Genetic diversity and demographic history of the endemic Southeastern Pacific sea urchin Arbacia spatuligera (Valenciennes 1846)

Abstract

Diversidad genética e historia demográfica del erizo de mar endémico del Pacífico Sureste Arbacia spatuligera (Valenciennes 1846

A new morphotype description of Arbacia spatuligera Valenciennes, 1846 (Arbacioida, Echinoidea) and bathymetric range extension from mesophotic reefs of the central coast of Chile

“…All seven specimens sequenced from Pichidangui correspond to one unique COI haplotype of A. spatuligera , already recorded by Millán et al . (2019). The haplotype sequence was deposited in the GenBank database (GenBank accession number: PP733318).…”

“…The absence of genetic difference in COI gene between the two morphotypes suggests that morphological differences observed between the specimens from Pichidangui and the typical form are not the result of a species differentiation linked to either geographic isolation or ecological niche evolution in deeper environments. Millán et al (2019) emphasized the absence of genetic structure and unexpectedly low genetic diversity in populations of A. spatuligera over its entire distribution range. Additionally, they found evidence of a recent demographic expansion of the species, estimated to have occurred 33,000-47,000 years ago.…”

“…The haplotype sequence was deposited in the GenBank database (GenBank accession number: PP733318). It corresponds to the COI haplotype 'AspaCN1' (GenBank accession number: MK382495.1), and this haplotype corresponds to the Hap1 on the haplotype network presented by Millán et al (2019) and aligns with the most prevalent haplotype (114 out of 140 individuals; Millán et al, 2019) within A. spatuligera, found from Concepción (Chile) to Lima (Peru) in shallow water (0-30 m).…”

“…The species A. spatuligera is located in the Southeastern Pacific Ocean from northern Peru to Puerto Montt, in south-central Chile (Larraín, 1975; Lessios et al ., 2012; Millán et al ., 2019). Valenciennes first described the species in 1846 with reliable and detailed drawings and descriptions for that time.…”

“…Bathymetric records of A. spatuligera indicate that the species occurs in shallow waters above 30 m depth (Larraín, 1975; Lessios et al ., 2012; Gianguzza and Bonaviri, 2013; Millán et al ., 2019). However, due to logistical limitations to recreational scuba diving (Kramer et al ., 2019), most of the knowledge about the distribution and ecology of A. spatuligera was based on information obtained from shallow areas (<30 m depth).…”