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- Title
Do hybrid-origin polyploid amphibians occupy transgressive or intermediate ecological niches compared to their diploid ancestors?
- Authors
Ficetola, G. Francesco; Stöck, Matthias
- Abstract
Aim Speciation can either proceed as gradual divergence, mostly in allopatry or parapatry, or by duplication of chromosome sets: polyploidization. Hybrid-origin or allopolyploidization is an important mechanism of hybrid speciation with strong, although often incomplete, postzygotic reproductive barriers between the polyploid hybrid and its diploid parents. Allopolyploids often present novel phenotypes that exceed the ranges of their ancestral lineages, leading to the hypothesis that niche shifts could be supportive of hybrid speciation. Although polyploidy is phylogenetically widespread in animals, ecological niches of diploid ancestral and derived allopolyploids have been rarely comparatively examined. Here, we do so for five species of Palaearctic green toads ( Bufo viridis subgroup), involving three ploidy levels. Location Central Asia, High Asia. Methods We gathered distributional records of genotyped toads, covering the whole range of the five toad species. We then used similarity and equivalency tests and examined whether bioclimatic (Grinellian) niches of allopolyploids are intermediate to those of the extant diploid relatives of their ancestral forms or whether they are transgressive (beyond those of both ancestors). Results We found evidence for both transgressive and conservative niches in allopolyploids. Allotetraploids ( Bufo pewzowi, B. oblongus) showed transgressive niche evolution; they inhabited environments that were harsher (more arid and with colder winters) than both of their parental species. In contrast, the allotriploid B. baturae exhibited a conserved niche, similar to an ancestral lineage that provided two-thirds of its hybrid genome. For most comparisons, niches of extant diploid ancestral lineages were significantly different from each other. Main conclusion We conclude that allopolyploidization in amphibians leads potentially but not a necessarily to transgressive niche evolution, and may facilitate hybrid speciation by allowing newly formed hybrids to colonize novel habitats and thus escape their parental lineages.
- Subjects
POLYPLOIDY; NATTERJACK toad; DIPLOIDY; GENETIC speciation; ECOLOGICAL niche; VICARIANCE; PHENOTYPES
- Publication
Journal of Biogeography, 2016, Vol 43, Issue 4, p703
- ISSN
0305-0270
- Publication type
Article
- DOI
10.1111/jbi.12667