Phylogeography and bindin evolution in Arbacia, a sea urchin genus with an unusual distribution

Abstract

Among shallow water sea urchin genera, Arbacia is the only genus that contains species found in both high and low latitudes. In order to determine the geographical origin of the genus and its history of speciation events, we constructed phylogenies based on cytochrome oxidase I and sperm bindin from all its species. Both the mitochondrial and the nuclear gene genealogies show that Arbacia originated in the temperate zone of the Southern Hemisphere and gave rise to three species in the eastern Pacific, which were then isolated from the Atlantic by the Isthmus of Panama. The mid-Atlantic barrier separated two additional species. The bindin data suggest that selection against hybridization is not important in the evolution of this molecule in this genus. Metz et al. in a previous publication found no evidence of selection on bindin of Arbacia and suggested that this might be due to allopatry between species, which obviated the need for species recognition. This suggestion formed the basis of the conclusion, widely spread in the literature, that the source of selection on sea urchin bindin (where it does occur) was reinforcement. However, the range of Arbacia spatuligera overlaps with that of two other species of Arbacia, and our data show that it is hybridizing with one of them. We found that even in the species that overlap geographically, there are no deviations from selective neutrality in the evolution of bindin.

Highly contrasted population genetic structures in a host–parasite pair in the Caribbean Sea

“…This pattern was previously detected within the Caribbean in other taxonomic groups (Johnston et al., 2012 ; Purcell et al., 2006; Silberman et al., 1994), as well as in other sea urchins (Lessios, Kane, & Robertson, 2003; Lessios, Kessing, & Pearse, 2001; Lessios et al., 2012; McCartney, Keller, & Lessios, 2000; Zigler & Lessios, 2004). The present study confirms this last observation, not only for mitochondrial DNA, but also for microsatellites.…”

Phylogeography of the sand dollar genus Mellita: Cryptic speciation along the coasts of the Americas

“…However, one species of Mellita, M. grantii Mortensen, 1948, proved problematic for Mayr (1954) and he chose to ignore it in his analysis, stating that Mortensen (1948) had described M. grantii based on a single specimen from the midst of the range of M. longifissa Michelin, 1858. Mayr's (1954 model of allopatric speciation in echinoids has been supported by molecular phylogenies of regular sea urchins (Lessios et al, 1999(Lessios et al, , 2001(Lessios et al, , 2003(Lessios et al, , 2012McCartney et al, 2000;Zigler and Lessios, 2004;Palumbi and Lessios, 2005), but to-date this hypothesis has not been tested with a molecular phylogeny of a sand dollar genus.…”

Nutrient allocation in the gonads of the sea urchinArbacia dufresniiin different stages of gonadal development

“…However, few studies have been done on South Atlantic species (Tavares 2004;Pérez et al 2008). Arbacia dufresnii (Blainville, 1825) is a common sea urchin in the southwestern Atlantic Ocean (Brogger et al 2013), and the only species of Arbacia inhabiting both coasts of South America (Lessios et al 2012). There are large differences between body size and density of the population in Nuevo Gulf (NG) and the one in San Jorge Gulf (SJOG).…”