Low Predictability of Colour Polymorphism in Introduced Guppy (Poecilia reticulata) Populations in Panama

Abstract

Colour polymorphism is a recurrent feature of natural populations, and its maintenance has been studied in a range of taxa in their native ranges. However, less is known about whether (and how) colour polymorphism is maintained when populations are removed from their native environments, as in the case of introduced species. We here address this issue by analyzing variation in colour patterns in recently-discovered introduced populations of the guppy (Poecilia reticulata) in Panama. Specifically, we use classic colour analysis to estimate variation in the number and the relative area of different colour spots across low predation sites in the introduced Panamanian range of the species. We then compare this variation to that found in the native range of the species under low- and high predation regimes. We found aspects of the colour pattern that were both consistent and inconsistent with the classical paradigm of colour evolution in guppies. On one hand, the same colours that dominated in native populations (orange, iridescent and black) were also the most dominant in the introduced populations in Panama. On the other, there were no clear differences between either introduced-low and native low- and high predation populations. Our results are therefore only partially consistent with the traditional role of female preference in the absence of predators, and suggest that additional factors could influence colour patterns when populations are removed from their native environments. Future research on the interaction between female preference and environmental variability (e.g. multifarious selection), could help understand adaptive variation in this widely-introduced species, and the contexts under which variation in adaptive traits parallels (or not) variation in the native range.

Water pollution affects fish community structure and alters evolutionary trajectories of invasive guppies (Poecilia reticulata)

“…Few studies have focused on pollution effects in guppies and reported, for example, that blue ornaments became more prevalent in a highly polluted Panamanian stream when compared with cleaner sites (Martínez et al, 2016). The magnitude of interaction effects in our present study suggests that multifarious selection affects phenotypic evolution.…”

“…We classified color ornaments as falling into the six color categories described by Endler (1978), i.e. red/orange, black (including 'fuzzy black': Ruell et al, 2013;Martínez et al, 2016), yellow, blue (which included 'purple': Millar et al, 2006), green, and white/iridescent (including 'blue-violet', 'green-bronze' and 'silver': Millar et al, 2006;Fig. 2a-g).…”

“…2a-g). For each color category we calculated the total number of spots on the left body side as well as the surface area covered by each spot, and we calculated the relative surface area covered by that color type (dividing the cumulative surface area for that color category by the total body surface area, Martínez et al, 2016).…”

Hidden biodiversity in Neotropical streams: DNA barcoding uncovers high endemicity of freshwater macroinvertebrates at small spatial scales

“…Assessing the patterns and drivers of macroinvertebrate diversity at different scales is particularly relevant, given the increasing rate of environmental degradation in Neotropical regions [ 30 – 33 ]. This includes alterations such as introduction of alien species [ 34 , 35 ], the development of megaprojects [ 36 ], habitat degradation, water pollution, and climate change [ 30 , 33 , 37 , 38 ]⁠. As a consequence, a large portion of this biodiversity risks being lost before discovery.…”

Hidden biodiversity in Neotropical streams: DNA barcoding uncovers high endemicity of freshwater macroinvertebrates at small spatial scales

“…Assessing the patterns and drivers of macroinvertebrate diversity at different scales is particularly relevant, given the increasing rate of environmental degradation in Neotropical regions [31–34]. This includes alterations such as introduction of alien species [35,36], habitat degradation, water pollution, and climate change [31,34,37,38]□. In consequence, a large portion of this biodiversity risks being lost before discovery.…”