Does GARP really fail miserably? A response to Stockman et al. (2006)

Stockman et al. (2006 ) found that ecological niche models built using DesktopGARP ‘failed miserably’ to predict trapdoor spider (genus Promyrmekiaphila) distributions in California. This apparent failure of GARP (Genetic Algorithm for Rule‐Set Production) was actually a failure of the authors’ methods, that is, attempting to build ecological niche models using single data points. In this paper, we present a re‐analysis of their original data using standard methods with the data appropriately partitioned into training/testing subsets. This re‐evaluation generated accurate distributional predictions that we contrast with theirs. We address the consequences of model‐building using single data points and the need for a foundational understanding of the principles of ecological niche modelling.     

How many buffalo does it take to change a savanna? A response to Bowman et al. (2008)

Bowman et al. (Journal of Biogeography, 2008, 35 , 1976–1988) aimed to explain observed increases in woody cover on floodplains and savannas of Kakadu National Park using estimates of buffalo (Bubalus bubalis) density as a causal variable. They found that buffalo were a minor model variable and concluded that buffalo are ‘not a major driver of floodplain and eucalypt dynamics’. However, the authors mislabelled the historical density of buffalo on their site, citing a period as high density instead of low density. Further, their results were not contextualized within the substantial body of scientific and historical evidence of the buffalo’s strong influence on vegetation in Kakadu. The authors instead postulated three unanalysed drivers of observed patterns of change: fire regime, rainfall and atmospheric CO₂. We suggest that further analyses of change in woody vegetation should make use of accurate historical records of grazers as well as available data sets on fire history.     

How to define nativeness in organisms with high dispersal capacities? A comment on Essl et al.

Essl and colleagues documented worldwide invasion patterns in bryophytes, which so far have been neglected in invasion biology. In the absence of historical evidence, Essl and colleagues used criteria such as anomalous geographical distribution, preference for disturbed habitats, and indirect associations with some means of human transport as criteria to identify aliens. Because bryophytes exhibit high long‐distance dispersal capabilities, disjunct distribution patterns are, however, the rule rather than the exception in the group. In our opinion, none of the previously proposed criteria to characterize aliens can be satisfactorily applied to groups like bryophytes, for which historical and fossil records are extremely scarce. We suggest that, in order to validate the conclusions of Essl and colleagues, further taxonomic and phylogeographical studies are needed. This is especially true for island floras, for which recent critical taxonomic work and updated checklists, which compose the primary source of information for biodiversity, are largely missing.     

Do microsatellites reflect genome‐wide genetic diversity in natural populations? A comment on Väli et al. (2008)

A recent study by Väli et al. (2008) highlights that microsatellites will often provide a poor prediction of the genome‐wide nucleotide diversity of wild populations, but does not fully explain why. To clarify and stress the importance of identity disequilibrium and marker variability for correlations between multilocus heterozygosity and genome‐wide genetic variability, we performed a simple simulation with different types of markers, corresponding to microsatellites and SNPs, in populations with different inbreeding history. The importance of identity disequilibrium was apparent for both markers and there was a clear impact of marker variability.     

Redundancy or progress? A response to Driscoll et al. (2019)

Driscoll et al. (Journal of Biogeography, 2019, 46, 2850–2859) provide a critique of ‘Countryside Biogeography’, but also include ‘Conservation Biogeography’ and ‘Agriculture Biogeography’ in their criticisms. Their main thesis is that these new sub-disciplines offer a ‘conceptual wrapper’ rather than distinctive frameworks and that the consequent redundancy of terms has the potential to sow confusion among biogeographers and slow progress. Here we argue that, far from sowing confusion Conservation Biogeography, for example, has provided important focal points for emerging scientific discourse, promoting new research, spawning undergraduate and graduate courses, and facilitating the formation of new scientific collaborations. The success or failure of a new sub-discipline depends on its utility. If new framings sow confusion, introduce redundancy and provide no new insights they will not be widely adopted and cited. The development of new sub-disciplines is a strong indicator of a vibrant, socially relevant and intellectually adventurous research area.     

