface record has two major patterns over the Tropics, one of which is connected to El Niño,southern oscillation. Satellite variability is instead described by only one pattern, most probably deriving from the merging of the two distinct patterns found for the near-surface records. In the eastern Antarctic a higher troposphere and lower stratosphere negative trend is found connected to ozone depletion. This signal prevails in the satellite record, despite evidence that it is confined only above 500 hPa. A pattern over Siberia is linked to the ,Euro-Siberian oscillation', i.e. the change in the pressure field determining the tracks of the Atlantic storms over the area Copyright © 2003 Royal Meteorological Society [source]

Patterns of speciation in endemic Mexican Goodeid fish: sexual conflict or early radiation?

Abstract Currently there is much interest in the potential for sexual selection or conflict to drive speciation. Theory proposes that speciation will be accelerated where sexual conflict is strong, particularly if females are ahead because mate choice will accentuate divergence by limiting gene flow. The Goodeinae are a monophyletic group of endemic Mexican fishes with an origin at least as old as the Miocene. Sexual selection is important in the Goodeinae and there is substantial interspecific variability in body morphology, which influences mate choice, allowing inference of the importance of female mate choice. We therefore used this group to test the relationship between sexual dimorphism and speciation rate. We quantified interspecific variation in sexual dimorphism amongst 25 species using a multivariate measure of total morphological differentiation between the sexes that accurately reflects sexual dimorphism driven by female mate choice and also used a mtDNA-based phylogeny to examine speciation rates. Comparative analyses failed to support a significant association between sexual dimorphism and speciation rate. In addition, variation in the time course of speciation throughout the whole clade was also examined using a similar tree containing 34 extant species. A constant rates model for the growth of this clade was rejected, but analyses instead indicated a decline in the rate of speciation over time. These results support the hypothesis of an early expansion of the group, perhaps due to an early radiation influenced by the key innovation of live bearing, or the prevalence of Miocene volcanism. In general, support for the role of sexual selection in generating patterns of speciation is proving equivocal and we argue that vicariance biogeography and adaptive radiations remain the most likely determinants of major patterns of diversification of continental organisms. [source]

Comparison of genetic (co)variance matrices within and between Scabiosa canescens and S. columbaria

In the current study, we used bootstrap analyses and the common principal component (CPC) method of Flury (1988) to estimate and compare the G -matrix of Scabiosa columbaria and S. canescens populations. We found three major patterns in the G -matrices: (i) the magnitude of the (co)variances was more variable among characters than among populations, (ii) different populations showed high (co)variance for different characters, and (iii) there was a tendency for S. canescens to have higher genetic (co)variances than S. columbaria. The hypothesis of equal G -matrices was rejected in all comparisons and there was no evidence that the matrices differed by a proportional constant in any of the analyses. The two ,species matrices' were found to be unrelated, both for raw data and data standardized over populations, and there was significant between-population variation in the G -matrix in both species. Populations of S. canescens showed conservation of structure (principal components) in their G -matrices, contrasting with the lack of common structure among the S. columbaria matrices. Given these observations and the results from previous studies, we propose that selection may be responsible for some of the variation between the G -matrices, at least in S. columbaria and at the between-species level. [source]

The relationship between stomach contents and maturity state for major northwest Atlantic fishes: new paradigms?

J. S. Link
Iteroparous species examined from the northwest Atlantic demonstrated distinct relationships between feeding and reproduction. Two species showed an increase in feeding during the developing, ripe and running stages of reproduction, indicative of the ramper pattern. Four species showed an increase in feeding after spawning in the spent or resting stage of reproduction, indicative of the rester pattern. Two species exhibited no distinct pattern. Evidence from other species confirms these major patterns. This information may be useful to determine the effectiveness of different management measures, particularly in relation to feeding or spawning aggregations. There are two major feeding-reproductive patterns for fishes along a continuum of possibilities. [source]

The interaction of plant genotype and herbivory decelerate leaf litter decomposition and alter nutrient dynamics

OIKOS, Issue 1 2005
Jennifer A. Schweitzer
We examined how plant genetic variation and a common herbivore (the leaf-galling aphid, Pemphigus betae) influenced leaf litter quality, decomposition, and nutrient dynamics in a dominant riparian tree (Populus spp.). Based on both observational studies and a herbivore exclusion experiment using trees of known genotype, we found four major patterns: 1) the quality of galled vs non-galled or gall-excluded litter significantly differed in the concentration of condensed tannins, lignin, nitrogen and phosphorus; 2) the difference in litter quality resulted in galled litter decomposing at rates 34 to 40% slower than non-galled litter; 3) plant genotype and herbivory had similar effects on the magnitude of decomposition rate constants; and 4) plant genotype mediated the herbivore effects on leaf litter quality and decomposition, as there were genotype-specific responses to herbivory independent of herbivore density. In contrast to other studies that have demonstrated accelerated ecosystem properties in response to arthropod herbivory, our findings argue that herbivore-induced secondary compounds decelerated ecosystem properties though their "after-life" effects on litter quality. Furthermore, these data are among the first to suggest that genotype-specific responses to herbivores can have a major impact on decomposition and nutrient flux, which likely has important consequences for the spatial distribution of nutrients at the landscape level. Due to the magnitude of these effects, we contend that it is important to incorporate a genetic perspective into ecosystem studies. [source]

Cytokine responses to mitogen and Schistosoma haematobium antigens are different in children with distinct infection histories

Janet T. Scott
Prevalence of Schistosoma haematobium infection in children from two neighbouring villages in Zimbabwe was 77·1% and 40·3%, respectively. The age-intensity data indicated peak intensities of infection at a lower age in the high prevalence village. This study investigated whether the difference in infection histories was reflected in a difference in cytokine profiles between children resident in these two villages. Blood samples were taken to assay for cytokine secretion 1 year after treatment for schistosomiasis. They were cultured with phytohaemagglutinin (PHA), schistosome egg antigens (SEA) or cultured without stimulant and tested for the presence of interleukin (IL)-4, IL-5, IL-10, granulocyte-macrophage colony-stimulating factor (GM-CSF) and IFN-,. Blood samples from children from the low prevalence village were more likely to produce IL-4 (P < 0·0001) and produced higher levels of IFN-, (P < 0·02) and GM-CSF (P < 0·03) when cultured with PHA for 24 h. Residence in the high prevalence village was associated with production of IL-10 (P < 0·006) and GM-CSF (P < 0·04) in response to culture with SEA and IL-5 (P < 0·02) with PHA for 48 h. The interaction between age and village was not significant for these results; however, there was a significant interaction between age and village for IL-5 detected in blood samples cultured with PHA for 24 h (P < 0·01). These results concur with previous observations that major patterns of cytokine production can be related to immunosuppression, but also indicate an underlying pattern which reflects the importance of history of infection to the immune response. [source]

The Age of Migration in China

Zai Liang
Using data from the 1987 and 1995 China One Percent Population Sample Surveys, this article examines migration patterns during 1982,95, a period of sweeping social and economic changes in China. Several major patterns are evident: the increase in overall migration and especially in temporary migration, the increasing importance of inter-provincial migration, and the concentration of migrants in the coastal region. Over time, migrants of rural origin were more likely to choose cities as destinations than towns. The consequences and implications of the changes in migration patterns are explored. [source]