Chromosomal polymorphism plays a major role in speciation processes in mammals with high rates of karyotypic evolution, as observed in the family Cervidae. One remarkable example is the genus Mazama that comprises wide inter- and intra-specific chromosomal variability. To evaluate the impact of chromosomal polymorphisms as reproductive barriers within the genus Mazama, inter-specific hybrids between Mazama gouazoubira and Mazama nemorivaga (MGO × MNE) and intra-specific hybrids between cytotypes of Mazama americana (MAM) differing by a tandem (TF) or centric fusion (Robertsonian translocations—RT) were evaluated. MGO × MNE hybrid fertility was evaluated by the seminal quality and testicular histology. MAM hybrids estimation of the meiotic segregation products was performed by sperm-FISH analysis. MGO × MNE hybrids analyses showed different degrees of fertility reduction, from severe subfertility to complete sterility. Regarding MAM, RT, and TF carriers showed a mean value for alternate segregation rate of 97.74%, and 67.23%, and adjacent segregation rate of 1.80%, and 29.07%, respectively. Our results suggested an efficient post-zygotic barrier represented by severe fertility reduction for MGO × MNE and MAM with heterozygous TF. Nevertheless, RT did not show a severe effect on the reproductive fitness in MAM. Our data support the validity of MGO and MNE as different species and reveals cryptic species within MAM.

中文翻译：

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染色体多态性和形态：山az属（Cetartiodactyla； Cervidae）

如在鹿角科（Cervidae）中所观察到的，染色体多态性在具有高核型进化率的哺乳动物的物种形成过程中起着重要作用。一个显着的例子是Mazama属，它具有广泛的种间和种内特异性染色体变异性。为了评估染色体多态性作为Mazama属内生殖屏障的影响，Mazama gouazoubira和Mazama nemorivaga之间的种间杂种（MGO×MNE）和美洲Mazama细胞型之间的种内杂种（MAM）的区别在于串联（TF）或中心融合（Robertsonian易位-RT）。通过精液质量和睾丸组织学评估MGO×MNE杂交育性。通过精子-FISH分析进行减数分裂分离产物的MAM杂种估计。MGO×MNE杂种的分析显示，从严重的亚生育力到完全的不育，生育力的降低程度不同。关于MAM，RT和TF载波，交替分离率的平均值分别为97.74％和67.23％，相邻分离率分别为1.80％和29.07％。我们的结果表明，以杂合TF导致的MGO×MNE和MAM的严重生育力降低为代表的有效的合子后屏障。然而，放疗对MAM的生殖适应性没有严重影响。