Publication
A landscape genetics approach to a contact zone of two salamandra salamandra subspecies in southwest Portugal
| Summary: | The fire salamander (Salamandra salamandra) is distributed in the center and south of Europe and has a high genetic and morphological variability. In Portugal there are two subspe-cies described, S. s. gallaica with a northern and central distribution and S. s crespoi with a more restricted distribution in the south. Defining the geographical boundaries between populations and subspecies is frequent-ly difficult because there are often uncertainties on their distribution limits at putative or proven contact areas. One approach being increasingly used to detect cryptic geographic boundaries between populations is landscape genetics. This is an emerging field that inte-grates population genetics, landscape ecology and spatial statistics and it aims to provide in-formation about the interaction between landscape features and microevolutionary processes. I attempted here to determine the geographic distribution and limits of the two aforemen-tioned subspecies at their putative contact zone in southwest Portugal, using data from mi-crosatellites and the mitochondrial gene cytochrome-b analysed with landscape genetics tools. This approach allowed evaluating if the two subspecies are currently in allopatry and the oc-currence of gene flow between them. Results show that the two subspecies are separated by a narrow barrier that contains the Sado River and imposes a very reduced gene flow, both contemporarily and historically, be-tween them. Currently, the most important feature of this barrier seems to be the area of sandy soil south of the Sado that was part of the riverbed of an extended river in historical times. Although both populations show signs that they have been large for some time, S. s. crespoi seems to have undergone a population expansion around 18,000 years BP. |
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| Main Authors: | Silva, Ana Catarina Afonso, 1988- |
| Subject: | Anfíbios - Portugal Salamandra - Portugal Variação genética Microsatélites |
| Year: | 2011 |
| Country: | Portugal |
| Document type: | master thesis |
| Access type: | open access |
| Associated institution: | Universidade de Lisboa |
| Language: | English |
| Origin: | Repositório da Universidade de Lisboa |
| Summary: | The fire salamander (Salamandra salamandra) is distributed in the center and south of Europe and has a high genetic and morphological variability. In Portugal there are two subspe-cies described, S. s. gallaica with a northern and central distribution and S. s crespoi with a more restricted distribution in the south. Defining the geographical boundaries between populations and subspecies is frequent-ly difficult because there are often uncertainties on their distribution limits at putative or proven contact areas. One approach being increasingly used to detect cryptic geographic boundaries between populations is landscape genetics. This is an emerging field that inte-grates population genetics, landscape ecology and spatial statistics and it aims to provide in-formation about the interaction between landscape features and microevolutionary processes. I attempted here to determine the geographic distribution and limits of the two aforemen-tioned subspecies at their putative contact zone in southwest Portugal, using data from mi-crosatellites and the mitochondrial gene cytochrome-b analysed with landscape genetics tools. This approach allowed evaluating if the two subspecies are currently in allopatry and the oc-currence of gene flow between them. Results show that the two subspecies are separated by a narrow barrier that contains the Sado River and imposes a very reduced gene flow, both contemporarily and historically, be-tween them. Currently, the most important feature of this barrier seems to be the area of sandy soil south of the Sado that was part of the riverbed of an extended river in historical times. Although both populations show signs that they have been large for some time, S. s. crespoi seems to have undergone a population expansion around 18,000 years BP. |
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