EPOW - Ecology Picture of the Week

Liolaemus Galore

Liolaemus "Sand" Lizard (Liolaemus cf. wiegmannii), Family Liolaemidae
Challhuaco Reserve, Argentina

Explanation:   We are in the high-country parkland of Challuaco Reserve in west-central Argentina, in the forests of southern beech (Nothofagus) trees and ... of this unassuming but amazing lizard with quite a story to tell.

First, I recognize this lizard as belonging to the taxonomic family Liolaemidae, and more precisely the genus Liolaemus.  I think it is a specimen of "sand lizard" of species Liolaemus wiegmannii.  But ... this species name is also the name of a wider group of some 11 species called "sand lizards" that share their adaptations to dry arid environments.  I might have the species identification incorrect, but the story continues. 

This genus of Liolaemus lizards are an evolutionary marvel.  Found in the Andes mountains and adjacent lowlands from Peru to the southern tip of South America, the genus has undergone "adaptive radiation" and formed what some purport to consist of "more than 200 species."  Wikipedia cites "more than 225 described species ... but the true number of species may be about double this number."  And, more recently, Ruiz et al. (2021) cite "approximately 277 species."  

Wow!

This is an astounding diversity of species within one genus and within one continental region!  And new species are indeed still being reported (Ruiz et al. 2021), such as from Bolivia (Abdala et al. 2019).

Photographed in the same region as the others on this page,
this Liolaemus lizard may be a juvenile of the same species
or perhaps a different species.  I could find no guides to identification.
  

More amazing facts from research at The Australian National University:  Unlike most other species of lizards, species of Liolaemus of the high Andes Mountains give birth to live young, because in that cold environment eggs would not incubate.  But as the lizards moved to lower elevations, they later evolved to bear eggs, not live young.  This transition from live young back to egg-laying is virtually unheard of in the animal kingdom.

Clearly, this lizard has much to teach about evolutionary ecology, adaptive strategies for survival, and how nature can work in contradiction to traditional understanding.  All this from a small unassuming reptile.

(And the adaptive diversity of species of this lizard genus also reminds me of the Microlophus lava lizards of the Galapagos Islands of Ecuador...)
  

  
Information:
     Abdala, C. S., A. Aguilar-Kirigin, R. V. Semhan, A. L. B. Arroyo, J. Valdes, M. M. Paz, R. G. Poblete, P. V. Faundez, R. Langstroth, and J. Aparicio. 2019. Description and phylogeny of a new species of Liolaemus (Iguania: Liolaemidae) endemic to the south of the Plurinational State of Bolivia. PLoS ONE 14(12):e0225815. https://doi.org/10.1371/journal.pone.0225815. 
     Portelli, S. N., and A. S. Quinteros. 2018. Phylogeny, time divergence, and historical biogeography of the South American Liolaemus alticolor-bibronii group (Iguania: Liolaemidae). PeerJ 6:e4404 
     Ruiz, S., M. Quipildor, M. R. Ruiz-Monachesi, L. Escalante, S. Valdecantos, and R. Lobo. 2021. Diversification and geological history of the Liolaemus ornatus group (Squamata: Iguania) of Argentina including the recognition of a new species. Zoologischer Anzeiger 292:126-138. 
     Valdecantos, S., V. Martínex, F. Lobo, and F. B. Cruz. 2013. Thermal biology of Liolaemus lizards from the high Andes: Being efficient despite adversity. Journal of Thermal Biology 38(3):126-134.