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bioRxiv · 10.1101/2022.03.30.485788

The interplay between habitat fragmentation and life traits affects specialization in lichen symbioses

Berlinches de Gea, A.·Perez-Ortega, S.·Verdu, M.·Villar-dePablo, M.
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Abstract

O_LIInteractions between organisms are determined by species traits and differ in specialization, from generalist to highly specialized relationships. Although we expect that the effect of habitat loss and fragmentation on the abundance and survival of species depends on their degree of specialization, few studies have deepened into the interplay between interaction specialization and habitat loss. C_LIO_LIHere, we investigate the combined effect of habitat fragmentation and life traits (growth type and reproductive mode) on the specialization of lichen-forming fungi (mycobionts) towards its photosynthetic partners (photobionts) in lichen symbioses. C_LIO_LIWe studied mycobiont specialization in epiphytic lichen communities present in ten fragments of Quercus rotundifolia trees embedded in an agricultural matrix. Both mycobionts and photobionts were identified through DNA sequencing and mycobiont specialization was measured through interaction parameters calculating the relative number of interactions (normalized degree; ND) and the specialization of each species based on its discrimination from a random selection of partners (d). Phylogenetic generalized linear mixed models were used to analyze the effect of patch size as well as the life traits growth type (crustose, foliose, fruticose) and reproduction mode (sexual vs asexual) on mycobiont specialization. C_LIO_LIBoth mycobiont and photobiont richness along the patch size gradient followed a hump-back pattern, which was more pronounced in photobionts. Mycobionts forming crustose biotypes established the largest number of interactions. Mycobiont specialization (d) was larger for fruticose and foliose biotypes and for species with vegetative reproduction. Along the gradient of fragment size, the relative number of interactions decreased and the specialization of mycobionts with vegetative reproduction increased. C_LIO_LISynthesis: The analysis of mycobiont specialization towards their photobionts in communities of epiphytic lichens in a fragmented Mediterranean forest revealed that the interaction between species life traits and habitat loss on specialization cannot be neglected. The results also pointed to the ability of some species to modulate their interactions to certain extent, suggesting that species might have a greater resilience to abiotic changes than expected, presumably creating extinction debt or even avoiding extinction processes to some extent. C_LI ResumenO_LILas interacciones entre organismos estan determinadas por los rasgos funcionales de las especies y difieren en su grado de especializacion, desde interacciones generalistas hasta las altamente especializadas. Aunque se espera que el efecto de la perdida y fragmentacion del habitat sobre la abundancia y la supervivencia de las especies dependa de su grado de especializacion, pocos estudios han profundizado en la interaccion entre la especializacion de las interacciones y la perdida de habitat. C_LIO_LIEn este articulo investigamos el efecto combinado de la fragmentacion del habitat y los rasgos funcionales de las especies (tipo de crecimiento y modo reproductivo) en la especializacion de los hongos liquenizados (micobiontes) hacia sus socios fotosinteticos (fotobiontes) en las simbiosis de liquenes. C_LIO_LISe estudio la especializacion de micobiontes en comunidades de liquenes epifitos presentes en diez fragmentos de arboles de Quercus rotundifolia incrustados en una matriz agricola. Tanto los micobiontes como los fotobiontes fueron identificados mediante la secuenciacion del ADN y la especializacion de los micobiontes se midio a traves de parametros de interaccion calculando el numero relativo de interacciones (grado normalizado; ND) y la especializacion de cada especie en funcion de su discriminacion de una seleccion aleatoria de simbiontes (d). Se utilizaron modelos lineales mixtos generalizados filogeneticos para analizar el efecto del tamano del parche, asi como los rasgos de tipo de crecimiento (crustaceo, folioso, frutal) y el modo de reproduccion (sexual frente a asexual) sobre la especializacion de los micobiontes. C_LIO_LITanto la riqueza de micobiontes como de fotobiontes a lo largo del gradiente de tamano de los parches siguio un patron de U inversa, que fue mas pronunciado en los fotobiontes. Los micobiontes que forman biotipos crustaceos establecieron el mayor numero de interacciones. La especializacion de los micobiontes (d) fue mayor para los biotipos fruticulosos y foliosos y para las especies con reproduccion vegetativa. A lo largo del gradiente del tamano del fragmento, el numero relativo de interacciones disminuyo y la especializacion de los micobiontes con reproduccion vegetativa aumento. C_LIO_LISintesis: El analisis de la especializacion de los micobiontes hacia sus fotobiontes en comunidades de liquenes epifitos en un bosque mediterraneo fragmentado revelo que no se puede descartar la interaccion entre los rasgos de vida de las especies y la perdida de habitat sobre la especializacion. Los resultados tambien apuntaron a la capacidad de algunas especies para modular sus interacciones hasta cierto punto, sugiriendo que las especies podrian tener una resiliencia a los cambios abioticos mayor de lo esperado, presumiblemente creando una deuda de extincion o incluso evitando los procesos de extincion hasta cierto punto. Palabras clave: Bosque mediterraneo, epifitos, fotobiontes, hongos liquenizados, selectividad. C_LI

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Berlinches de Gea, A., Perez-Ortega, S., Verdu, M., Villar-dePablo, M.. 2022-04-01. The interplay between habitat fragmentation and life traits affects specialization in lichen symbioses. https://doi.org/10.1101/2022.03.30.485788

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