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Author(s): G. M. Mace [1]; A. Balmford [2]; L. Boitani [3]; G. Cowlishaw [4]; A. P. Dobson [5]; D. P. Faith [6]; K. J. Gaston [7]; C. J. Humphries [8]; [...]

A set of priority sites for wildfowl conservation in Mexico was determined using contemporary count data (1991-2000) from the U.S. Fish & Wildlife Service mid-winter surveys. We used a complementarity approach implemented through linear integer programming that addresses particular conservation concerns for every species included in the analysis and large fluctuations in numbers through time. A set of 31 priority sites was identified, which held more than 69% of the mid-winter count total in Mexico during all surveyed years. Six sites were in the northern highlands, 12 in the central highlands, six on the Gulf of Mexico coast and seven on the upper Pacific coast. Twenty-two sites from the priority set have previously been identified as qualifying for designation as wetlands of international importance under the Ramsar Convention and 20 sites are classified as Important Areas for Bird Conservation in Mexico. The information presented here provides an accountable, spatially-explicit, numerical basis for ongoing conservation planning efforts in Mexico, which can be used to improve existing wildfowl conservation networks in the country and can also be useful for conservation planning exercises elsewhere. [ABSTRACT FROM AUTHOR]

The article focuses on the Macrophysiology, as the investigation of variation in physiological traits over large geographical and temporal scales and the ecological implications of this variation. It has not only produced several potentially profound changes in understanding of biological systems, but also revealed a number of surprising gaps in that understanding. From this perspective, two of these are particularly significant. First, despite widespread extinctions and range alteration caused by humans, the relationship between animal diversity and ecosystem functioning is not well understood. Second, macroecological and macrophysiological studies have revealed potentially major differences in the structure and functioning of Southern and Northern Hemisphere systems.

Transformation of data to normality may be illuminating and useful statistically. There are two standard families of transformations, power transformations for positive numbers, bounded at the left, and folded transformations for proportions, bounded both at the left and theright. It has been shown that there is no one satisfactory power transformation for range size data. However, such measures are limited to the right as well as the left, and we consider applying folded transformations to them. Seven data sets of range sizes recorded by 10 kmsquares are studied. Six are British (native and introduced plants, mammals, dragonflies and two breeding bird surveys) the seventh is ofSwiss breeding birds. Using these we show that the right hand limit of the distribution can be estimated and the best folded transformation found. In all cases the right hand limit is larger than the range size of the most widespread species and smaller than the notional scope of the survey. In all cases the logit or flog, the logarithmic folded transformation, is satisfactory; in five cases it is the best. Itis well known that abundance is approximately (though not exactly) log-normally distributed. The relationship of that to our discovery that range size data are approximately logit-normal is discussed. Thereis no fully satisfactory explanation for either observation at present. [ABSTRACT FROM AUTHOR]

Positive interspecific and intraspecific relationships between localabundance and regional occupancy have been widely documented. The former are essentially pervasive. These patterns have some potentially significant applied implications: (1) Biodiversity inventorying - there can be no simple and effective trade-off between the intensity andspatial extent of biodiversity inventorying, (2) Population monitoring - intraspecific, and to a more limited extent interspecific, population monitoring may be based on measures of occupancy, particularly where only crude indications of marked shifts in abundance are required, (3) Harvesting - harvesting of local populations may often resultin a reduction in wider occupancy, but if local extinctions are caused by over-exploitation this may not generally result in a reduction in local abundance elsewhere in the range of a species, (4) Conservation - species of conservation concern may face the double jeopardy oflow abundance and small range size, but depending on the extent of acausal link between levels of abundance and occupancy it may be possible to cheat the abundance-occupancy relationship and maintain species at relatively high local densities for their range sizes, and (5) Invasions - pest species may become more of a problem in those areas in which they already occur, because their local densities will increase, as they spread. [ABSTRACT FROM AUTHOR]

