Does a polymorphic species have a ‘polymorphic’ diet? A case study from a lacertid lizard

Scali, Stefano; Sacchi, Roberto; Mangiacotti, Marco; Pupin, Fabio; Gentilli, Augusto; Zucchi, Carlo; Sannolo, Marco; Pavesi, Maurizio; Zuffi, Marco Alberto Luca

doi:10.1111/bij.12652

Cited by 28 publications

(27 citation statements)

References 57 publications

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“…We propose that the morphs are ecologically segregated and that their frequencies reflect the amount of available niche space in which the fitness of each morph approaches equality in the appropriate niche. Similar themes have been recently demonstrated in polymorphic lacertid lizards (Scali et al, 2016). Given the very low population numbers of bears on these islands, it seems that inbreeding effects would have compromised long-term persistence without occasional migration from the mainland (Hedrick & Ritland, 2011) as well as fitness differentials between the morphs (Klinka & Reimchen, 2009a).…”

Section: Discussionsupporting

confidence: 73%

Niche differentiation between coat colour morphs in the Kermode bear (Ursidae) of coastal British Columbia

Reimchen

Klinka

2017

Biological Journal of the Linnean Society

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One of the most distinctive colour polymorphisms of any mammal occurs in black bears (Ursus americanus kermodei Hornaday) of the Great Bear Rainforest of coastal British Columbia. We use carbon and nitrogen stable isotope values and C/N ratios along segments of hair shafts obtained from 14 white and 12 black individual bears to quantify dietary niche of the morphs as a test of the multi-niche model for a polymorphism. On Gribbell Island, where the white bear reaches 30%, 15 N is significantly (GLM repeated measures) more enriched (more marine-derived nitrogen) in the white morph than in the black morph in each season (spring, summer, autumn). On the adjacent Princess Royal Island, where the white morph is less common, both morphs are highly enriched during autumn (~δ 15 N = +11‰), but there are no isotopic differences between morphs in any season. On both islands, C/N ratios (~3.1) of the black morph decrease from spring to autumn, converging on the lower average values for the white morph. Our data suggest that niche of the white morph involves increased use of a marine-associated diet and that ecological segregation between the morphs has facilitated the historical persistence of the polymorphism. ADDITIONAL KEYWORDS: C/N ratios-Great Bear Rainforest-hair shaft-marine-derived nutrients-multiniche polymorphism-salmon-Spirit bear-stable isotopes-Ursus americanus kermodei.

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Section: Discussionsupporting

confidence: 73%

Niche differentiation between coat colour morphs in the Kermode bear (Ursidae) of coastal British Columbia

Reimchen

Klinka

2017

Biological Journal of the Linnean Society

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“…This mechanism also allows morphs to vary in their degree of trophic specialization (e.g. generalist or specialist) as they do in mating behaviour and other physiological traits [ 2 – 4 , 18 , 29 , 52 – 54 ]. Our hypothesis synthesizes and expands on the mechanisms proposed by Skúlason & Smith [ 13 ] and Karpestam & Forsman [ 17 ] to explain the evolution of a trophic polymorphism.…”

Section: Discussionmentioning

confidence: 99%

“…Dietary divergence among morphs is expected to arise via one of two mechanisms [ 17 ]: morph-specific differences in microhabitat exploitation or morphological constraints (e.g. gape limitation) that influence prey selectivity [ 16 , 18 , 19 ]. These two hypotheses differ in that the first proposes that a trophic polymorphism is unrelated to diet selection and instead is a function of differences in prey diversity arising from segregation of morphs among different microhabitats.…”

Section: Introductionmentioning

confidence: 99%

Trophic niche divergence among colour morphs that exhibit alternative mating tactics

