Automotive

Remnants fragments preserve genetic diversity of the old forest lichen Lobaria pulmonaria in a fragmented Mediterranean mountain forest

Description
Fragmentation represents a serious threat to biodiversity worldwide, however its effects on epiphytic organisms is still poorly understood. We study the effect of habitat fragmentation on the genetic population structure and diversity of the
Categories
Published
of 16
All materials on our website are shared by users. If you have any questions about copyright issues, please report us to resolve them. We are always happy to assist you.
Related Documents
Share
Transcript
  ORIGINAL PAPER Remnants fragments preserve genetic diversity of the oldforest lichen  Lobaria pulmonaria  in a fragmentedMediterranean mountain forest Mo´nica G. Ota´lora  • Isabel Martı´nez  • Rocı´o Belincho´n  • Ivo Widmer  • Gregorio Arago´n  • Adria´n Escudero  • Christoph Scheidegger Received: 6 October 2010/Accepted: 14 February 2011/Published online: 26 February 2011   Springer Science+Business Media B.V. 2011 Abstract  Fragmentation represents a serious threat to biodiversity worldwide, howeverits effects on epiphytic organisms is still poorly understood. We study the effect of habitatfragmentation on the genetic population structure and diversity of the red-listed epiphyticlichen,  Lobaria pulmonaria , in a Mediterranean forest landscape. We tested the relativeimportance of forest patch quality, matrix surrounding fragments and connectivity on thegenetic variation within populations and the differentiation among them. A total of 855thalli were sampled in 44 plots (400 m 2 ) of 31 suitable forest fragments (beeches andoaks), in the Sierra de Ayllo´n in central Spain. Variables related to landscape attributes of the remnant forest patches such as size and connectivity and also the nature of the matrix ortree species had no significant effects on the genetic diversity of   L. pulmonaria.  Values of genetic diversity (Nei’s) were only affected by habitat quality estimated as the age patches.Most of the variation (76%) in all populations was observed at the smallest sampled unit(plots). Using multiple regression analysis, we found that habitat quality is more importantin explaining the genetic structure of the  L. pulmonaria  populations than spatial distance.The relatively high level of genetic diversity of the species in old forest patches regardlessof patch size indicates that habitat quality in a highly structured forest stand determines thepopulation size and distribution pattern of this species and its associated lichen community.Thus, conservation programmes of Mediterranean mountain forests have to prioritize areaand habitat quality of old forest patches. Keywords  Lichens    Habitat fragmentation    Landscape genetics    Microsatellites   Mediterranean forest M. G. Ota´lora ( & )    I. Martı´nez    R. Belincho´n    G. Arago´n    A. EscuderoA´rea de Biodiversidad y Conservacio´n, ESCET, Universidad Rey Juan Carlos,C/Tulipa´n s/n, 28933 Mostoles, Spaine-mail: monica.garcia@urjc.esM. G. Ota´lora    I. Widmer    C. ScheideggerWSL, Swiss Federal Institute for Forest, Snow and Landscape Research,Zu¨rcherstrasse. 111, 8903 Birmensdorf, Switzerland  1 3 Biodivers Conserv (2011) 20:1239–1254DOI 10.1007/s10531-011-0025-0  Introduction Anthropogenic impacts to ecosystems result in changes in the distribution and abundance of species, particularly in areas affected by habitat destruction (Johansson and Ehrle´n 2003;Riesetal.2004).Fragmentationrepresentsathreattobiodiversityworldwidebyreducingthe amount of suitable habitat, increasing isolation between habitat patches, and changing bioticand abiotic conditions within remnants (Fahrig 2003). Population genetics theory predicts that habitat fragmentation can disrupt breeding systems, resulting in increased inbreedingand erosion of genetic diversity within populations, together with a substantial populationdifferentiation(Youngetal.1996;Hamrick 2004).Inaddition,apopulationsubjecttohabitat fragmentationfacesincreasingisolationoftheresultingsubpopulations,leadingtotwomajorgenetic effects: genetic drift leading to increasing differentiation among subpopulations anddeclining genetic diversity within subpopulations (Templeton et al. 1990). It is also well known that some species are at greater risk of