Editing Vole (section)

==Mating system==
Voles may be either monogamous or polygamous, which leads to differing patterns of [[mate choice]] and parental care. Environmental conditions play a large part in dictating which system is active in a given population. Voles live in colonies due to the young remaining in the family group for relatively long periods.<ref>{{cite journal |last1=Potapov |first1=M. |last2=Zadubrovskaya |first2=I. |last3=Zabudrovskii |first3=P. |last4=Potapova |first4=O. |last5=Eviskov |first5=V. |year=2011 |title=Mating Systems in the Steppe Lemming (''Lagurus lagurus'') and Narrow-Skulled Vole (''Microtus gregalis'') from the Northern Kulunda Steppe |journal=Russian Journal of Ecology |volume=43 |issue=1 |pages=40–44 |doi=10.1134/S1067413612010109 |s2cid=16261654 }}</ref> In the genus ''[[Microtus]]'', monogamy is preferred when resources are spatially homogeneous and population densities are low; where the opposites of both conditions are realized, polygamous tendencies arise.<ref name="St">{{cite journal |last1=Streatfeild |first1=C. |last2=Mabry |first2=K. |last3=Keane |first3=B. |last4=Crist |first4=T. |last5=Solomon |first5=N. |year=2011 |title=Intraspecific Variability in the Social and Genetic Mating System of Prairie Voles, ''Microtus ochrogaster'' |journal=Animal Behaviour |volume=82 |issue=6 |pages=1387–1398 |doi=10.1016/j.anbehav.2011.09.023 |s2cid=53257008 }}</ref> Vole [[mating system]]s are also sensitive to the [[operational sex ratio]] and tend toward monogamy when males and females are present in equal numbers. Where one sex is more numerous than the other, [[animal sexual behaviour#Polygamy|polygamy]] is more likely.<ref>{{cite journal |last1=Zhang |first1=J. |last2=Zhang |first2=Z. |year=2003 |title=Influence of Operational Sex Ratio and Density on the Copulatory Behaviour and Mating System of Brandt's Vole ''Microtus brandt'' |journal=Acta Theriologica |volume=48 |issue=3 |pages=335–346 |doi=10.1007/BF03194173 |s2cid=42697613 }}</ref> However the most marked effect on mating system is population density and these effects can take place both inter and intra-specifically.<ref name="St" />

Male voles are territorial and tend to include territories of several female voles when possible. Under these conditions polygyny exists and males offer little parental care.<ref>{{cite journal |last=Ostfeld |first=R. |year=1986 |title=Territoriality and Mating System of California Voles |journal=Journal of Animal Ecology |volume=55 |issue=2 |pages=691–706 |doi=10.2307/4748 |jstor=4748 |bibcode=1986JAnEc..55..691O }}</ref> Males mark and aggressively defend their territories since females prefer males with the most recent marking in a given area.<ref name="Park">{{cite journal |last1=Parker |first1=K. |last2=Phillips |first2=K. |last3=Lee |first3=T. |year=2001 |title=Development of Selective Partner Preferences in Captive Male and Female Meadow Voles, ''Microtus pennsylvanicus'' |journal=Animal Behaviour |volume=61 |issue=6 |pages=1217–1226 |doi=10.1006/anbe.2000.1707 |s2cid=36508541 }}</ref>

Voles prefer familiar mates through olfactory sensory exploitation. Monogamous voles prefer males who have yet to mate, while non-monogamous voles do not.<ref name="Salo">{{cite journal |last1=Salo |first1=A. |last2=Dewsbury |first2=D. |year=1995 |title=Three Experiments on Mate Choice in Meadow Voles (''Microtus pennsylvanicus'') |journal=Journal of Comparative Psychology |volume=109 |issue=1 |pages=42–46 |doi=10.1037/0735-7036.109.1.42 |pmid=7705059 }}</ref> Mate preference in voles develops through cohabitation in as little as 24 hours.<ref name="Park" /> This drives young male voles to show non-limiting preference toward female siblings. This is not inclusive to females' preference for males which may help to explain the absence of interbreeding indicators.{{clarify|date=May 2019}}

Although females show little territoriality, under pair bonding conditions they tend to show aggression toward other female voles.<ref name="Salo" /> This behavior is flexible as some ''[[Microtus]]'' females share dens during the winter months, perhaps to conserve heat and energy.<ref>{{cite journal |last1=Lambin |first1=X. |last2=Krebs |first2=C. |last3=Scott |first3=B. |year=1992 |title=Spacing Systems of the Tundra Vole (''Microtus oeconomus'') During the Breeding Season in Canada's Western Arctic |journal=Canadian Journal of Zoology |volume=70 |issue=10 |pages=2068–2072 |doi=10.1139/z92-278 }}</ref> Populations which are monogamous show relatively minor [[sexual dimorphism|size differences between genders]] compared with those using polygamous systems.<ref>{{cite journal |last1=Lee |first1=C. |last2=Chui |first2=C. |last3=Lin |first3=L. |last4=Lin |first4=Y. |year=2014 |title=Partner Preference and Mating System of the Taiwan Field Vole (Microtus kikuchii) |journal=Taiwania |volume=59 |issue=2 |pages=127–138 |doi=10.6165/tai.2014.59.127 }}</ref>

The grey-sided vole (''[[Myodes rufocanus]]'') exhibits male-biased dispersal as a means of avoiding incestuous matings.<ref name="pmid19140979">{{cite journal |vauthors=Ishibashi Y, Saitoh T |title=Role of male-biased dispersal in inbreeding avoidance in the grey-sided vole (Myodes rufocanus) |journal=Mol. Ecol. |volume=17 |issue=22 |pages=4887–96 |year=2008 |pmid=19140979 |doi=10.1111/j.1365-294X.2008.03969.x |bibcode=2008MolEc..17.4887I |s2cid=44992920 }}</ref>  Among those matings that involve inbreeding, the number of weaned juveniles in litters is significantly fewer than that from noninbred litters, due to [[inbreeding depression]].

Brandt's vole (''[[Lasiopodomys brandtii]]'') lives in groups that mainly consist of close relatives.  However, they show no sign of inbreeding.<ref name=Liu>{{cite journal |vauthors=Liu XH, Yue LF, Wang da W, Li N, Cong L |title=Inbreeding avoidance drives consistent variation of fine-scale genetic structure caused by dispersal in the seasonal mating system of Brandt's voles |journal=PLOS ONE |volume=8 |issue=3 |pages=e58101 |year=2013 |pmid=23516435 |pmc=3597616 |doi=10.1371/journal.pone.0058101 |bibcode=2013PLoSO...858101L |doi-access=free }}</ref>  The mating system of these voles involves a type of [[Polygyny in animals|polygyny]] for males and extra-group [[Polyandry in animals|polyandry]] for females.  This system increases the frequency of mating among distantly related individuals, and is achieved mainly by dispersal during the [[mating season]].<ref name=Liu />  Such a strategy is likely an adaptation to avoid the inbreeding depression that would be caused by expression of deleterious recessive alleles if close relatives mated.