Morphological Differentiation and Genetic Structure in Island Lizard Populations

Fulgione, Domenico; Guglielmi, Serena; Odierna, Gaëtano; Rippa, Daniela; Caliendo, Marco; Rastogi, Rakesh K.

doi:10.2108/zsj.25.465

Cited by 8 publications

(12 citation statements)

References 56 publications

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“…The notion that the Licosa lizard is a large-sized variant of mainland Podarcis sicula [41,42] was confirmed by our data. However, insular lizards were, on average, older, and the higher mean SVL on the island could be a result of different age structure (perhaps related to lower predation) rather than the result of direct selection on size.…”

Section: Discussionsupporting

confidence: 84%

“…Despite the fact that the two populations analyzed here diverged a short time ago, and that there is sizeable genetic introgression between them [42], we found striking evolutionary change in the Licosa lizards. Compared to their mainland relatives, these blue lizards were much more aggressive, voracious and dimorphic, as predicted by the RIS hypothesis (Table 1).…”

Section: Discussionmentioning

confidence: 65%

“…We estimated a maximum population size of only 250 individuals (see Additional file 1: Table S11), that is lizard density is some 300 lizards per Ha (one-sixth of the average for lizard in islands around the world [38]). In five years of field censuses (2001-2006) we noted the number of individuals may change by up to 40% from one year to the next (range: 148.1-246.7, mean: 205.3, see also [42]). Since no freshwater source is present on the islet, mortality can be intense in drought years.…”

Section: Methodsmentioning

confidence: 99%

“…In a previous study we demonstrated selection was operating on a mtDNA gene sequence of Licosa lizard [42]. …”

Section: Methodsmentioning

confidence: 99%

“…This is a large-sized, melanistic variant of the Italian Wall lizard P. sicula from mainland Italy [41,42]. P. s. klemmeri population size fluctuates yearly by up to 40% (Tables 2 and Additional file 1: Table S11).…”

Section: Introductionmentioning

confidence: 99%

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The blue lizard spandrel and the island syndrome

et al. 2010

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BackgroundMany small vertebrates on islands grow larger, mature later, lay smaller clutches/litters, and are less sexually dimorphic and aggressive than their mainland relatives. This set of observations is referred to as the 'Island Syndrome'. The syndrome is linked to high population density on islands. We predicted that when population density is low and/or fluctuating insular vertebrates may evolve correlated trait shifts running opposite to the Island Syndrome, which we collectively refer to as the 'reversed island syndrome' (RIS) hypothesis. On the proximate level, we hypothesized that RIS is caused by increased activity levels in melanocortin receptors. Melanocortins are postranslational products of the proopiomelanocortin gene, which controls pleiotropically pigmentation, aggressiveness, sexual activity, and food intake in vertebrates.ResultsWe tested the RIS hypothesis performing a number of behavioral, genetic, and ontogenetic tests on a blue colored insular variant of the Italian Wall lizard Podarcis sicula, living on a small island off the Southern Italian coast. The population density of this blue-colored variant was generally low and highly fluctuating from one year to the next.In keeping with our predictions, insular lizards were more aggressive and sexually dimorphic than their mainland relatives. Insular males had wide, peramorphic heads. The growth rate of insular females was slower than growth rates of mainland individuals of both sexes, and of insular males. Consequently, size and shape dimorphism are higher on the Island. As predicted, melanocortin receptors were much more active in individuals of the insular population. Insular lizards have a higher food intake rate than mainland individuals, which is consistent with the increased activity of melanocortin receptors. This may be adaptive in an unpredictable environment such as Licosa Island. Insular lizards of both sexes spent less time basking than their mainland relatives. We suspect this is a by-product (spandrel) of the positive selection for increased activity of melanocortins receptors.ConclusionsWe contend that when population density is either low or fluctuating annually as a result of environmental unpredictability, it may be advantageous to individuals to behave more aggressively, to raise their rate of food intake, and allocate more energy into reproduction.

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Section: Discussionsupporting

confidence: 84%

Section: Discussionmentioning

confidence: 65%

Section: Methodsmentioning

confidence: 99%

“…In a previous study we demonstrated selection was operating on a mtDNA gene sequence of Licosa lizard [42]. …”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The blue lizard spandrel and the island syndrome

et al. 2010

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Gut microbiota plasticity in insular lizards under reversed island syndrome

Buglione

Ricca

Petrelli

et al. 2022

Sci Rep

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Animals living on small islands are more drastically exposed to environmental changes, such as food or water starvation, and rapid temperature shifts. Facing such conditions, and probably thank to adaptive plasticity mechanisms, some animals display a Reversed Island Syndrome (RIS), a suite of traits, including skin pigmentation, voracity, sexual dimorphism, showed differently from mainland relatives. Here, we analyse a so far poorly explored aspect of RIS: the effect of this on the microbiota composition of host Italian wall lizard (Podarcis siculus), strongly influenced by the animal’s lifestyle, and conditioning the same. We compare mainland and island populations, assessing the difference between their microbial communities and their response under unexpected food, experimentally provided. Our observations showed a significant difference in microbiota communities between island and mainland groups, depended mainly from changes in relative abundance of the shared genera (difference due to decrease/increase). Exposure to experimental diet regimes resulted into significative reshaping of bacterial composition of microbiota and a greater variation in body mass only in the island population. Our results could be an evidence that gut microbial community contributes to adaptive plasticity mechanisms of island lizards under RIS to efficiently respond to unexpected changes.

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Physiological change in an insular lizard population confirms the reversed island syndrome

Monti

Raia

Vroonen

et al. 2012

Biol J Linn Soc Lond

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Unpredictable environmental conditions and highly fluctuating population densities are believed to have produced a ‘reversed island syndrome’ (RIS) in an insular population of the Wall lizard on Licosa Islet, Italy. Several of the physiological, behavioural, and life‐history changes that constitute the RIS could result from positive selection on increased activity of melanocortins. For example, increased levels of α‐melanocyte‐stimulating hormone (MSH) should lead to increased investment in reproduction and increased immunocompetence in the island population. We tested the crucial assumption of this idea that plasma levels of α‐MSH in Licosa Islet lizards are elevated compared to those of the mainland relatives. We also tested for differences in reproductive effort between populations, by measuring plasma levels of 5‐α‐dihydrotestosterone in males and clutch mass in females. In addition, we assessed ectoparasite load as an indicator for the lizards’ resistance to environmental stress. In agreement with the RIS, we found that insular lizards exhibit higher α‐MSH levels, allocate more energy to reproduction, and have a reduced ectoparasite load compared to the nearest mainland population. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●●, ●●–●●.

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Morphological Differentiation and Genetic Structure in Island Lizard Populations

Cited by 8 publications

References 56 publications

The blue lizard spandrel and the island syndrome

The blue lizard spandrel and the island syndrome

Gut microbiota plasticity in insular lizards under reversed island syndrome

Physiological change in an insular lizard population confirms the reversed island syndrome

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