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Ecological speciation in Nolina parviflora (Asparagaceae): lacking spatial connectivity along of the Trans-Mexican Volcanic Belt.

Ruiz-Sanchez E, Specht CD - PLoS ONE (2014)

Bottom Line: Using species distribution models, climatic analyses, spatial connectivity and morphological comparisons, we found significant differences in climatic and morphological variables between populations of N. parviflora in two distinct Trans-Mexican Volcanic Belt regions (east vs. west).Spatial connectivity analysis revealed no connectivity between these regions under the present or last glacial maximum climate models, indicating a lack of gene flow between the populations of the two regions.The results imply that these populations may encompass more than a single species.

View Article: PubMed Central - PubMed

Affiliation: Red de Biodiversidad y Sistemática, Centro Regional de Bajío, Instituto de Ecología AC, Pátzcuaro, Michoacán, Mexico.

ABSTRACT
The hypothesis of ecological speciation states that as populations diverge in different niches, reproductive isolation evolves as a by-product of adaptation to these different environments. In this context, we used Nolina parviflora as a model to test if this species evolved via ecological speciation and to explore current and historical gene flow among its populations. Nolina parviflora is a montane species endemic to Mexico with its geographical distribution restricted largely to the Trans-Mexican Volcanic Belt. This mountain range is one of the most complex geological regions in Mexico, having undergone volcanism from the mid-Miocene to the present. Ecologically, the Trans-Mexican Volcanic Belt possesses different types of vegetation, including tropical dry forest; oak, pine, pine-oak, and pine-juniper forests; and xerophytic scrub--all of which maintain populations of N. parviflora. Using species distribution models, climatic analyses, spatial connectivity and morphological comparisons, we found significant differences in climatic and morphological variables between populations of N. parviflora in two distinct Trans-Mexican Volcanic Belt regions (east vs. west). This could mean that the geographically isolated populations diverged from one another via niche divergence, indicating ecological speciation. Spatial connectivity analysis revealed no connectivity between these regions under the present or last glacial maximum climate models, indicating a lack of gene flow between the populations of the two regions. The results imply that these populations may encompass more than a single species.

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Related in: MedlinePlus

Connectivity maps among populations (black circles) for Nolina parviflora.A  =  current environment, B  =  Last Glacial Maximum under the CCSM model, and C  =  Last Glacial Maximum under the MIROC model. Blue and light shades of blue indicate areas with higher current density; areas where connectivity is most tenuous are shown in yellow to red colours.
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pone-0098754-g004: Connectivity maps among populations (black circles) for Nolina parviflora.A  =  current environment, B  =  Last Glacial Maximum under the CCSM model, and C  =  Last Glacial Maximum under the MIROC model. Blue and light shades of blue indicate areas with higher current density; areas where connectivity is most tenuous are shown in yellow to red colours.

Mentions: Climatic spatial resistance surfaces (present, CCSM and MIROC) showed connectivity corridors between neighbouring populations in the easternmost part of the TMVB (populations 4–6; 7–10; 11,12,13–22) for present day conditions (Fig. 4A) and during the last glacial maximum (CCSM; Fig. 4B, MIROC; Fig 4C); but no connectivity was detected between the populations of the eastern and western regions, and likewise no connectivity was maintained between the populations of the western region (Fig. 4) for any of the three climatic spatial resistance surfaces (Fig. 4A,B,C). Spatial genetic correlations showed significant positive correlations between both genetic FST/(1-FST) pairwise distances and spatial resistance distances among populations in the current or LGM models (present: r = 0.27; P = 0.005; CCSM: r = 0.52; P = 0.001 MIROC: r = 0.28; P = 0.004).


Ecological speciation in Nolina parviflora (Asparagaceae): lacking spatial connectivity along of the Trans-Mexican Volcanic Belt.

Ruiz-Sanchez E, Specht CD - PLoS ONE (2014)

Connectivity maps among populations (black circles) for Nolina parviflora.A  =  current environment, B  =  Last Glacial Maximum under the CCSM model, and C  =  Last Glacial Maximum under the MIROC model. Blue and light shades of blue indicate areas with higher current density; areas where connectivity is most tenuous are shown in yellow to red colours.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4048214&req=5

pone-0098754-g004: Connectivity maps among populations (black circles) for Nolina parviflora.A  =  current environment, B  =  Last Glacial Maximum under the CCSM model, and C  =  Last Glacial Maximum under the MIROC model. Blue and light shades of blue indicate areas with higher current density; areas where connectivity is most tenuous are shown in yellow to red colours.
Mentions: Climatic spatial resistance surfaces (present, CCSM and MIROC) showed connectivity corridors between neighbouring populations in the easternmost part of the TMVB (populations 4–6; 7–10; 11,12,13–22) for present day conditions (Fig. 4A) and during the last glacial maximum (CCSM; Fig. 4B, MIROC; Fig 4C); but no connectivity was detected between the populations of the eastern and western regions, and likewise no connectivity was maintained between the populations of the western region (Fig. 4) for any of the three climatic spatial resistance surfaces (Fig. 4A,B,C). Spatial genetic correlations showed significant positive correlations between both genetic FST/(1-FST) pairwise distances and spatial resistance distances among populations in the current or LGM models (present: r = 0.27; P = 0.005; CCSM: r = 0.52; P = 0.001 MIROC: r = 0.28; P = 0.004).

Bottom Line: Using species distribution models, climatic analyses, spatial connectivity and morphological comparisons, we found significant differences in climatic and morphological variables between populations of N. parviflora in two distinct Trans-Mexican Volcanic Belt regions (east vs. west).Spatial connectivity analysis revealed no connectivity between these regions under the present or last glacial maximum climate models, indicating a lack of gene flow between the populations of the two regions.The results imply that these populations may encompass more than a single species.

View Article: PubMed Central - PubMed

Affiliation: Red de Biodiversidad y Sistemática, Centro Regional de Bajío, Instituto de Ecología AC, Pátzcuaro, Michoacán, Mexico.

ABSTRACT
The hypothesis of ecological speciation states that as populations diverge in different niches, reproductive isolation evolves as a by-product of adaptation to these different environments. In this context, we used Nolina parviflora as a model to test if this species evolved via ecological speciation and to explore current and historical gene flow among its populations. Nolina parviflora is a montane species endemic to Mexico with its geographical distribution restricted largely to the Trans-Mexican Volcanic Belt. This mountain range is one of the most complex geological regions in Mexico, having undergone volcanism from the mid-Miocene to the present. Ecologically, the Trans-Mexican Volcanic Belt possesses different types of vegetation, including tropical dry forest; oak, pine, pine-oak, and pine-juniper forests; and xerophytic scrub--all of which maintain populations of N. parviflora. Using species distribution models, climatic analyses, spatial connectivity and morphological comparisons, we found significant differences in climatic and morphological variables between populations of N. parviflora in two distinct Trans-Mexican Volcanic Belt regions (east vs. west). This could mean that the geographically isolated populations diverged from one another via niche divergence, indicating ecological speciation. Spatial connectivity analysis revealed no connectivity between these regions under the present or last glacial maximum climate models, indicating a lack of gene flow between the populations of the two regions. The results imply that these populations may encompass more than a single species.

Show MeSH
Related in: MedlinePlus