Ancestral-area algorithms are unreliable.

Area of Science:

• Phylogenetics and Biogeography
• Computational Systematics
• Evolutionary Biology

Background:

• Current ancestral-area algorithms often misinterpret standard phylogenetic-biogeographic patterns.
• Patterns like basal paraphyletic grades and star patterns are frequently localized to overlap regions by these algorithms.
• This interpretation overlooks alternative explanations such as vicariance followed by range expansion.

Purpose of the Study:

• To re-evaluate the interpretation of common phylogenetic-biogeographic patterns by ancestral-area algorithms.
• To propose a simpler, more robust method for inferring biogeographic histories from clade distributions.
• To distinguish between primary clade overlap (sympatry) and secondary clade overlap.

Main Methods:

• Examination of two standard phylogenetic-biogeographic patterns: basal paraphyletic grades and star patterns.
• Critique of ancestral-area algorithm outputs versus alternative explanations (vicariance and dispersal).
• Direct analysis of distributional relationships among clade localities, emphasizing geometric features like allopatry and overlap.

Main Results:

• Ancestral-area algorithms incorrectly infer centers of origin in overlap regions for both examined patterns.
• Both patterns can be explained by vicariance leading to allopatry, followed by range expansion causing overlap.
• Overlap regions are often secondary expansions, not primary centers of origin for widespread ancestors.

Conclusions:

• A proposed method, 'allopatry indicates vicariance; overlap indicates dispersal,' offers a simpler explanation for distribution patterns.
• This approach re-interprets overlap regions as phylogenetic-biogeographic breaks (nodes) in widespread ancestors.
• Mapping clade distributions directly reveals patterns missed by current algorithms, providing clearer biogeographic histories.