The Effect of Isolation by Waterfalls and Dams on Stream Fish Morphology

<p>Large dams with upstream reservoirs can cause divergent selection in fish morphology; however, the effect of isolation from small dams without upstream reservoirs is largely unknown. This study investigated the effects of isolation on stream fish body morphology and the related effect of isolation time on morphological divergence by comparing fish associated with older barriers (waterfalls) to very new barriers (dams). These effects were investigated in five species from the southern Lake Superior basin. Geometric morphometric techniques were used to quantify differences in fish body shape based on species-specific landmarks. Significant intraspecific differences between stream populations and between above-barrier and below-barrier populations were found in three species. The majority of body shape variation was associated with deeper body depths (<em>Salvelinus fontinalis</em> and <em>Rhinichthys atratulus</em>) and position of pre-opercular spine and head length (<em>Cottus bairdi</em>). There was greater morphological divergence between <em>Cottus bairdi</em> separated by waterfalls than by dams. Nonparametric multiplicative regression identified the best environmental predictor for body shape as wetted width (<em>Rhinichthys atratulus</em>), stream velocity (<em>Salvelinus fontinalis</em>), or stream population (<em>Cottus bairdi</em>). These results suggest that for some species isolation by dams and waterfalls is associated with divergent intraspecific morphology.</p>

Name thesis:degree_name

Master of Science

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Biology

Year dc:date.available

2015

Author dc:creator

• Knoll, Kayla M

Contributors dc:contributor

• Dr. Jill B.K. Leonard

• stream fish
• waterfall
• dam
• isolation
• geometric morphometrics
• Ecology and Evolutionary Biology

Repository record dc:identifier

https://commons.nmu.edu/theses/62

OAI identifier oai:identifier

oai:commons.nmu.edu:theses-1061