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1.
    
Németh et al. (Mammal Review 46, 2016, 204) recently reviewed the relationships between Old World blind mole rats (Spalacidae) and their predators. They concluded that blind mole rats are regularly taken by predators throughout their range, and that predation pressure probably contributed to blind mole rat evolution and underground behaviour. I argue instead that blind mole rats are rare or accidental prey for most predators, and list a number of alternative explanations for cases where a high predation rate was observed. I conclude that no blind mole rat species that has been studied is important prey for any predator species that can encounter it.  相似文献   

2.
Linking patterns in macroecology   总被引:6,自引:0,他引:6  
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3.
  总被引:2,自引:0,他引:2  
Using coarse resolution data on the spatial distribution of the entire New World avifauna, we test for phylogenclic patterns in the mean and total geographic range sizes of taxa. The analyses reveal that (i) the species-range size distribution is only approximately normalized, and remains significantly left-skewed, under logarithmic transformation. Most variance in range sizes is explained at the level of species within genera; (ii) there is no effect of the age of taxa on mean clade range size, although older taxa are more likely to have larger total range sizes; (iii) there is some evidence that taxa comprising more species have larger total range sizes; (iv) there is little or no evidence for a relationship between rate of cladogenesis and range size. The results suggest that geographic range size is a labile trait, at least for New World birds, and that the influence of evolutionary history is only weakly detectable in the range size variation of extant taxa, at least at the scale of analysis used here. In addition to these conclusions, two general and important procedural issues emerge.  相似文献   

4.
  总被引:5,自引:0,他引:5  
Aim I examine the relationship between geographical range size and three variables (body size, an index of habitat breadth, and an index of local abundance) within a phylogenetic framework in North American species of suckers and sunfishes. Location North America Methods Regressions after independent contrasts of geographical range size, body size, habitat breadth, and local abundance. Results Species with large range sizes tend to be larger-bodied, be more locally abundant, and have higher habitat breadths. Character reconstructions support the prediction that variables associated with rarity (small geographical range size, low local abundance, low niche breadth, and large body size) evolve in unison, although large body size was associated with the opposite traits in these taxa. Gaston & Blackburn (1996a) suggested using visual identification of the lower boundary of the geographical range-body size relationship to identify extinction-prone species; this resulted in thirteen species that are potentially extinction-prone. Main conclusions Similar evolutionary mechanisms appear to operate on body size and other variables related to rarity, even in distantly related taxa.  相似文献   

5.
6.
1. Dispersal is a crucial process in maintaining population structures in many organisms, and is hypothesized as a process underlying the interspecific relationship between abundance and distribution. Here we examined whether there was a link between the dispersal and developmental modes of marine macroinvertebrates and the slopes and elevations of interspecific abundance-occupancy relationships. We predicted that if within-site retention of larvae ranks in the order brooders > lecithotrophs > planktotrophs, for any given level of mean abundance, occupancy should increase in the order brooders < lecithotrophs < planktotrophs. We also predicted that propensity to form metapopulations should be greater for planktonic dispersers (i.e. lecithotrophs and planktotrophs combined) than for non-planktonic (i.e. brooders), resulting in steeper abundance-occupancy relationships for the former. 2. Predictions were tested using a data set for 362 subtidal marine macroinvertebrates occurring across 446 1-km(2) grid squares around the British Isles; analyses were performed on the data set as a whole and for separate phyla. 3. The total data set had a Z-transformed effect size of 0.79, within the confidence intervals described by Blackburn et al. (2006; Journal of Animal Ecology, 75, 1426-1439), and was consistently present with relatively homogeneous effect size in separate analyses of polychaetes, crustaceans, molluscs and echinoderms. 4. In all cases, planktonic dispersing organisms showed an abundance-occupancy relationship with greater elevation than that for non-planktonic organisms; in polychaetes the elevation of slopes was in the rank order planktotrophs > lecithotrophs > brooders. No differences between the slopes of the abundance-occupancy relationship were apparent for different dispersal modes either within, or across phyla. 5. We conclude that dispersal capacity may play an important part in determining the elevation of the abundance-occupancy relationship, the corollary of low dispersal in the marine realm being greater local retention of larvae and greater local population abundance at low extents of geographical distribution.  相似文献   