An increase in the altitudinal range of occurrence of species in an assemblage with increasing elevation has been explained as a consequence of individual organisms having to be able to withstand a broader range of climatic conditions at higher elevations; the climatic variability hypothesis. Here we show that for scarab dung beetles (26 species) across an elevational transect (approx. 2500 m) in southern Africa thermal tolerance range does increase with increasing elevation across individuals and across species. The maximal thermal tolerance range exhibited increases slowly with elevation and the minimum range increases more rapidly. The mechanistic basis of the change appears tobe one of rapidly changing critical thermal minimum (CTmin) with elevation and only small changes in critical thermal maximum (CTmax). Of course, even if the pattern of tolerance of species assumed by the climatic variability hypothesis is correct, an increase in altitudinal range with increasing elevation need not necessarily follow. However, although sampling has been limited, there does appear to be an elevational increase in altitudinal range for this species assemblage. [ABSTRACT FROM AUTHOR]

The detailed forms of species-range size distributions in Britain are determined and contrasted for ten taxonomic assemblages (liverworts, vascular plants, molluscs [aquatic and terrestrial], dragonflies, macro-moths, butterflies, birds [breeding and wintering], mammals). All are strongly right-skewed when range sizes are untransformed. A logarithmic transformation fails to normalise the distribution for all but one group, and the distributions for several groups are not readily normalised at all. Taxa with larger median range sizes have species-range size distributions that are less strongly right-skewed. The median observed range sizes of species in each of the taxonomic groups fall, in terms of decreasing range size, in the sequence wintering birds > breeding birds > mammals > butterflies > terrestrial molluscs >dragonflies > aquatic molluscs > vascular plants > moths > liverworts. Despite the difficulties in deriving a simple and sensible mechanistic model for range size distributions, this is likely to be the most important next step towards understanding their forms. [ABSTRACT FROM AUTHOR]

Quantitative information on large scale spatial patterns of biodiversity remains poor, especially for pelagic systems. In this paper the regional diversity of procellariiforms is mapped worldwide at the species level. These seabirds do not display a conventional latitudinal gradient of decreasing species richness towards high latitudes, but rather are most speciose between 37 and 59S in all ocean basins. Basedon data for foraging ranges, areas with the highest species richnessand the most species with smaller range sizes are all found in the vicinity of New Zealand and its sub-Antarctic islands. In contrast, data for breeding ranges show islands in the southern Indian and Atlantic oceans to have the highest number of breeding species, while theseislands and New Zealand have the most species with smaller range sizes. No northern hemisphere regions are amongst the top ten grid cellsfor foraging and breeding species richness, although Hawaii has the highest species richness of procellariiforms north of the equator. Northern Baja California, Madeira, the Canary islands, and the west coast of South America are all important sites of narrow endemism in thenorthern hemisphere. High species richness and narrow endemism coincide with areas of significant longline fishing activity in the southern hemisphere. Near-minimum sets based on one and three representations demonstrate that if all procellariiform species are to be retained, large areas of the ocean and almost all breeding sites require conservation. [ABSTRACT FROM AUTHOR]

The relationship between the geographic distribution of consumers and of their hosts (foodplants) is examined using the resident butterfly fauna of Britain. On average, butterfly species that feed on more widely distributed hosts are themselves more widely distributed. However, the relationship is approximately triangular and the upper constraint imposed by the range sizes of hosts is not closely followed; some species have much more restricted ranges than their hosts have. There is no relationship between the proportion of the range of the foodplant that is occupied and the size of the range of the foodplant. Monophagous butterfly species have smaller range sizes than polyphagousspecies, probably as a consequence of the greater potential range sizes of the latter. Those plant species that are used as hosts by butterflies have larger range sizes than expected by chance, and individual polyphagous butterfly species tend disproportionately to be found in areas containing larger numbers of their host plant species. In sum, this study reveals a complex relationship between the distributionof butterflies and that of their resources (foodplants). [ABSTRACT FROM AUTHOR]

