The evolution of eye size in response to increased fish predation in Daphnia

Abstract

Variation in eye size is ubiquitous across taxa. Increased eye size is correlated with improved vision and increased fitness via shifts in behavior. Tests of the drivers of eye size evolution have focused on macroevolutionary studies evaluating the importance of light availability. Predator‐induced mortality has recently been identified as a potential driver of eye size variation. Here, we tested the influence of increased predation by the fish predator, the alewife (Alosa pseudoharengus) on eye size evolution in waterfleas (Daphnia ambigua) from lakes in Connecticut. We quantified the relative eye size of Daphnia from lakes with and without alewife using wild‐caught and third‐generation laboratory reared specimens. This includes comparisons between lakes where alewife are present seasonally (anadromous) or permanently (landlocked). Wild‐caught specimens did not differ in eye size across all lakes. However, third‐generation lab reared Daphnia from lakes with alewife, irrespective of the form of alewife predation, exhibited significantly larger eyes than Daphnia from lakes without alewife. This genetically based increase in eye size may enhance the ability of Daphnia to detect predators. Alternatively, such shifts in eye size may be an indirect response to Daphnia aggregating at the bottom of lakes. To test these mechanisms, we collected Daphnia as a function of depth and found that eye size differed in Daphnia found at the surface versus the bottom of the water column between anadromous alewife and no alewife lakes. However, we found no evidence of Daphnia aggregating at the bottom of lakes. Such results indicate that the evolution of a larger eye may be explained by a connection between eyes and enhanced survival. We discuss the cause of the lack of concordance in eye size variation between our phenotypic and genetic specimens and the ultimate drivers of eye size.

Transgenerational plasticity in the eye size ofDaphnia

“…Given that the induction of TGP is dependent upon the ability of organisms to accurately receive information from environmental signals, it follows logically that components of the sensory system may also respond to environmental signals to ultimately enhance organismal performance. Yet, the link between the environment and transgenerational responses in sensory systems is largely unexplored [17].…”

Coordinated evolution of brain size, structure, and eye size in Trinidadian killifish

“…Evolutionary shifts in eye size have also been linked to changes in ecological conditions. For example, studies have quantified selection on eye size due to such factors as light availability (Hall, 2008; Hiller‐Adams & Case, 1988; Kröger & Fernald, 1994; Veilleux & Lewis, 2011), predation (Glazier & Deptola, 2011; Møller & Erritzøe, 2010; Nilsson et al., 2012), and competition (Beston et al., 2017, 2019; Beston & Walsh, 2019). This growing body of work illustrating similar shifts in brain and eye size in response to ecologically mediated selection foreshadows the possibility that selection favors coordinated shifts in these neurosensory systems.…”

Natural selection favours a larger eye in response to increased competition in natural populations of a vertebrate

“…Indeed, studies have shown that ecological factors such as habitat complexity, foraging, diel activity and predation are associated with evolved differences in eye size (Banks, Sprague, Schmoll, Parnell, & Love, ; Beston, Dudycha, Post, & Walsh, in press; Beston, Wostl, & Walsh, ; Brandon, James, & Dudycha, ; Caves et al, ; Glazier & Deptola, ; Hammerschlag et al, ; Thomas et al, , ; Veilleux & Kirk, ; Zaret & Kerfoot, ). Although such studies provide information on the relationship between eye size and the environment, the vast majority of this work has compared eye size across species (but see Beston, Wostl, et al, ; Beston et al, in press; Brandon et al, ; Lönnstedt, McCormick, & Chivers, ). Despite years of research, very little work has experimentally tested how natural selection shapes the evolution of complex traits, such as the vertebrate eye.…”