Limits...
Spatial Structure of Evolutionary Models of Dialects in Contact.

Murawaki Y - PLoS ONE (2015)

Bottom Line: We found that a group of dialects can be considered tree-like even if it has not evolved in a temporally tree-like manner but has a temporally invariant, spatially tree-like structure.In addition, the simulation experiments appear to reproduce unnatural results observed in reconstructed trees for real data.These results motivate further investigation into the spatial structure of the evolutionary history of dialect lexicons as well as other cultural characteristics.

View Article: PubMed Central - PubMed

Affiliation: Department of Advanced Information Technology, Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka, Japan.

ABSTRACT
Phylogenetic models, originally developed to demonstrate evolutionary biology, have been applied to a wide range of cultural data including natural language lexicons, manuscripts, folktales, material cultures, and religions. A fundamental question regarding the application of phylogenetic inference is whether trees are an appropriate approximation of cultural evolutionary history. Their validity in cultural applications has been scrutinized, particularly with respect to the lexicons of dialects in contact. Phylogenetic models organize evolutionary data into a series of branching events through time. However, branching events are typically not included in dialectological studies to interpret the distributions of lexical terms. Instead, dialectologists have offered spatial interpretations to represent lexical data. For example, new lexical items that emerge in a politico-cultural center are likely to spread to peripheries, but not vice versa. To explore the question of the tree model's validity, we present a simple simulation model in which dialects form a spatial network and share lexical items through contact rather than through common ancestors. We input several network topologies to the model to generate synthetic data. We then analyze the synthesized data using conventional phylogenetic techniques. We found that a group of dialects can be considered tree-like even if it has not evolved in a temporally tree-like manner but has a temporally invariant, spatially tree-like structure. In addition, the simulation experiments appear to reproduce unnatural results observed in reconstructed trees for real data. These results motivate further investigation into the spatial structure of the evolutionary history of dialect lexicons as well as other cultural characteristics.

No MeSH data available.


A diagram in which the distances between four nodes are decomposed.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4519344&req=5

pone.0134335.g009: A diagram in which the distances between four nodes are decomposed.

Mentions: We use phylogenetic methods to analyze the binary representations of dialects obtained through our simulations. Following [26], we first assess the degree to which the data follow a tree-like structure using the δ score [42]. We thus obtain a real number between 0 and 1 inclusive. Lower values indicate that the data are more tree-like. The basis of the δ score is a quartet of nodes x, y, u and v. Let dxy be the distance between x and y, and dxy∣uv = dxy + duv. Without loss of generality, we assume dxy∣uv ≤ dxu∣yv ≤ dxv∣yu and define δxyuv as follows:δxyuv=dxv/yu-dxu/yvdxv/yu-dxy/uv.Note that we set δxyuv = 0 if dxy∣uv = dxu∣yv = dxv∣yu. To illustrate the above, the distances between nodes can be decomposed as shown in Fig 9. The box indicates non-tree-likeness. Here l1 = dxv∣yu − dxy∣uv, l2 = dxv∣yu − dxu∣yv and δxyuv = l2/l1. The quartet is perfectly tree-like if l2 = 0. δxyuv is calculated for every possible quartet and is averaged to obtain the overall δ score.


Spatial Structure of Evolutionary Models of Dialects in Contact.

Murawaki Y - PLoS ONE (2015)

A diagram in which the distances between four nodes are decomposed.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4519344&req=5

pone.0134335.g009: A diagram in which the distances between four nodes are decomposed.
Mentions: We use phylogenetic methods to analyze the binary representations of dialects obtained through our simulations. Following [26], we first assess the degree to which the data follow a tree-like structure using the δ score [42]. We thus obtain a real number between 0 and 1 inclusive. Lower values indicate that the data are more tree-like. The basis of the δ score is a quartet of nodes x, y, u and v. Let dxy be the distance between x and y, and dxy∣uv = dxy + duv. Without loss of generality, we assume dxy∣uv ≤ dxu∣yv ≤ dxv∣yu and define δxyuv as follows:δxyuv=dxv/yu-dxu/yvdxv/yu-dxy/uv.Note that we set δxyuv = 0 if dxy∣uv = dxu∣yv = dxv∣yu. To illustrate the above, the distances between nodes can be decomposed as shown in Fig 9. The box indicates non-tree-likeness. Here l1 = dxv∣yu − dxy∣uv, l2 = dxv∣yu − dxu∣yv and δxyuv = l2/l1. The quartet is perfectly tree-like if l2 = 0. δxyuv is calculated for every possible quartet and is averaged to obtain the overall δ score.

Bottom Line: We found that a group of dialects can be considered tree-like even if it has not evolved in a temporally tree-like manner but has a temporally invariant, spatially tree-like structure.In addition, the simulation experiments appear to reproduce unnatural results observed in reconstructed trees for real data.These results motivate further investigation into the spatial structure of the evolutionary history of dialect lexicons as well as other cultural characteristics.

View Article: PubMed Central - PubMed

Affiliation: Department of Advanced Information Technology, Graduate School of Information Science and Electrical Engineering, Kyushu University, Fukuoka, Japan.

ABSTRACT
Phylogenetic models, originally developed to demonstrate evolutionary biology, have been applied to a wide range of cultural data including natural language lexicons, manuscripts, folktales, material cultures, and religions. A fundamental question regarding the application of phylogenetic inference is whether trees are an appropriate approximation of cultural evolutionary history. Their validity in cultural applications has been scrutinized, particularly with respect to the lexicons of dialects in contact. Phylogenetic models organize evolutionary data into a series of branching events through time. However, branching events are typically not included in dialectological studies to interpret the distributions of lexical terms. Instead, dialectologists have offered spatial interpretations to represent lexical data. For example, new lexical items that emerge in a politico-cultural center are likely to spread to peripheries, but not vice versa. To explore the question of the tree model's validity, we present a simple simulation model in which dialects form a spatial network and share lexical items through contact rather than through common ancestors. We input several network topologies to the model to generate synthetic data. We then analyze the synthesized data using conventional phylogenetic techniques. We found that a group of dialects can be considered tree-like even if it has not evolved in a temporally tree-like manner but has a temporally invariant, spatially tree-like structure. In addition, the simulation experiments appear to reproduce unnatural results observed in reconstructed trees for real data. These results motivate further investigation into the spatial structure of the evolutionary history of dialect lexicons as well as other cultural characteristics.

No MeSH data available.