Single-Copy Nuclear Genes Place Haustorial Hydnoraceae within Piperales and Reveal a Cretaceous Origin of Multiple Parasitic Angiosperm Lineages

Abstract

Extreme haustorial parasites have long captured the interest of naturalists and scientists with their greatly reduced and highly specialized morphology. Along with the reduction or loss of photosynthesis, the plastid genome often decays as photosynthetic genes are released from selective constraint. This makes it challenging to use traditional plastid genes for parasitic plant phylogenetics, and has driven the search for alternative phylogenetic and molecular evolutionary markers. Thus, evolutionary studies, such as molecular clock-based age estimates, are not yet available for all parasitic lineages. In the present study, we extracted 14 nuclear single copy genes (nSCG) from Illumina transcriptome data from one of the “strangest plants in the world”, Hydnora visseri (Hydnoraceae). A ∼15,000 character molecular dataset, based on all three genomic compartments, shows the utility of nSCG for reconstructing phylogenetic relationships in parasitic lineages. A relaxed molecular clock approach with the same multi-locus dataset, revealed an ancient age of ∼91 MYA for Hydnoraceae. We then estimated the stem ages of all independently originated parasitic angiosperm lineages using a published dataset, which also revealed a Cretaceous origin for Balanophoraceae, Cynomoriaceae and Apodanthaceae. With the exception of Santalales, older parasite lineages tend to be more specialized with respect to trophic level and have lower species diversity. We thus propose the “temporal specialization hypothesis” (TSH) implementing multiple independent specialization processes over time during parasitic angiosperm evolution.

Deceptive Ceropegia dolichophylla fools its kleptoparasitic fly pollinators with exceptional floral scent

“…Oelschlägel et al (2015) described it for the first time for a deceptive Aristolochia species pollinated by kleptoparasitic Chloropidae. Independently from each other, the early diverged lineage Aristolochia (39.5 million years ago; Naumann et al, 2013) and the much younger group Ceropegia (10 million years ago; Rapini et al, 2007) evolved both, the trap flowers and the kleptomyiophilous pollination strategy.…”

Consideraciones sobre la sistemática de las familias y los géneros de plantas vasculares endémicos de Chile

“…Respecto a esta última asociación, no se ha logrado esclarecer con certeza la posición de Lactoris respecto a las dos subfamilias de Aristolochiaceae, la cual suele aparecer parafilética con Lactoris en su interior (Neinhuis et al 2005, Naumann et al 2013. Sin embargo, ni el sustento estadístico de esta topología, ni los análisis morfológicos que se han llevado a cabo, permiten adoptar una decisión coherente al respecto.…”

Hydnora ­arabica (Aristolochiaceae), a new species from the Arabian Peninsula and a key to Hydnora

“…The two genera of obligate root holoparasites, Prosopanche and Hydnora, previously in the Hydnoraceae, are now placed in the Aristolochiaceae (APG IV 2016) based on molecular work (Nickrent et al 2002, Naumann et al 2013 and aligning with the earliest placement by Meyer (1833) and Ballion (1886). In the old-world genus Hydnora, seven species are recognized and two major lineages have been identified (Bolin et al 2011), aligning with the subgeneric sections delineated in the monograph by Harms (1935), based on their host preference and several major synapomorphies.…”