Phosphoglucose isomerase polymorphism in the common goby, <i>Pomatoschistus microps</i> (Krøyer) (TeleosteirGobiidae), around the British Isles

Abstract

Phosphoglucose isomerase (PGI) polymorphism has been investigated by horizontal starch‐gel electrophoresis in the common goby, Pomatoschistus microps (Krøyer), from 21 localities around the British Isles and at Roscoff, France. Sixteen PGI phenotypes were observed, consistent with occurrence of four alleles at each of the two loci (A,B). In the Teign estuary at Shaldon, Devon, seasonal fluctuation in PGI‐A allele frequencies was accompanied in some months by departure from Hardy‐Weinberg equilibrium. At this locality, a significant change in PGI‐A allele frequencies was found with increasing modal age of sample (within a year class) but not between year‐classes over eight years. Similar stability is noted for other areas. Major alleles (PGI‐A2, A3; PGI‐B2, B3) were found at all localities, but with marked differences in proportions. Atlantic coast populations tended to have higher A2 and B2 frequencies than those of the North Sea and English Channel, with Irish Sea populations having high A2 but low B2. Historical and selective causes for this geographical variation are discussed. A significant correlation exists between the frequencies of the major PGI‐A alleles and maximum monthly mean sea temperature for the same area.