Diversity and Host Specificity in the Genus Sarea Fr. (Ascomycota) · 2020. 7. 29. · genera in...
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Diversity and Host Specificity in the Genus Sarea Fr. (Ascomycota) James K. Mitchell 1,2,* , Isaac Garrido-Benavent 3 , Luis Quijada 1,4 , Jason M. Karakehian 1 , Donald H. Pfister 1,4 1 Farlow Herbarium of Cryptogamic Botany, Harvard University, 22 Divinity Avenue, Cambridge, MA 02138; 2 Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138; 3 Department of Biogeochemistry and Microbial Ecology, National Museum of Natural Sciences, Spanish National Research Council, Calle Serrano 115 bis, 28006 Madrid, Spain; 4 Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138 *Corresponding author, email address: [email protected] I. Introduction First published by Fries in 1825, the genus Sarea today comprises two accepted species of resinicolous discomycetes, Sarea difformis and Sarea resinae. Both species have a very broad geographic range, with S. difformis reported from North America, Europe, and northwestern Africa, and S. resinae reported from North America, Europe, northern and central Africa, and central and eastern Asia. Both species have also been reported in southern hemisphere locations, such as New Zealand, on non-native trees. Sarea species have a broad range of hosts in the Pinaceae, with S. difformis reported on Cedrus atlantica and both Sarea species reported on species of Pinus, Picea, Larix, Pseudotsuga, Abies and Tsuga. In addition, S. resinae has been reported on species in the Cupressaceae, including members of the genera Cupressus, Chamaecyparis, Juniperus and Taxodium. Though often described as ”rare” in older texts, the number of literature and herbarium records of these fungi, together with the general reliability of finding them when one checks their substrate, suggest that they are actually quite common, but often overlooked. Despite their unusual substrate, commonness, and breadth of geographic and host range, little molecular work has been done in this genus. The most recent taxonomic assessment of these fungi is based entirely on morphological characters, and is now 37 years old [Hawksworth & Sherwood 1981]. II. Materials and Methods Specimens were mostly collected fresh on resinous exudates of conifers in North America and Europe, with some herbarium specimens from unusual or exotic localities additionally requested and included. DNA was extracted from samples with a Qiagen DNEasy Plant Mini Kit or a Qiagen QIAamp DNA Micro Kit (Qiagen, Hilden, DE). The nuclear internal transcribed spacer (ITS) region, nuclear ribosomal large subunit (LSU) and mitochondrial ribosomal small subunit (mtSSU) regions were amplified by polymerase chain reaction (PCR) with Lucigen EconoTaq DNA Polymerase (Lucigen, Middleton, WI) or REDExtract-N-Amp PCR ReadyMix (MilliporeSigma, Burlington, MA) using primarily the primer pairs ITS1F-ITS4, LR0R-LR5, and mrSSU1-mrSSU3R. Sanger sequencing of PCR products was performed by Genewiz (South Plainfield, NJ) using the same primers. Morphological examination was performed by rehydrating dried specimens in tap water. Rehydrated apothecia were then sectioned in gum arabic on a freezing-stage microtome at 15 µm. Sections were mounted in a dilute solution of eosin in glycerol, and mounted using a modified “double cover-glass method” [Kohlmeyer & Kohlmeyer 1972]. Figure 1. Macro- and microphotographs of Sarea specimens. A-C) macro photographs of representative apothecia. D-I) microphotographs of 15 µm thick sections mounted in a dilute solution of eosin in glycerol. A,D,G) A specimen of Sarea resinae collected on Picea glauca at the Eagle Hill Institute in Maine, number JM0006. B,E,H) A specimen of a possible undescribed Sarea species, collected on Chamaecyparis lawsoniana in Klamath National Forest in northern California, number JM0068.1. C,F,I) A specimen of Sarea difformis collected on Pinus tabuliformis planted at the Arnold Arboretum in Massachusetts, number JM0011. Scale bar: A-C) 500 µm, D-F) 75 µm, G-I) 30 µm. A B C D E F G I H III. Results Molecular