extinction in fragmentedlandscapes than others (Hoehn et al. 2007). Identifying the factors that make these species so sensitive to fragmentation and understanding how fragmented habitat may affect pop-ulation viability are essentials for conservation management of fragmented populations.Only with this information available can integrative ecological and evolutionary principlesof species at risk be implemented in conservation planning. For instance, the currentparadigm in plant population genetics has not been tested in other groups of organisms.Cryptogamic epiphytes, associated to old forests, are especially sensitive to habitat quality,which may be affected by fragmentation. Consequently many epiphyte species haveexperienced sharp population declines parallel to the conversion of continuous forests intosmall fragments of sheltered landscape (Sjo¨berg and Ericson 1992; Sna ¨ll et al. 2004; Lo ¨belet al. 2006; Scheidegger and Werth 2009). However, the effects of habitat fragmentation on the genetic structure and diversity of epiphytic organisms have been largely neglected andthe genetic consequences on these organisms remain poorly understood (La¨ttman et al.2009).How landscape fragmentation affects individual organisms is dependent on the attri-butes of the organisms (Henle et al. 2004; Schmuki et al .  2006) and their interaction withthe biotic and abiotic changes produced after the fragmentation. Therefore, the combina-tion of molecular genetics tools with landscape ecological concepts, more specificallylandscape genetics (Manel et al. 2003), can aid in understanding the processes driving genetic diversity, structure and population persistence (Holderegger and Wagner 2008).Patch size and isolation are the predictors often used to describe fragmented landscapesand to investigate the effects of habitat fragmentation on community and species dynamics(Hanski and Gaggiotti 2004). More recently using landscape genetic approaches, the rel-evance of habitat quality, landscape history and also the nature of the matrix surroundingeach remnant have taken in account when studying the genetic effects of fragmentation onspecies (Nielsen et al. 2006; Williams et al. 2006; Werth et al. 2007; Holderegger and Wagner 2008).A consensus exists in which the effect of fragmentation is dependent on the ability of species to disperse and colonize such habitats at different scales (Hanski and Gaggiotti2004; Mu¨nzbergova´ and Herben 2005; Pohjamo et al. 2008; Lo ¨bel et al. 2009). Geneticmarkers provide a powerful tool for obtaining indirect estimates of dispersal and gene flowin natural populations by evaluating the genetic structure and diversity of species at nestedspatial and temporal scales. The genetic structure and diversity of lichen-forming fungi hasbeen the subject recently of many studies, reporting mixed conclusions regarding dispersalabilities, habitat characteristics and landscape levels (La¨ttman et al. 2009). 1240 Biodivers Conserv (2011) 20:1239–1254  1 3  Our main goal is to evaluate the effect of habitat fragmentation on the genetic structureand diversity of the epiphytic lichen,  Lobaria pulmonaria , in a Mediterranean forestlandscape.  L. pulmonaria  is one the most studied lichen species. It is mainly an epiphyticlichen of humid temperate and boreal regions of the northern hemisphere and coolerparts of the tropics occupying also well conserved stands in the Mediterranean region(Belincho´n 2009; Belincho´n et al. 2009).  Lobaria pulmonaria  produces both vegetativeand sexual propagules and it has been historically considered a dispersal-limited species.However, recent studies suggest that in many parts of the species’ distribution area themost important factor for the population persistence of this species is the establishmentstage and recruitment rather than dispersal (Werth et al. 2006a; Belincho ´n 2009;Scheidegger and Werth 2009).In Mediterranean fragmented mountain forest, habitat quality (i.e. tree species andforest stand age) profoundly affects the occurrence and cover of   Lobaria pulmonaria , atseveral spatial scales from the tree to the patch level (Belincho´n et al. 2009). Therefore, wehypothesized that genetic differentiation between habitat types and qualities would resultfrom genetic drift during dispersal, recruitment or growth in relation to spatial isolation of forest patches in a fragmented forest landscape. To test our hypothesis we compared thelocal genetic diversity and structure of this species in forest patches with the characteristicsof the patches (including host tree species, patch size, connectivity and surrounding matrix)and a complete set of environmental predictors taken at different scales in the forestfragments .  