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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

Potential distribution of Nolina parviflora identified using species distribution modelling (SDM).A  =  prediction of suitable habitat in the current environment. B  =  prediction projected onto the past climatic layers (LGM; CCSM), and C  =  prediction under past climatic conditions (LGM; MIROC). Blue colour indicates high probability of prediction of suitable habitat and red colour indicates areas with unsuitable habitat.
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pone-0098754-g003: Potential distribution of Nolina parviflora identified using species distribution modelling (SDM).A  =  prediction of suitable habitat in the current environment. B  =  prediction projected onto the past climatic layers (LGM; CCSM), and C  =  prediction under past climatic conditions (LGM; MIROC). Blue colour indicates high probability of prediction of suitable habitat and red colour indicates areas with unsuitable habitat.

Mentions: The modelled distribution (AUC = 0.991) corresponds to the known distribution of Nolina parviflora in the TMVB. The SDM for the ten current climate variables across all populations of N. parviflora predicted an accurate distribution of N. parviflora for the eastern region of the TMVB, but underpredicts the occurrence of populations in the western region of the TMVB (Fig. 3A). When the models were projected onto past climate (21K) layers, two different scenarios were retrieved (Fig. 3B, 3C). For the climate layers based on CCSM (Fig. 3B), a large area of suitable habitat is recovered in the east and easternmost region of the TMVB and extends to the western area of the TMVB beyond the current occurrence. Habitat with some suitability connects these areas. For the projections under MIROC (Fig. 3C) a much smaller area of suitable habitat is predicted and is located mostly in the eastern region, with no connection between the eastern and western predicted areas of suitable habitat (Fig. 3).


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

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

Potential distribution of Nolina parviflora identified using species distribution modelling (SDM).A  =  prediction of suitable habitat in the current environment. B  =  prediction projected onto the past climatic layers (LGM; CCSM), and C  =  prediction under past climatic conditions (LGM; MIROC). Blue colour indicates high probability of prediction of suitable habitat and red colour indicates areas with unsuitable habitat.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0098754-g003: Potential distribution of Nolina parviflora identified using species distribution modelling (SDM).A  =  prediction of suitable habitat in the current environment. B  =  prediction projected onto the past climatic layers (LGM; CCSM), and C  =  prediction under past climatic conditions (LGM; MIROC). Blue colour indicates high probability of prediction of suitable habitat and red colour indicates areas with unsuitable habitat.
Mentions: The modelled distribution (AUC = 0.991) corresponds to the known distribution of Nolina parviflora in the TMVB. The SDM for the ten current climate variables across all populations of N. parviflora predicted an accurate distribution of N. parviflora for the eastern region of the TMVB, but underpredicts the occurrence of populations in the western region of the TMVB (Fig. 3A). When the models were projected onto past climate (21K) layers, two different scenarios were retrieved (Fig. 3B, 3C). For the climate layers based on CCSM (Fig. 3B), a large area of suitable habitat is recovered in the east and easternmost region of the TMVB and extends to the western area of the TMVB beyond the current occurrence. Habitat with some suitability connects these areas. For the projections under MIROC (Fig. 3C) a much smaller area of suitable habitat is predicted and is located mostly in the eastern region, with no connection between the eastern and western predicted areas of suitable habitat (Fig. 3).

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