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In an influential paper, Harte et al. highlighted the scaling or ‘self-similar’ character of the power law species–area relationship (SAR), and used this feature to derive a species abundance distribution (SAD) and an endemics–area relationship. Here I show that their analysis was incorrect and leads to unrealistic results. I develop a different approach and obtain different results, both for SAD and for endemism. In particular, I show that the power law SAR is naturally associated with the power law statistical distribution, which is the only self-similar distribution and closely matches empirical SADs. The results in this paper shed light on some of the main issues that have been discussed with regard to SARs: their relationship with the lognormal and with the neutral theory, the relative importance of sampling effects vs other mechanisms, and the deviations from a power law. The equations that I develop are simple and easy to apply to field studies. [ABSTRACT FROM AUTHOR]

Species distributions often show an aggregated pattern, which can be due to a number of endo- and exogenous factors. While autologistic models have been used for modelling such data with statistical rigour, little emphasis has been put on disentangling potential causes of aggregation. In this paper we ask whether it is possible to infer sources of aggregation in species distributions from a single set of occurrence data by comparing the performance of various autologistic models. We create simulated data sets, which show similar occupancy patterns, but differ in the process that causes the aggregation. We model the distribution of these data with various autologistic models, and show how the relative performance of the models is sensitive to the factor causing aggregation in the data. This information can be used when modelling real species data, where causes of aggregation are typically unknown. To illustrate, we use our approach to assess the potential causes of aggregation in data of seven bird species with contrasting statistical patterns. Our findings have important implications for conservation, as understanding the mechanisms that drive population fluctuations in space and time is critical for the development of effective management actions for long-term conservation. [ABSTRACT FROM AUTHOR]

The species–time relationship (STR) describes how the species richness of a community increases with the time span over which the community is observed. This pattern has numerous implications for both theory and conservation in much the same way as the species–area relationship (SAR). However, the STR has received much less attention and to date only a handful of papers have been published on the pattern. Here we gather together 984 community time-series, representing 15 study areas and nine taxonomic groups, and evaluate their STRs in order to assess the generality of the STR, its consistency across ecosystems and taxonomic groups, its functional form, and its relationship to local species richness. In general, STRs were surprisingly similar across major taxonomic groups and ecosystem types. STRs tended to be well fit by both power and logarithmic functions, and power function exponents typically ranged between 0.2 and 0.4. Communities with high richness tended to have lower STR exponents, suggesting that factors increasing richness may simultaneously decrease turnover in ecological systems. Our results suggest that the STR is as fundamental an ecological pattern as the SAR, and raise questions about the general processes underlying this pattern. They also highlight the dynamic nature of most species assemblages, and the need to incorporate time scale in both basic and applied research on species richness patterns. [ABSTRACT FROM AUTHOR]

The two main fire response traits found in the Mediterranean basin are the resprouting capacity (R) and the propagule-persistence capacity (P). Previous studies suggested that these two traits might be correlated. In this paper we first test whether R and P have evolved independently. Then, we ask if the correlation occurs because (a) one trait is not the target of selection but it is genetically linked to the other trait which is the one under selection pressure (indirect selection), or (b) because different evolutionary responses to the same selective pressure are acting in parallel on populations at different genetic starting points (parallel selection). Finally, we test to what extent resprouting is associated with some vegetative and reproductive traits.To answer these questions we used a traits database for the eastern Iberian Peninsula and we assembled the phylogenetic tree on the basis of published information. The results indicate that the two traits are negatively associated and support the parallel selection scenario in which changes in R precedes changes in P. The phylogenetic–informed associations of resprouting with other traits (plant height, age at maturity) support the existence of allocation tradeoffs.The results are consistent with the biogeographical history of the Mediterranean basin flora where most of lineages already resprouted to persist after a disturbance during the Tertiary, thus making it improbable that an additional costly persistence strategy would evolve under the Quaternary climatic conditions. [ABSTRACT FROM AUTHOR]