The threatened epiphytic lichen Lobaria pulmonaria in the Iberian Peninsula: Genetic diversity and structure across a latitudinal gradient

• Genetic diversity and structure of Lobaria pulmonaria populations were analysed.
• We investigated the influence of latitudinal gradients on genetic diversity.
• We obtained high levels of genetic diversity.
• High levels of genetic diversity were found, both in northern and in spatially isolated southern Iberian populations.
• Southern populations showed certain genetic differentiation.

The current genetic diversity and structure of a species plays a marked role in the species' future response to environmental changes. Identification of the factors that might ensure the long-term viability of populations along its distribution area is therefore important for conserving biodiversity. In this work, infraspecific genetic diversity and structure of the threatened lichen Lobaria pulmonaria was investigated along a latitudinal gradient, spanning the Spanish latitudinal range of L. pulmonaria. Eighteen populations in Northern, Central, and Southern Spain were analysed using six specific fungal microsatellites of L. pulmonaria. Genetic diversity indices were calculated and compared among populations. Genetic differentiation was assessed using AMOVA and Bayesian methods. Additionally, a redundancy analysis was used to estimate the relative importance of environmental factors on the genetic variation among populations. Annual precipitation was the only factor affecting the genetic diversity probably through its influence on population and thallus size of L. pulmonaria, and significantly higher levels of genetic diversity were detected in southern populations. Isolation by distance was not significant, being environmental variables most important factors controlling genetic variation in L. pulmonaria populations.