Morphological and genetic structuring in the Utah Lake sucker complex.

Area of Science:

• Conservation genetics
• Ichthyology
• Ecology

Background:

• The federally endangered June sucker (Chasmistes liorus), endemic to Utah Lake, faces population decline partly due to hybridization with the Utah sucker (Catostomus ardens).
• Suckers in Utah Lake display significant external morphological variation, with intermediate forms blurring species identification due to hybridization.
• Differentiating between June and Utah suckers is challenging due to overlapping morphological traits, impacting conservation strategies.

Purpose of the Study:

• To evaluate the morphological and genetic variation within the Utah Lake sucker complex.
• To compare morphological analyses with genetic data (amplified fragment length polymorphism and microsatellite analyses).
• To inform conservation strategies for the endangered June sucker and the Utah sucker complex.

Main Methods:

• Morphological analysis focused on mouth characters differentiating feeding strategies (planktivory in June suckers, benthivory in Utah suckers).
• Genetic variation assessed using amplified fragment length polymorphism (AFLP) and microsatellite markers.
• Bayesian model-based genetic clustering was employed to detect population structure.

Main Results:

• No deep genetic divergence was found between June and Utah sucker morphs.
• Significant, though slight, population structuring was observed alongside substantial morphological variation.
• Bayesian clustering identified two sucker populations, but these did not strongly align with morphological groups or marker systems.

Conclusions:

• The Utah Lake sucker complex exhibits considerable morphological variation with limited genetic structuring, posing a conservation dilemma.
• Conservation decisions must weigh focusing on the endangered June sucker morphotype versus conserving the broader morphotypic variation for evolutionary potential.
• Understanding the interplay of morphology and genetics is crucial for effective management of this unique fish complex.