1. Appearance of Місrotus agrestis in the territory of Ukraine in the Middle Pleistocene
- Author
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Lilia Popova, Yevheniia Nezdolii, O. I. Krokhmal, and Leonid Rekovets
- Subjects
pleistocene ,arvalis-like voles ,microtus nivaloides ,m. agrestis ,Biology (General) ,QH301-705.5 ,Geology ,QE1-996.5 - Abstract
Morphometric study of Middle Pleistocene arvalis-like voles from the localities Ozerne 2, Morozivka 2 (Odesa Oblast), and Medzhybizh 1 (Khmelnitsky Oblast) confirms the close phylogenetic relations between Microtus nivaloides and M. agrestis. The time of the first appearance of M. agrestis was different in Central and Eastern Europe, Western Europe, and the Northern Black Sea region. The replacement of M. nivaloides with M. agrestis corresponds to phyletic speciation with different rates of the process within different parts of the (future) species range. Appearance of M. agrestis in Central Europe (Kozi Grzbiet) precedes the appearance of this species in Western Europe. Later, at the beginning of the Zavadivka stage, the species appears in the northern part of Eastern Europe. Then, in the second part of the Zavadivka stage of the Middle Pleistocene, the transition occurs in Ukraine (the Middle Southern Bug area). It is possible that the process of the replacement of M. nivaloides with M. agrestis in the south, in the Northern Black Sea region, was even more impeded. The Azov region was beyond the area of this transition, although it was the part of the range of M. nivaloides. An important factor that slowed down the emergence of M. agrestis in the south of Ukraine could be the positive correlation between body size and increasing water demand of M. agrestis with the increase of temperature. Here, in the southern periphery of the species range, a small form of M. agrestis existed during dry climatic stages. Some specimens of M. agrestis from Medzhybizh 1 were below the low limit of size variation of any recent population of the species. Further expansion to the south and to the east, towards more arid climatic conditions, could have led to further decrease in size in order to optimise water metabolism, which would conflict with other demands, such as competitive success and thermoregulation, and, respectively, could become non-adaptive. Fossil samples with morphology intermediate between M. nivaloides and M. agrestis (Morozivka 2) show that the processes of phyletic evolution rather than expansion is the most probable scenario of the appearance of M. agrestis in the territory of Ukraine.
- Published
- 2021
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