This study applies landscape genetic methods with a multimodel approach thatevaluates alternative hypotheses and identifies a combination of environmental factors thatappear to drive gene flow in this fragmented Mediterranean landscape. We identified whichfactors are affecting the genetic diversity and structure of this model lichen species anddiscuss implications for the conservation of this species. Materials and methods SamplingThe study area is a mosaic of beech ( Fagus sylvatica ) and Mediterranean oak ( Quercus pyrenaica ) forest remnants embedded in a matrix dominated by heathlands ( Erica arborea and  E. australis ) and pine afforestations ( Pinus sylvestris ). It covers 5600 ha and is locatedin the Sierra de Ayllo´n, at the eastern most tip of the Sistema Central Range, Spain(41  13 0 N 3  21 0 W). The climate is Mediterranean with a mean annual temperature of 7.8  C(0.10  C January–19.2  C July) and an annual rainfall of 1039 mm (1408–1835 m a.s.l.).Loss and forest fragmentation have occurred extensively, although some well-preservedbeech forests restricted to areas of difficult access remain. From the 1960s to date, mostforests have been clear-cut and modern forestry practices have maintained a  Pinus syl-vestris  afforestations and extense  Erica  communities (Herna´ndez and Sainz 1978). Thestudied area included both north and south facing slopes of the Ayllo´n Mountains. Thesouthern slopes are currently under protection within the Natural Park ‘‘Hayedo de TejeraNegra’’ whereas the northern slope (Riaza) is not formally protected. The south facingslopes include two valleys, both with different topographic and landscape characteristics:Zarzas River and Lillas River. The management and intensity of fragmentation has alsovaried in these three regions. The forest patches matrix of Riaza is dominated by heath-lands, and in Lillas and Zarzas the matrixes are a mixture among pine afforestation andheathlands. For more details about the study area and landscape characteristics see Biodivers Conserv (2011) 20:1239–1254 1241  1 3  Belincho´n et al. (2009). A hierarchical sampling design was implemented, Riaza, Lillasand Zarzas were considered regions, each region comprise several forest patches of bee-ches and oaks, and each forest patches may include several plots of 400 m 2 . A total of 44plots in 31 forest patches along the three regions were sampled. The forest patches arearanged from 0.75 to 209.80 ha and the distance between patches ranged from 200 m to8 km, with a mean distance of 3.10 km (SD  =  1.63) (Belincho´n et al. 2009).Aerial photographs 1:1000 were taken from SigPac (http://sigpac.jccm.es/visorSigpac/ )and analyzed to identify forest patches, which were delimited and drawn in a GIS. Fromthe 55 plots of 20  9  20 m 2 randomly sampled by Belincho´n et al. (2009), the 44 plots with  Lobaria pulmonaria  were selected for this study (34 plots were in beech patches and 10plots were in oak patches). Variables describing forest patch characteristics: area (ha),connectivity, and percentaje of matrix pine perimeter were estimated using GIS (ArcViewGIS 3.1) as described by Belincho´n et al. (2009). Within each plot we sampled 20 lichenthalli each from a different tree. Multiple thalli from the same tree were sampled in plotswith fewer than 20 trees occupied by  L. pulmonaria . In seven plots less than 20-thalli werecollected (see Table 1). Thus, we sampled a total of 855 thalli of   L. pulmonaria . Each plotwas georeferenced. At the plot level we measured the total number of trees per plot, treescarrying  L. pulmonaria  per plot  ,  diameter at breast height (dbh, cm), tree species (oak orbeech) and plot distance to the nearest permanent water course (m, using GIS) (Table 1).Lichen species cover below 2-m height was measured in square centimetres (  L. pulmonaria rarely grows above this height in the study area). Because the surrounding matrix mayinfluence the persistence and dispersal of   