Lattanzio¹,

Miles²

2016

R. Soc. open sci.

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Discrete colour morphs associated with alternative mating tactics are assumed to be ecologically equivalent. Yet suites of behaviours linked with reproduction can also favour habitat segregation and exploitation of different prey among morphs. By contrast, trophic polymorphisms are usually attributed to morphs exhibiting habitat or prey selectivity. An alternative hypothesis is that habitat variation generates a trophic polymorphism driven by differences in morph reproductive behaviour, the spatial dispersion of morphs in a landscape and their exposure to different prey types. In this scenario, morphs are allowed to vary in habitat or diet selectivity (e.g. specialist or generalist) as they do in behaviour, rather than being assumed to exhibit equivalent levels of ecological specialization. We test this hypothesis using male Urosaurus ornatus lizards that exhibit a discrete dewlap colour polymorphism that reflects alternative mating tactics. We found blue morphs specialize on prey at higher trophic levels, yellow males display plasticity in trophic and morphological attributes and orange males are trophic generalists. Our results also demonstrate that morph diet differences are enhanced in resource-limited habitats. We conclude that discrete behavioural morphs may also diverge in morphology and trophic niche. Jointly, these processes may enhance speciation rates in colour polymorphic taxa.

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“…For example, studies from the Pyrenees describe up to five ventral colour morphs in both adult males and females: white, yellow and orange pure morphs, and white‐orange and yellow‐orange intermediate morphs (Pérez i de Lanuza et al ., ; but see the proposal for a sixth white‐yellow morph in Calsbeek et al ., ; Zajitschek et al ., ). In contrast, studies from Northern Italy describe from four to six morphs and, remarkably, have reported the existence of a red (rather than orange) morph in this area (Sacchi et al ., , , ; Galeotti et al ., ; Scali et al ., , ; Pellitteri‐Rosa et al ., , ). The discrepancy between the orange and the red morphs might indicate some underlying biological meaningful difference (e.g.…”

Section: Introductionmentioning

confidence: 99%

Colour variation between different lineages of a colour polymorphic lizard

et al. 2019

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Colour polymorphic animals offer useful models to study the evolution of polymorphisms and studies with colour polymorphic lizards have contributed many advances in this field. Unfortunately, few studies address basic questions such as how observers (e.g. conspecifics) perceive the polymorphism or whether there is chromatic variability among evolutionary lineages or distant geographic areas within a species' range. The common wall lizard (Podarcis muralis) shows a striking colour polymorphism in its ventral surface, presenting up to five alternative colour morphs, that is white, yellow and orange/red (depending on the lineage), and two intermediate mosaic morphs: white‐orange and yellow‐orange. Here we compare this polymorphism in two geographically distant areas, the Po valley (Northern Italy) and the Eastern Pyrenees (Iberian Peninsula), corresponding to separate phylogeographic lineages. Using objective techniques of colour measurement and lizard vision models, we examine the chromatic differences between these two polymorphic lineages. We also search for chromatic differences in other colour traits present in P. muralis: the cryptic dorsal coloration and the ultraviolet‐blue spots of the outer ventral scales (UV‐blue OVS) used for intraspecific communication. Although we detected significant differences among lineages in colour variables, the main variation was found between the alternative ventral colour morphs. The most striking inter‐lineage divergence was between the orange Pyrenean morph and the red Italian morph, mainly caused by achromatic (but not chromatic) differences. In addition, although the UV‐blue OVS show strong chromatic and achromatic variation between lineages, the dorsal coloration shows the smallest degree of variation, and mainly between localities rather than lineages. Overall, the ventral colour pattern of P. muralis is shared by at least two geographically and phylogenetically distant lineages. Nevertheless, body coloration also shows signs of historical divergence (Pyrenean orange vs. Italian red) and local adaptation (mainly in the dorsal pattern).

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Does a polymorphic species have a ‘polymorphic’ diet? A case study from a lacertid lizard

Cited by 28 publications

References 57 publications

Niche differentiation between coat colour morphs in the Kermode bear (Ursidae) of coastal British Columbia

Niche differentiation between coat colour morphs in the Kermode bear (Ursidae) of coastal British Columbia

Trophic niche divergence among colour morphs that exhibit alternative mating tactics

Colour variation between different lineages of a colour polymorphic lizard

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