7.
We used eigenvector mapping in space and phylogeny to investigate the relationships among space, phylogeny and environment on body size and range size variation across two groups of venomous snakes – Viperidae and Elapidae – from the New World. Data on species geographic range sizes, maximum body sizes and phylogenetic relationships were compiled from the available literature. The distributional data were also used to calculate the latitudinal and longitudinal midpoint and the environmental centroids for each species. The eigenvectors extracted from the pair wise spatial and phylogenetic distance matrices were integrated with environmental variables into a method of variation partitioning where the variation in each trait was quantitatively attributed to ‘pure’ and/or shared effects of phylogeny, environment and space. Our results showed that variation in body size was predominantly determined by phylogeny in both groups of snakes. For Viperidae, we found that pure ‘effects’ of phylogeny were the strongest, indicating that most of the body size evolution that was phylogenetically determined in this group occurred independently of environment and geographical proximity. Regarding range sizes, pure phylogenetic influences were very low in both groups, whereas the largest single fraction of explained variation corresponded to overlapped influences of the three sets of predictors, especially for Elapidae. Along with this, we found evidence that niche conservatism is an important processes underlying variation in body size and range size in both groups of snakes.  相似文献   

8.
1. A positive interspecific relationship between abundance and distribution is widely considered to be one of the most general patterns in ecology. However, the relationship appears to vary considerably across assemblages, from significant positive to significant negative correlations and all shades in between. 2. This variation has led to the suggestion that the abundance-distribution relationship has multiple forms, with the corollary that different patterns may inform about, or have different, causes. However, this variation has never been formally quantified, nor has it been determined whether the observed variation is indicative of sampling error in estimating a single effect or of real heterogeneity in such relationships. Here, we use the meta-analytical approach to assess variation in abundance-distribution relationships, and to test different hypotheses for it. 3. Analysis of 279 relationships found a mean effect size of 0.655, which was both highly significantly different from zero and indicative of a strong positive association between abundance and distribution. However, effect sizes were highly heterogeneous, supporting the contention that this relationship does indeed have multiple forms. 4. Most notably, relationships vary significantly in strength across realms, with the strongest in the marine and intertidal, intermediate relationships for terrestrial and parasitic assemblages, and the weakest relationships in freshwater systems. Effect sizes in all of the aquatic realms are homogeneous, suggesting that realm is an important source of the heterogeneity observed across all studies. We posit that this may be because the different spatial structure of the environment in each realm affects the opportunity for the dispersal of individuals between sites. 5. Some of the remaining heterogeneity in effect sizes for terrestrial assemblages could be explained by partitioning assemblages by habitat, scale, biogeographical region and taxon, but considerable heterogeneity in effect sizes for terrestrial and parasitic assemblages remained unexplained.  相似文献   

9.
1.  The abundance and distribution of species tend to be linked, such that species declining in abundance often tend also to show declines in the number of sites they occupy, while species increasing in abundance tend also to be increasing in occupancy. Therefore, intraspecific abundance–occupancy relationships are commonly positive.
2.  The intraspecific pattern is mirrored by more general positive interspecific abundance–occupancy relationships: widespread species tend to be abundant, and narrowly distributed species rare.
3.  Here, we review recent research on these patterns based on the flora and fauna of the British Isles. We assess their generality, describe what is currently known about their structure, and summarize the results of tests of the several hypotheses proposed to explain their existence.
4.  The positive form generally exhibited by abundance–occupancy relationships, intraspecific or interspecific, has consequences for several areas of applied ecology, including conservation, harvesting, biological invasions and biodiversity inventorying. These implications are discussed briefly.  相似文献   

10.
    
