1. Persistence of long-distance, insect-mediated pollen movement for a tropical canopy tree species in remnant forest patches in an urban landscape
- Author
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Matti A. Niissalo, Shawn K. Y. Lum, Edward L. Webb, and Annika M. E. Noreen
- Subjects
0106 biological sciences ,0301 basic medicine ,Gene Flow ,Conservation of Natural Resources ,Insecta ,Pollination ,Population ,Biodiversity ,Forests ,medicine.disease_cause ,010603 evolutionary biology ,01 natural sciences ,Trees ,03 medical and health sciences ,Pollen ,Human population genetics ,Genetics ,medicine ,Animals ,education ,Genetics (clinical) ,Tree canopy ,education.field_of_study ,Singapore ,biology ,Ecology ,Urbanization ,Genetic Variation ,Fabaceae ,biology.organism_classification ,030104 developmental biology ,Genetics, Population ,Koompassia malaccensis ,Biological dispersal ,Original Article ,Microsatellite Repeats - Abstract
As deforestation and urbanization continue at rapid rates in tropical regions, urban forest patches are essential repositories of biodiversity. However, almost nothing is known about gene flow of forest-dependent tree species in urban landscapes. In this study, we investigated gene flow in the insect-pollinated, wind-dispersed tropical tree Koompassia malaccensis in and among three remnant forest patches in the urbanized landscape of Singapore. We genotyped the vast majority of adults (N=179) and a large number of recruits (N=2103) with 8 highly polymorphic microsatellite markers. Spatial genetic structure of the recruit and adult cohorts was significant, showing routine gene dispersal distances of ~100–400 m. Parentage analysis showed that 97% of recruits were within 100 m of their mother tree, and a high frequency of relatively short-distance pollen dispersal (median ~143–187 m). Despite routine seed and pollen dispersal distances of within a few hundred meters, interpatch gene flow occurred between all patches and was dominated by pollen movement: parentage analysis showed 76 pollen versus 2 seed interpatch dispersal events, and the seedling neighborhood model estimated ~1–6% seed immigration and ~21–46% pollen immigration rates, depending on patch. In addition, the smallest patch (containing five adult K. malaccensis trees) was entirely surrounded by >2.5 km of ‘impervious’ substrate, yet had the highest proportional pollen and seed immigration estimates of any patch. Hence, contrary to our hypothesis, insect-mediated gene flow persisted across an urban landscape, and several of our results also parallel key findings from insect-pollinated canopy trees sampled in mixed agricultural–forest landscapes.
- Published
- 2015