Fine-scale local adaptation in life histories along a continuous environmental gradient in Trinidadian guppies

Torres Dowdall, J., Handelsman, C.A., Ruell, E.W., Auer, S.K., Reznick, D.N. and Ghalambor, C.K. (2012) Fine-scale local adaptation in life histories along a continuous environmental gradient in Trinidadian guppies. Functional Ecology, 26(3), pp. 616-627. (doi: 10.1111/j.1365-2435.2012.01980.x)

Abstract

<p>1. Theoretical models of life-history evolution predict a continuum of fast to slow life histories, yet most of empirical support for this theory comes from studies that have considered dichotomous environments (i.e. high vs. low food, presence or absence of major predators). Although this approach has been very successful in identifying the signature of local adaptation, it might limit our ability to identify the causes of underlying patterns of phenotypic variation. By studying the variation in life-history traits along continuous gradients, we can gain better insight into the diversity of adaptations exhibited by natural populations.</p> <p>2. We studied the evolution of life-history traits along a gradient of predation pressure in the Trinidadian guppy (Poecilia reticulata). Six localities along the Guanapo–Caroni River drainage were selected with respect to their predator community, going from upstream localities where guppies only coexist with a single gape-limited fish predator, to lowland sites where guppies coexist with a complex fish community. Along this gradient, we characterized the field pattern of phenotypic variation in age and size at maturity and reproductive effort. Further, to determine the genetic basis of this variation, we measured these traits in second-generation laboratory-born fish from the same localities sampled in the wild.</p> <p>3. In nature, we found a fine-scale pattern of phenotypic variation in most life-history traits that paralleled the continuous predation gradient. In the laboratory, we observed that reproductive allocation and brood size progressively decrease while age at maturity and interbrood interval progressively increase with a reduction in the predator community, suggesting a genetic basis to the parallel patterns observed in the field for reproductive allocation and offspring number.</p> <p>4. However, there were some exceptions to the observed pattern of variation. Females from one low-predation locality matured younger and reproduced more frequently than expected based upon the simple nature of the fish community. We also found significant differences between our field and laboratory results for embryo size, suggesting that this trait is highly plastic.</p> <p>5. Our results imply that local adaptation in guppies occurs at a finer scale than has previously been shown. Furthermore, while our results are consistent with predator-driven life-history variation, we also find patterns of plasticity that would not be apparent in the traditional dichotomous approach.</p>

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Auer, Dr Sonya
• Authors: Torres Dowdall, J., Handelsman, C.A., Ruell, E.W., Auer, S.K., Reznick, D.N., and Ghalambor, C.K.
• College/School: College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Journal Name: Functional Ecology
• Publisher: Blackwell
• ISSN: 0269-8463
• ISSN (Online): 1365-2435