1. Cross-species macroecological comparisons in freshwater invertebrates have been restricted by a lack of large-scale distributional data, and robust phylogenies. Here, we use data from the OdonataCentral database to explore body length–range size and wing length–range size relationships in damselflies from the genus Enallagma ; the recent publication of a phylogeny for this group meant that, as well as a cross-species analysis, we were able to assess relationships in a phylogenetically controlled manner.
2. For cross-species comparisons, only wing length showed significant (positive) regression relationships with range size and occupancy, although the inclusion of body length in multiple regressions increased the fit of the models. Damselflies with larger wings relative to their body length had larger distributions, a result confirmed by a significant positive relationship between range size and residuals from the regression of wing size on body size.
3. For the phylogenetically controlled analyses, only wing length contrast scores were significantly related to distribution patterns and entered into regression models; the significant positive relationships between wing length contrasts and both range size and occupancy contrasts suggested that evolutionary increases in wing length had occurred alongside range expansions.
4. Together these results suggest that species of Enallagma with larger wings (both absolute and relative to body length) tend to be more widely distributed in North America and that the evolution of wing size may have played a role in range expansion. No such relationships were evident for body size. We discuss the potential importance of wing morphometrics for studying the evolutionary ecology of freshwater insects.  相似文献   

11.
  总被引:1,自引:0,他引:1  
Aim To assess the extent to which the resolution at which geographical range sizes are measured influences macroecological patterns in this variable. Location Global. Methods Data on the geographical ranges of parrot species were digitized, and a Geographic Information System used to produce nine range size estimates for each species using different degrees of spatial resolution. The inter‐correlation of these estimates was then compared, together with their patterns of covariation with population size, body mass and migratory behaviour (across species and controlling for phylogeny), their pattern of phylogenetic correlation, and the frequency distributions of the different measures. Results Strong correlations exist among all nine range size measures across species, albeit that measures of similar spatial resolution are more strongly correlated. All measures show similar patterns of covariation with population size, body mass and migratory behaviour, and similar patterns of phylogenetic correlation. The skewness of frequency distributions increases towards zero as the resolution of the range size measure declines. Main conclusions The results of macroecological analyses are little affected by the resolution with which geographical range sizes are calculated, at least for the parrots of the world. Previously published studies based on crude measures of range size would be unlikely to have produced markedly different conclusions had they used more refined range size metrics.  相似文献   

12.
  总被引:2,自引:0,他引:2  
Data for five closely related species of gammarid crustaceans are used to examine interspecific relationships between the breadth of fundamental tolerance or capacity and geographical range size. Gammarus duebeni is, almost without exception, the most tolerant species and that with the best physiological performance. Although there is some limited variation, the remaining species can be ranked broadly in the sequence G. zaddachi  > G. salinus  >  G. oceanicus > G. locusta . The wide tolerance and high performance of G. duebeni is associated with the occupation of a wider range of environmental 'types' than any other of the species. In terms of geographical range size, the species can be ranked from most to least widespread in the sequence G. oceanicus  > G. duebeni  >  G. zaddachi  >  G. salinus  >  G. locusta . This provides little support for Brown's hypothesis, or the argument that the more widely distributed species within a taxonomic assemblage also tend to have the widest fundamental niches. However, if marine ( G. oceanicus and G. locusta ) and estuarine ( G. duebeni , G. zaddachi , G. salinus) species are considered separately, then in each case the species with the largest geographical range is also the most tolerant/best performer. In this sense, the jack-of-all-trades is the master-of-all, rather than the master-of-none.  相似文献   

13.
Ecological communities that experience stable climate conditions have been speculated to preserve more specialized interspecific associations and have higher proportions of smaller ranged species (SRS). Thus, areas with disproportionally large numbers of SRS are expected to coincide geographically with a high degree of community-level ecological specialization, but this suggestion remains poorly supported with empirical evidence. Here, we analysed data for hummingbird resource specialization, range size, contemporary climate, and Late Quaternary climate stability for 46 hummingbird–plant mutualistic networks distributed across the Americas, representing 130 hummingbird species (ca 40% of all hummingbird species). We demonstrate a positive relationship between the proportion of SRS of hummingbirds and community-level specialization, i.e. the division of the floral niche among coexisting hummingbird species. This relationship remained strong even when accounting for climate, furthermore, the effect of SRS on specialization was far stronger than the effect of specialization on SRS, suggesting that climate largely influences specialization through species'' range-size dynamics. Irrespective of the exact mechanism involved, our results indicate that communities consisting of higher proportions of SRS may be vulnerable to disturbance not only because of their small geographical ranges, but also because of their high degree of specialization.  相似文献   

14.
    
