Bromeliaceae subfamilies show divergent trends of genome size evolution

Lilian-Lee B Müller,Gerhard Zotz,Dirk C Albach

doi:10.1038/s41598-019-41474-w

Lilian-Lee B Müller, Gerhard Zotz + Show 1 more

Open Access

https://doi.org/10.1038/s41598-019-41474-w

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Abstract

Genome size is known to vary widely across plants. Yet, the evolutionary drivers and consequences of genome size variation across organisms are far from understood. We investigated genome size variation and evolution in two major subfamilies of the Neotropical family Bromeliaceae by determining new genome size values for 83 species, testing phylogenetic signal in genome size variation, and assessing the fit to different evolutionary models. For a subset of epiphytic bromeliad species, we also evaluated the relationship of genome size with thermal traits and relative growth rate (RGR), respectively. Genome size variation in Bromelioideae appears to be evolutionary conserved, while genome size among Tillandsioideae varies considerably, not just due to polyploidy but arguably also due to environmental factors. The subfamilies show fundamental differences in genome size and RGR: Bromelioideae have, on average, lower genome sizes than Tillandsioideae and at the same time exhibit higher RGR. We attribute this to different resource use strategies in the subfamilies. Analyses among subfamilies, however, revealed unexpected positive relationships between RGR and genome size, which might be explained by the nutrient regime during cultivation. Future research should test whether there is indeed a trade-off between genome size and growth efficiency as a function of nutrient supply.

Highlights

Genome size, i.e., the total amount of nuclear DNA per cell, is known to vary greatly across organisms
Knight et al.[14] investigated the cost of carrying a large amount of non-coding DNA and formulated the “large genome constraint hypothesis”: large genomes constrain a species’ evolution, ecology, and phenotype. This might explain why species with very large genomes appear to be excluded from stressful habitats, whereas species with smaller genomes are distributed in widely varying habitats[8,13,15], which has even been used to explain the evolutionary success of angiosperms as a whole[12]
We evaluated the relationship of genome size and thermal niche for growth, relative growth rate and growth components, respectively, for a subset of epiphytic bromeliad species

Summary

Introduction

I.e., the total amount of nuclear DNA per cell, is known to vary greatly across organisms. Either decreasing or increasing genome size, have been proposed to explain the wide variation in genome size[5,7], the functional significance of non-coding DNA is still unresolved[8]. Knight et al.[14] investigated the cost of carrying a large amount of non-coding DNA and formulated the “large genome constraint hypothesis”: large genomes constrain a species’ evolution, ecology, and phenotype This might explain why species with very large genomes appear to be excluded from stressful habitats, whereas species with smaller genomes are distributed in widely varying habitats[8,13,15], which has even been used to explain the evolutionary success of angiosperms as a whole[12]. There appears to be an evolutionary pressure towards smaller, more “efficient”, genomes in nutrient-poor environments

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