B Bertolasi1, C Leonarduzzi1, A Piotti2, S Leonardi1, L Zago1, L Gui1, F Gorian1, I Vanetti1, G Binelli1. 1. Centro Nazionale per lo Studio e la Conservazione della Biodiversità Forestale, Corpo Forestale dello Stato, Via del Ponte 256, 37059 Peri (VR), Italy, Dipartimento di Bioscienze, Università di Parma, Viale Usberti 11/A, Parma, Italy, Institute of Biosciences and BioResources, National Research Council, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy and Department of Theoretical and Applied Sciences, University of Insubria, Via J.H. Dunant 3, 21100 Varese (VA), Italy. 2. Centro Nazionale per lo Studio e la Conservazione della Biodiversità Forestale, Corpo Forestale dello Stato, Via del Ponte 256, 37059 Peri (VR), Italy, Dipartimento di Bioscienze, Università di Parma, Viale Usberti 11/A, Parma, Italy, Institute of Biosciences and BioResources, National Research Council, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy and Department of Theoretical and Applied Sciences, University of Insubria, Via J.H. Dunant 3, 21100 Varese (VA), Italy Centro Nazionale per lo Studio e la Conservazione della Biodiversità Forestale, Corpo Forestale dello Stato, Via del Ponte 256, 37059 Peri (VR), Italy, Dipartimento di Bioscienze, Università di Parma, Viale Usberti 11/A, Parma, Italy, Institute of Biosciences and BioResources, National Research Council, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy and Department of Theoretical and Applied Sciences, University of Insubria, Via J.H. Dunant 3, 21100 Varese (VA), Italy andrea.piotti@gmail.com.
Abstract
BACKGROUND AND AIMS: Ulmus minor has been severely affected by Dutch elm disease (DED). The introduction into Europe of the exotic Ulmus pumila, highly tolerant to DED, has resulted in it widely replacing native U. minor populations. Morphological and genetic evidence of hybridization has been reported, and thus there is a need for assessment of interspecific gene flow patterns in natural populations. This work therefore aimed at studying pollen gene flow in a remnant U. minor stand surrounded by trees of both species scattered across an agricultural landscape. METHODS: All trees from a small natural stand (350 in number) and the surrounding agricultural area within a 5-km radius (89) were genotyped at six microsatellite loci. Trees were morphologically characterized as U. minor, U. pumila or intermediate phenotypes, and morphological identification was compared with Bayesian clustering of genotypes. For paternity analysis, seeds were collected in two consecutive years from 20 and 28 mother trees. Maximum likelihood paternity assignment was used to elucidate intra- and interspecific gene flow patterns. KEY RESULTS: Genetic structure analyses indicated the presence of two genetic clusters only partially matching the morphological identification. The paternity analysis results were consistent between the two consecutive years of sampling and showed high pollen immigration rates (∼0·80) and mean pollination distances (∼3 km), and a skewed distribution of reproductive success. Few intercluster pollinations and putative hybrid individuals were found. CONCLUSIONS: Pollen gene flow is not impeded in the fragmented agricultural landscape investigated. High pollen immigration and extensive pollen dispersal distances are probably counteracting the potential loss of genetic variation caused by isolation. Some evidence was also found that U. minor and U. pumila can hybridize when in sympatry. Although hybridization might have beneficial effects on both species, remnant U. minor populations represent a valuable source of genetic diversity that needs to be preserved.
BACKGROUND AND AIMS: Ulmus minor has been severely affected by Dutch elm disease (DED). The introduction into Europe of the exotic Ulmus pumila, highly tolerant to DED, has resulted in it widely replacing native U. minor populations. Morphological and genetic evidence of hybridization has been reported, and thus there is a need for assessment of interspecific gene flow patterns in natural populations. This work therefore aimed at studying pollen gene flow in a remnant U. minor stand surrounded by trees of both species scattered across an agricultural landscape. METHODS: All trees from a small natural stand (350 in number) and the surrounding agricultural area within a 5-km radius (89) were genotyped at six microsatellite loci. Trees were morphologically characterized as U. minor, U. pumila or intermediate phenotypes, and morphological identification was compared with Bayesian clustering of genotypes. For paternity analysis, seeds were collected in two consecutive years from 20 and 28 mother trees. Maximum likelihood paternity assignment was used to elucidate intra- and interspecific gene flow patterns. KEY RESULTS: Genetic structure analyses indicated the presence of two genetic clusters only partially matching the morphological identification. The paternity analysis results were consistent between the two consecutive years of sampling and showed high pollen immigration rates (∼0·80) and mean pollination distances (∼3 km), and a skewed distribution of reproductive success. Few intercluster pollinations and putative hybrid individuals were found. CONCLUSIONS: Pollen gene flow is not impeded in the fragmented agricultural landscape investigated. High pollen immigration and extensive pollen dispersal distances are probably counteracting the potential loss of genetic variation caused by isolation. Some evidence was also found that U. minor and U. pumila can hybridize when in sympatry. Although hybridization might have beneficial effects on both species, remnant U. minor populations represent a valuable source of genetic diversity that needs to be preserved.
Authors: Sean M Hoban; Tim S McCleary; Scott E Schlarbaum; Sandra L Anagnostakis; Jeanne Romero-Severson Journal: Evol Appl Date: 2012-11 Impact factor: 5.183
Authors: Andrea Piotti; Stefano Leonardi; Myriam Heuertz; Joukje Buiteveld; Thomas Geburek; Sophie Gerber; Koen Kramer; Cristina Vettori; Giovanni Giuseppe Vendramin Journal: PLoS One Date: 2013-09-05 Impact factor: 3.240