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Proceedings of the 8th CMAPSEEC
Section I "MAP diversity at all levels and tools for its evaluation" Page 59
Original scientific paper
GEOGRAPHIC DISTRIBUTION AND SPATIAL GAPS ASSESSMENT IN EX SITU
COLLECTION OF ORIGANUM VULGARE L. STORED IN ALBANIAN GENEBANK
Gixhari Belul1, Hobdari Valbona1, Kadiasi Najada2, Faslia Ndoc2
1Albanian genebank, Agricultural University of Tirana, Tirana, Albania 2Plant Production Department, Agricultural University of Tirana, Tirana, Albania
ABSTRACT
The geographic distribution and spatial gaps using circular buffer zones (1 and 10 km radius)
around the ex situ and external data of 117 oregano (Origanum vulgaris L.) populations in ten
districts of Albania was investigated. Spatial analysis and comparisons of quantitative
diversity variables: richness, ex situ and external present points, no spatial gaps, mid-priority
gaps, high-priority gaps, priority sites, and potential size increase of collection show the areas
with higher richness of oregano populations were Kukes, Shkodra, Dibra and Gjirokastra
districts areas. Study results show the areas with higher ‘‘no gaps data’’ were Lezha, Fieri
and Berat districts (index range from 0.75 to 0.80), the areas with mid-priority spatial gaps
were Vlora, Elbasan, Fieri and Shkodra districts (index range from 0.22 to 0.29), and the
areas with high-priority spatial gaps were Tirana, Vlora, Gjirokastra, Kukes, Shkodra, and
Elbasan districts (index range from 0.40 to 0.86). Higher numbers of priority sites were
observed at the Shkodra, Kukesi, Gjirokastra and Elbasan district areas, which suggest these
possible priority sites, can be used to increase size of oregano collection. Cluster analysis
method on correlation data show clearly similarity among Shkodra and Kukes districts,
among Dibra and Gjirokastra, Fieri and Vlora, and Lezha and Tirana district areas (similarity
index ranges from 0.83 to 0.95).
Key words: Diversity indices, geographic distribution, O. vulgaris L., spatial gaps.
INTRODUCTION
Albania, a small Mediterranean country on the Balkan Peninsula in the south of Europe, is
very rich in biological and landscape diversity, in cultivated crops, in wild plant species
including medicinal plants. This diversity is attributable to the country's geographic position
as well as geological, hydrological, climatic, and soil and relief factors. Medicinal and
aromatic plants are economically, socially, and culturally important plants grown over a wide
range of ecological habitats in the country, in wild habitats, in forest habitats, on the hills and
mountains habitats [22, 25]. Oregano plants (Origanum vulgare L.), growing in natural
habitats, are collected and used as raw materials in the pharmaceutical, cosmetic and food
industry [22, 2].
Proceedings of the 8th CMAPSEEC
Section I "MAP diversity at all levels and tools for its evaluation" Page 60
Wild medicinal species provide an invaluable source of genes that can be used for the
improvement of cultivated species, but the information on medicinal plants biodiversity in
Albania is generally lacking especially in terms of species. There are still flora and taxonomic
medicinal groups, which are unknown or have not been studied.
Collection of Plant Genetic Resources (PGR) provides access to the greatest possible amount
of genetic variability in a particular species and helps reveal the ecological and geographic
distribution of plant species [3]. A genebank is a collection of a particular crop and its wild
relatives and, ideally, includes at least one example of each alternative allele for each locus
[5]. Because researchers can hope to sample only a fraction of genetic variation that occurs in
nature, it is important that this sample be as large as possible and contains the maximum
amount of useful variation for both present and future use [1, 4]. In our days the conservation
of PGR is regarded as an important need for human society, and genebanks offer the main
means to store, and protect valuable raw genetic materials. As the number of accessions of
different crops and wild species included in genebanks increases, improvement of quality and
representativeness of ex situ collections is an important goal for PGR conservation.
Diversity is not uniformly distributed in space or among taxonomic groups, and ecological
factors are a major determinant of genetic diversity [3]. Spatial distribution of a species is
necessarily a product of environmental influences, including human activities [12, 10], life
story traits and demographic past history of the plant species. Knowledge of spatial genetic
structures provides a valuable tool for inferring these causal factors and also the underlying
genetic processes such as selective pressures, gene flow, and drift [25].
