The study of evolutionary rates dates back to the work of Simpson and Haldane in the 1940s. Smallmammals, especially Plio-Pleistocene arvicolids (voles and lemmings), are particularly suited for suchstudies because they have an unusually complete fossil record and exhibit significant evolutionarychange through time. In recent decades, arvicolids have been the focus of intensive research devoted tothe tempo and mode of evolutionary change and the identification of trends in dental evolution that canbe used to correlate and date fossil sites. These studies have raised interesting questions about whethervoles and lemmings had unique evolutionary trajectories, or show convergent evolutionary patterns withother hypsodont rodents. Here we review evolutionary patterns in selected arvicolid lineages andendemic Messinian murids (Mikrotia spp.) and discuss reasons for convergence in dental morphology inthese two groups of hypsodont rodents. The results substantiate previously detected patterns, but thelarger dataset shows that some trends are less regular than previous studies have suggested. With theexception of a pervasive and sustained trend towards increased hypsodonty, our results show that otherfeatures do not follow consistent patterns in all lineages, exhibiting a mosaic pattern comprising stasis,variable rate evolution and gradual unidirectional change through time. Evidence for higher evolutionaryrates is found in lineages apparently undergoing adaptations to new ecological niches. In the case ofMikrotia, Microtus voles and the water vole (MimomyseArvicola) lineage, a shift to a fossorial lifestyleappears to have been an important driving force in their evolution. For other characters, different causescan be invoked; for example a shift to a semi-aquatic lifestyle may be responsible for the trend towardsincreasing size in Arvicola. Biochronological application of the data should take into account thecomplexity and biases of the data.
|Numero di pagine||19|
|Rivista||Quaternary Science Reviews|
|Stato di pubblicazione||Published - 2014|
All Science Journal Classification (ASJC) codes
- Global and Planetary Change
- Ecology, Evolution, Behavior and Systematics