SUMMARYComparisons of closely related species are needed to understand the fine-scale dynamics of retrotransposon evolution in flowering plants. Towards this goal, we classified the long terminal repeat (LTR) retrotransposons from six diploid and one tetraploid species of Orobanchaceae. The study species are the autotrophic, non-parasitic Lindenbergia philippensis (as an out-group) and six closely related holoparasitic species of Orobanche [O. crenata, O. cumana, O. gracilis (tetraploid) and O. pancicii] and Phelipanche (P. lavandulacea and P. ramosa). All major plant LTR retrotransposon clades could be identified, and appear to be inherited from a common ancestor. Species of Orobanche, but not Phelipanche, are enriched in Ty3/Gypsy retrotransposons due to a diversification of elements, especially chromoviruses. This is particularly striking in O. gracilis, where tetraploidization seems to have contributed to the Ty3/Gypsy enrichment and led to the emergence of seven large species-specific families of chromoviruses. The preferential insertion of chromoviruses in heterochromatin via their chromodomains might have favored their diversification and enrichment. Our phylogenetic analyses of LTR retrotransposons from Orobanchaceae also revealed that the Bianca clade of Ty1/Copia and the SMART-related elements are much more widely distributed among angiosperms than previously known.

Kin selection theory provides a strong theoretical framework to explain the evolution of altruism and cooperative behaviour among genetically related individuals. However, the proximate mechanisms underlying kin discrimination, a necessary process to express kin-related behaviour, remain poorly known. In particular, no study has yet unambiguously disentangled mechanisms based on learned familiarity from true phenotype matching in kin discrimination based on vocal signals. Here we show that in addition to genetic background, social accommodation also shapes individual voices in an Old World monkey (Mandrillus sphinx), even though primate vocalizations were thought to be innate and little flexible. Nonetheless, social shaping of voice parameters does not impair kin discrimination through phenotype-matching of unknown relatives, revealing unexpected discriminatory versatility despite signal complexity. Accurate signal production and perception, therefore, provide a basis for kin identification and kin-biased behaviour in an Old World primate.