Geometric morphometric analyses of Razorback Sucker, Flannelmouth Sucker and their hybrids

Authors: Pilar Wolters, Dave Rogowski, Alice Gibb

Year: 2017 (xlix)

Abstract

Hybridization between two sucker species, Razorback Sucker and Flannelmouth Sucker, historically occurred but has been facilitated by habitat alteration by the construction of dams The Razorback Sucker has since been listed as endangered because natural recruitment is rare It is important for the recovery of the Razorback Sucker to be able to discern between young Razorback, young Flannelmouth Suckers, and young hybrids The purpose of our study was to aid in the management and recovery of Razorback Suckers by identifying the length at which we could correctly classify Razorback Sucker, Flannelmouth Sucker, and their hybrids Razorback Sucker and Flannelmouth Sucker were artificially spawned to produce four progenies: Razorback Sucker, Flannelmouth Sucker, Razorback Sucker female X Flannelmouth Sucker male hybrid, and Flannelmouth Sucker female X Razorback Sucker male hybrid We conducted geometric morphometric analyses and used conditional inference trees to determine what length the four progenies’ shapes begin to differentiate We also used piecewise-linear models to determine how each progeny’s shape changes with total length There was no shape difference between the two hybrid progenies, so hybrids were pooled together for analysis The results of our study showed that fish smaller than 137mm total length are difficult to differentiate by shape We also showed that Razorback Sucker and hybrid shapes change differently with growth With the information provided in this study, field biologists should be cautious when identifying suckers smaller than 137mm TL in the Colorado River Basin