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Is climate change altering the geographic distribution of truffles?

November 2012
Frontiers in Ecology and the Environment 10(9):461

DOI:10.2307/41811851

Authors:

Richard Splivallo

Goethe-Universität Frankfurt am Main

Rengenier C. Rittersma

Johannes Gutenberg-Universität Mainz

Gerard. Chevalier

French National Centre for Scientific Research

Show all 7 authorsHide

Peer-reviewed letter Truffles (Tuber spp) – the aromatic fruiting bodies of fungi that grow underground and symbiotically colo-nize the roots of hazels, oaks, and other trees or shrubs – are a luxury food item, with prices often compa-rable to those of caviar. The exorbi-tant prices of truffles reflect a decreasing worldwide production (Hall et al. 2003) and an increasing international demand. By mostly relying on a rare occurrence of the Burgundy truffle (Tuber uncinatum syn T aestivum; Paolocci et al. 2004; Wedén et al. 2005) (Figure 1a) in southwest Germany, Büntgen et al. (Front Ecol Environ 2011; 9[3]: 150–151) speculated that climate change has expanded the species' geographic distribution. Here, on the basis of historical data and an updated distribution map of the Burgundy truffle, we offer an alternative view to Büntgen et al.'s hypothesis. Historical evidence suggests that truffles were present throughout Europe well before late 19th-century climate change. Since the 17th cen-tury, truffles have been harvested in regions of the UK, Slovakia, Poland, Austria, and Germany (Robinson 1691–1693; Brückmann 1730; Rittersma 2010, a and b). The sudden interest in truffles outside of tradi-tional truffle-consuming countries like France and Italy resulted from the emergence of the court society, which reached its zenith between 1648 and 1789 (Rittersma 2010b). During the 19th century, Germany emerged as a truffle-consuming nation that contributed to the myco-logical, culinary, and commercial spectrum of the European truffle tra-dition of that time (Figure 1b; Rittersma 2010a). This clearly demonstrates that truffles' perception and appreciation in Germany and elsewhere in Northern Europe has been strongly determined by culture. The natural habitat of the Burgundy truffle covers Europe (WebFigure 1a, based on data from Chevalier and Frochot [1997] and Splivallo et al. [2012]). Büntgen et al.'s distribution map, which limited the occurrence of the Burgundy truffle to a few European sites, is incomplete, perhaps because the authors attempted to distinguish summer Burgundy truffles from winter Burgundy truffles. If so, this distinction has no taxonomical relevance because winter and summer Burgundy truffles are a single species (Paolocci et al. 2004; Wedén et al. 2005) and have similar aromas (Splivallo et al. 2012). The Burgundy truffle's European-wide distribution indicates that the species can adapt to a broad temperature range. In beetles, upper thermal toler-ance has been positively linked to the extent of geographic ranges (Calosi et al. 2010); similarly, the high toler-ance of the Burgundy truffle to both high and low temperatures suggests that, contrary to the hypothesis of Büntgen et al., climate change might have a minimal effect on its geo-graphic distribution. In wines, a few growing regions (eg Bordeaux) traditionally dominated the market until the emergence of global competition in the 20th cen-tury. A similar trend is currently hap-pening with truffles, the market for which has been overshadowed in recent decades by the two most expensive species: the Piedmont (T magnatum, ~ €5000 kg –1) and the Périgord (T melanosporum, ~ €2500 kg –1) truffle. Being three to ten times cheaper and more widely distributed than the latter two species, the Burgundy truffle offers an attractive and readily available substitute. The increase in Burgundy truffle demand throughout Europe can be attributed in part to the recent creation of numerous truffle grower/hunter asso-ciations (eg The German Truffle Association [www.ahrtrueffel.com], The Swiss Burgundy Truffle Associa-tion [www.uncinatum.ch/web], The Hungarian Truffle Growers Associa-tion [www.szarvasgombaegyesulet.hu]). These associations contribute to rais-ing public awareness of the Burgundy truffle by conducting educational efforts, organizing events (eg truffle tastings), and supporting the estab-lishment of truffle orchards. Truffles might have colonized Europe about 10 000 years ago, after the last glacial period, as documented for the Périgord truffle (Murat et al. 2004). This hypothesis has not yet been tested for the Burgundy truffle. Geographic and genetic distance were not correlated when considering all eight populations in our study (Web-Figure 1); however, a significant cor-relation was observed when consider-ing only the five populations on the gradient from the South of France toward the UK. This indicates that the overall European distribution of the Burgundy truffle does not result from isolation caused by distance (ie not attributable to range expansion); however, species range expansion might have happened northward from southern France toward the UK.

