Synapsis and recombination in intra- and interspecies hybrids between two voles species Microtus (Alexandromys)

Long way to speciation (in case of parapatry)

Interpopulation hybrids A x E ♂ (2n=38) reveals the types of

Interpopulation hybrids A x E ♂ (2n=38) show normal synapsis and

Interpopulation hybrids A x C ♂ (2n=36) show normal synapsis and

Chromosome shuffling: Robertsonian fusions followed by inversions

Interspecies hybrids M x E ♂ (2n=40) are sterile

Interpopulation hybrids are

Interspecies hybrids show sex difference in synapsis and crossingover suppression

Gene flow between populations is suppressed

E

A

C

Gene flow between species is blocked via males, severely suppressed via

Parental species vs Interspecies hybrids

SYCP3
RAD51

SYCP3
γH2A.X
centromere

Caryotype polymorphism of the parental species

A. maximowiczii

A. ev. evoronensis

XY

XY

SYCP3
MLH1
centromere

Interpopulation hybrids show transient inactivation of asynapsed regions

SYCP3
γH2A.X
centromere

XY

A x C ♂
(2n=36)

A

E

A

C

M

Parental species:
A ♂
#11: 22.0±1.4
#12: 21.5±1.8
E ♂
#17: 22.1±1.1
#18: 22.0±1.2
M ♂
#19: 25.0±1.2
#20: 25.0±1.3

M

Interpopulation

Interspecies hybrids M x E ♂ (2n=40) are sterile

Interpopulation hybrids are