Rapid Evolution of Escape Ability in Trinidadian Guppies (Poecilia Reticulata)

Abstract

Abstract. Predators are widely assumed to create selection that shapes the evolution of prey escape abilities. However, this assumption is difficult to test directly due to the challenge of recording both predation and its evolutionary consequences in the wild. We examined these events by studying natural and experimental populations of Trinidadian guppies, Poecilia reticulata, which occur in distinct high-predation and low-predation environments within streams. Importantly, in the last two decades several populations of guppies have been experimentally introduced from one type of predatory environment into the other, allowing measurements of the consequences of change. We used this system to test two hypotheses: First, that changes in predatory environments create phenotypic selection favoring changes in escape ability of guppies, and second, that this selection can result in rapid evolution. For the first test we compared escape ability of wild caught guppies from high-versus low-predation environments by measuring survival rates during staged encounters with a major predator, the pike cichlid Crenicichla alta. We used guppies from three streams, comparing two within-stream pairs of natural populations and three within-stream pairs of an introduced population versus its natural source population. In every comparison, guppies from the high-predation population showed higher survival. These multiple, parallel divergences in guppy survival phenotype suggest that predatory environment does create selection of escape ability. We tested our second hypothesis by rearing guppies in common garden conditions in the laboratory, then repeating the earlier experiments using the F 2 generation. As before, each comparison resulted in higher survival of guppies descended from the high-predation populations, demonstrating that population differences in escape ability have a genetic basis. These results also show that escape ability can evolve very rapidly in nature, that is, within 26-36 generations in the introduced populations. Interestingly, we found rapid evolutionary loss of escape ability in populations introduced into low-predation environments, suggesting that steep fitness trade-offs may influence the evolution of escape traits.Key words. Genetic divergence, geographic variation, phenotypic selection, Poecilia reticulata, predator-prey interaction. Many fields of biology assume that predators are the primary factor shaping the evolution of prey escape abilities. However, this causal hypothesis is difficult to test due to the challenge of measuring selection by predators and the evolutionary consequences for prey in a single, natural system. Several studies demonstrate that predators create phenotypic selection favoring enhanced escape ability of prey (e.g., Brodie 1992;Dugatkin 1992;McCollum and Van Buskirk 1996;Watkins 1996), and others show that genetically based differences in escape ability among related prey populations or species are correlated with predatory environment (e.g., Seghers 1974;Sinervo and Losos 199...

Predator-induced morphology enhances escape locomotion in crucian carp

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Speciation through the lens of biomechanics: locomotion, prey capture and reproductive isolation

“…And in guppies and mosquitofish, variation in predation risk also leads to evolution of functional divergence independent of trophic niche (e.g. predator evasion, [69,97]). A major question in evolutionary biology concerns the predictability and repeatability of evolutionary change and its role in the origin of species.…”

Strikes and startles of northern pike (Esox lucius): a comparison of muscle activity and kinematics between S-start behaviors

“…Webb and Skadsen, 1980;Rand and Lauder, 1981), post-feeding turns (Canfield and Rose, 1993) and social interactions (Fernald, 1975). Because of its importance in feeding and escape, faststart behavior is closely linked to survival and has been found to evolve quickly with changes in predator pressure (O'Steen et al, 2002).…”

“…C-starts have been examined in a wide range of species (reviewed by Domenici and Blake, 1997), through ontogeny (e.g. Taylor and McPhail, 1985;Fuiman, 1994;Hale, 1996Hale, , 1999 and within ecological (O'Steen et al, 2002) and evolutionary (e.g. Zottoli, 1978;Hale et al, 2002;O'Steen et al, 2002) contexts.…”

“…Taylor and McPhail, 1985;Fuiman, 1994;Hale, 1996Hale, , 1999 and within ecological (O'Steen et al, 2002) and evolutionary (e.g. Zottoli, 1978;Hale et al, 2002;O'Steen et al, 2002) contexts. Because C-start escape behavior is controlled by a small population of reticulospinal neurons and because of the simplicity and accessibility of its neural circuits (e.g.…”