Influence of physical environmental characteristics and anthropogenic factors on the position and structure of a contact zone between two chromosomal races of the house mouse on the island of Madeira (North Atlantic, Portugal)

• Published in: Journal of Biogeography
• Main Authors: Nunes, A. C., Britton‐Davidian, J., Catalan, J., Ramalhinho, M. G., Capela, R., Mathias, M. L., Ganem, G.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2005
• Subjects: North Atlantic
• Online Access: http://dx.doi.org/10.1111/j.1365-2699.2005.01337.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-2699.2005.01337.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2699.2005.01337.x

Abstract Aim This study aimed to investigate if and how environmental characteristics (physical factors of the natural environment and the human impact on the landscape) influence the position and structure of a contact zone between two chromosomal races of the house mouse ( Mus musculus domesticus Rutty 1712) from the island of Madeira. Location The western part of Madeira, a volcanic island in the North Atlantic. Methods Mice were sampled along a south/north‐western transect following the main road, in human‐modified outdoor habitats. Karyotypes of mice were determined using the yeast‐stimulated bone marrow cell method. Trapping sites were characterized in terms of their physical (altitude, temperature, precipitation and soil type) and habitat (human landscape use and occupancy) features. Demographic parameters of mouse populations, based on trapping‐with‐removal techniques, were also analysed (relative abundance, sex‐ratio, juvenile ratio and female fertility ratio), as well as body size (weight and length). Results Four chromosomal zones were identified on the basis of the frequency of two diagnostic rearrangements (Rb(6.7) in race E. Calheta and Rb(7.15) in race A. Cruz). E. Calheta was present in the two southern‐most zones, followed by the contact zone characterized by the presence of two inter‐racial hybrids and the co‐occurrence of mice belonging to the two races. The northern‐most part of the transect was occupied by A. Cruz. Environmental features differed leading us to split the transect into two parts. The southern part is characterized by lower altitude and precipitation, milder temperature, better soil quality supporting vegetable crops and vineyards, and more abundant and evenly distributed human habitats. This southern part is occupied by E. Calheta mice. The north‐western part presents characteristics opposite to those described above with cereals as the main cultivated crop, and it includes the contact zone as well as the zone inhabited by A. Cruz mice. The demographic parameters evaluated in ...