Aliger gigas is an economically important and vulnerable marine species. We present a new mitogenome of A. gigas from the Mexican Caribbean and use the eight publicly available Strombidae mitogenomes to analyze intra- and interspecific variation. We present the most complete phylogenomic understanding of Hypsogastropoda to date (17 superfamilies, 39 families, 85 genera, 109 species) to revisit the phylogenetic position of the Stromboidea and evaluate divergence times throughout the phylogeny. The A. gigas mitogenome comprises 15,460 bp including 13 PCGs, 22 tRNAs, and two rRNAs. Nucleotide diversity suggested divergence between the Mexican and Colombian lineages of A. gigas. Interspecific divergence showed high differentiation among Strombidae species and demonstrated a close relationship between A. gigas and Strombus pugilis, between Lambis lambis and Harpago chiragra, and among Tridentarius dentatus/Laevistrombus canarium/Ministrombus variabilis. At the intraspecific level, the gene showing the highest differentiation is ATP8 and the lowest is NAD4L, whereas at the interspecific level the NAD genes show the highest variation and the COX genes the lowest. Phylogenomic analyses confirm that Stromboidea belongs in the non-Latrogastropoda clade and includes Xenophoridea. The phylogenomic position of other superfamilies, including those of previously uncertain affiliation, is also discussed. Finally, our data indicated that Stromboidea diverged into two principal clades in the early Cretaceous while Strombidae diversified in the Paleocene, and lineage diversification within A. gigas took place in the Pleistocene.

We have examined the phylogeographical distribution of chloroplast DNA (cpDNA) lineages of Fouquieria columnaris (Kellogg) Kellogg ex Curran (Fouquieriaceae) in the Sonoran Desert, to understand how historical climatic and/or geological changes have influenced genetic patterns in the species. Using two chloroplast intergenic DNA spacers (psbJ-petA and ndhF-rpl32), we found low levels of nucleotide diversity (π = 0.0025) but high levels of haplotype diversity (h = 0.9339). Analysis of 28 haplotypes revealed four lineages, one belonging to the continental massif and three to the peninsula of Baja California. This structure may be explained and dated by three events: (1) formation of the Gulf of California during the late Miocene (7.24 Mya), (2) activity of the Tres Vírgenes volcanic field (1.20 Mya) and (3) opening of the mid-peninsula seaway during the late Pleistocene (1.53 Mya). Furthermore, the cpDNA lineages show evidence for population contraction during the Last Glacial Maximum, with a subsequent population expansion in the Holocene.

No abstract