Using point data to assess biogeographical signal, endemicity and factors associated with macrofungal diversity in the data‐poor Pacific oceanic island bioregion

Abstract

AbstractAimOceanic hotspot archipelagos are important systems for studying evolutionary and ecological processes; however, studies of macrofungi in these habitats are extremely limited. We assessed diversity across habitat types, using DNA point data to draw inferences about biogeographical signal, endemicity and potential radiation for fungi of a representative isolated island (Moorea, French Polynesia) within the poorly known South Pacific bioregion, comparing resulting patterns to those previously inferred for more comprehensively sampled plants and animals.LocationMoorea and Tahiti, French Polynesia.TaxonFungi (Basidiomycota, Ascomycota).MethodsMorphological characters and similarity assessment of rDNA‐ITS sequence data were used to measure diversity and habitat associations. A Monte Carlo simulation method was developed to detect biogeographical signal and assess its significance.ResultsA total of 553 specimens yielded 205 morphospecies; 433 sequenced specimens yielded a molecular:morphological richness ratio of 1.24:1. Approximately 58% of sequences lacked a close (≥98%) GenBank match. Community composition differed by vegetation type, with highest similarity between forest types occupying similar low‐elevation habitats. A predominant Australian/Oceanean biogeographical signal was detected.Main conclusionsMoorea fungi exhibit a strong Australian biogeographical affinity as reported for other taxa, supplemented by more recent introductions. Like Society Islands plants and animals, macrofungi may have high endemism. Morphological evidence does not indicate that intra‐island radiation has occurred, though molecular evidence suggests possible cryptic speciation. Habitat types differ in their biogeographical affinities, but habitat does not appear to be driving radiation. This study introduces a robust method for inferring biogeographical signal using sequence database comparisons, applicable to other taxa and systems for which only point data are available.