analyses have shown a high degree of genetic diversity in the genus Sarea. Sarea difformis was not recovered as monophyletic in the 1-marker ML analysis, but specimens of S. difformis in both analyses fall into three clades. Specimens of S. difformis sequenced were collected on hosts from three genera in the Pinaceae, but do not sort in a manner consistent with a hypothesis of host specificity at the genus level. Sarea resinae, on the other hand, exhibits less structure. Sequenced specimens fall into many clades, with 8-13 specimens as singletons. Although most clades exhibit host specificity at the family level, one well supported clade is composed of three specimens collected on resin of Picea spp., and one on resin of Cupressus forbesii. Geography exhibits an erratic influence on clade composition in both species. Clades range from composed of specimens collected in a single city (Boston, MA) to specimens collected over 9000 kilometers apart. Additionally, specimens collected in close geographic proximity are often distributed among multiple clades. For example, specimens of S. resinae from New England are distributed among five clades. Morphological examination of specimens reveals little obvious intraspecific variation that aligns with the molecular analysis. One clear exception is a specimen collected in Klamath National Forest on the resinous exudates of Chamaecyparis lawsoniana. The black color and pigment distribution resemble S. difformis, but molecular analysis suggests it is more closely related to S. resinae. The pruinose exterior, the presence of hyaline granules in the hymenium, and the absence of an amyloid reaction in the hymenium differentiate it from either Sarea species, and suggest that it may be a new species, the first in the genus in 120 years. V. Acknowledgements Funding for this project was granted by Friends of the Farlow and the New England Botanical Club. Some early sequencing was done by Danny Haelewaters as part of his Fungal Inventory of the Boston Harbor Islands National Recreation Area project, funded by the National Park Service. Specimens were also provided by Mike Haldeman and Elizabeth Kneiper. Specimens were loaned with permission for destructive sampling by the Duke Herbarium (DUKE), the Herbarium of the Botanical Museum of Lund University (LD), and the Larry F. Grand Mycological Herbarium of North Carolina State University (NCSLG). Collecting permits were provided by the National Park Service, United States Forest Service, The Nature Conservancy, the California State Parks, and Harvard University. Travel funding for the authors was provided through Royall T. Moore Travel Grants, and a Mycological Society of America International Travel Award. VI. Bibliography Hawksworth, D. L. & Sherwood M. A. (1981) A reassessment of three widespread resinicolous discomycetes. Canadian Journal of Botany 59(3): 357-372. Kohlmeyer J. & Kohlmeyer E. (1972) Permanent Microscopic Mounts. Mycologia 64(3): 666-669. Lambert, J. D. , Wu, Y. & Santiago-Blay, J. A. (2005) Taxonomic and Chemical Relationships Revealed by Nuclear Magnetic Resonance Spectra of Plant Exudates. Journal of Natural Products 68(5): 635-648. JM0006a (USA, Maine) JM0008a (USA, Maine) JM00077a (USA, California) JM00068.2a (USA, California) JM00036a (USA, Massachusetts) JM00044a (USA, Massachusetts) IGB317a (Spain, Valencia) IGB450a (Spain, Valencia) DUKE0133124a (China, Yunnan) NCSLG17391a (USA, North Carolina) BHI-F779e (USA, Massachusetts) JM0004a (USA, Massachusetts) JM0010.2a (USA, Georgia) JM0012b (USA, Massachusetts) JM0014a (USA, Massachusetts) JM00064.1a (USA, California) Hald2514a (USA, Idaho) JM00065.1a (USA, California) Hald2747a (USA, Washington) JM0009a (USA, Georgia) BHI-F871b (USA, Massachusetts) BHI-F779c (USA, Massachusetts) LD1356193a (USA, Arizona) IGB456a (Cape Verde, Santiago) JM0068.1a (USA, California) JM0068.1b (USA, California) JM0072.1a (USA, California) IGB457a (Cape Verde, Santo Antão) JM0065.2a (USA, California) JM0074.1a (USA, California) JMEKa (USA, Maine) JM0009.2a (USA, Georgia) JM0007a (USA, Maine) JM0010a (USA, Georgia) BHI-F925a (USA, Massachusetts) BHI-F926a (USA, Massachusetts) JM0011a (USA, Massachusetts) Myriospora smaragdula Myriospora scabrida Pleopsidium chlorophanum Pleopsidium flavum Trimmatothelopsis gordensis 0.03 substitutions/site Legend Picea Pinus Pseudotsuga Pinaceae Tsuga Cupressaceae Chamaecyparis Cupressus Juniperus S. resinae S. sp. nov. S. difformis Acarosporaceae A * * * LD1356193a (USA, Arizona) BHI-F779c (USA, Massachusetts) IGB456a (Cape Verde, Santiago) BHI-F871b (USA, Massachusetts) JM0010.2a (USA, Georgia) JM0014a (USA, Massachusetts) BHI-F779e (USA, Massachusetts) JM0004a (USA, Massachusetts) JM0012b (USA, Massachusetts) JM0009a (USA, Georgia) JM00064.1a (USA, California) Hald2514a (USA, Idaho) JM00065.1a (USA, California) Hald2747a (USA, Washington) NCSLG17391a (USA, North Carolina) DUKE0133124a (China, Yunnan) JM0006a (USA, Maine) JM0074.2a (USA, California) JM0008a (USA, Maine) JM00077a (USA, California) JM00036a (USA, Massachusetts) JM00044a (USA, Massachusetts) IGB317a (Spain, Valencia) JM00068.2a (USA, California) IGB450a (Spain, Valencia) JM0068.1a (USA, California) JM0068.1b (USA, California) JM0065.2a (USA, California) JM0074.1a (USA, California) JMEKa (USA, Maine) JM0009.2a (USA, Georgia) JM0007a (USA, Maine) JM0010a (USA, Georgia) JM0072.1a (USA, California) IGB457a (Cape Verde, Santo Antão) BHI-F925a (USA, Massachusetts) BHI-F926a (USA, Massachusetts) JM0011a (USA, Massachusetts) Myriospora smaragdula Myriospora scabrida Pleopsidium chlorophanum Pleopsidium flavum Trimmatothelopsis gordensis 0.02 substitutions/site Legend Picea Pinus Pseudotsuga Pinaceae Tsuga Cupressaceae Chamaecyparis Cupressus Juniperus S. resinae S. sp. nov. S. difformis Acarosporaceae B * * * Figure 2. The maximum likelihood (ML) trees estimated from A) a dataset of one ribosomal marker (ITS) and B) a concatenated dataset of two ribosomal (ITS, LSU) and one mitochondrial (mtSSU) markers representing Sarea species. Thickened branches represent Bayesian posterior probabilities ≥ 0.95 from the BEAST analysis and ML bootstrap values ≥ 70% from the PAUP analysis, and asterisks on a branch indicate that only one of these thresholds was exceeded. Colored blocks represent current species concepts. JM0068.1 is excluded from the species concept of “S. resinae” due to its pigmentation and some differences in morphology. IV. Discussion Although most clades show support for a hypothesis of different lineages exhibiting host specificity at the host family level, there is at least one exception. One possible explanation for this is that resin composition, and not genetic relatedness, is preferred by different Sarea lineages. While in most cases, these coincide [Lambert et al. 2005], it is possible that convergent evolution in resin composition has occurred between species of Picea and Cupressus forbesii that results in a similar habitat. Resin composition of different hosts can be assessed to test this hypothesis. Geography will be more difficult to separate as a factor. Many conifers have been introduced worldwide, either as ornamentals or for commercial purposes. It is clear that, in some areas, Sarea species must have been introduced. For instance, the Cape Verde Islands host no native conifers, but specimens of Sarea were collected there on pines introduced from the Canary Islands and Europe. It seems reasonable that these Sarea lineages were likewise introduced from Europe, but in both cases molecular data shows them to be most related to specimens collected in North America. Additional specimens must be collected and analyzed to clarify the origin of these different lineages. Finally, it is possible that these lineages in both S. difformis and S. resinae, with their intraspecific variation in ITS of up to 7%, may more truly represent novel species. Biometrical analysis of sequenced specimens and additional analysis of new specimens must be performed to verify whether these lineages are distinct at a specific or infraspecific level. * *
Transcript of Diversity and Host Specificity in the Genus Sarea Fr. (Ascomycota) · 2020. 7. 29. · genera in...