Because the distribution of diversity is not known prior to data analysis, successful collecting
in terms of diversity may depend on the proper identification of populations closely adapted
to specific environments and land-use patterns [4]. In this case analysis of georeferenced
genebank data proves useful in identifying areas of high diversity [21, 8], targeting genetic
resources for breeding programs [21, 13], and selecting and designing sites for in situ
conservation [13].
Geographic information systems (GIS), as useful tools for eco-geographical analysis [11],
provide important information about the geographic distribution and diversity present in
specific geographic areas [20] of a target species. GIS studies can be used to detect
ecogeographical gaps in ex situ collections and subsequently identify where to prioritize
collection efforts, which are effective for management of a genebank.
Assessment of the current conservation status of PGR, identification of gaps, formulation,
and implementation of more effective collecting and conservation strategies for PGR [12],
can improve genetic representativeness (GR) and the quality of ex situ collections. Since ex
situ collections aim to cover the maximum amount of genetic variation and the entire range of
environmental adaptation of the target species, nowadays the objective in collecting
expeditions is frequently to fill gaps in the representativeness of collections [15].
The aim of this study was to assess the genetic diversity, relative spatial gaps of Oregano
(Origanum vulgare L.), and to optimize the representativeness of medicinal plants collection
stored in Albanian Gene Bank (AGB).
MATERIAL AND METHODS
Proceedings of the 8th CMAPSEEC
Section I "MAP diversity at all levels and tools for its evaluation" Page 61
Data sampling and geographic distribution: The study was conducted in the more natural
growing areas of Oregano (O. vulgare L.) populations in Albania, and there were ten districts
of Albania: Berat (BR), Dibra (DI), Elbasan (EL), Fieri (FR), Gjirokaster (GJ), Kukes (KU),
Lezha (LE), Shkoder (SH), Tirana (TR), and Vlora (VL) included for geographic distribution
analysis of oregano (O. vulgaris L.). Data sampling is realized using information on the total
occurrence of oregano species in Albania gathered from ex situ collection data in database of
medicinal plants stored in AGB and external data. External data, including all oregano
populations surveyed (not collected) and not included in ex situ collection, were gathered
from EURISCO database [7], from the Global Biodiversity Information Facility (GBIF)
database [9], from publishing data [18, 19, 24], and information gathered from contact
persons of Albanian genebank.
Each population (group of individuals) represent a georefernced observation, where one
observation supposes presence of an oregano population [10]. All georeferenced observations
(ex situ data and external data) chosen to carry out spatial analysis, were entered into the GIS
analysis, as presence points [16, 10] and were spatially represented as point maps using
DIVA-GIS [16, 17, 10]. The analysis focuses only on the study of geographic distribution
and diversity at the population levels (unit of alpha diversity). The measurement of
distribution, diversity, and relative gaps of Oregano (O. vulgare L.) was realized analyzing
the number of observations per populations and per district, and the area of occupancy. The
total area occupied, was selected as an indicator of abundance or rarity of species/ population.
Maps containing geographic distribution of oregano in all Albania and per each district were
created using DIVA-GIS tools [6].
Relative spatial gaps detection: Circular buffer zones (or buffer areas) that determined the
distance in km under which are consider two presence or collection sites to represent in fact
the same population [23], with a 1 and 10 km radius were created around the AGB ex situ
data points and circular buffer zones with a 1 and 3 km radius were also created around the
external data points. There were three possible situations: The first case, when the external
data buffer zones intersect the AGB ex situ data buffer zones with a 1 km radius, indicates
‘‘no gaps data’’. The second case, when external data buffer zones only intersect the AGB
data buffer zones with a 10 km radius, indicates mid-priority spatial gaps. The third case,
when the external data buffer zones do not intersect any of the AGB data buffer zones (those
with a 1 km or 10 km radius), indicates high-priority spatial gaps. Maps containing mid and
high-priority spatial gaps were created for oregano (O. vulgare L.) using DIVA-GIS tools [6].
