Background and Aims: The evolutionary history of hornworts has been significantly explored through phylogenomic analyses, revealing unexpected complexities in the placement of Leiosporoceros, a putative sister lineage to other hornworts. Our understanding of the evolutionary history of hornworts and the role of incomplete lineage sorting (ILS) or ancient reticulation poses challenges in resolving their exact position and comprehending the diversification and evolutionary processes of hornworts. Methods: Using the GoFlag probe set, we sequenced 405 exons representing 234 nuclear genes, sampling 79 hornwort specimens, including representatives of all hornwort genera. We inferred the species phylogeny from gene tree analyses using concatenated and coalescence approaches, assessed ancient reticulation, ILS, and estimated the timing of divergences based on fossil calibrations.

AUTHORS:Salzman, Shayla1, M.R.L. Whitaker2, A.M. Sierra3, E.D Bustos-Díaz4, A. Cibrián-Jaramillo5, Y. Liu6, F. Barona-Gómez4, S.Z. Zhang6, S.K. Sahu7,9, J.C. Villarreal A.3,8,91 University of Georgia, Entomology, Athens, GA, US2 East Tennessee State University, Biological Sciences, Johnson City, TN, US3 Département de Biologie, Université Laval, G1V 0A6, Québec, Canada4 Institute of Biology, University of Leiden, 2333 BE, Leiden, NL.5 Naturalis Biodiversity Center, Darwinweg 2 2333 CR Leiden, The Netherlands6 Shenzhen & Chinese Academy of Sciences, Fairy Lake Botanical Garden, Shenzhen, CN7 State Key Laboratory of Agricultural Genomics, Key Laboratory of Genomics, Ministry of Agriculture, BGI Research, Shenzhen 518083, China8 Smithsonian Tropical Research Institute, Ancón, Panamá9 Corresponding authors

Patch size and connectivity are the main predictors of population demographic and genetic stability. Habitat fragmentation continues at unprecedented rates justly affecting plant functional connectivity worldwide. However, few terrestrial plant groups have sufficiently foreshortened generation times in which to empirically disentangle the demographic and genetic consequences of reduced patch size and connectivity. Herein, we combine evidence from long-term (15 yr.) population censuses of two epiphyllous bryophytes and population genetic estimates in an experimentally fragmented Amazonian landscape to create a profile of the eco-evolutionary impacts of reduced habitat connectivity. Single nucleotide polymorphisms (SNPs) derived from Genotyping by Sequencing were used to analyze genetic patterns among fragmented (1-, 10- and 100-ha) and continuous forests. In the context of the world’s most diverse biome, fragmentation induces marked effects on plant population demography and genetic differentiation. Declines in colonization events in small patches (1- and 10-ha), associated with reduced colony densities, led to accelerated genotypic differentiation (genetic drift) compared to 100-ha fragment and continuous forests. Furthermore, the mating system was related to differential sensitivities to the intensity of fragmentation. Unexpectedly, the unisexual species (hypothesized to be more challenged in terms of spore output) was characterized by higher migration rates among smaller patches than its bisexual counterpart. These results point to the complex and unpredictable patterns revealed when life history strategies, demography, and plant genetic structure are simultaneously evaluated in the context of the long-term effects of reduced landscape connectivity.

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