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Variation and genetic structure in Platanus mexicana (Platanaceae) along riparian altitudinal gradient.

Galván-Hernández DM, Lozada-García JA, Flores-Estévez N, Galindo-González J, Vázquez-Torres SM - Int J Mol Sci (2015)

Bottom Line: However, studies on the altitudinal effect on genetic variation to riparian species are scarce.The genetic structuring resulted from limited gene flow and genetic drift.This research highlights its importance as a dominant species, and its ecological and evolutionary implications in altitudinal gradients of riparian ecosystems.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biotecnología y Ecología Aplicada (INBIOTECA), Universidad Veracruzana, Av. de las Culturas Veracruzanas No. 101 Col. Emiliano Zapata, Xalapa 91090, Mexico. dulcegalvn@yahoo.com.

ABSTRACT
Platanus mexicana is a dominant arboreal species of riparian ecosystems. These ecosystems are associated with altitudinal gradients that can generate genetic differences in the species, especially in the extremes of the distribution. However, studies on the altitudinal effect on genetic variation to riparian species are scarce. In Mexico, the population of P. mexicana along the Colipa River (Veracruz State) grows below its reported minimum altitude range, possibly the lowest where this tree grows. This suggests that altitude might be an important factor in population genetics differentiation. We examined the genetic variation and population structuring at four sites with different altitudes (70, 200, 600 and 1700 m a.s.l.) using ten inter-simple sequence repeats (ISSR) markers. The highest value for Shannon index and Nei's gene diversity was obtained at 1700 m a.s.l. (He = 0.27, Ne = 1.47, I = 0.42) and polymorphism reached the top value at the middle altitude (% p = 88.57). Analysis of molecular variance (AMOVA) and STRUCTURE analysis indicated intrapopulation genetic differentiation. The arithmetic average (UPGMA) dendrogram identified 70 m a.s.l. as the most genetically distant site. The genetic structuring resulted from limited gene flow and genetic drift. This is the first report of genetic variation in populations of P. mexicana in Mexico. This research highlights its importance as a dominant species, and its ecological and evolutionary implications in altitudinal gradients of riparian ecosystems.

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UPGMA diagram based on Nei’s genetic distances for P. mexicana on the Colipa River, Veracruz, Mexico.
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ijms-16-02066-f001: UPGMA diagram based on Nei’s genetic distances for P. mexicana on the Colipa River, Veracruz, Mexico.

Mentions: The AMOVA analysis corroborated the genetic structure, the value of ΦST that represents the genetic differentiation among sites was 0.2 (p = 0.001); the main variation component (80%) was attributable within sites. Paired AMOVA showed the existing differentiation between sites mainly between 70 m a.s.l. and the others elevations (Table 3). A UPGMA dendrogram (Figure 1) based on Nei’s genetic distances exhibited three groups; one formed by the intermediate sites between 200 and 600 m a.s.l., (0.034), followed by the site at 1700 m a.s.l. (0.05) and the most distant being the site at the lowest altitude 70 m a.s.l., (0.058). The most likely number of clusters (K) in STRUCTURE was determined using the ΔK method. We assumed K = 8 as the best model that explains the genetic structure of P. mexicana population in the Colipa river (Figure 2) (See Supplementary Table S1) where well-defined altitude groups are observed. This suggests strong intra-population genetic differentiation. The Mantel test revealed that the pairwise ΦST are not correlated with geographic distances (r = 0.44, Z = 20.98, p = 0.251) and so the hypothesis of isolation due to distance was discarded.


Variation and genetic structure in Platanus mexicana (Platanaceae) along riparian altitudinal gradient.

Galván-Hernández DM, Lozada-García JA, Flores-Estévez N, Galindo-González J, Vázquez-Torres SM - Int J Mol Sci (2015)

UPGMA diagram based on Nei’s genetic distances for P. mexicana on the Colipa River, Veracruz, Mexico.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4307349&req=5

ijms-16-02066-f001: UPGMA diagram based on Nei’s genetic distances for P. mexicana on the Colipa River, Veracruz, Mexico.
Mentions: The AMOVA analysis corroborated the genetic structure, the value of ΦST that represents the genetic differentiation among sites was 0.2 (p = 0.001); the main variation component (80%) was attributable within sites. Paired AMOVA showed the existing differentiation between sites mainly between 70 m a.s.l. and the others elevations (Table 3). A UPGMA dendrogram (Figure 1) based on Nei’s genetic distances exhibited three groups; one formed by the intermediate sites between 200 and 600 m a.s.l., (0.034), followed by the site at 1700 m a.s.l. (0.05) and the most distant being the site at the lowest altitude 70 m a.s.l., (0.058). The most likely number of clusters (K) in STRUCTURE was determined using the ΔK method. We assumed K = 8 as the best model that explains the genetic structure of P. mexicana population in the Colipa river (Figure 2) (See Supplementary Table S1) where well-defined altitude groups are observed. This suggests strong intra-population genetic differentiation. The Mantel test revealed that the pairwise ΦST are not correlated with geographic distances (r = 0.44, Z = 20.98, p = 0.251) and so the hypothesis of isolation due to distance was discarded.

Bottom Line: However, studies on the altitudinal effect on genetic variation to riparian species are scarce.The genetic structuring resulted from limited gene flow and genetic drift.This research highlights its importance as a dominant species, and its ecological and evolutionary implications in altitudinal gradients of riparian ecosystems.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biotecnología y Ecología Aplicada (INBIOTECA), Universidad Veracruzana, Av. de las Culturas Veracruzanas No. 101 Col. Emiliano Zapata, Xalapa 91090, Mexico. dulcegalvn@yahoo.com.

ABSTRACT
Platanus mexicana is a dominant arboreal species of riparian ecosystems. These ecosystems are associated with altitudinal gradients that can generate genetic differences in the species, especially in the extremes of the distribution. However, studies on the altitudinal effect on genetic variation to riparian species are scarce. In Mexico, the population of P. mexicana along the Colipa River (Veracruz State) grows below its reported minimum altitude range, possibly the lowest where this tree grows. This suggests that altitude might be an important factor in population genetics differentiation. We examined the genetic variation and population structuring at four sites with different altitudes (70, 200, 600 and 1700 m a.s.l.) using ten inter-simple sequence repeats (ISSR) markers. The highest value for Shannon index and Nei's gene diversity was obtained at 1700 m a.s.l. (He = 0.27, Ne = 1.47, I = 0.42) and polymorphism reached the top value at the middle altitude (% p = 88.57). Analysis of molecular variance (AMOVA) and STRUCTURE analysis indicated intrapopulation genetic differentiation. The arithmetic average (UPGMA) dendrogram identified 70 m a.s.l. as the most genetically distant site. The genetic structuring resulted from limited gene flow and genetic drift. This is the first report of genetic variation in populations of P. mexicana in Mexico. This research highlights its importance as a dominant species, and its ecological and evolutionary implications in altitudinal gradients of riparian ecosystems.

Show MeSH