Characteristic morphology of the Burgundy truffle, Tuber uncinatum. The inside tissue (or gleba, left) bears mature spores and is light brown with characteristic white veins, whereas the outer layer (or peridium, right) is melanized and black. (b) 19th-century illustration of women carrying baskets filled with truffles in Baden, in southwestern Germany (from Dumaine J-M. 2010. Trüffeln, die heimischen Exoten).

…

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Content uploaded by Rengenier C. Rittersma

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461

Is climate change altering

the geographic distribution

of truffles?

Peer-reviewed letter

Truffles (Tuber spp) – the aromatic

fruiting bodies of fungi that grow

underground and symbiotically colo-

nize the roots of hazels, oaks, and

other trees or shrubs – are a luxury

food item, with prices often compa-

rable to those of caviar. The exorbi-

tant prices of truffles reflect a

decreasing worldwide production

(Hall et al. 2003) and an increasing

international demand. By mostly

relying on a rare occurrence of the

Burgundy truffle (Tuber uncinatum

syn T aestivum; Paolocci et al. 2004;

Wedén et al. 2005) (Figure 1a) in

southwest Germany, Büntgen et al.

(Front Ecol Environ 2011; 9[3]:

150–151) speculated that climate

change has expanded the species’

geographic distribution. Here, on the

basis of historical data and an updated

distribution map of the Burgundy

truffle, we offer an alternative view to

Büntgen et al.’s hypothesis.

Historical evidence suggests that

truffles were present throughout

Europe well before late 19th-century

climate change. Since the 17th cen-

tury, truffles have been harvested in

regions of the UK, Slovakia, Poland,

Austria, and Germany (Robinson

1691–1693; Brückmann 1730;

Rittersma 2010, a and b). The sudden

interest in truffles outside of tradi-

tional truffle-consuming countries

like France and Italy resulted from

the emergence of the court society,

which reached its zenith between

1648 and 1789 (Rittersma 2010b).

During the 19th century, Germany

emerged as a truffle-consuming

nation that contributed to the myco-

logical, culinary, and commercial

spectrum of the European truffle tra-

dition of that time (Figure 1b;

Rittersma 2010a). This clearly

demonstrates that truffles’ perception

and appreciation in Germany and

elsewhere in Northern Europe has

been strongly determined by culture.

The natural habitat of the Burgundy

truffle covers Europe (WebFigure 1a,

based on data from Chevalier and

Frochot [1997] and Splivallo et al.

[2012]). Büntgen et al.’s distribution

map, which limited the occurrence of

the Burgundy truffle to a few European

sites, is incomplete, perhaps because

the authors attempted to distinguish

summer Burgundy truffles from winter

Burgundy truffles. If so, this distinction

has no taxonomical relevance because

winter and summer Burgundy truffles

are a single species (Paolocci et al.

2004; Wedén et al. 2005) and have

similar aromas (Splivallo et al. 2012).

The Burgundy truffle’s European-wide

distribution indicates that the species

can adapt to a broad temperature

range. In beetles, upper thermal toler-

ance has been positively linked to the

extent of geographic ranges (Calosi

et al. 2010); similarly, the high toler-

ance of the Burgundy truffle to both

high and low temperatures suggests

that, contrary to the hypothesis of

Büntgen et al., climate change might

have a minimal effect on its geo-

graphic distribution.