Phylogenetic legacy and phylogenetic trends affect the ecology of species-except, apparently, for the width of their distribution. As a result, \"macroecological\" patterns of species distributions emerge constantly in phylogenetically very distinct species assemblages. The width of the global distribution of species, for instance, constantly correlates positively to the width of their regional distribution. However, such patterns primarily reflect the phylogenetically derived species that dominate most assemblages. Basal species, in contrast, might show different macroecological patterns. We tested the hypothesis that the correlation between global and regional distributions of species diminishes among the phylogenetically basal species. We considered central European higher plants and defined global distribution as the occupancy of global floristic zones, regional distribution as the grid occupancy in Eastern Germany, and phylogenetic position as the rank distance to tree base. We also took into account a number of confounding variables. We found that, across all lineages, the global/regional correlation diminished among basal species. We then reanalyzed 19 lineages separately and always found the same pattern. The pattern reflected both increases in global distributions and decreases in regional distributions among basal species. The results indicate that many basal species face a risk of global or at least regional extinction, but have escaped the downward spiral of mutually reinforcing extinction risks at multiple scales. We suggest that many basal species had much time to expand their global ranges but are presently displaced locally by more derived species. Overall, the study shows that macroecological patterns may not be static and universal, but may undergo macroevolutionary trends. Analyses of macroecological patterns across a phylogeny may thus provide insights into macroevolutionary processes.  相似文献   

15.
The macroecology of Australian frogs   总被引:2,自引:1,他引:2  
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16.
    
Geographic range size is the manifestation of complex interactions between intrinsic species traits and extrinsic environmental conditions. It is also a fundamental ecological attribute of species and a key extinction risk correlate. Past research has primarily focused on the role of biological and environmental predictors of range size, but macroecological patterns can also be distorted by human activities. Here, we analyse the role of extrinsic (biogeography, habitat state, climate, human pressure) and intrinsic (biology) variables in predicting range size of the world's terrestrial mammals. In particular, our aim is to compare the predictive ability of human pressure vs. species biology. We evaluated the ability of 19 intrinsic and extrinsic variables in predicting range size for 4867 terrestrial mammals. We repeated the analyses after excluding restricted‐range species and performed separate analyses for species in different biogeographic realms and taxonomic groups. Our model had high predictive ability and showed that climatic variables and human pressures are the most influential predictors of range size. Interestingly, human pressures predict current geographic range size better than biological traits. These findings were confirmed when repeating the analyses on large‐ranged species, individual biogeographic regions and individual taxonomic groups. Climatic and human impacts have determined the extinction of mammal species in the past and are the main factors shaping the present distribution of mammals. These factors also affect other vertebrate groups globally, and their influence on range size may be similar as well. Measuring climatic and human variables can allow to obtain approximate range size estimations for data‐deficient and newly discovered species (e.g. hundreds of mammal species worldwide). Our results support the need for a more careful consideration of the role of climate change and human impact – as opposed to species biological characteristics – in shaping species distribution ranges.  相似文献   

17.
Data from the British Trust for Ornithology Common Birds Census and two atlases of breeding birds were used to examine the form of the interspecific abundance–range size relationship for the British avifauna. The relationship is positive for both farmland and woodland habitats and over two different periods, with some evidence of curvilinearity, using either proportion of occupied sites or numbers of occupied 10 × 10 km squares as measures of range size, and mean density at occupied sites as a measure of abundance. A log-linear plot gives the highest correlation. The relationship is stronger if based on maximum local densities than if based on average densities, but there is no relationship using minimum local densities. Relationships based on abundances at individual sites are uniformly positive for all sites, although the relationships for many sites also show evidence of curvilinearity, especially when range size is measured as the proportion of occupied sites. Species show significant concordance in their rank abundances across sites. We discuss some implications of these results.  相似文献   