Diversity and Host Specificity in the Genus Sarea Fr. (Ascomycota)James K. Mitchell1,2,*, Isaac Garrido-Benavent3, Luis Quijada1,4, Jason M. Karakehian1, Donald H. Pfister1,4
1Farlow Herbarium of Cryptogamic Botany, Harvard University, 22 Divinity Avenue, Cambridge, MA 02138; 2Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138; 3Department of Biogeochemistry and Microbial Ecology, National Museum of Natural Sciences, Spanish National Research Council, Calle Serrano 115 bis, 28006 Madrid, Spain; 4Department of Organismic and Evolutionary Biology, Harvard University, 26 Oxford Street, Cambridge, MA 02138
*Corresponding author, email address: [email protected]
I. Introduction
First published by Fries in 1825, the genus Sarea today comprises two accepted species of resinicolous discomycetes, Sarea difformis and Sarea resinae. Both species have a very broad geographic range, with S. difformis reported from North America, Europe, and northwestern Africa, and S. resinaereported from North America, Europe, northern and central Africa, and central and eastern Asia. Both species have also been reported in southern hemisphere locations, such as New Zealand, on non-native trees. Sarea species have a broad range of hosts in the Pinaceae, with S. difformis reported on Cedrus atlantica and both Sarea species reported on species of Pinus, Picea, Larix, Pseudotsuga, Abies and Tsuga. In addition, S. resinae has been reported on species in the Cupressaceae, including members of the genera Cupressus, Chamaecyparis, Juniperus and Taxodium. Though often described as ”rare” in older texts, the number of literature and herbarium records of these fungi, together with the general reliability of finding them when one checks their substrate, suggest that they are actually quite common, but often overlooked. Despite their unusual substrate, commonness, and breadth of geographic and host range, little molecular work has been done in this genus. The most recent taxonomic assessment of these fungi is based entirely on morphological characters, and is now 37 years old [Hawksworth & Sherwood 1981]. II. Materials and Methods
Specimens were mostly collected fresh on resinous exudates of conifers in North America and Europe, with some herbarium specimens from unusual or exotic localities additionally requested and included. DNA was extracted from samples with a Qiagen DNEasy Plant Mini Kit or a Qiagen QIAamp DNA Micro Kit (Qiagen, Hilden, DE). The nuclear internal transcribed spacer (ITS) region, nuclear ribosomal large subunit (LSU) and mitochondrial ribosomal small subunit (mtSSU) regions were amplified by polymerase chain reaction (PCR) with Lucigen EconoTaq DNA Polymerase (Lucigen, Middleton, WI) or REDExtract-N-Amp PCR ReadyMix (MilliporeSigma, Burlington, MA) using primarily the primer pairs ITS1F-ITS4, LR0R-LR5, and mrSSU1-mrSSU3R. Sanger sequencing of PCR products was performed by Genewiz (South Plainfield, NJ) using the same primers.Morphological examination was performed by rehydrating dried specimens in tap water. Rehydrated apothecia were then sectioned in gum arabic on a freezing-stage microtome at 15 µm. Sections were mounted in a dilute solution of eosin in glycerol, and mounted using a modified “double cover-glass method” [Kohlmeyer & Kohlmeyer 1972].
Figure 1. Macro- and microphotographs of Sareaspecimens. A-C) macro photographs of representative apothecia. D-I) microphotographs of 15 µm thick sections mounted in a dilute solution of eosin in glycerol.A,D,G) A specimen of Sarea resinae collected on Picea glauca at the Eagle Hill Institute in Maine, number JM0006. B,E,H) A specimen of a possible undescribed Sarea species, collected on Chamaecyparis lawsoniana in Klamath National Forest in northern California, number JM0068.1. C,F,I) A specimen of Sarea difformis collected on Pinus tabuliformis planted at the Arnold Arboretum in Massachusetts, number JM0011. Scale bar: A-C) 500 µm, D-F) 75 µm, G-I) 30 µm.