In wines, a few growing regions (eg

Bordeaux) traditionally dominated

the market until the emergence of

global competition in the 20th cen-

tury. A similar trend is currently hap-

pening with truffles, the market for

which has been overshadowed in

recent decades by the two most

expensive species: the Piedmont (T

magnatum, ~ €5000 kg–1) and the

Périgord (T melanosporum, ~ €2500

kg–1) truffle. Being three to ten times

cheaper and more widely distributed

than the latter two species, the

Burgundy truffle offers an attractive

and readily available substitute. The

increase in Burgundy truffle demand

throughout Europe can be attributed

in part to the recent creation of

numerous truffle grower/hunter asso-

ciations (eg The German Truffle

Association [www.ahrtrueffel.com],

The Swiss Burgundy Truffle Associa-

tion [www.uncinatum.ch/web], The

Hungarian Truffle Growers Associa-

tion [www.szarvasgombaegyesulet.hu]).

These associations contribute to rais-

ing public awareness of the Burgundy

truffle by conducting educational

efforts, organizing events (eg truffle

tastings), and supporting the estab-

lishment of truffle orchards.

Truffles might have colonized

Europe about 10 000 years ago, after

the last glacial period, as documented

for the Périgord truffle (Murat et al.

2004). This hypothesis has not yet

been tested for the Burgundy truffle.

Geographic and genetic distance were

not correlated when considering all

eight populations in our study (Web-

Figure 1); however, a significant cor-

relation was observed when consider-

ing only the five populations on the

gradient from the South of France

toward the UK. This indicates that

the overall European distribution of

the Burgundy truffle does not result

from isolation caused by distance (ie

not attributable to range expansion);

however, species range expansion

might have happened northward from

southern France toward the UK.

WRITE BACK WRITE BACK WRITE BACK

Figure 1. (a) Characteristic morphology of the Burgundy truffle, Tuber uncinatum.

The inside tissue (or gleba, left) bears mature spores and is light brown with characteristic

white veins, whereas the outer layer (or peridium, right) is melanized and black. (b) 19th-

century illustration of women carrying baskets filled with truffles in Baden, in

southwestern Germany (from Dumaine J-M. 2010. Trüffeln, die heimischen Exoten).

(a) (b)

462

www.frontiersinecology.org © The Ecological Society of America

Write Back

Considering that truffles were har-

vested throughout Europe during

the 17th century, the Burgundy

truffle might have, similarly to the

Périgord truffle (Murat et al. 2004),

recolonized Europe from some

southern refugia, possibly following

the last ice age. The observed corre-

lation is not necessarily evidence of

a climate-driven range expansion,

however, given that other factors

(eg competition with other fungi,

shift in host-plant range) might

lead to such a finding. Clearly, more

specimens and a more comprehen-

sive approach, accounting for all

variables (eg climate, soil, associ-

ated species), will be needed to

identify the possible driving forces

behind the Burgundy truffle’s cur-

rent distribution.

Here, our analysis suggests that cli-

mate change that started in the late

19th century has had little effect on

the present distribution of the

Burgundy truffle. Büntgen et al.’s

conclusions might nevertheless

apply to other truffle species with

narrower ranges and higher commer-

cial values (eg Périgord or Piedmont

truffles). If climate does limit the dis-

tribution of the latter two species,

even the slight warming in northern

Europe envisioned by Büntgen et al.

might induce northern expansion. In

addition to temperature, other fac-

tors – including precipitation, soil

properties (Chevalier et al. 2001),

and mating type (Rubini et al. 2011)

– determine whether truffles produce

fruiting bodies. Successful truffle cul-

tivation will consequently succeed

only if truffle orchard management

shifts from current empirical prac-

tices to practices based on scientific

evidence. Increasing temperatures

alone will not be sufficient for suc-

cessful truffle cultivation in more

northern parts of Europe.

Richard Splivallo1*, Rengenier

Rittersma2, Nayuf Valdez1, Gérard

Chevalier3, Virginie Molinier4,

Daniel Wipf4, and Petr Karlovsky1

1Molecular Phytopathology and

Mycotoxin Research, University of

Goettingen, Goettingen, Germany

*(ricsi17@hotmail.com);

2Beltheim-Heyweiler, Germany;

3Résidence Cristelle, Cournon

d’Auvergnes, France; 4UMR 1347

Agroécologie AgroSup/INRA/uB, Pôle

IPM CNRS ERL 6300, Dijon, France

Brückmann FE. 1730. Epistolae itinerar-

ium XX: de tuberibus terrae.

