Genome sequences and population genomics reveal climatic adaptation and genomic divergence between two closely related sweetgum species.

Understanding the genetic basis of population divergence and adaptation is an important goal in population genetics and evolutionary biology. However, the relative roles of demographic history, gene flow, and/or selective regime in driving genomic divergence, climatic adaptation, and speciation in non-model tree species are not yet fully understood. To address this issue, we generated whole-genome resequencing data of Liquidambar formosana and L. acalycina, which are broadly sympatric but altitudinally segregated in the Tertiary relict forests of subtropical China. We integrated genomic and environmental data to investigate the demographic history, genomic divergence, and climatic adaptation of these two sister species. We inferred a scenario of allopatric species divergence during the late Miocene, followed by secondary contact during the Holocene. We identified multiple genomic islands of elevated divergence that mainly evolved through divergence hitchhiking and recombination rate variation, likely fostered by long-term refugial isolation and recent differential introgression in low-recombination genomic regions. We also found some candidate genes with divergent selection signatures potentially involved in climatic adaptation and reproductive isolation. Our results contribute to a better understanding of how late Tertiary/Quaternary climatic change influenced speciation, genomic divergence, climatic adaptation, and introgressive hybridization in East Asia's Tertiary relict flora. In addition, they should facilitate future evolutionary, conservation genomics, and molecular breeding studies in Liquidambar, a genus of important medicinal and ornamental values.

Laparoscopic Duhamel Procedure with Ex-Anal Rectal Transection for Right-Sided Hirschsprung's Disease.

BACKGROUND: Increased defecation frequency and soiling are common complications of surgery for right-sided Hirschsprung's disease (HD). Though the laparoscopic Duhamel procedure is a favorable option in right-sided HD, the conventional laparoscopic technique is time consuming and has complications that are associated with the reservoir. In this study, we described a modified laparoscopic Duhamel technique with ex-anal rectal transection combined with the Deloyer's procedure for right-sided HD. MATERIALS AND METHODS: Between March 2010 and January 2015, 18 right-sided HD underwent this modified laparoscopic Duhamel procedure (MLDP). The main modifications were to mobilize the colon and to dissect the retrorectal space under laparoscopy, pull out, and transect ex-anally by using a linear stapling device through a transverse incision on posterior wall of the rectum. Seven age-matched patients who underwent a conventional laparoscopic Duhamel procedure (CLDP) between March 2008 and December 2010 were included as the control group. Demographics, surgical procedures, operative data, postoperative complications, and clinical outcomes were compared between these two groups. RESULTS: Operative time was significantly shorter in the MLDP group (150 minutes versus 195 minutes; P = .03). There was no significant difference in mean timespan to obtain a normal defecation frequency (3.8 months versus 3.6 months), incidence of soiling (11.1% versus 14.3%; P = .34), and constipation (5.6% versus 14.3%; P = .69). Pouchitis were not found in the MLDP group, whereas 2 patients in the CLDP group (28.6%) presented with pouchitis and intractable diarrhea, requiring spur division. The incidence of postoperative enterocolitis was not significantly different in the two groups (11.1% in MLDP versus 14.3% in CLDP; P = .68). All 22 patients had a normal defecation over 4 years of age. CONCLUSIONS: Laparoscopic Duhamel with ex-anal rectal transection is a simple, easy-to-learn, and effective procedure for right-sided HD. It has low postoperative pouchitis because of a short pouch.