Morphological Integration of the Mandible in Yellow-necked Field mice: The Effects of B Chromosomes

• Published in: Journal of mammalogy Vol. 88; no. 3; pp. 689 - 695
• Main Authors: JOJIC, Vida, BLAGOJEVIC, Jelena, IVANOVIC, Ana, BUGARSKI-STANOJEVIC, Vanja, VUJOSEVIC, Mladen
• Format: Journal Article
• Language: English
• Published: Provo, UT American Society of Mammalogists 01.06.2007; Brigham Young University, Department of Zoology; Oxford University Press
• Subjects: Animal ethology; Animal morphology; Apodemus flavicollis; B chromosomes; Biological and medical sciences; Biological evolution; Chromosome morphology; Chromosomes; Correlations; Environmental conditions; Evolutionary genetics; FEATURE ARTICLES; Fundamental and applied biological sciences. Psychology; Genetic engineering; Mammalia; Mandible; Mice; morphological integration; Phenotypic traits; Population density; Psychology. Psychoanalysis. Psychiatry; Quantitative genetics; Vertebrata; Vertebrata; Mandible; Mammalia; B chromosomes; Morphology; Rodentia; Chromosome; morphological integration; Apodemus flavicollis
• ISSN: 0022-2372; 1545-1542
• DOI: 10.1644/06-MAMM-A-019R1.1

As a complex skeletal organ consisting of 2 functional and developmental units (ascending ramus and alveolar region), the mandible represents a well-established model in morphological integration studies. The concept of morphological integration assumes that developmentally or functionally related traits are more correlated than others and hence evolve together. We compared the level and pattern of mandibular morphological integration between groups of adult yellow-necked field mice (Apodemus flavicollis), with and without B chromosomes (Bs) in a population from Mt. Avala, Serbia. Bs are dispensable supernumerary chromosomes characterized by irregular and non-Mendelian modes of inheritance. The level of morphological integration was higher in animals with Bs. One of the 2 regions of the mandible tested (alveolar region) was significantly more affected by the presence of Bs than the other, with an increase in intensity of integration of 41.61% versus 15.86%. The hypothesis of morphological integration, which postulates disunion of the mandible into 2 distinct functional and developmental modules, was confirmed in animals with Bs. Bs probably have a function because they affect mandible phenotype (although the mechanism is unknown), increase variability within populations, and could lead to selective advantage.