Wolfenbüttel, Germany.

Calosi P, Bilton DT, Spicer JI, et al. 2010.

What determines a species’ geo-

graphical range? Thermal biology

and latitudinal range size relation-

ships in European diving beetles

(Coleoptera: Dytiscidae). J Anim Ecol

79: 194–204.

Chevalier G and Frochot H. 1997. La

truffe de Bourgogne: Tuber uncinatum

Chatin. Levallois-Perret, France: Edi-

tions Pétrarque.

Chevalier G, Gregori G, Frochot H, and

Zambonelli A. 2001. The cultivation of

the Burgundy truffle. In: Bencivenga M

and Granetti B (Eds). Proceedings of the

Second International Conference on

Edible Mycorrhizal Mushrooms. 3–6 Jul

2001. Spoleto, Italy: Comunità Montana

dei Monti Martani e del Serano.

Hall IR, Yun W, and Amicucci A. 2003.

Cultivation of edible ectomycorrhizal

mushrooms. Trends Biotechnol 21:

433–38.

Murat C, Díez J, Luis P, et al. 2004.

Polymorphism at the ribosomal DNA

ITS and its relation to postglacial re-

colonization routes of the Perigord

truffle Tuber melanosporum. New Phytol

164: 401–11.

Paolocci F, Rubini A, Riccioni C, et al.

2004. Tuber aestivum and Tuber uncina-

tum: two morphotypes or two species?

FEMS Microbiol Lett 235: 109–15.

Rittersma RC. 2010a. Die verspätete

Trüffelnation. Zu Geschichte, Gegen-

wart und Zukunft der Trüffel in

Deutschland. In: Dumaine JM and

Wojtko N (Eds). Trüffeln: die heimis-

chen Exoten. Aarau/München, Ger-

many: AT Verlag.

Rittersma RC. 2010b. Only the sky is the

limit of the soil. Manifestations of truf-

fle mania in Northern Europe in the

18th century. In: Bencivenga M and

Granetti B (Eds). Proceedings of the

Second International Conference on

Edible Mycorrhizal Mushrooms. 3–6

Jul 2001. Spoleto, Italy: Comunità

Montana dei Monti Martani e del

Serano.

Robinson T. 1691–1693. An account of

the Tubera Terrae, or truffles found at

Rushton in Northamptonshire. Philos

T Roy Soc London 7: 824–26.

Rubini A, Belfiori B, Riccioni C, et al.

2011. Tuber melanosporum: mating type

distribution in a natural plantation and

dynamics of strains of different mating

types on the roots of nursery-inocu-

lated host plants. New Phytol 189:

723–35.

Splivallo R, Valdez N, Kirchhoff N, et al.

2012. Intraspecific genotypic variabil-

ity determines concentrations of key

truffle volatiles. New Phytol 194:

823–35.

Wedén C, Danell E, and Tibell L. 2005.

Species recognition in the truffle genus

Tuber – the synonyms Tuber aestivum

and Tuber uncinatum. Environ Microbiol

7: 1535–46.

doi:10.1890/12.WB.020

Illuminating the mysterious

world of truffles

On the basis of discovering ~2 kg of

truffles (belonging to several Tuber

spp, including a >410-g mature Bur-

gundy truffle [T aestivum syn uncina-

tum]) at >70 sites in southwest

Germany, we postulated in our origi-

nal letter that ongoing climate change

was one possible factor contributing to

species-specific range shifts, as well as

to variation in fruiting body produc-

tion and maturation, in truffles.

A warming-induced extension of

the growing period – together with

redistributed precipitation regimes –

was hypothesized to likely affect the

optimum rather than the entire distri-

bution of individual truffle species.

