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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].



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



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].



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).



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


Section I "MAP diversity at all levels and tools for its evaluation" 4

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



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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