Performance-related stress mediates the online control and integration of sequential movements.

The effects of stress on directing attention within performance have been broadly explained by self-focus and distraction perspectives, where stress causes attention to be drawn internally or toward the sources of worry, respectively. Recent studies that have adopted manual aiming under different levels of stress have illuminated our understanding of the stress-performance framework. The present study seeks to elaborate on this current trend by introducing a sequential task, where the integration of individual movement segments enhances the demands on preparation and control, and thus closely examines the explanatory power of the self-focus and distraction perspectives. This study involved executing aiming movements solely to one-target (1T), or continuing by extending (2TE) and reversing (2TR) the limb to a second target. Participants were instructed to simply execute rapid and accurate movements (low-stress), and additionally provided a socio-comparative stressor (high-stress). While there was no one- (1 T vs. 2TE) or two-target (1T vs. 2TR) advantage, there was a shorter movement time in the first segment of the one-target task that appeared to dissipate when under high-stress. In addition, the high-stress conditions caused shorter reaction and pause times, while the proportion of the sequence time decreased within the pause, but increased within the second segment. Consequently, the overall sequence time failed to differ between low- and high-stress. These findings indicate that the online control of movement is accommodated under high-stress. We suggest these procedures unfold following a primary focus to uphold the performance outcome. Thus, these findings appear to be consistent with the distraction perspective.

Mitochondrial Analysis of the Most Basal Canid Reveals Deep Divergence between Eastern and Western North American Gray Foxes (Urocyon spp.) and Ancient Roots in Pleistocene California.

Pleistocene aridification in central North America caused many temperate forest-associated vertebrates to split into eastern and western lineages. Such divisions can be cryptic when Holocene expansions have closed the gaps between once-disjunct ranges or when local morphological variation obscures deeper regional divergences. We investigated such cryptic divergence in the gray fox (Urocyon cinereoargenteus), the most basal extant canid in the world. We also investigated the phylogeography of this species and its diminutive relative, the island fox (U. littoralis), in California. The California Floristic Province was a significant source of Pleistocene diversification for a wide range of taxa and, we hypothesized, for the gray fox as well. Alternatively, gray foxes in California potentially reflected a recent Holocene expansion from further south. We sequenced mitochondrial DNA from 169 gray foxes from the southeastern and southwestern United States and 11 island foxes from three of the Channel Islands. We estimated a 1.3% sequence divergence in the cytochrome b gene between eastern and western foxes and used coalescent simulations to date the divergence to approximately 500,000 years before present (YBP), which is comparable to that between recognized sister species within the Canidae. Gray fox samples collected from throughout California exhibited high haplotype diversity, phylogeographic structure, and genetic signatures of a late-Holocene population decline. Bayesian skyline analysis also indicated an earlier population increase dating to the early Wisconsin glaciation (~70,000 YBP) and a root height extending back to the previous interglacial (~100,000 YBP). Together these findings support California's role as a long-term Pleistocene refugium for western Urocyon. Lastly, based both on our results and re-interpretation of those of another study, we conclude that island foxes of the Channel Islands trace their origins to at least 3 distinct female founders from the mainland rather than to a single matriline, as previously suggested.

Chromosomal variation and perinatal mortality in San Diego zoo Soemmerring's gazelles.

Chromosomal translocations play a fundamental role in the evolution and speciation of antelopes (Antilopinae, Bovidae), with several species exhibiting polymorphism for centric fusions. For the past 35 years, the San Diego Zoo Global (SDZG) captive population of Soemmerring's gazelles has revealed complex karyotypes resulting from chromosomal translocations with diploid numbers ranging from 34 to 39. Poor reproductive performance of this species in captivity and elevated mortality the first month of life (perinatal) has been attributed to this chromosomal dynamism. We have extended the studies of karyotypic variation in the SDZG Soemmerring's gazelle population and analyzed the effect of chromosomal and genetic variation upon perinatal mortality. Karyotypes from 149 captive Soemmerring's gazelles were evaluated revealing two unreported autosomal combinations, now constituting a total of 15 distinct karyotypes for the 3 Robertsonian centric fusions originally described for this population. Among SDZG founders, distinct chromosomal variation and nuclear and mitochondrial genetic structure were detected corresponding to the institution of origin of the founders. Low levels of genetic distance and nucleotide diversity among individuals, in addition to high relatedness values, suggested that outbreeding is less of a concern than inbreeding for maintaining a sustainable captive population. Finally, analysis of karyotypes of offspring born into the SDZG Soemmerring's gazelle herds, in conjunction with the maternal karyotype showed association of chromosomal makeup with perinatal mortality. This supports the importance of continuing cytogenetic screening efforts, particularly to evaluate the presence of deleterious chromosomal rearrangements in stillborns.