The detection of not only T aestivum

but also T brumale, T excavatum, T

fulgens, T macrosporum, T mesenter-

icum, and T rufum in the same region

and at the same time, together with

substantial temperature anomalies,

suggested that climatic effects were

involved. Associated environmental

changes may have impacted condi-

tions at local to regional scales but did

not necessarily shift the geographic

scope of entire ecosystems. Our

“hypogeous evidence”, in line with

European-wide myco-phenological

observations (Kauserud et al. 2012),

supports a reported long-term decline

in Périgord black truffle (T melanospo-

rum) harvests across its natural and

cultivated Mediterranean habitats

(Hall et al. 2003; Mello et al. 2006). A

possible reason for this southern

European truffle yield decrease is a loss

in soil moisture.

Nevertheless, we agree with Spli-

R Splivallo et al. – Supplementary information

WebFigure 1. Geographic distribution and population genetics of Tuber uncinatum. (a)

Countries in which the Burgundy truffle naturally occurs are marked with black circles

(based on reports by Chevalier and Frochot [1997] and Splivallo et al. [2012]). Colored

circles represent the locations of the populations (the number of samples are indicated

inside the circles) used for the genetics study presented here. Background map is available

on Wikimedia Commons (Ssolbergj). Genetic fingerprints were generated by amplified

fragment length polymorphism (AFLP) for the samples depicted by colored circles (as

described in Splivallo et al. [2012]). (b) Dendrogram (unweighted pair group method

with arithmetic mean) based on AFLP data for 14 Burgundy truffle samples collected

from six countries. Black triangles indicate nodes >80% (2000 bootstraps). The Mantel

test did not reveal a significant correlation (P= 0.413, r= 0.028, 10 000 permutations)

between genetic distances (using Jaccard’s distances = 1 – Jaccard’s similarity coefficient)

and geographic distances (log kilometers) among the eight populations depicted in color on

the map. Results of the Mantel test, however, were significant when considering the five

populations on a north–south gradient from southern France toward the UK (P= 0.008,

r= 0.645, 10 000 permutations; http://ibdws.sdsu.edu/; Jensen et al. 2005).

nWebReferences

Chevalier G and Frochot H. 1997. Latruffe de Bourgogne: Tuber

uncinatum Chatin. Levallois-Perret, France: Editions

Pétrarque.

Jensen JL, Bohonak AJ, and Kelley ST. 2005. Isolation by dis-

tance, web service. BMC Genet 6: 13.

Splivallo R, Valdez N, Kirchhoff N, et al. 2012. Intraspecific

genotypic variability determines concentrations of key truf-

fle volatiles. New Phytol 194: 823–35.

Influence of annual climatic variations, climate changes, and sociological factors on the production of the Périgord black truffle (Tuber melanosporum Vittad.) from 1903–1904 to 1988–1989 in the Vaucluse (France)

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Mar 2012
NEW PHYTOL

Aroma variability in truffles has been attributed to maturation (Tuber borchii), linked to environmental factors (Tuber magnatum), but the involvement of genetic factors has been ignored. We investigated aroma variability in Tuber uncinatum, a species with wide distribution. Our aim was to assess aroma variability at different spatial scales (i.e. trees, countries) and to quantify how aroma was affected by genotype, fruiting body maturity, and geographical origin. A volatile fingerprinting method was used to analyze the aroma of 223 T. uncinatum fruiting bodies from seven European countries. Maturity was estimated from spore melanization. Genotypic fingerprinting was performed by amplified fragment length polymorphism (AFLP). Discriminant analysis revealed that, regardless of the geographical origin of the truffles, most of the aroma variability was caused by eight-carbon-containing volatiles (C8-VOCs). In an orchard of T. uncinatum, truffles producing different concentrations of C8-VOCs clustered around distinct host trees. This clustering was not associated with maturity, but was associated with fungal genotype. These results indicate that the variation in C8-VOCs in truffles is most likely under genetic control. They exemplify that understanding the factors behind aroma variability requires a holistic approach. Furthermore, they also raise new questions regarding the ecological role of 1-octen-3-ol in truffles.

