Research interests

• Tropical ecology
• Seed dispersal
• Spatial genetic structure of tree populations
• Phyllostomid bats as seed dispersers
• Forest fragmentation and regeneration

 

 

 

Scientific projects

In tropical rain forests, most tree species depend on animals as pollen and seed dispersers. As many of the dispersers are highly mobile, the direct assessment of dispersal distances is a challenging task. The development of highly polymorphic genetic markers allows estimations of the genetic relationship between pairs of individuals. If pairwise genetic relationship is correlated with geographic distance between individuals, this so-called spatial genetic structure (SGS) indicates restricted pollen and/or seed dispersal.
We studied several species of bat-dispersed Ficus species (Moraceae) in Panama and Costa Rica. In Neotropical dioecious Ficus species, pollen is transported by mutualistic fig wasp over large distances. Thus, Neotropical figs are regarded as broadly panmictic and most authors that studies figs of the Old World predicted the absence of SGS.
Neotropical fruit-eating bats (Phyllostomidae, Chiroptera) are considered to be the main dispersers of many fig species and to effectively disperse large amounts of viable seeds. The fruit-eating bats use temporal feeding roosts for fruit consumption that are located within 50 – 200 m around the fruiting tree and gut passage times are relatively short. Thus, we hypothesize that the majority of the seeds is dispersed within this range which should result in significant SGS despite the long-distance pollen dispersal.
In cooperation with Dr. Christopher W. Dick (University of Michigan, US) and Dr. Carlos Machado (University of Maryland, US) we developed highly polymorphic microsatellites for Ficus insipida, F. yoponensis, F. citrifolia and F. obtusifolia to assess the SGS. The studied species differ in growth form (strangler vs. frees-standing fig) as well as in the assemblage of bat species that act as seed dispersers.
Furthermore, we want to test whether there is evidence for non-species specific pollination. According to Machado et al. 2005 pollination across species seems to take place more frequently than previously expected. As microsatellite data sets allow detecting hybridization, we will compare genotypes of nine Ficus species for patters of introgression.

Collaborators

Dr. Christopher W. Dick (University of Michigan, US)

Dr. Carlos Machado (University of Maryland, US)

Dr. Edward Allen Herre (Smithsonian Tropical Research Institute, Panama)

Other projects

To interpret results of genetic studies on spatial genetic structure adequately, detailed knowledge about the ecology of the dispersal agent is required. Thus, in a complementary approach, we investigate movement patters, dietary habits and factors that influence the presence of absence of fruit-eating bats.

Community study of frugivorous bats in a fragmented landscape in Bahia, Brazil
Frugivorous bats are considered to be important seed dispersers especially in fragmented landscapes. In Bahia, Brazil, we study assemblages of frugivorous bats in forest fragments and rubber plantations of different management regimes in the “Reserva Ecologica Michelin”. The study was conducted in collaboration with Dr. Marco Mello and Dipl. Biol. Maria Helbig (both University of Ulm).

Home range size of Ectophylla alba (Phyllostomidae) in Sarapiqui, Costa Rica
As movement patters of frugivores shape the seed shadow produced by a frugivore, we use radio-telemetry to study movement patters of Ectophylla alba (Chiroptera, Stenodermatinae) in Costa Rica. The small, fruit-eating bats roosts in leaf tents in secondary forests and consumes exclusively fruits of the mainly bird-dispersed fig Ficus colubrinae (Moraceae). The study is conducted in the ecological Reserve “La Tirimbina” in Sarapiqui, Costa Rica in collaboration with Dr. Bernal Rodriguez Herreara and David Villalobos.

http://www.tirimbina.org/

Publications

Heer K, Albrecht L, Kalko EKV (2010) Effects of ingestion by neotropical bats on germination parameters of native free-standing and strangler figs (Ficus sp., Moraceae). Oecologia 163:425-435

Conference contributions

Heer K, Dick CW, Herre, EA, Kalko EKV (2011) How pollen and seed dispersal shape spatial genetic structure of Neotropical figs. Talk presented at the Annual Meeting of the Ecological Society of Germany, Austria and Switzerland (GfÖ), Oldenburg, Germany

Helbig, M, Heer K, Mello MAR, Kalko EKV (2011) Responses of bats to habitat disruption in a plantation-forest mosaic in Bahia, Brazil. Talk presented at the Annual Meeting of the ATBC, Arusha, Tanzania

Heer K, Kalko EKV, Herre EA, Dick CW (2011) Fine-scale spatial genetic structure of Neotropical bat-dispersed fig species (Ficus spp., Moraceae). Talk presented at the Plant Population Biology Conference (GfÖ), Oxford, UK

Heer K, Dick CW, Kalko EKV (2011) The spatial genetic structure of bat-dispersed Neotropical fig species. Talk presented at the Annual Conference of the Society for Tropical Ecology (GTÖ), Frankfurt, Germany

Heer K, Kalko EVK (2010) Influence of Neotropical bats on germination parameters of free-standing and strangler figs (Ficus sp., Moraceae). Poster presented at the Frugivory and Seed Dispersal conference, Montpellier, France.

Heer K (2009) Influence of neotropical bats on germination parameters of free-standing and strangler figs (Ficus sp., Moraceae). Talk presented at the joint meeting of ATBC and GTÖ, Marburg, Germany

Heer K, Kalko EKV (2009) Influence of Artibeus jamaicensis (Phyllostomidae) on germination of fig seeds (Ficus spp., Moraceae). Poster presented at the workgroup meeting of bat researchers, Frauenwörth, Chiemsee, Germany