Coexistence of congeneric native and invasive species: The case of the green algae Codium spp. in northwestern Spain

We examined the patterns of distribution and abundance, and reproductive traits (presence of gametophytes and size at time of reproduction) in the invasive Codium fragile ssp. fragile and the native C. tomentosum and C. vermilara on intertidal habitats of NW Spain at two dates. All three species coexist in the locations and habitats studied, although abundances were low. We found a greater proportion of C. fragile ssp. fragile towards the east of the Cantabrian coast and on upper levels on the shore, where conditions are more stressful. The proportion of thalli bearing gametangia in C. fragile ssp. fragile was greater than in the native species in all habitats. The presence of gametangia was size-dependent for all species, with the invasive species maturing at a smaller size, which combined with the previous features, might confer competitive advantages to this species over the native species. We also demonstrated that molecular analyses are necessary for the correct identification of C. fragile subspecies.

The View from the Edge: The Proyecto Arqueológico Chihuahua (PAC) 1990 to 2010: An Overview

The work of the Proyecto Arqueológico Chihuahua (PAC) has played an integral role in defining the origins and characteristics of the Chihuahua culture area, also known as the Casas Grandes Regional System. PAC has developed a critical suite of radiocarbon dates for the southern zone, undertaken the first substantial investigations of the Viejo period (ca. A.D. 800textendash1200 or 1250) since the early 1960s, and added to knowledge of the southern Medio period (ca. A.D. 1250textendash1450). The project has also elucidated the chronology, settlement patterns, subsistence strategies, and technology for both periods. Results of our research indicate continuity between the Viejo period, characterized by small pithouse settlements, and the pueblo focused Medio period in the southern zone, with some poorly understood external influences from both western Mesoamerica to the south and the American Southwest to the north shaping events within the area.