Introduction
A myriad of microorganisms can be found living in the gastrointestinal
tract of all animals. These microorganisms have a significant impact on
host biology and can influence a variety of processes that affect host
fitness [1, 2]. While certain variations in the composition of gut
microbial communities can cause disease [3, 4], gut microbiome may
also increase resistance to pathogens, besides being important for
xenobiotics metabolism, nutrient uptake and energy acquisition [e.g.
5, 6]. Moreover, gut microbiota may also contribute towards host
adaptation to environmental changes by enabling a response to new
challenges, such as exploitation of novel food sources [7, 8].
Ultimately, gut microbiome can have major impacts on host development,
behaviour and fitness, with cascading effects to the dynamics of
ecosystems [2]. In turn, it can also be modulated by several host
traits, such as host taxonomy, sex and size, as well as the external
environmental, such as habitat or prey availability [e.g. 9, 10). In
addition, social interactions between hosts can also influence the gut
microbiome in many animal species, although these mechanisms remain less
studied [see review by 11].
Gut microbiome dynamics has been studied in many mammals [e.g., 2],
birds [e.g., 12], fishes [e.g., 13] and amphibians [e.g.,
14]. Comparatively, fewer studies have been performed in reptiles, and
only a handful of these addressed lizards [15]. Nevertheless, host
taxonomy and ecology were seen to be important drivers of gut microbiota
diversity in reptiles. For example, feeding habits influence the gut
microbiota of the Chinese crocodile lizard, Shinisaurus
crocodilurus Ahl 1930, with potential effects on host health due to the
influence of diet on the abundances of pathogenic or opportunistic gut
bacteria [16]. Diet and habitat of the Australian water dragon,Intellagama lesueurii (Gray, 1831), also have an effect on
its gut microbiome, with lizards living in urban areas presenting higher
bacterial diversity than populations living in natural habitats
[17]. Moreover, host taxonomy and habitat also influence the gut
microbiota of venomous snakes [18].
Here, we analyzed and compared the diversity and composition of gut
bacterial communities of five phylogenetic related lacertid species
captured in Portugal: Podarcis siculus (Rafinesque-Schmaltz,
1810), Podarcis virescens Geniez, Sá-Sousa, Guillaume, Cluchier
and Crochet, 2014, Podarcis bocagei (Lopez-Seoane,
1885), Podarcis lusitanicus Geniez, Sá-Sousa, Guillaume, Cluchier
and Crochet, 2014 and Teira dugesi (Milne-Edwards, 1829).Podarcis species are considered as model organisms to study
ecotoxicology, immune/histochemical reactions, among other processes
[e.g. 19,20]; however, microbiome studies are still largely lacking,
with a single study on the Balearic Podarcis lilfordi (Günther,
1874) showing that islet and time since islet separation from mainland
are significant factors contributing to gut microbiome structure
[21]. Our main objective was to determine whether locality (which
also corresponded to different habitats) and host factors such as
species, size and sex modulate the gut bacterial diversity of these five
lizards. To achieve our goal, we swabbed individuals’ cloacal exudate,
known to be a good proxy for lizard gut bacterial communities [22],
which were then characterized through the high-throughput sequencing of
the V4 region of the 16S rRNA gene.