Environmental and morphological drivers of mutualistic plant–lizard interactions: a global review

Abstract

Plant-lizard interactions are still poorly studied, despite lizards are known to interact with flowering plants in many parts of the world. They are commonly reported on islands although the number of documented interactions has also increased in mainland, mostly in isolated environments. In this study, we first performed a global review to explore whether lizard-flower and lizard double mutualistic interactions in continents occur in environments similar to those of islands. Then, we aimed at explaining the factors driving the current distribution of such interactions worldwide. To do this, we considered four environmental factors (latitude, altitude, rainfall and temperature), and phylogeny and body size of lizards that may influence flower visitation. Furthermore, we investigated for the first time the functional role (legitimate visit versus florivory) of lizards in plant reproduction and the conditions under which each type of interaction occurs. Finally, we explored the factors influencing the distribution of lizard double mutualisms worldwide. We recorded a total of 452 lizard-flower interactions (ca 3.4% and 0.1% of the extant lizard and plant species, respectively). Lizard-flower interactions were more frequently recorded on islands (79%) regardless of phylogeny and lizard body size, whereas in mainland the number of interactions increased with altitude. Our analyses also revealed that only 20% of all interactions confirmed pollination effectiveness and a strong association of the type of interaction with environmental factors and species traits. Regarding the distribution of lizard double mutualisms, we found a positive effect of island and rainfall, but a decrease in their occurrence with latitude, altitude, temperature and body size. We predict that mutualistic plant-lizard interactions will be increasingly documented, especially in isolated environments (both on islands and continents), which will help us to better understand the biological patterns of this phenomenon and the mechanisms underlying them.

Assessing the Role of Lizards as Potential Pollinators of an Insular Plant Community and Its Intraspecific Variation

“…obs.). In this island, the Balearic lizard is a legitimate flower visitor of Lavatera maritima but can eat the flowers of this same species under dry conditions when other food resources are scarce [ 19 ]. Thus, it is also possible that the relationship between lizards and plants is as relevant as it is volatile in specific and delicate island habitats and that it is conditioned by a complex set of factors that deserve attention in future studies, such as food availability, the size of the island and environmental conditions, among others.…”

“…The Balearic lizard consumes plant matter regularly [ 37 , 38 ], including both fruits [ 39 , 40 , 41 , 42 , 43 , 44 ] and floral resources [ 39 , 45 , 46 , 47 ]. Considering its entire current distribution (Cabrera archipelago, Dragonera and small islets of Mallorca and Menorca), it is known to interact with the flower of at least 59 plant species (51% legitimate visitation, 32% florivory), 21 (36%) of which have been reported from the Cabrera archipelago and 6 (10%; Lavatera maritima , Globularia alypum , Ephedra fragilis , Euphorbia dendroides , Euphorbia characias and Fumana ericoides ) from the island of Cabrera Gran [ 19 ]. In addition to the Balearic lizard, two geckos with a wide distribution in the Mediterranean basin are found in Cabrera: the Moorish gecko, Tarentola mauritanica , and the Turkish gecko, Hemidactylus turcicus .…”

“…These high densities of lizards, in areas where arthropods, which are their usual prey, are scarce, lead to a broadening of the trophic niche [ 18 ]. This is typical of islands, but also of isolated mainland ecosystems with similar environmental conditions to those on islands [ 19 ]. Specifically, the dietary changes that reptiles undergo, adapting the size of the resource to that of the individual, are relevant in these environments with high intraspecific competition [ 20 , 21 , 22 ].…”

“…Lizards that interact with flowers can damage the reproductive structures by feeding directly from them (i.e., florivory, 39.1% of all cases, as recently reviewed by Justicia Correcher et al [ 19 ]. When visits are legitimate (i.e., come into contact with the reproductive organs of the flower without damaging them), lizards present low pollinating potential compared to other more mobile animals, such as birds, mammals and insects with better adhesion to pollen grains, and this can be a disadvantage.…”

“…In areas where they have disappeared, the distribution of some lizard-depending plants for pollen and/or seed dispersal have undergone radical changes [ 35 ]. Although some lizard–flower interactions have been reported (see review in Justicia Correcher et al [ 19 ]), the relationship of the Balearic lizard with most of the flora is still unknown. In this study, we used a novel approach to estimate the potential pollinator role of the Balearic lizard at the community level, including the floristic diversity of its trophic spectrum (possibly underestimated) and analyzing the relevance of legitimate visits versus those involving florivory.…”