Juan Manuel López-Vivas

Post-Glacial Expansion and Population Genetic Divergence of Mangrove Species Avicennia germinans (L.) Stearn and Rhizophora mangle L. along the Mexican Coast

Mangrove forests in the Gulf of California, Mexico represent the northernmost populations along the Pacific coast and thus they are likely to be source populations for colonization at higher latitudes as climate becomes more favorable. Today, these populations are relatively small and fragmented and prior research has indicated that they are poor in genetic diversity. Here we set out to investigate whether the low diversity in this region was a result of recent colonization, or fragmentation and genetic drift of once more extensive mangroves due to climatic changes in the recent past. By sampling the two major mangrove species, Rhizophora mangle and Avicennia germinans, along the Pacific and Atlantic coasts of Mexico, we set out to test whether concordant genetic signals could elucidate recent evolution of the ecosystem. Genetic diversity of both mangrove species showed a decreasing trend toward northern latitudes along the Pacific coast. The lowest levels of genetic diversity were found at the range limits around the Gulf of California and the outer Baja California peninsula. Lack of a strong spatial genetic structure in this area and recent northern gene flow in A. germinans suggest recent colonization by this species. On the other hand, lack of a signal of recent northern dispersal in R. mangle, despite the higher dispersal capability of this species, indicates a longer presence of populations, at least in the southern Gulf of California. We suggest that the longer history, together with higher genetic diversity of R. mangle at the range limits, likely provides a gene pool better able to colonize northwards under climate change than A. germinans.

Taxonomic Reassessment of the Genus Padina (Dictyotales, Phaeophyta) from the Gulf of California

A monographic reassessment of Padina Adanson species from the Gulf of California was developed based on an exhaustive review of the character and characters states that have been used to delimit species in recent and historically valuable collections. Eight names (P. caulescens Thivy in Taylor, P. concrescens Thivy in Taylor, P. crispata Thivy in Taylor, P. durvillaei Bory Saint-Vincent, P. gymnospora [Kutzing] Sonder, P. mexicana Dawson, P. tetrastromatica Hauck and P. vickersiae Hoyt in Howe) were reported from the region. An analysis of 1,200 specimens led to the conclusion that only three species (P. durvillaei, P. concrescens and P. mexicana) can be recognized for the area based on four discriminating characters: presence of calcium carbonate in the cell wall; number of medullary cell layers in the basal area; number of medullary cell layers in the middle part and presence/absence of cortical cells. Comparative analysis of the species in the Gulf of California in relation to other recently evaluated species has shown a clear distinction among them suggesting Padina species were overestimated in our area.

Endemic Pyropia species (Bangiales, Rhodophyta) from the Gulf of California, Mexico

The evaluation of geographic distribution of Pyropia along the Gulf of California, Mexico, was realized using molecular data from two loci, the plastid rbcL gene and the partial 18S ribosomal DNA (rDNA), in conjunction with morphological observations. Dawson described two endemic species for the genus Pyropia (Pyropia hollenbergii and Pyropia pendula) in the Gulf of California based on taxonomic characteristics. In this study, we collected 130 samples from 13 locations from February 1998 to April 2008. Samples showed similar morphologies and growth habits and share a very similar type descriptions and habitat records. Using morphological and anatomical characteristics, we identify individuals as P. hollenbergii and P. pendula. However, using the molecular data, we identified five identities, which we have classified as P. hollenbergii, P. pendula, Pyropia sp. Gulf of California I (GCI), Pyropia sp. GCII, and Pyropia sp. GCIII. Phylogenetic trees based on partial 18S rDNA and rbcL sequence data showed a deep division in the genus that is not obviously correlated with existing morphological characteristics and indicate that representatives of the Gulf of California flora have undergone long reproductive isolation.

Range extension for Kallymenia spp. (Kallymeniaceae: Rhodophyta) associated with rhodolith beds, new records from the Gulf of California, México

Usually, Halymenia and Cryptonemia species have been reported as associated with rhodolith beds, but based on surveys of rhodolith beds and rocky areas along the Gulf of California (60 localities), in five localities we found the range extension (5 localities) of three other blade-like species, Kallymenia norrisii and K. oblongifructa previously reported on the North Pacific coast of California State (USA) and K. pertusa previously reported in the northern Gulf of California. The present study reports for the first time the presence of K. norrisii, K. oblongifructa and K. pertusa associated with rodolith beds. This suggests that the understanding of biodiversity of marine plants from the Gulf of California still needs attention, especially in deeper areas and habitats such as rhodolith beds.

New Record of the non-Native Seaweed Gracilaria parvispora in Baja California - A Note on Vergara-Rodarte et al. (2016)

Abstract The delimitation of species in the Gracilariales is often difficult due to the lack of diagnostic morphological characters. As a result, non-native species are often misidentified without the use of molecular tools. Recently, studies have investigated the agar quality of the dominant gracilarioid species in the Laguna San Ignacio in Baja Califronia Sur, Mexico, including Vergara-Rodarte et al., (2016) published in the May edition of Cryptogamie, Algologie. The species has been reported as Gracilaria pacifica, G. vermiculophylla and Gracilariopsis sp. Using a combination of three mitochondrial and plastid markers, we identified this species as G. parvispora, extending the known distribution of this non-native species in Baja California. Due to the potential of G. parvispora as a source of agar, more detailed studies of on the invasion history and surveys are necessary in the eastern Pacific to determine its current distribution and impacts on the native biodiversity.