as New Zealand (45°S) and as far north as Finland, Norway (60°N), and Saskatoon, Canada.
Their habitats spread over six continents including Asia, Europe, Africa, Oceania, North America, and South America. Thanks to this
cosmopolitan distribution, the International
Organization for Standardization (ISO) and the
Organization for Economic Co-operation and
Development (OECD) both use L. minor and
L .gibba in water quality and chemical safety
tests. L. minuta has a similar distribution pattern;
however, it is spread across a comparatively
smaller area. These three Lemna species are not
collected in typical tropical zones.
In contrast to L. minor and L. gibba,
L. aequinoctialis, L. valdiviana, and L. obscura
are mostly habituated in the tropical and subtropical areas between 35°N and 27°S. L. valdiviana and L. obscura are mainly distributed in
South America and North America, while
L. aequinoctialis is distributed more widely in
Asia, North America, South America, Africa, and
Europe. L. aequinoctialis has occasionally been
collected in high latitude in Europe, such as
France (45°N). L. tenera is a typical tropical
species and mainly located in Northern Australia
and Southeast Asia. L. trisulca is mainly distributed in the subtropical region of the northern
hemisphere; however, it is also collected in the
tropical region (Uganda and Kenya).
L. turionifera and L. perpusilla are mainly
distributed in the temperate zone of the northern
hemisphere in Asia and North America, while L.
yungensis and L. disperma are distributed in
small regions in South America and Oceania,
respectively. L. japonica is mainly located in
East Asia such as China and Japan. Some
accessions have been collected in Finland, Germany, and USA, but their identities have not
been confirmed by DNA barcodes.
There are ten species in the genus Wolffiella.
Most species in this genus have narrow distribution. They are mostly distributed in North and
South America and Africa in a latitude continuous pattern from the southern hemisphere to the
northern hemisphere. W. lingulata, W. oblonga,
and W. gladiate are collected from North
America, while W. lingulata, W. oblonga, W.
neotropica, W. welwitschii, and W. caudate are
collected from South America. W. welwitschii,
W. denticulate, W. repanda, W. hyalina, and W.
rotunda have been collected from Africa.
There are 11 species in the genus Wolffia;
they are mostly distributed in Asia, Europe,
North America, South America, Oceania, and
Africa. Similar to the genus Wolffiella, most
species in this genus distributed in a latitude
continuous pattern. W. arrhiza is the most widely
distributed species in this genus. It has been
collected from 50°N to 35°S in Asia, Europe,
Africa, and South America. W. columbiana and
W. brasiliensis are widely distributed in the
tropical and subtropical zones of North and
South America. W. elongate, W. neglecta,
W. globosa, W. microscopica, and W. borealis
are mainly located in the northern hemisphere,
while W. australiana and W. cylindracea are
mostly located in the southern hemisphere. W.
angusta is collected from both Australia and
Southeast Asia.
5.2 Population and Genetic
Diversity
Duckweeds often exist in bi- or tri-species
communities, although occasionally they can be
found in single or more complex communities
(Fig. 5.1). The presence or absence of a species
in a water body is largely determined by occasion
and has no significant relation to nitrate and
phosphate concentration and pH of the water
body (Xu et al. 2015). The genetic diversity in
populations of seven species in genus Lemna and
Spirodela from China and Vietnam was once
analyzed by ISSR-PCR. The genetic distance of
Lemna populations varied from 0.127 to 0.784
and from 0.138 to 0.902 for Spirodela (Xue et al.
2012). Clustering analysis indicated that the
geographic differentiation of collected sites correlated closely with the genetic differentiation of
duckweeds, suggesting that geographic differentiation had great influence on genetic diversity of
duckweeds.
5 Genetic Diversity and DNA Barcoding in the Duckweed Family
61
Their habitats spread over six continents including Asia, Europe, Africa, Oceania, North America, and South America. Thanks to this
cosmopolitan distribution, the International
Organization for Standardization (ISO) and the
Organization for Economic Co-operation and
Development (OECD) both use L. minor and
L .gibba in water quality and chemical safety
tests. L. minuta has a similar distribution pattern;
however, it is spread across a comparatively
smaller area. These three Lemna species are not
collected in typical tropical zones.
In contrast to L. minor and L. gibba,
L. aequinoctialis, L. valdiviana, and L. obscura
are mostly habituated in the tropical and subtropical areas between 35°N and 27°S. L. valdiviana and L. obscura are mainly distributed in
South America and North America, while
L. aequinoctialis is distributed more widely in
Asia, North America, South America, Africa, and
Europe. L. aequinoctialis has occasionally been
collected in high latitude in Europe, such as
France (45°N). L. tenera is a typical tropical
species and mainly located in Northern Australia
and Southeast Asia. L. trisulca is mainly distributed in the subtropical region of the northern
hemisphere; however, it is also collected in the
tropical region (Uganda and Kenya).
L. turionifera and L. perpusilla are mainly
distributed in the temperate zone of the northern
hemisphere in Asia and North America, while L.
yungensis and L. disperma are distributed in
small regions in South America and Oceania,
respectively. L. japonica is mainly located in
East Asia such as China and Japan. Some
accessions have been collected in Finland, Germany, and USA, but their identities have not
been confirmed by DNA barcodes.
There are ten species in the genus Wolffiella.
Most species in this genus have narrow distribution. They are mostly distributed in North and
South America and Africa in a latitude continuous pattern from the southern hemisphere to the
northern hemisphere. W. lingulata, W. oblonga,
and W. gladiate are collected from North
America, while W. lingulata, W. oblonga, W.
neotropica, W. welwitschii, and W. caudate are
collected from South America. W. welwitschii,
W. denticulate, W. repanda, W. hyalina, and W.
rotunda have been collected from Africa.
There are 11 species in the genus Wolffia;
they are mostly distributed in Asia, Europe,
North America, South America, Oceania, and
Africa. Similar to the genus Wolffiella, most
species in this genus distributed in a latitude
continuous pattern. W. arrhiza is the most widely
distributed species in this genus. It has been
collected from 50°N to 35°S in Asia, Europe,
Africa, and South America. W. columbiana and
W. brasiliensis are widely distributed in the
tropical and subtropical zones of North and
South America. W. elongate, W. neglecta,
W. globosa, W. microscopica, and W. borealis
are mainly located in the northern hemisphere,
while W. australiana and W. cylindracea are
mostly located in the southern hemisphere. W.
angusta is collected from both Australia and
Southeast Asia.
5.2 Population and Genetic
Diversity
Duckweeds often exist in bi- or tri-species
communities, although occasionally they can be
found in single or more complex communities
(Fig. 5.1). The presence or absence of a species
in a water body is largely determined by occasion
and has no significant relation to nitrate and
phosphate concentration and pH of the water
body (Xu et al. 2015). The genetic diversity in
populations of seven species in genus Lemna and
Spirodela from China and Vietnam was once
analyzed by ISSR-PCR. The genetic distance of
Lemna populations varied from 0.127 to 0.784
and from 0.138 to 0.902 for Spirodela (Xue et al.
2012). Clustering analysis indicated that the
geographic differentiation of collected sites correlated closely with the genetic differentiation of
duckweeds, suggesting that geographic differentiation had great influence on genetic diversity of
duckweeds.
5 Genetic Diversity and DNA Barcoding in the Duckweed Family
61