Cultivation of edible ectomycorrhizal mushrooms

Article

Full-text available

Nov 2003
TRENDS BIOTECHNOL

The edible mycorrhizal mushrooms include some of the world's most expensive foods and have a global market measured in US$ billions. Despite this, few have been cultivated with any degree of success, and certainly not in volumes that are likely to reverse the catastrophic declines in production that have occurred over the past 100 years. The main obstacles to their cultivation are their need to be associated with a host plant to successfully grow and fruit, contamination with other ectomycorrhizal fungi both before and after the establishment of plantations, and a general lack of understanding of each mushroom's trophic relationships, and biotic, edaphic and climatic requirements.

Tuber aestivum and Tuber uncinatum: Two morphotypes or two species?

Article

Full-text available

Jul 2004

Tuber spp. are ectomycorrhizal fungi that establish symbioses with shrubs and trees. Because of their different smell and taste, Tuber uncinatum and Tuber aestivum are two truffle morphotypes with a different market value, but whether or not T. uncinatum and T. aestivum are different taxa is still an open debate among mycologists. In order to identify molecular keys characterizing both T. aestivum and T. uncinatum morphotypes, ITS/RFLPs analyses were carried out on a large collection of samples from all over Italy and from other European countries, followed by a study of the phylogenesis of ITS, beta-tubulin and EF 1-alpha genes, on representative samples. The present study provides compelling evidence that: (i) T. uncinatum and T. aestivum belong to the same species, (ii) neither morphotype presents a specific molecular fingerprint, but they may even share identical alleles at any of the loci analysed; (iii) T. aestivum is most likely under a selfing reproductive mode. Our findings suggest that ecological, rather than genetic causes may account for differences in sporal morphology, taste and smell between T. aestivum and T. uncinatum truffles.

La truffe de Bourgogne (Tuber uncinatum Chatin)

Book

Jan 1997

G. Chevalier

Polymorphism at the ribosomal DNA ITS and its relation to postglacial re-colonization routes of the Perigord truffle Tuber melanosporum

Article

Nov 2004
NEW PHYTOL

5 These authors contributed equally to this work; 6 Present address: Institut für Botanik – Terrestrische Ökologie, Universität Leipzig – Johannisallee 21–23 D-04103 Leipzig, Germany Summary • Glaciations and postglacial migrations are major factors responsible for the present patterns of genetic variation we see in natural populations in Europe. For ectomyc-orrhizal fungi, escape from refugia can only follow range expansion by their specific hosts. • To infer phylogeographic relationships within Tuber melanosporum , sequences of internal transcribed spacers (ITS) and the 5.8S coding region of the ribosomal DNA repeat were obtained for 188 individuals sampled over the entire distribution of this species in France, and in north-western Italy and north-eastern Spain. • Ten distinct ITS haplotypes were distinguished, mapped and treated using F -and N ST -statistics and nested clade (NCA) analyses. They showed a significant genetic differentiation between regional populations. NCA revealed a geographical associ-ation of ITS haplotypes, an old fragmentation into two major groups of populations, which likely colonized regions on different sides of the French Central Massif. • This re-colonization pattern is reminiscent of the one observed for host trees of the Perigord truffle, such as oaks and hazelnut trees. This suggests that host postglacial expansion was one of the major factors that shaped the mycobiont population structure.

Tuber melanosporum: Mating type distribution in a natural plantation and dynamics of strains of different mating types on the roots of nursery-inoculated host plants

Article

Oct 2010
NEW PHYTOL

• In light of the recent finding that Tuber melanosporum, the ectomycorrhizal ascomycete that produces the most highly prized black truffles, is a heterothallic species, we monitored the spatial distribution of strains with opposite mating types (MAT) in a natural truffle ground and followed strain dynamics in artificially inoculated host plants grown under controlled conditions. • In a natural truffle ground, ectomycorrhizas (ECMs), soil samples and fruit bodies were sampled and genotyped to determine mating types. Simple sequence repeat (SSR) markers were also used to fingerprint ECMs and fruit bodies. The ECMs from nursery-inoculated host plants were analysed for mating type at 6 months and 19 months post-inoculation. • In open-field conditions, all ECMs from the same sampling site showed an identical mating type and an identical haploid genotype, based on SSR analysis. Interestingly, the gleba of fruit bodies always demonstrated the same genotype as the surrounding ECMs. Although root tips from nursery-grown plants initially developed ECMs of both mating types, a dominance of ECMs of the same MAT were found after several months. • The present study deepens our understanding of the vegetative and sexual propagation modes of T. melanosporum. These results are highly relevant for truffle cultivation.

