Using environmental niche models to test the ‘everything is everywhere’ hypothesis for Badhamia

Abstract

It is often discussed whether the biogeography of free-living protists is better explained by the 'everything is everywhere'(EiE) hypothesis, which postulates that only ecology drives their distribution, or by the alternative hypothesis of 'moderate endemicity' in which geographic barriers can limit their dispersal. To formally test this, it would be necessary not only to find organisms restricted to a geographical area but also to check for their presence in any other place with a similar ecology. We propose the use of environmental niche models to generate and test null EiE distributions. Here we have analysed the distribution of 18S rDNA variants (ribotypes) of the myxomycete Badhamia melanospora (belonging to the protozoan phylum Amoebozoa) using 125 specimens from 91 localities. Two geographically structured groups of ribotypes congruent with slight morphological differences in the spores can be distinguished. One group comprises all populations from Argentina and Chile, and the other is formed by populations from North America together with human-introduced populations from other parts of the world. Environmental climatic niche models constructed separately for the two groups have significant differences, but show several overlapping areas. However, only specimens from one group were found in an intensively surveyed area in South America where both niche models overlap. It can be concluded that everything is not everywhere for B. melanospora. This taxon constitutes a complex formed by at least two cryptic species that probably diverged allopatrically in North and South America.

Biogeographical assessment of myxomycete assemblages from Neotropical and Asian Palaeotropical forests

“…Indeed, 18S rRNA gene sequences of the commonly highland fruiting nivicolous genus Meriderma were already detected in lowland regions, indicating persistence (presumably of amoebae) where this taxon never fruits (Fiore‐Donno et al ., ). Furthermore, another explanation is to assume the existence of barriers to distribution, at least between continents (Estrada‐Torres et al ., ; Aguilar et al ., ). Long‐distance dispersal has been reported for myxomycetes (Kamono et al ., ), and the patchy occurrence of nivicolous myxomycetes in mountain ranges of the Northern and Southern Hemispheres corroborates this (Ronikier & Lado, ).…”

Land scale biogeography of arsenic biotransformation genes in estuarine wetland

“…The underlying mechanisms of these microbial biogeographic patterns can be classified into two types: deterministic (also termed niche-based) processes, and stochastic or neutral processes (Martiny et al, 2006). The deterministic processes imposed by environmental filters select certain species according to their environmental preferences (Aguilar et al, 2014;Hambright et al, 2015), while stochastic processes are driven by ecological drift and dispersal limitation (Martiny et al, 2011;Zhou et al, 2014). Notably, most of the current biogeographic microbial studies are focussed on 16S rRNA genes, despite a resurging interest in understanding the microbial biogeographic patterns of functional genes (Green et al, 2008), which serve as the basis of the biotransformation of various elements on the earth and contribute to the elemental cycle.…”

Genetic barcoding of dark‐spored myxomycetes (Amoebozoa)—Identification, evaluation and application of a sequence similarity threshold for species differentiation in NGS studies

“…However, no clearly attributable morphological differences were found in three putative species within Trichia varia defined by three independent genetic markers (SSU, EF1A and COI) and group I intron distribution within the first marker (Feng & Schnittler, ). Lastly, Aguilar, Fiore‐Donno, Lado, and Cavalier‐Smith () found a minimum of two highly distinct genetic subclades (and suggested up to six clades) in a case study of B. melanospora . In this case, as well as for H. serpula , habitat preferences of different subclades were indicated by the implementation of an environmental niche model in the analyses, which also suggested limited dispersal for the respective taxa at a transcontinental scale.…”