Because of urbanization, snakes are more prone to inbreed and lose their ability to adapt


Fig 1. Map the studied populations of Notechis scutatus occidentalis and land-use of Perth, Western Australia. Red points represent individual Western tiger snakes, and yellow points represent Eastern tiger snakes Notechis scutatus scutatus). Gray shading represents the current distribution extent of the species (light = Western, dark = Eastern; modified from the IUCN Red List of Threatened Species [37]). Land-use was classified by the 2016 Australian Land Use and Management Classification. Credit: Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra. CC BY 3.0
Fig 1. Map the studied populations of Notechis scutatus occidentalis and land-use of Perth, Western Australia. Red points represent individual Western tiger snakes, and yellow points represent Eastern tiger snakes Notechis scutatus scutatus). Gray shading represents the current distribution extent of the species (light = Western, dark = Eastern; modified from the IUCN Red List of Threatened Species [37]). Land-use was classified by the 2016 Australian Land Use and Management Classification. Credit: Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra. CC BY 3.0

According to Curtin University research, isolated Perth tiger snake groups, such as those surrounded by urban development or seawater, are more prone to resort to inbreeding than ones that are less "shut off."


A research team led by Ph.D. candidate Mr. Damian Lettoof and project supervisor Research Associate Dr. Brenton von Takach from Curtin's School of Molecular and Life Sciences discovered that more geographically isolated Western tiger snake populations were less genetically varied than expected. Mr. Lettoof explained that the study focused on six tiger snake populations spread across the Swan Coastal Plain and one offshore island. Tiger snake populations north of the Perth rivers, such as Herdsman Lake, Lake Joondalup, and Yanchep National Park, were found to be genetically diverse, whereas wetlands south of the Swan/Canning River system were found to be the most genetically diverse, indicating that they were less prone to inbreeding.


If tiger snake populations are isolated by urbanization, they may lose their ability to adapt in order to withstand ever-changing conditions caused by development, pollution, and climate change. Mr. Lettoof stated that populations north of the Perth rivers have lower genetic diversity, most likely due to a long history of isolation from the rest of the species' larger population.


According to Mr. Lettoof, this is most likely due to their inability to transverse unsuitable habitats such as huge rivers, desert areas, and now the urban landscape. Tiger snakes are near the top of the food chain and have extremely precise ecological requirements, therefore a wetland with a snake population deficient in genetic variety was indicative of an unhealthy or under-functioning ecosystem.


This means that many other small species, such as frogs, lizards, and fish, who live in these wetlands that are rapidly being 'cut off' by urban development, maybe suffer and be at risk of population reduction, extinction, or both. This research shows that bigger wetlands encroached upon by development, like as those on the Swan coastal plain, should be managed as 'islands' of urban biodiversity to conserve the animal groups that occupy there.


Journal Information: Damian C. Lettoof et al, Bioindicator snake shows genomic signatures of natural and anthropogenic barriers to gene flow, PLOS ONE (2021). DOI: 10.1371/journal.pone.0259124

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