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Using environmental niche models to test the 'everything is everywhere' hypothesis for Badhamia
María Aguilar1, Anna-Maria Fiore-Donno2, Carlos Lado3
11] Mycology Department, Real Jardín Botánico, CSIC, Madrid, Spain [2] Department of Cell Biology, Medical Sciences, University of Alberta, Edmonton, AB, Canada.
The ISME Journal
|October 18, 2013
Summary
The "everything is everywhere" hypothesis is challenged for the protist Badhamia melanospora. Ecological niche models reveal distinct North and South American groups, suggesting limited dispersal and cryptic speciation.
Area of Science:
- Protist biogeography
- Molecular ecology
- Evolutionary biology
Background:
- The distribution of free-living protists is debated between the 'everything is everywhere' (EiE) hypothesis and 'moderate endemicity'.
- The EiE hypothesis suggests ecology solely drives protist distribution, while moderate endemicity posits geographic barriers limit dispersal.
- Testing these hypotheses requires identifying geographically restricted organisms and assessing their presence in ecologically similar areas.
Purpose of the Study:
- To formally test the biogeography of the myxomycete Badhamia melanospora against the EiE hypothesis.
- To utilize environmental niche modeling to generate and test null EiE distributions for B. melanospora ribotypes.
- To investigate the potential for cryptic speciation within the B. melanospora taxon.
Main Methods:
- Analysis of 18S rDNA variants (ribotypes) from 125 specimens of Badhamia melanospora across 91 localities.
- Construction and comparison of environmental climatic niche models for distinct ribotype groups.
- Field surveys in South America to assess the presence of B. melanospora groups in overlapping niche areas.
Main Results:
- Two geographically structured groups of B. melanospora ribotypes were identified, correlating with slight spore morphological differences.
- Environmental niche models showed significant differences between the North and South American groups, with some overlapping areas.
- Despite niche overlap in South America, only the South American ribotype group was found in an intensively surveyed area.
Conclusions:
- The 'everything is everywhere' hypothesis is not supported for Badhamia melanospora; distribution is not solely driven by ecology.
- B. melanospora represents a cryptic species complex, likely with allopatric divergence in North and South America.
- Geographic factors and limited dispersal play a significant role in the biogeography of this protist taxon.
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