Feline chimerism revealed by DNA profiling

In dogs and cats, unusual coat colour phenotypes may result from various phenomena, including chimerism. In the domestic cat, the tortoiseshell coat colour that combines red and non-red hairs is the most obvious way to identify chimeras in males. Several cases of tortoiseshell males have been reported, some of which were diagnosed as chimeras without any molecular confirmation. Here, we report the case of a female feline chimera identified thanks to its coat colour and confirmed through DNA profiling and a coat colour test. We ruled out the hypothesis of mosaicism and aneuploidy. All the data were consistent with a natural case of female chimerism.     

Genetic structure in Orkney island mice: isolation promotes morphological diversification

Following human occupation, the house mouse has colonised numerous islands, exposing the species to a wide variety of environments. Such a colonisation process, involving successive founder events and bottlenecks, may either promote random evolution or facilitate adaptation, making the relative importance of adaptive and stochastic processes in insular evolution difficult to assess. Here, we jointly analyse genetic and morphometric variation in the house mice (Mus musculus domesticus) from the Orkney archipelago. Genetic analyses, based on mitochondrial DNA and microsatellites, revealed considerable genetic structure within the archipelago, suggestive of a high degree of isolation and long-lasting stability of the insular populations. Morphometric analyses, based on a quantification of the shape of the first upper molar, revealed considerable differentiation compared to Western European populations, and significant geographic structure in Orkney, largely congruent with the pattern of genetic divergence. Morphological diversification in Orkney followed a Brownian motion model of evolution, suggesting a primary role for random drift over adaptation to local environments. Substantial structuring of human populations in Orkney has recently been demonstrated, mirroring the situation found here in house mice. This synanthropic species may thus constitute a bioproxy of human structure and practices even at a very local scale.Subject terms: Evolutionary ecology, Population genetics     

Adjustment of the fetal head and adult pelvis in modern humans

In nonhuman anthropoids, the anteroposterior (AP) diameters of the fetus are greater than the transverse (TR) diameters and the AP diameters of the pelvic planes are greater than the TR diameters: during labor, therefore, the fetus moves through the birth canal without changing position or orientation. In modern humans, the fetal head at term is encephalized and the fetal chest is flattened. The maternal pelvic inlet is flattened in an AP direction, the sacral promontory and the ischial spines are prominent. As a result, AP<TR at the inlet, but AP>TR at the midpelvis and outlet. In addition, the birth canal presents a marked sacral curvature in the AP direction. The human fetus successfully negotiates the birth canal because the three crucial fetal adaptations: (1) spheroidicity of the presenting part of the fetal head, which allows it to “roll” in the pelvis; (2) mobility of the head and chest in all directions; and (3) a capacity for cranial molding, which adapts fetal head dimensions to pelvic dimensions. The result is that the human fetal head and chest can perform multiple rotational movements in order to always present the greatest fetal diameters to the greatest pelvic diameters. Monkeys show a limited degree of encephalization and suffer from narrow TR pelvic diameters without any possibility of fetal adaptations as shown by humans. Apes also show some encephalization but, because of wider TR diameters in the pelvis, they achieve an easy delivery with no need of fetal adaptations.     

A comparative study of different populations of Mus musculus domesticus: emotivity as an index of adaptation to commensalism.

1. Emotivity is assessed by the amplitude of the corticoadrenal response to a novelty stress at three different seasons. 2. Commensal and outdoor populations of the house mouse are compared. 3. Outdoor mice display on one hand, lower mean levels of standard corticosterone, and on the other higher amplitude of response to the novelty stress when compared with the commensal mice. 4. Results are discussed in terms of divergent adaptive strategies of mice in respect with their social environment. 5. We underline the originality of the Robertsonian commensal population which displays a particular strategy consisting of a mix of outdoor and commensal traits.