A general positive interspecific relationship between local abundance and geographic range size in animals has prompted speculation that a similar relationship might exist intraspecifically, such that a species is widespread at times when it is locally abundant, and more restricted in distribution when it is locally rare. Current evidence suggests that intraspecific relationships often are positive, but that there is considerable variation in the pattern exhibited by species. Here, we use data on British birds to test the hypotheses that speciesshowing a high mean or wide spread of local densities or range sizeswill be more likely to show strong intraspecific relationships between abundance and geographic range size. These data show only inconsistent support for an effect of the range of densities or of occupancies on intraspecific abundance-range size relationships. However, the strength of an intraspecific relationship does seem to be related to the mean occupancy of species, and whether or not a species exhibits temporal trends in density, with the strongest relationships found in species with simultaneous trends in both density and occupancy. We suggest that these results are explained by time lags in the loss or gain of species at occupied sites in response to reductions or increases in density. [ABSTRACT FROM AUTHOR]

A number of mechanisms have been proposed to explain the widely observed positive interspecific relationship between local abundance and extent of geographic distribution in animals. Here, we use data on British birds to assess two of these hypotheses: that the relationship results from the relative position of a study area with respect to the geographic ranges of the species which occur there, and that the relationship results from a simple difference between taxonomic groups,rather than any general tendency for more abundant species to have larger range sizes. We find support for neither hypothesis. Phylogenetically controlled comparative analyses reveal that the positive abundance-range size relationship is consistently found within taxa, even when abundance and range size are calculated at a variety of spatial and temporal scales. Analyses both across species and within taxa show that bird species for which Britain is near to the centre of their distribution in Europe tend to have larger British range sizes and higher abundances than do species where Britain is close to the edge oftheir range in Europe. However, these relationships do not cause that between abundance and range size, because this latter relationship persists within different range position categories. Whether a species is near the centre or edge of its geographic range in Britain may affect its position on the. abundance-range size relationship, but does not produce the relationship. Range position in Britain does, however, seem to be related to the magnitude of temporal changes in the range sizes of British birds. There is some evidence to suggest that species for which Britain is nearer to their European range centre haveshown smaller changes in distribution over the period 1970--1990 than have species for which Britain is close to their European range edge. [ABSTRACT FROM AUTHOR]

The numbers of published macroecological studies are increasing dramatically. Yet, progress within the field of macroecology, and a wideracceptance of its goals and rationale, do not seem to be developing at an equivalent rate. In this paper we examine the criticisms which have been, and can be, made. Attention is drawn to those which withstand scrutiny and are therefore of concern, and some solutions are proffered. We attempt to dispel those criticisms which are misplaced or ill-considered. We conclude that macroecology is likely to progress most effectively in the immediate future, and to make the greatest contribution to the broader study of ecology, if research follows three paths. It needs first to establish a more balanced and better documented body of published patterns, second to establish not simply the presence of patterns but also how in an 'anatomical' sense they come about, and third to expand the program of tests of multiple hypotheses that have been generated to explain observed patterns. [ABSTRACT FROM AUTHOR]

There is a general, positive, interspecific abundance--range size relationship. On the basis of this pattern it has been predicted that when the local abundance of a species is reduced its regional distribution should decline, and vice versa (i.e. there is a positive intraspecific abundance--range size relationship). We test this prediction using data for North American breeding passerines. Whilst it is supported by a number of species, all combinations of increasing, decreasing and stable local abundances and distributional occurrence are observed, when one or other variable is declining. [ABSTRACT FROM AUTHOR]

In many taxa, the sizes of species' geographic ranges and their average local abundances at sites where they occur are positively correlated. We develop a simple population model that predicts this relationship which does not rely upon spatial dynamics. The simple, but fundamental, fact which should link distribution and abundance is that thedistribution of species i is given by the number of sites at which its intrinsic rate of increase, r{sub}i{end} greater than 0, whereas its equilibrium local abundance should often vary directly with r{sub}i{end}. Any factor which tends to increase r{sub}i{end} across all sites will simultaneously enlarge the number of sites potentially occupied, and increase abundance at each occupied site. If species differ principally in their response to density-independent factors influencing birth and death rates, but are similar in density-dependence, then in a broad range of circumstances one should observe a range-abundance correlation. The model also predicts particular circumstances in which there is no, or even a negative, correlation between range and abundance. The general occurrence of this correlation in a broad range of taxa may reflect the operation of a number of distinct mechanisms. [ABSTRACT FROM AUTHOR]