Assessment of geographic distribution: Assessment of diversity distribution and relative
spatial gaps of Oregano (O. vulgare L.) populations is carried out using several quantitative
diversity indices or variables. Richness of oregano population (S), ex situ present points
(EXS-PP), external present points (EXT-PP), ‘‘no spatial gaps data’’ (NGD), mid-priority
spatial gaps (MPG), high-priority spatial gaps (HPG), number of priority sites (NPS), and
potential size increase (PSI %) of oregano collection (calculated by the ratio NPS/S) were the
quantitative diversity variables calculated and used in this study. A value from 0 to 1 was
given to each variable showing respectively 0 no variability and 1 high variability.
Analysis of distances: A cluster analysis method on correlation was used to identify groups of
relatively similar material [14], and to measure distances/similarities between georeferenced
data using presence/absence population of oregano and quantitative diversity
indices/variables in different observed areas of ten districts in Albania. Quantitative indices
or variables were calculated using the SAS JMP Statistical Discovery [26].
Proceedings of the 8th CMAPSEEC
Section I "MAP diversity at all levels and tools for its evaluation" Page 62
RESULTS AND DISCUTION
Collected and quality data: In ex situ collection of medicinal plants stored in AGB data for
125 populations of oregano were gathered. Data quality including the accuracy and precision
of geographic coordinates firstly presence or georeferenced data were checked for
inconsistencies. Data points without coordinates were removed from ex situ medicinal data.
Data points with incorrect coordinates on the administrative unit (county) were assigned
coordinates where possible while duplicate or doubtful data were removed [27]. After
checking the presence or absence of accessions the data included in the medicinal plants
database with partial or complete information for a total of 125 presence points, in total only
117 presence points (72 ex situ presence data and 45 external verified presence data) of
oregano populations were compiled and used to evaluate the geographic distribution,
diversity of currently oregano populations observed per each district and in all Albania.
Geographic diversity distribution: Geographic distribution results of observed oregano
populations given on the map as present points in all Albanian territory (left map, Figure 1)
show the areas with higher richness of oregano populations were KU, SH, DI and GJ districts
areas. At the second range of richness were BR, FR, and VL district areas (Table 1). A more
detailed analysis related to ex situ present points (points in red colour) and external present
points (points in blue colour) presented on the right map (Figure 1) show higher number of
ex situ present points were at the KU, SH, DI and GJ districts areas, and higher number of
external present points were in KU and SH districts areas. In these areas possible oregano
populations can be collected and stored in genebank.
Figure 1. Geographic distribution of oregano (O. vulgare L.) populations in Albania (left
map). Distribution of ex situ data (points in red colour) and external data (points in blue
colour) per each district areas (right map).
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Section I "MAP diversity at all levels and tools for its evaluation" Page 63
Relative spatial gaps: Quantitative analysis of diversity and spatial gaps indices (Richness-S,
EXS-PP, EXT-PP, NGD, MPG, HPG, NPS, and PSI) (Table 1) show presence of significant
differences among districts areas analyzed. Quantitative variables results and their variances
(Table 1) show the higher significant differences related to oregano (O. vulgare L.)
distribution and spatial gaps were expected at the KU, SH, DI and GJ districts areas (where
variance Ϭ2 range from 34.29 at DI district to 68.19 at KU district). To identify the relative
spatial gaps of oregano, geographic distribution maps of ex situ data and external data
containing mid spatial gaps and high-priority spatial gaps were superimposed and possible
relative spatial gaps per each district were evaluated (Figure 2).
Study results show the areas with higher ‘‘no gaps data’’ were LE, FR and BR districts (NGD
index range from 0.75 to 0.80) (Table 1). In these areas most of the external data buffer
zones intersect the AGB ex situ data buffer zones with a 1 km radius, showing ‘‘no gaps’’ as
it would imply that collecting of oregano populations located less than 2 km from the ex situ
present point is represented in the AGB database (Figure 2).
