Comparative pollen morphology and viability among endangered species of Butia (Arecaceae) and its implications for species delimitation and conservation

Abstract

The present study reports the results of pollen analyses on four species of Butia (Arecaceae), Butia odorata, B. yatay, B. paraguayensis and B. lallemantii. Pollen grains were described using light microscopy (LM) and scanning electron microscopy (SEM), and pollen viability was determined by the fluorochromatic reaction (FCR) test. All species of Butia studied produce monosulcate pollen grains with a tectate perforate exine. Additionally, B. odorata and B. paraguayensis produce two pollen grain types, mono- and also trichotomosulcate, which has been considered a derived state of the character. Regarding pollen grain size and shape, there are significant differences in long and short axis lengths, and their ratio. Despite serious regeneration problems which jeopardise population survival in the short-term future, results showed that pollen viability of all species of Butia analysed was high enough to ensure good pollination. Therefore, pollen viability is not the limiting factor for population continuity. This is the first study dealing both with pollen morphology and assessment of pollen viability with the aim of species delimitation within this genus. Additionally, this is the first study providing new information regarding the status of the current Butia populations of southern South America from a palynological point of view.

Keywords:

• Butia
• Palmae
• pollen differentiation
• pollen viability
• population continuity

Acknowledgements

We wish to thank César Fagúndez for kindly providing samples of Butia odorata, and Pamela Scaraffuni for assistance in pollen viability sample processing.

Additional information

Funding

This work was supported by the Agencia Nacional de Investigación e Innovación (ANII), Uruguay, under Grant Fondo Clemente Estable (project ID FCE2007–612). We thank Prof. Ángeles Beri who kindly provided laboratory and Palynological Collection facilities at Facultad de Ciencias, Universidad de la República, and Dr. Larry Noblick for species identification.

Notes on contributors

Dominique Mourelle

DOMINIQUE MOURELLE is a palynologist and Quaternary palaeoecologist, and has an MSc in biology. She is currently a PhD candidate at the Universidad Nacional de Mar del Plata, Argentina. Dominique's research interests are on modern pollen-vegetation relationships and vegetational reconstructions using palynology in Uruguay.

Paola Gaiero

PAOLA GAIERO is a botanist with an MSc in agricultural sciences. She is currently a PhD candidate at Wageningen University in The Netherlands. Paola is also a teaching assistant at the Faculty of Agronomy, Universidad de la República in Montevideo, Uruguay, working on conservation genetics and comparative cytogenetics and genomics.

Gabriela Speroni

GABRIELA SPERONI has a PhD in botany and is a Professor of Botany at the Faculty of Agronomy, Universidad de la República in Montevideo, Uruguay. Her principal research interest is on the reproductive biology of economically significant wild plant species.

Carina Millán

CARINA MILLÁN is a biology student at the Faculty of Sciences of the Universidad de la República, in Montevideo, Uruguay. Her main research interest is on the native flora of South America, especially the reproductive biology of vascular plants.

Lucía Gutiérrez

LUCIA GUTIÉRREZ CHACÓN has a PhD in botany and evolutionary biology from Iowa State University, USA. She is currently an Associate Professor at the Faculty of Agronomy, Universidad de la República in Montevideo, Uruguay, where her main research is on statistical genetics.

Cristina Mazzella

CRISTINA MAZZELLA has a PhD in biology from the Universidad Autónoma de Madrid, Spain. She is currently a professor at the Faculty of Agronomy, Universidad de la República in Montevideo, Uruguay, and researches on plant genetics.