18.
In a companion paper, we started an examination of the anatomy of the interspecific relationship between local abundance and geographical range size in the British avifauna by analysing its spatial dynamics. Here, we use the same data to extend this study to a consideration of the temporal dynamics of the relationship. Most species of British breeding bird show a positive intraspecific abundance–range size relationship through time: i.e. in years when a species is locally more abundant it also occupies a higher proportion of census sites. However, the majority of such relationships are not statistically significant, and other relationships that are statistically significant are negative. Therefore, intraspecific abundance–range size relationships do not simply mirror the relationship across species. Where they do arise, positive relationships are more likely to be associated with positive intraspecific relationships between range size and maximum rather than minimum abundance. The interspecific abundance–range size relationship is remarkably consistent across years, and is always significantly positive. The relationships for woodland and farmland census sites show correlated variation, so that in years when the linear regression slope and coefficient of determination are high across species on farmland plots, they also tend to be high across species on woodland plots. Common species tend to be common on both farmland and woodland plots, and tend to be common in all years. Likewise, rare species tend to be rare in all habitats and years. This concordance means that the positive interspecific abundance–range size relationship can be viewed as occurring largely independently of intraspecific relationships. It follows from the above that developing an understanding of intraspecific abundance–range size relationships may be of only limited value in ascertaining the determinants of positive interspecific abundance–range size relationships. We conclude that for interspecific relationships, it will be important to know why some species are consistently common and others rare, whereas for intraspecific relationships it will be important to understand the dynamic links between local abundances across sites.  相似文献   

19.
  总被引:3,自引:0,他引:3  
Aim To identify the factors determining the range size of pteridophytes (ferns and allied plants) in an Andean region. Location Humid eastern Andean slope in Carrasco National Park, Bolivia. Methods I used a macroecological approach to search for correlations of range size to elevation, habitat type, life form, reproductive strategy, the species’ elevational range, and its frequency, among the 473 pteridophyte species recorded in the park. Results Range sizes were smallest at 1800–3500 m elevation and in localized habitats with little disturbance (ravines, ridges), while regularly disturbed habitats (pastures, roadsides) supported widespread species. Families and genera differed with respect to the range sizes of their species, but this pattern was not correlated to any other studied factor and could not be explained. Species with restricted ranges tended to be more frequent in the study area than widespread species. Widespread species tended to have large elevational ranges, implying that they are ecologically more adaptable than localized species. There was no relationship of range size to life form or to the studied reproductive aspects (sexual vs. asexual reproduction, chlorophyllous vs. achlorophyllous spores). Conclusions The above trends were mostly uncorrelated and explained a rather small portion of the observed range size variance. Thus, it is not yet possible to draw a cohesive picture of the factors determining pteridophyte range size. Intriguing questions for future research include the relationship of range size to dispersal, competitive ability, and taxonomic affinity.  相似文献   

20.
    
Aim  To analyse quantitatively the extent to which several methodological, geographical and taxonomic variables affect the magnitude of the tendency for the latitudinal ranges of species to increase with latitude (the Rapoport effect).
Location  Global.
Methods  A meta-analysis of 49 published studies was used to evaluate the effect of several methodological and biological moderator variables on the magnitude of the pattern.
Results  The method used to depict the latitudinal variation in range sizes is a strong moderator variable that accounts for differences in the magnitude of the pattern. In contrast, the extent of the study or the use of areal or linear estimations of range sizes does not affect the magnitude of the pattern. The effect of geography is more consistent than the effect of taxonomy in accounting for differences in the magnitude of the pattern. The Rapoport effect is indeed strong in Eurasia and North America. Weaker or non-significant latitudinal trends are found at the global scale, and in Australia, South America and the New World. There are no significant differences in the magnitude of the pattern between different habitats, however, the overall pattern is weaker in oceans than in terrestrial regions of the world.
Main conclusions  The Rapoport effect is indeed strong in continental landmasses of the Northern Hemisphere. The magnitude of the effect is primarily affected by methodological and biogeographical factors. Ecological and spatial scale effects seem to be less important. We suggest that not all methodological approaches may be equally useful for analysing the pattern.  相似文献   

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