New findings of Neurospora in Europe and comparisons of diversity in temperate climates on continental scales

Abstract

The life cycles of the conidiating species of Neurospora are adapted to respond to fire, which is reflected in their natural history. Neurospora is found commonly on burned vegetation from the tropic and subtropical regions around the world and through the temperate regions of western North America. In temperate Europe it was unknown whether Neurospora would be as common as it is in North America because it has been reported only occasionally. In 2003 and 2004 a multinational effort surveyed wildfire sites in southern Europe. Neurospora was found commonly from southern Portugal and Spain (37° N) to Switzerland (46° N). Species collected included N. crassa, N. discreta, N. sitophila and N. tetrasperma. The species distribution and spatial dynamics of Neurospora populations showed both similarities and differences when compared between temperate Europe and western North America, both regions of similar latitude, climate and vegetation. For example the predominant species in western North America, N. discreta phylogenetic species 4B, is common but not predominant in Europe, whereas species rare in western North America, N. crassa NcB and N. sitophila, are much more common in Europe. The meiotic drive element Spore killer was also common in European populations of N. sitophila and at a higher proportion than anywhere else in the world. The methods by which organisms spread and adapt to new environments are fundamental ecosystem properties, yet they are little understood. The differences in regional diversity, reported here, can form the basis of testable hypotheses. Questions of phylogeography and adaptations can be addressed specifically by studying Neurospora in nature.

• ecology
• fire
• meiotic drive
• natural history
• phylogentic species
• Spore killer

D.J. conceived and coordinated the project with the assistance of J.T., M.M., T.R., A.V., and L.M.C. D.J., C.B. and S.S. collected and cultured most strains. M.D., I.M., A.U., P.C. and A.V. collected and cultured Portugal strains, identifying some. L.M.C., L.N.S. and M.O. collected in Seville and provided needed logistical help in locating other collection sites in Spain. D.J. identified or confirmed identification of all strains. J.D., R.A. and D.J. sequenced and performed phylogenetic analyses. D.J. analyzed the data and with J.T. wrote the paper. The work was supported by a grant from the US National Science Foundation to J.T. (DEB-0316710); by grants from the Deutsche Forschungsge-meinschaft and the Meyer-Struckman Stiftung to T.R.; by grants from Fundação para a Ciência e a Tecnologia to A.V.; and by grants from the Ministerio de Educación y Ciencia, Spain, (INIA RM2004-00007) and Junta de Andalucía (CVI 0119) to L.M.C. D.J. also is supported in part by US National Science Foundation grant MCB-0417282, awarded to David D. Perkins, Stanford University. We thank David Perkins for allowing part of this work to be completed in his laboratory and N.B. Raju for the photomicrographs used in Fig. 3.