L. pulmonaria  (Belincho´n et al. 2009), theperimeter pine afforestations bordering each patch was also recorded as a surrogate of thecomplex nature of the matrix (Table 2).Genetic analyses  Lobaria pulmonaria  samples from fresh material were ground in liquid nitrogen. Totalgenomic DNA was extracted using the DNeasy Plant Mini Kit (Qiagen) according to themanufacturer’s instructions with slight modifications described in Crespo et al. (2001). Three unlinked fungal microsatellites LPu03, LPu09 and LPu15 were analyzed (Walseret al. 2003, 2004). The loci were amplified in a multiplex PCR of 10  l l using 1  l l of genomic DNA, 2  l l of the Qiagen Multiplex PCR Master Mix solution and 25 nM of theprimers LPu03, LPu09 and LPu15. DNA amplifications were carried out in a Peltierthermal cyclers (PTC-100) and performed using the following programs: initial denatur-ation at 95  C for 15 min, and 27 cycles 94  C for 45 s, 55  C for 90 s, 72  C for 60 s,followed by a final extension at 72  C for 30 min. Fragmented sizes of PCR products weredetermined on an ABI3100-avant automatic sequencer (Applied Biosystems). Alleleassignment was performed using GeneMapper v3.7.Numerical analyses Genetic diversity within plots As a measurement of genetic variation Nei’s unbiased gene diversity (  H  ; Nei 1978) was calculated as well as the number of multilocus genotypes per population ( G ). Both geneticdiversity estimators were calculated using the codes written by Werth et al. (2006a) in R (R Development Core Team 2004). 1242 Biodivers Conserv (2011) 20:1239–1254  1 3  Table 1  Environmental variables values and genetic diversity data of each one of the plots studiedPatch Plot Distancefromriver (m 2 )No. of treesMeanDBH(cm)Cover of   L. pulmonaria (cm 2 )No. of treesoccupied by  L. pulmonaria H G n Lillas-Beech 1 1 694.10 21 29.79 100 2 0.59 9 20Lillas-Beech 1 2 285.43 22 30.30 6341 9 0.57 10 20Lillas-Beech 1 3 354.00 24 28.60 1278 7 0.56 7 20Lillas-Beech 2 4 642.46 40 20.84 9669 8 0.28 5 20Lillas-Beech 2 5 144.70 28 19.46 3382 3 0.64 7 20Lillas-Beech 2 6 660.66 35 19.06 1602 11 0.35 4 20Lillas-Beech 2 7 719.64 22 32.32 3704 4 0.63 6 14Lillas-Beech 2 8 128.75 42 22.19 3760 12 0.51 6 20Lillas-Beech 2 9 192.26 35 20.26 5878 11 0.42 7 20Lillas-Beech 2 10 502.25 44 19.62 26,105 18 0.36 5 20Lillas-Beech 3 11 113.79 33 22.07 743 4 0.41 5 20Zarzas-Beech 6 12 400.85 26 32.31 4552 8 0.43 7 19Zarzas-Beech 7 13 198.93 21 31.01 4525 10 0.23 3 20Zarzas-Beech 8 14 223.62 40 24.38 5179 10 0.43 7 20Zarzas-Beech 9 15 215.62 13 60.88 56,301 12 0.63 9 20Zarzas-Beech 10 16 424.58 35 23.95 2264 16 0.58 7 20Zarzas-Beech 10 17 287.61 18 31.72 7056 9 0.48 6 20Zarzas-Beech 11 18 27.65 23 32.29 13,943 21 0.64 9 20Zarzas-Beech 12 19 516.76 26 29.43 17,378 10 0.50 5 20Zarzas-Beech 12 20 542.74 13 49.22 291 2 0.58 12 20Zarzas-Beech 13 21 63.71 23 27.54 8513 5 0.59 10 20Zarzas-Beech 13 22 95.31 27 26.05 8784 18 0.50 6 20Riaza-Beech 16 23 828.80 19 37.86 60,807 17 0.47 7 19Riaza-Beech 16 24 745.58 7 74.02 3898 6 0.51 6 20Riaza-Beech 17 25 600.04 41 22.49 24,613 25 0.25 3 17Riaza-Beech 17 26 643.06 45 24.99 10,260 10 0.44 9 20Riaza-Beech 17 27 490.58 25 33.44 5948 17 0.65 8 20Riaza-Beech 17 28 223.53 21 39.51 6879 11 0.49 6 20Riaza-Beech 18 29 73.20 72 16.37 16,701 22 0.16 3 20Riaza-Beech 19 30 463.28 25 27.87 17,196 8 0.38 4 14Riaza-Beech 21 31 1506.72 25 28.46 5905 11 0.16 3 20Riaza-Beech 21 32 1419.66 23 35.05 4790 10 0.59 9 20Riaza-Beech 22 33 1351.04 16 47.23 7307 9 0.69 11 20Riaza-Beech 23 34 1996.65 9 66.45 4431 5 0.42 6 20Lillas-Oaks 24 35 85.57 29 20.01 78,276 27 0.50 9 20Lillas-Oaks 25 36 339.79 48 17.04 1350 4 0.60 8 20Lillas-Oaks 26 37 9.64 24 28.20 20,099 19 0.27 4 18Lillas-Oaks 26 38 37.78 60 18.05 14,439 17 0.45 6 20Lillas-Oaks 27 39 132.95 122 11.22 6598 33 0.34 2 20Zarzas-Oaks 28 40 459.46 63 15.84 5641 6 0.55 10 20Zarzas-Oaks 29 41 1520.11 82 14.65 15,640 42 0.00 1 20Zarzas-Oaks 30 42 179.26 33 21.19 91,384 33 0.62 10 20Biodivers Conserv (2011) 20:1239–1254 1243  1 3
Search
Similar documents
View more...
Tags
Related Search
We Need Your Support
Thank you for visiting our website and your interest in our free products and services. We are nonprofit website to share and download documents. To the running of this website, we need your help to support us.

Thanks to everyone for your continued support.

No, Thanks