Reproductive systems and evolution in vascular plants

Differences in the frequency with which offspring are produced asexually, through self-fertilization and through sexual outcrossing, are a predominant influence on the genetic structure of plant populations. Selfers and asexuals have fewer genotypes within populations than outcrossers with similar allele frequencies, and more genetic diversity in selfers and asexuals is a result of differences among populations than in sexual outcrossers. As a result of reduced levels of diversity, selfers and asexuals may be less able to respond adaptively to changing environments, and because genotypes are not mixed across family lineages, their populations may accumulate deleterious mutations more rapidly. Such differences suggest that selfing and asexual lineages may be evolutionarily short-lived and could explain why they often seem to be of recent origin. Nonetheless, the origin and maintenance of different reproductive modes must be linked to individual-level properties of survival and reproduction. Sexual outcrossers suffer from a cost of outcrossing that arises because they do not contribute to selfed or asexual progeny, whereas selfers and asexuals may contribute to outcrossed progeny. Selfing and asexual reproduction also may allow reproduction when circumstances reduce opportunities for a union of gametes produced by different individuals, a phenomenon known as reproductive assurance. Both the cost of outcrossing and reproductive assurance lead to an over-representation of selfers and asexuals in newly formed progeny, and unless sexual outcrossers are more likely to survive and reproduce, they eventually will be displaced from populations in which a selfing or asexual variant arises.     

Robotic harvest of the latissimus dorsi muscle: laboratory and clinical experience

Minimally invasive harvest of the latissimus dorsi (LD) muscle is a desirable goal because of both the wide utility of this muscle and the length of incision required to harvest it. In this study, robotic harvest of the LD muscle was evaluated in a cadaver model and clinical series. Ten LD flaps were robotically harvested in eight cadavers. Positioning, port placement, procedural steps, instrumentation, and technical obstacles were all critically analyzed and reported. After modifying the technique based on experience gained in the cadaver study, eight LD muscles were robotically harvested and transferred in eight patients. Access included a short axillary incision and two additional port sites along the anterior border of the muscle. Insufflation was used to maintain the optical cavity. Indications included pedicled flaps for implant-based breast reconstruction and free flaps for scalp reconstruction. All flaps were successfully transferred without converting to open technique. In the clinical series, average time for setup and port placement was 23 minutes, and average robotic time was 1 hour and 51 minutes. There were no major complications. Robotic harvest of the LD is feasible and effective and permits full muscle harvest without a visible incision.