The Landscape Genetics of Novel Environments: How Urban Environments Structure the Introduced Lizards of Honolulu

Abstract

Globalization has led to the unintended introduction of non-native species to novel environments. The urban landscape presents new challenges and opportunities for introduced species, but there is a lack of understanding about how these species interact with the urban environment and the timing in which those impacts may begin to manifest in genetic patterns. Our study investigated the landscape genetics of three well-established introduced reptile species on Oahu, HI; Anolis sagrei, Hemidactylus frenatus, and Phelsuma laticauda, with the goal of understanding the application of landscape genetics methods at small spatial and temporal scales and identifying what features of the urban landscape impact urban introduced species on Oahu.We collected approximately 100 individuals of each species, sampled primarily from a 10 x10 km area in urban Honolulu, and across the larger island. Using reduced representation sequencing and landscape genetic tools, we identified roads as barriers to gene flow for two of the three species, and urban land use and very dry to seasonally mesic climates as conducive to gene flow in both A. sagrei and P. laticauda. All three species had low genetic differentiation across the island, and limited evidence of isolation by distance in Honolulu, which accords with the fact that they are recent introductions. Genetic patterns and relationships were not the same across the three species, nor between Honolulu and Oahu. Our data shows weak support for human mediated jump dispersal at an island-wide scale, and diffusive dispersal at a city-wide scale, but we suspect these patterns are obscured by the lack of time since introduction. The analysis provides insights into the genetics of urban introduced species on Oahu, how they interact with their urban environment, and into the timescales with which landscape genetic patterns emerge across an urban landscape.