A B C
D E F
G IH
III. Results
Molecular analyses have shown a high degree of genetic diversity in the genus Sarea. Sarea difformis was not recovered as monophyletic in the 1-marker ML analysis, but specimens of S. difformis in both analyses fall into three clades. Specimens of S. difformis sequenced were collected on hosts from three genera in the Pinaceae, but do not sort in a manner consistent with a hypothesis of host specificity at the genus level. Sarea resinae, on the other hand, exhibits less structure. Sequenced specimens fall into many clades, with 8-13 specimens as singletons. Although most clades exhibit host specificity at the family level, one well supported clade is composed of three specimens collected on resin of Picea spp., and one on resin of Cupressus forbesii. Geography exhibits an erratic influence on clade composition in both species. Clades range from composed of specimens collected in a single city (Boston, MA) to specimens collected over 9000 kilometers apart. Additionally, specimens collected in close geographic proximity are often distributed among multiple clades. For example, specimens of S. resinae from New England are distributed among five clades.Morphological examination of specimens reveals little obvious intraspecific variation that aligns with the molecular analysis. One clear exception is a specimen collected in Klamath National Forest on the resinous exudates of Chamaecyparis lawsoniana. The black color and pigment distribution resemble S. difformis, but molecular analysis suggests it is more closely related to S. resinae. The pruinose exterior, the presence of hyaline granules in the hymenium, and the absence of an amyloid reaction in the hymenium differentiate it from either Sarea species, and suggest that it may be a new species, the first in the genus in 120 years.
V. Acknowledgements
Funding for this project was granted by Friends of the Farlow and the New England Botanical Club. Some early sequencing was done by Danny Haelewaters as part of his Fungal Inventory of the Boston Harbor Islands National Recreation Area project, funded by the National Park Service. Specimens were also provided by Mike Haldeman and Elizabeth Kneiper. Specimens were loaned with permission for destructive sampling by the Duke Herbarium (DUKE), the Herbarium of the Botanical Museum of Lund University (LD), and the Larry F. Grand Mycological Herbarium of North Carolina State University (NCSLG). Collecting permits were provided by the National Park Service, United States Forest Service, The Nature Conservancy, the California State Parks, and Harvard University. Travel funding for the authors was provided through Royall T. Moore Travel Grants, and a Mycological Society of America International Travel Award.
VI. Bibliography
Hawksworth, D. L. & Sherwood M. A. (1981) A reassessment of three widespread resinicolous discomycetes. Canadian Journal of Botany 59(3): 357-372. Kohlmeyer J. & Kohlmeyer E. (1972) Permanent Microscopic Mounts. Mycologia 64(3): 666-669.Lambert, J. D. , Wu, Y. & Santiago-Blay, J. A. (2005) Taxonomic and Chemical Relationships Revealed by Nuclear Magnetic Resonance Spectra of Plant Exudates. Journal of Natural Products 68(5): 635-648.
0.03
BHI-F779e_S._resinae_Pin._cf._nigra_MA
Trimmatothelopsis_gordensis
JM0004a_S._resinae_Pin._sp._MA
BHI-F871b_S._resinae_Pin._strobus_MA
JM0068.1b_S._sp._nov._Ch._lawsoniana_CA
IGB317a_S._resinae_Cu._arizonica_ES
JM0009a_S._resinae_Pin._sp._GA
JM0072.1a_S._difformis_T._heterophylla_CA
JM0009.2_S._difformis_Pin._sp._GA
JM0011a_S._difformis_Pin._tabuliformis_MA
Hald2747a_resinae_Ps._menziesii_WA
LD1356193a_S._resinae_Pin._aristata_AZ
Myriospora_scabrida
DUKE0133124a_S._resinae_Pin._sp._CN