Do Antarctic lichens modify microclimate and facilitate vascular plants in the maritime Antarctic? A comment to Molina‐Montenegro et al. ()

A recent article published by Molina‐Montenegro et al. (Journal of Vegetation Science24: 463) examines the association of Antarctic native plant and lichen species to the lichen Usnea antarctica on Fildes Peninsula, King George Island, maritime Antarctica. The authors report that on two sites, five out of 13 and four out of 11 species of lichens and mosses were spatially associated with U. antarctica, suggesting positive interactions between them. Although Deschampsia antarctica does not grow naturally associated with U. antarctica, Molina‐Montenegro et al. carried out a transplantation experiment to demonstrate that the macrolichen acts as a nurse plant, improving the survival of the grass. Serious conceptual and methodological discrepancies emerge from a critical evaluation of this study, challenging their conclusions. First, we suspect that the author confused some lichen taxa, and we also disagree with macrolichens being treated as cushion plants, because rootless, poikilohydric and poikilothermic thallophytes such as lichens are unable to create a stable, enclave‐like microhabitat as vascular cushion plants do. Indeed, a critical evaluation of some of the micro‐environmental parameters measured indicates that there are no biologically meaningful differences between the U. antarctica thalli and surrounding open areas. Second, the lack of consideration of the life history of the species under study leads to confusion when (a) referring to the succession sequence of species that colonize the studied area and (b) interpreting the putative distribution patterns promoted by Usnea versus the substrate preferences of associated species. Third, the authors intend to demonstrate experimentally that Usnea can facilitate the survival of D. antarctica plants, transplanting adult plants and not seedlings between the lichen thalli, and it is not clear how the grass was planted – between or within the lichens – as at both experimental sites the lichens grow on stones or rocks. Facilitative interactions are present in the Antarctic and may play a pivotal role in the structure and functioning of the fragile Antarctic ecosystems. However, more rigorous and well‐planned research is needed to assess its presence, importance and involved mechanisms.     

Does host plant richness explain diversity of ectomycorrhizal fungi? Re‐evaluation of Gao et al. (2013) data sets reveals sampling effects

The generally positive relationship between biodiversity of groups of directly or indirectly interacting organisms is one of the most important ecological concepts (Gaston, 2000 Nature, 405 , 220–227; Scherber C, Eisenhauer N, Weisser WW et al., 2010 Nature, 468 , 553–556). In a recent issue of Molecular Ecology, Gao C, Shi N‐N, Liu Y‐X et al. (2013: 22 , 3403–3414) reported that the richness of plants and ectomycorrhizal fungi is positively correlated both at local and at global scales. Here, we challenge these findings by re‐analysis of data and ascribe the reported results to sampling effect and poor data compilation.     

Reply to the letter of Soliman et al. regarding ‘Randomised comparison of a balloon-expandable and self-expandable valve with quantitative assessment of aortic regurgitation using magnetic resonance imaging’

Netherlands Heart Journal -     

Retraction: Tusk shells in trouble? Physiology and behavior in response to changing temperature in a scaphopod (Mollusca: Scaphopoda: Dentaliida). Sigwart et al. (2016)

The above article, published online on 3 June 2016 in Wiley Online Library, is retracted voluntarily by agreement among the authors, the Editor‐in‐Chief (Michael Hart), and the Editor (Amy Moran). The study focused on behavior and mass‐specific oxygen consumption rates in specimens of the northeastern Pacific scaphopod species Rhabdus rectius (Carpenter 1864) collected from a wild study population in September 2013. The authors used a method that we assumed to be reliable, based on the literature for similar scaphopod species, to distinguish males from females by gonad color (white or slightly pink ovaries; yellow testes) visible through the thin shell. After the article was published, the corresponding author notified the editors of new observations by the authors indicating that our published identifications of sex were in error. Histological sections of gonads from a small number of individuals of R. rectius, sampled from the same wild study population, revealed that, contrary to expectations, yellow individuals were female, and white individuals were male. These results contradict the identifications of sex made in the published article. Uncertainty in the sex identifications affects some quantitative analyses in the published article that were based in part on sex differences. The article has been retracted only for that reason. The other data reported in the published article (burying times; body masses; individual oxygen consumption rates) are not directly affected by the error in sex identification. The authors apologize for any confusion caused. We are grateful to the editors, Amy Moran and Michael Hart, for their helpful support in resolving this matter and correcting the scientific record. Reference Sigwart JD, Carey N, & Sumner‐Rooney LH 2016. Tusk shells in trouble? Physiology and behavior in response to changing temperature in a scaphopod (Mollusca: Scaphopoda: Dentaliida). Invertebr. Biol. 135: 191–199 doi: 10.1111/ivb.12127 .