Shared and unique morphological responses of stream fishes to anthropogenic habitat alteration

Abstract

Understanding population-level responses to novel selective pressures can elucidate evolutionary consequences of human-altered habitats. Stream impoundments (reservoirs) alter riverine ecosystems worldwide, exposing stream fishes to uncommon selective pressures. Assessing phenotypic trait divergence in reservoir habitats will be a first step in identifying the potential evolutionary and ecological consequences of stream impoundments. We tested for body shape divergence in four stream-adapted fishes found in both habitats within three separate basins. Shape variation among fishes was partitioned into shared (exhibited by all species) and unique (speciesspecific) responses to reservoir habitats. All fishes demonstrated consistent significant shared and unique morphological responses to reservoir habitats. Shared responses were linked to fin positioning, decreased body depths and larger caudal areas; traits likely related to locomotion. Unique responses were linked to head shape, suggesting species-specific responses to abiotic conditions or changes to their trophic ecology in reservoirs. Our results highlight how human-altered habitats can simultaneously drive similar and unique trait divergence in native populations.

Shared and unique patterns of phenotypic diversification along a stream gradient in two congeneric species

“…Circumstantial evidence for the role of stream velocity governing morphological evolution stems from studies on the effects of impoundments (dams), where water reservoirs reduce flow velocity and thus create artificial ‘downstream conditions’293031. Physical characteristics of reservoirs (i.e., altered flow characteristics) appear to drive changes in a set of morphological traits: fish are usually deeper-bodied and have smaller heads in reservoirs2931. This likely increases manoeuvrability when feeding on prey suspended in the water column, while more streamlined body contours increase locomotor performance in lotic environments32.…”

Repeatability of locomotor performance and of morphology – locomotor performance relationships

“…Common patterns of repeated ( parallel or convergent) evolution of the same performance-environment relationships emphasise the role that selection plays in generating among-taxa variation in locomotor performance, and in the physiological, morphological and behavioural traits that determine performance (Taylor and McPhail, 1985;McGuigan et al, 2003;Langerhans and DeWitt, 2004;Langerhans et al, 2006;Dalziel et al, 2012;Franssen et al, 2013;Fu et al, 2013;da Silva et al, 2014;Haas et al, 2015;Nelson et al, 2015). Despite the adaptive significance of locomotion, how the variation in locomotion is generated among individuals within a population, which is what natural selection acts upon, is relatively poorly understood.…”

The effect of chronic volcanic pollution on the morphometric characteristics of juvenile Dolly Varden (Salvelinus malma W.) on the Kamchatka peninsula

“…The correlation among morphological traits is timedependent and displays high developmental plasticity (Grunbaum et al, 2007). It has been demonstrated that environmental factors such as current velocity, oxygen concentration, water temperature, and salinity may have a significant effect on fish morphotype (Mahon, 1984;Imre et al, 2002;Grunbaum et al, 2007;Paez et al, 2008;Crispo & Chapman, 2011;Franssen et al, 2012;Rajput et al, 2013).…”

“…Fish morphology constitutes an important element of the phenotype, being largely defined by the lifestyle, locomotion activity, and habitat conditions (Webb, 1984;Guill et al, 2003;Franssen et al, 2012). Environmental factors can either directly influence body proportions or indirectly affect morphometric variation, when changes in one trait result in correlated changes in others (Crispo & Chapman, 2011).…”