Jhan C. Salazar | Adam C. Algar | Steven Poe | Jonathan B. Losos | Julián A. Velasco

Abstract

Aim: The evolution of montane species provides critical insights into the drivers of adaptation and diversification. Topographiccomplexity, a defining feature of many mountainous landscapes, promotes ecological and geographic isolation, often acceleratingspeciation rates. However, the extent to which topographic complexity directly shapes diversification remains unresolved. Here,we investigate the evolutionary dynamics of Anolis lizards across Neotropical mountain ranges to test two hypotheses: (1) higherelevation environments promote higher speciation rates in species that inhabit them; and (2) greater topographic complexity andclimatic stability (i.e., lower past climatic-change velocity) positively influence speciation rates.

Location: The Americas.

Time Period: Present.

Major Taxa Studied: Anolis lizards.

Methods: We gathered topographic complexity and past climatic-change velocity data for 303 anole species and performed phy-logenetic analyses to assess how speciation rates change across mountain ranges in the Americas.

Results: We found that topographic complexity and past climatic-change velocity do not significantly influence speciation rates,diverging from prior studies that link rugged landscapes or past climatic-change velocity to high diversification rates.

Main Conclusions: Our findings challenge assumptions about the direct role of topographic complexity in speciation, high-lighting the need to consider multifaceted ecological and biogeographical factors driving evolutionary processes. By disentan-gling the relative contributions of climatic stability (i.e., lower past climatic-change velocity) and topographic heterogeneity, thisstudy highlights the complex dynamics shaping biodiversity in tropical mountains and calls for further integrative approaches tounderstand species diversification in the face of climatic and geological change.