Table 1. Quantitative variables used to assess the diversity and spatial gaps of oregano
Variables BR DI EL FR GJ KU LE SH TR VL Average
Richness (S) 8 16 7 8 17 21 5 20 5 9 11.6±6.22
INS-PP 0.50 0.63 0.57 0.75 0.59 0.52 1.00 0.55 0.60 0.78 0.65±0.15
EXT-PP 0.50 0.38 0.43 0.25 0.41 0.48 0.00 0.45 0.40 0.22 0.35±0.15
NGD 0.75 0.69 0.14 0.75 0.53 0.43 0.80 0.40 0.60 0.56 0.56±0.20
MPG 0.00 0.13 0.29 0.25 0.12 0.19 0.00 0.25 0.00 0.22 0.14±0.11
HGP 0.25 0.31 0.86 0.25 0.47 0.57 0.20 0.60 0.40 0.44 0.44±0.15
NPS 2 5 6 2 8 12 1 12 2 4 5.40±4.09
PSI (%) 25% 31% 86% 25% 47% 57% 20% 60% 40% 44% 44% ± 20
Variance (Ϭ2) 8.09 34.3 8.83 7.98 41.5 68.2 3.09 62.92 3.08 10.85 22.9±22.4
St. Dev. 2.84 5.86 2.97 2.82 6.44 8.26 1.76 7.93 1.75 3.29 4.25±2.34
The areas with mid-priority spatial gaps were VL, EL, FR and SH districts (MPG index range
from 0.22 to 0.29) (Table 1). In these areas the external data buffer zones intersect the AGB
ex situ data buffer zones with a 3 to 10 km radius, showing ‘mid-priority spatial gaps’ as it
would imply collecting of oregano populations located between 3 to 10 km from the ex situ
present point represented in the AGB database (Figure 2).
The areas with high-priority spatial gaps were VL, GJ, KU, SH, and EL districts (HPG index
range from 0.44 to 0.86) (Table 1). In these areas the external data buffer zones do not
intersect the AGB ex situ data buffer zones with a 10 km radius, showing ‘high-priority
spatial gaps’ as it would imply collecting of surveyed (not collected) of oregano populations
located out of buffer zones with a 10 km radius from the ex situ present point represented in
the AGB database (Figure 2) Presence of oregano populations (external data) out of zones
with a 10 km radius (ex situ data) increased the difficulties of trying and collecting of those
oregano populations.
Results of the study show the total number of priority sites (54 sites) includes external and ex
situ data for all Albanian territory. Higher number of priority sites (38 sites) were observed at
the SH, KU, GJ and EL district areas. The concentration of priority sites (70%) only in four
districts (SH, KU, GJ and EL) suggests in these areas the possible priority sites can be used to
increase size of oregano collection, and the priority of genebank is to identify the real
Proceedings of the 8th CMAPSEEC
Section I "MAP diversity at all levels and tools for its evaluation" Page 64
geographic position of these priority sites. Identification of priority sites increases the
effectiveness of collecting missions in these four district areas having the possibility to
increase (ideally) the potential size of oregano (O. vulgare L.) collection with 32 – 33% (ratio
between priority sites and total present points).
Figure 2. Geographic distribution map, mid-priority and high-priority spatial gaps of oregano
(Origanum vulgare L.)
Cluster analysis on correlation: Cluster analysis method using similarity and correlation
matrix data proved the presence of similarity among areas where oregano populations, mid-
priority, and high-priority gaps were observed.
Figure 3. Cluster dendrogram and similarity indices among oregano district areas observation
Proceedings of the 8th CMAPSEEC
Section I "MAP diversity at all levels and tools for its evaluation" Page 65
Cluster dendrogram show clearly similarity among KU and SH districts, DI and GJ, FR and
VL, LE and TR district areas (Figure 3). For all observed areas the similarity matrix indices
range from 72 to 95.9 and coefficient of correlation (r) range from 0.48 in cluster 2 to 0.96 in
cluster 9. Low similarity and higher distances was among BR and DI counties (distance index
28.00, similarity index 72.00)
CONCLUSION
o Ex situ collection of oregano (Origanum vulgare L.) stored in Albanian genebank
represent 61.5% of potential size of oregano collection.
o The study identified the areas with higher richness of oregano populations were KU,
SH, DI and GJ districts. The areas with mid-priority spatial gaps were VL, EL, FR
and SH districts, the areas with high-priority spatial gaps were TR, VL, GJ, KU, SH,
and EL districts.
o Higher number of priority sites were observed at the SH, KU, GJ and EL district
areas. The concentration of priority sites (70%) only in four districts suggests in these
areas the possible priority sites can be used to increase size of ex situ oregano
collection.
o Application of GIS tools and gap detection methodology can improve
representativeness of gene-bank collections through identifying prioritized collecting
sites and potential priority areas for in situ conservation.
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