Biology subjects

Karremans, A. P.

Publications and source records attributed to Karremans, A. P..

3 recordsLinked to original sources

bioRxiv2025

Exceptional diversification of floral form in a specialized orchid pollination system

Traits that facilitate specialized interactions, such as those in flowers that promote pollination, are often invoked as targets of stabilizing selection across macroevolutionary timescales. However, the diversity of pollination mechanisms across flowering plants begs further investigation into the generality of this pattern. We fit a model of multivariate character evolution on a dataset of 140 orchid species sampled across 65 genera from the diverse neotropical Cymbidieae clade to characterize the role of pollination mode on the pace of flower shape evolution. We find that, contrary to the expectation of pollinator-mediated stabilizing selection causing stasis, orchids pollinated by specialized scent-collecting male euglossine bees ("perfume flowers" sensu (1, 2)) exhibit elevated rates of floral evolution compared to plants utilizing other rewarding or deceptive mechanisms. This pattern is recapitulated across at least 5 independent origins of this pollination system amidst a complex backdrop of background rate evolution. The rapid rates of change we observed in perfume flowers may be facilitated by weak evolutionary coupling between functional regions in their flowers, allowing for independent trajectories of evolution. Our results provide novel insights into the capacity for pollinators to generate selective pressures on flowers at macroevolutionary scales, providing an engine for trait diversification in some of the worlds most floristically rich regions.

evolutionary biology↗

bioRxiv2021

Trick or Treat? Pollinator attraction in Vanilla pompona (Orchidaceae)

Natural pollination of species belonging to the pantropical orchid genus Vanilla remains poorly understood. Based on sporadic records, euglossine bees have been observed visiting flowers of Neotropical Vanilla species. Our research aimed at better understanding the pollinator attraction mechanism of the Neotropical species Vanilla pompona, a crop wild relative with valuable traits for vanilla crop improvement programs. Using video footage, we identified floral visitors and examined their behavior. The flowers of V. pompona attracted Eulaema cingulata males, which distinctively displayed two behaviors: floral scent collection and nectar search; with the latter leading to pollen removal. Morphological measurements of floral and visitor traits showed that other Eulaema species may also act as potential pollinators. Additionally, we recorded natural fruit set in three populations and over a period of two years, tested for nectar presence and analyzed floral fragrances through gas chromatography - mass spectrometry. We observed a low natural fruit set (2.42%) and did not detect nectar. Twenty floral volatile compounds were identified, with the dominant compound trans-carvone oxide previously found to attract Eulaema cingulata males. We hypothesize a dual attraction of Eulaema cingulata males to V. pompona flowers, based on floral fragrance reward as the primary long-distance attraction, and food deception for successful pollen removal. Further research confirming this hypothesis is recommended to develop appropriate conservation policies for Vanilla crop wild relatives, which are the primary reserves of this crops genetic variation.

plant biology↗

bioRxiv2017

Recent origin of Neotropical orchids in the world’s richest plant biodiversity hotspot

* The Andean mountains of South America are the most species-rich biodiversity hotspot worldwide with about 15% of the worlds plant species, in only 1% of the worlds land surface. Orchids are a key element of the Andean flora, and one of the most prominent components of the Neotropical epiphyte diversity, yet very little is known about their origin and diversification.\n\n* We address this knowledge gap by inferring the biogeographical history and evolutionary dynamics of the two largest Neotropical orchid groups (Cymbidieae and Pleurothallidinae), using two unparalleled, densely-sampled orchid phylogenies (including 400+ newly generated DNA sequences), comparative phylogenetic methods, geological and biological datasets.\n\n* We find that the majority of Andean orchid lineages only originated in the last 15 million years. Most Andean lineages are derived from lowland Amazonian ancestors, with additional contributions from Central America and the Antilles. Species diversification is correlated with Andean orogeny, and multiple migrations and re-colonizations across the Andes indicate that mountains do not constrain orchid dispersal over long timescales.\n\n* Our study sheds new light on the timing and geography of a major Neotropical radiation, and suggests that mountain uplift promotes species diversification across all elevational zones.

evolutionary biology↗