PHOSPHOGLUCONATE DEHYDROGENASE POLYMORPHISM AND SALINITY IN THE WHITE SANDS PUPFISH

Area of Science:

• Genetics
• Ecology
• Conservation Biology

Background:

• The White Sands pupfish (Cyprinodon tularosa), a New Mexico state endangered species, was studied to understand its genetic diversity.
• Allozyme electrophoresis revealed polymorphism at only one of 37 examined loci: phosphogluconate dehydrogenase (Pgdh).

Purpose of the Study:

• To investigate the potential association between phosphogluconate dehydrogenase (Pgdh) allozyme polymorphism and environmental salinity in White Sands pupfish populations.
• To determine if temperature influences Pgdh allozyme frequencies.

Main Methods:

• Examined allozyme frequencies at the Pgdh locus across four White Sands pupfish populations.
• Correlated Pgdh allozyme frequencies with environmental salinity and temperature data from various habitats.
• Compared allele frequencies between native and introduced populations and their respective habitats.

Main Results:

• The phosphogluconate dehydrogenase (Pgdh) locus was the sole polymorphic locus identified among 37 loci in the White Sands pupfish.
• Pgdh allozyme frequencies, specifically Pgdh¹⁰⁰, showed a significant correlation with salinity levels but not with temperature.
• Differences in Pgdh¹⁰⁰ frequencies were observed between low and high salinity sites within Malpais Spring, irrespective of apparent fish movement barriers.
• Introduced pupfish populations exhibited Pgdh¹⁰⁰ frequencies that differed from the presumed founding stock and were correlated with their current habitat salinities.

Conclusions:

• The phosphogluconate dehydrogenase (Pgdh) polymorphism in White Sands pupfish is strongly associated with habitat salinity.
• Salinity acts as a significant environmental factor shaping the genetic structure of this endangered species.
• Understanding this genetic-salinity relationship is crucial for effective conservation and management strategies for Cyprinodon tularosa.