JM0010a_S._difformis_Pin._taeda_GA
Pleopsidium_chlorophanum
JM0064.1a_S._resinae_Ps._menziesii_CA
Hald2514a_resinae_Ps._menziesii_ID
IGB456a_S._resinae_Pin._canariensis_CV
JM0008a_S._resinae_Pic._glauca_ME
JM0036a_S._resinae_Ch._obtusa_MA
JM0012b_S._resinae_Pin._sylvestris_MA
JM0077a_S._resinae_Cu._forbesii_CA
JM0074.1a_S._difformis_Pic._sitchensis_CA
IGB457a_S._difformis_Pin._cf._nigra_CV
BHI-F779c_S._resinae_Pin._cf._nigra_MA
JMEKa_S._difformis_Pic._rubens_ME
NCSLG17391a_resinae_J._scopulorum_NC
BHI-F925a_S._difformis_Pin._nigra_MA
JM0068.1a_S._sp._nov._Ch._lawsoniana_CA
JM0044a_S._resinae_Ch._thyoides_MA
Myriospora_smaragdula
Pleopsidium_flavum
JM0014a_S._resinae_Pin._strobus_MA
JM0006a_S._resinae_Pic._glauca_ME
JM0065.2a_S._difformis_Pin._lambertiana_CA
IGB450a_S._resinae_Cu._sempervirens_ES
JM0068.2a_S._resinae_Ch._lawsoniana_CA
JM0010.2a_S._resinae_Pin._taeda_GA
BHI-F926a_S._difformis_Pin._nigra_MA
JM0007a_S._difformis_Pic._glauca_ME
JM0065.1a_S._resinae_Pin._lambertiana_CA
JM0006a (USA, Maine)JM0008a (USA, Maine)
JM00077a (USA, California)JM00068.2a (USA, California)
JM00036a (USA, Massachusetts)JM00044a (USA, Massachusetts)
IGB317a (Spain, Valencia)IGB450a (Spain, Valencia)
DUKE0133124a (China, Yunnan)NCSLG17391a (USA, North Carolina)
BHI-F779e (USA, Massachusetts)JM0004a (USA, Massachusetts)JM0010.2a (USA, Georgia)JM0012b (USA, Massachusetts)JM0014a (USA, Massachusetts)JM00064.1a (USA, California)Hald2514a (USA, Idaho)
JM00065.1a (USA, California)Hald2747a (USA, Washington)
JM0009a (USA, Georgia)BHI-F871b (USA, Massachusetts)
BHI-F779c (USA, Massachusetts)LD1356193a (USA, Arizona)
IGB456a (Cape Verde, Santiago)JM0068.1a (USA, California)
JM0068.1b (USA, California)JM0072.1a (USA, California)
IGB457a (Cape Verde, Santo Antão)
JM0065.2a (USA, California)JM0074.1a (USA, California)
JMEKa (USA, Maine)JM0009.2a (USA, Georgia)
JM0007a (USA, Maine)
JM0010a (USA, Georgia)BHI-F925a (USA, Massachusetts)BHI-F926a (USA, Massachusetts)JM0011a (USA, Massachusetts)
Myriospora smaragdulaMyriospora scabrida
Pleopsidium chlorophanumPleopsidium flavum
Trimmatothelopsis gordensis
0.03 substitutions/site
Legend
PiceaPinusPseudotsuga
Pinaceae
TsugaCupressaceae
ChamaecyparisCupressusJuniperus
S. resinae
S. sp. nov.
S. difformis
Acarosporaceae
A
*
*
*
0.02
BHI-F871b_S._resinae_Pin._strobus_MA
JM0068.1a_S._sp._nov._Ch._lawsoniana_CA
IGB450a_S._resinae_Cu._sempervirens_ES
JM0014a_S._resinae_Pin._strobus_MA
Hald2747a_resinae_Ps._menziesii_WA
JM0010a_S._difformis_Pin._taeda_GA
BHI-F925a_S._difformis_Pin._nigra_MA
JM0065.2a_S._difformis_Pin._lambertiana_CA
JM0068.2a_S._resinae_Ch._lawsoniana_CA
DUKE0133124a_S._resinae_Pin._sp._CN
JM0009a_S._resinae_Pin._sp._GA
JM0074.1a_S._difformis_Pic._sitchensis_CA
BHI-F926a_S._difformis_Pin._nigra_MA
BHI-F779c_S._resinae_Pin._cf._nigra_MA
BHI-F779e_S._resinae_Pin._cf._nigra_MA
Pleopsidium_chlorophanum
Trimmatothelopsis_gordensis
Myriospora_smaragdula
JM0074.2a_S._resinae_Pic._sitchensis_CA
JM0072.1a_S._difformis_T._heterophylla_CA
JM0007a_S._difformis_Pic._glauca_ME
JM0064.1a_S._resinae_Ps._menziesii_CA
JM0044a_S._resinae_Ch._thyoides_MA
JM0011a_S._difformis_Pin._tabuliformis_MA
JM0036a_S._resinae_Ch._obtusa_MA
JM0065.1a_S._resinae_Pin._lambertiana_CA
IGB456a_S._resinae_Pin._canariensis_CV
LD1356193a_S._resinae_Pin._aristata_AZ
IGB317a_S._resinae_Cu._arizonica_ES
JM0008a_S._resinae_Pic._glauca_ME
JM0009.2_S._difformis_Pin._sp._GA
NCSLG17391a_resinae_J._scopulorum_NC
Myriospora_scabrida
JM0004a_S._resinae_Pin._sp._MA
JM0006a_S._resinae_Pic._glauca_ME
Hald2514a_resinae_Ps._menziesii_ID
JM0010.2a_S._resinae_Pin._taeda_GA
JM0012b_S._resinae_Pin._sylvestris_MA
IGB457a_S._difformis_Pin._cf._nigra_CV
