Madagascar’s orphans of extinction

OCTF seminar followed by drinks – all welcome

The extinction of Madagascar’s megafauna between c. 2000 and 400 years ago had and continues to have consequences for biodiversity and a number of ecosystem processes, such as the dispersal of large-seeded plant species. Today, some species produce fruits and seeds obviously too big to be dispersed by any living frugivores. These anachronistic species are missing their extinct mutualistic partners, such as giant lemurs and elephant birds. As a starting point, we looked for dispersal anachronisms in endozoochorously dispersed members of the legume family (Fabaceae). In Madagascar, the Fabaceae are the third most species-rich flowering plant family, comprising 667 species of which 449 are endemic. The extant frugivorous guild in Madagascar is strikingly small compared to other tropical areas. Only 21 lemur, three bat, five bird and one tortoise species are mainly frugivorous (excl. granivores), and, among those, only some lemurs are able to disperse (i.e. swallow) very large (> 10 mm) seeds. Out of endemic Fabaceae species in Madagascar, we were able to estimate the degree of dispersal anachronism for 438 endemic species (98%). For the remaining 11 species, sufficient information about fruits and seeds was unavailable. We found at least 6 species of Fabaceae in which the mismatch between fruit and seed morphology, and the physical limitations and sensory preferences of living fauna strongly indicates dispersal anachronism. In Madagascar, many species from a wide range of plant families possess large pulpy fruits with big seeds. Therefore, it is a mere certainty that dysfunctional dispersal due to anachronism reaches far beyond the Fabaceae and, in fact, is a common problem affecting Madagascar’s unique flora. It has been demonstrated that the loss of animal seed dispersers considerably increases the risk of extinction for plants with zoochorous fruits or seeds. Hence, apart from habitat destruction, dysfunctional seed dispersal is likely to be one of the main reasons why most of these species are now on the edge of extinction.

Wolfgang Stuppy joined the Royal Botanic Gardens, Kew in 1999 to work on ex-situ conservation in Kew’s Living collections. An expert on comparative seed morphology and anatomy, he then became Kew’s Seed Morphologist at Kew’s Millennium Seed Bank in 2003. He is currently Research Leader in Comparative Seed Biology. A specialist in a rarely studied field, Wolfgang Stuppy has taught students and partners of the Millennium Seed Bank Partnership within the UK and overseas. His popular three-to five-day ‘crash-course’ on fruit and seed morphology has been held at Kings Park & Botanic Garden, Perth, the University of Queensland, Brisbane, Lincoln University, Christchurch, UNAM in Mexico City and the Amazonas Research Institute (INPA) in Manaus, Brazil.
He has authored numerous scientific and popular scientific publications and books. He is a keen photographer and his images have been widely published. His first book entitled ‘Seeds – Time Capsules of Life’, published in 2006 in collaboration with artist Rob Kesseler, won the title of ‘Outstanding Book of the Year’ for ‘Most Original Concept’ and was awarded a Gold Medal by the Independent Publisher Book Awards. Wolfgang Stuppy’s second book, also in collaboration with Rob Kesseler, entitled “Fruit – Edible, Inedible, Incredible”, was released in 2008. His third book, ‘Wonders of the Plant Kingdom’ was published in 2014.