What Determines a Species' Geographical Range? Thermal Biology and Latitudinal Range Size Relationships in European Diving Beetles (Coleoptera: Dytiscidae)

Article

Sep 2009
J ANIM ECOL

1. The geographical range sizes of individual species vary considerably in extent, although the factors underlying this variation remain poorly understood, and could include a number of ecological and evolutionary processes. A favoured explanation for range size variation is that this result from differences in fundamental niche breadths, suggesting a key role for physiology in determining range size, although to date empirical tests of these ideas remain limited. 2. Here we explore relationships between thermal physiology and biogeography, whilst controlling for possible differences in dispersal ability and phylogenetic relatedness, across 14 ecologically similar congeners which differ in geographical range extent; European diving beetles of the genus Deronectes Sharp (Coleoptera, Dytiscidae). Absolute upper and lower temperature tolerance and acclimatory abilities are determined for populations of each species, following acclimation in the laboratory. 3. Absolute thermal tolerance range is the best predictor of both species’ latitudinal range extent and position, differences in dispersal ability (based on wing size) apparently being less important in this group. In addition, species’ northern and southern range limits are related to their tolerance of low and high temperatures respectively. In all cases, absolute temperature tolerances, rather than acclimatory abilities are the best predictors of range parameters, whilst the use of independent contrasts suggested that species’ thermal acclimation abilities may also relate to biogeography, although increased acclimatory ability does not appear to be associated with increased range size. 4. Our study is the first to provide empirical support for a relationship between thermal physiology and range size variation in widespread and restricted species, conducted using the same experimental design, within a phylogenetically and ecologically controlled framework.

Species recognition in the truffle genus Tuber - The synonyms Tuber aestivum and Tuber uncinatum

Article

Nov 2005

The two morphologically similar truffles Tuber aestivum and T. uncinatum have caused confusion because T. uncinatum is regarded by different authors, as either a distinct species, variety, subspecies, or synonym of T. aestivum. A clarification of the relationship between the two truffles would help both conservation biology and cultivation. We aimed both to test the reliability of the only quantitative morphological character used to distinguish the two taxa, i.e. the height of the spore reticulum, and to compare sequences of the ribosomal DNA (rDNA) internal transcribed spacer (ITS) region. Our study included 117 fruit bodies of T. aestivum and T. uncinatum, originating from eight European countries. The results showed that the spore reticulum height is not diagnostic. The phylogenetic analysis of ITS sequences from 81 fruit bodies and an additional 32 sequences from GenBank showed that T. aestivum and T. uncinatum were intermingled in one highly supported (100% bootstrap) monophyletic clade, separate from its sister species Tuber mesentericum. We conclude that T. aestivum and T. uncinatum are synonyms and the species should be named T. aestivum, as the oldest name has priority. For traders, T. aestivum syn. T. uncinatum should be used until conformity has been reached.

The cultivation of the Burgundy truffle

Jul 2001

G Chevalier
G Gregori
H Frochot
A Zambonelli

Chevalier G, Gregori G, Frochot H, and Zambonelli A. 2001. The cultivation of the Burgundy truffle. In: Bencivenga M and Granetti B (Eds). Proceedings of the Second International Conference on Edible Mycorrhizal Mushrooms. 3-6 Jul 2001. Spoleto, Italy: Comunità Montana dei Monti Martani e del Serano.

Die verspätete Trüffelnation Zu Geschichte, Gegenwart und Zukunft der Trüffel in Deutschland Trüffeln: die heimischen Exoten

Rc Rittersma

Rittersma RC. 2010a. Die verspätete Trüffelnation. Zu Geschichte, Gegenwart und Zukunft der Trüffel in Deutschland. In: Dumaine JM and Wojtko N (Eds). Trüffeln: die heimischen Exoten. Aarau/München, Germany: AT Verlag.