JM0068.1b_S._sp._nov._Ch._lawsoniana_CA
JMEKa_S._difformis_Pic._rubens_ME
Pleopsidium_flavum
JM0077a_S._resinae_Cu._forbesii_CA
LD1356193a (USA, Arizona)
BHI-F779c (USA, Massachusetts)IGB456a (Cape Verde, Santiago)
BHI-F871b (USA, Massachusetts)JM0010.2a (USA, Georgia)
JM0014a (USA, Massachusetts)BHI-F779e (USA, Massachusetts)JM0004a (USA, Massachusetts)JM0012b (USA, Massachusetts)
JM0009a (USA, Georgia)JM00064.1a (USA, California)
Hald2514a (USA, Idaho)JM00065.1a (USA, California)Hald2747a (USA, Washington)
NCSLG17391a (USA, North Carolina)DUKE0133124a (China, Yunnan)
JM0006a (USA, Maine)JM0074.2a (USA, California)
JM0008a (USA, Maine)JM00077a (USA, California)
JM00036a (USA, Massachusetts)JM00044a (USA, Massachusetts)IGB317a (Spain, Valencia)
JM00068.2a (USA, California)IGB450a (Spain, Valencia)
JM0068.1a (USA, California)JM0068.1b (USA, California)
JM0065.2a (USA, California)JM0074.1a (USA, California)
JMEKa (USA, Maine)
JM0009.2a (USA, Georgia)
JM0007a (USA, Maine)JM0010a (USA, Georgia)
JM0072.1a (USA, California)IGB457a (Cape Verde, Santo Antão)
BHI-F925a (USA, Massachusetts)BHI-F926a (USA, Massachusetts)JM0011a (USA, Massachusetts)
Myriospora smaragdulaMyriospora scabrida
Pleopsidium chlorophanumPleopsidium flavum
Trimmatothelopsis gordensis
0.02 substitutions/site
Legend
PiceaPinusPseudotsuga
Pinaceae
TsugaCupressaceae
ChamaecyparisCupressusJuniperus
S. resinae
S. sp. nov.
S. difformis
Acarosporaceae
B
*
*
*
Figure 2. The maximum likelihood (ML) trees estimated from A) a dataset of one ribosomal marker (ITS) and B) a concatenated dataset of two ribosomal (ITS, LSU) and one mitochondrial (mtSSU) markers representing Sarea species. Thickened branches represent Bayesian posterior probabilities ≥ 0.95 from the BEAST analysis and ML bootstrap values ≥ 70% from the PAUP analysis, and asterisks on a branch indicate that only one of these thresholds was exceeded. Colored blocks represent current species concepts. JM0068.1 is excluded from the species concept of “S. resinae” due to its pigmentation and some differences in morphology.
IV. Discussion
Although most clades show support for a hypothesis of different lineages exhibiting host specificity at the host family level, there is at least one exception. One possible explanation for this is that resin composition, and not genetic relatedness, is preferred by different Sarea lineages. While in most cases, these coincide [Lambert et al. 2005], it is possible that convergent evolution in resin composition has occurred between species of Picea and Cupressus forbesii that results in a similar habitat. Resin composition of different hosts can be assessed to test this hypothesis.Geography will be more difficult to separate as a factor. Many conifers have been introduced worldwide, either as ornamentals or for commercial purposes. It is clear that, in some areas, Sarea species must have been introduced. For instance, the Cape Verde Islands host no native conifers, but specimens of Sarea were collected there on pines introduced from the Canary Islands and Europe. It seems reasonable that these Sarea lineages were likewise introduced from Europe, but in both cases molecular data shows them to be most related to specimens collected in North America. Additional specimens must be collected and analyzed to clarify the origin of these different lineages.Finally, it is possible that these lineages in both S. difformis and S. resinae, with their intraspecific variation in ITS of up to 7%, may more truly represent novel species. Biometrical analysis of sequenced specimens and additional analysis of new specimens must be performed to verify whether these lineages are distinct at a specific or infraspecific level.
*
*
