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Abiotic environments and biotic neighbourhoods interact to influence plant growth and community assembly. However, the nature of this interaction depends very much on how biotic neighbourhoods are measured, including their relatedness to focal plants. In a tropical seasonal rainforest, we examine the growth of a dominant canopy species in response to environmental factors, the densities and relatedness of conspecific and heterospecific neighbours, and their interactions. We find significant environmental effects and conspecific negative density dependence on growth. Furthermore, conspecific neighbour density has stronger negative effects on growth under high light and soil water resource levels, but weaker negative effects under low light and soil water resource levels. In addition, more closely related heterospecifics in the neighbourhood have negative effects on growth under high soil phosphorus availability, but positive effects under low soil phosphorus availability. In contrast, more closely related conspecifics in the neighbourhood have negative effects on growth under low soil potassium availability, but positive effects under high soil potassium availability. Our study emphasizes the importance of both intra- and interspecific neighbourhood composition and their interactions with resource levels for understanding tree growth. This enhances our understanding of the complex processes in community assembly and species coexistence within forest communities.
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Fitness consequences of marine larval dispersal: the role of neighbourhood density, arrangement, and genetic relatedness on survival, growth, reproduction, and paternity in a sessile invertebrate
Abstract Dispersal can evolve as an adaptation to escape competition with conspecifics or kin. Locations with a low density of conspecifics, however, may also lead to reduced opportunities for mating, especially in sessile marine invertebrates with proximity-dependent mating success. Since there are few experimental investigations, we performed a series of field experiments using an experimentally tractable species (the bryozoan Bugula neritina) to test the hypothesis that the density, spatial arrangement, and genetic relatedness of neighbours differentially affect survival, growth, reproduction, paternity, and sperm dispersal. We manipulated the density and relatedness of neighbours and found that increased density reduced survival but not growth rate, and that there was no effect of relatedness on survival, growth, or fecundity, in contrast to previous studies. We also manipulated the distances to the nearest neighbour and used genetic markers to assign paternity within known mother–offspring groups to estimate how proximity affects mating success. Distance to the nearest neighbour did not affect the number of settlers produced, the paternity share, or the degree of multiple paternity. Overall, larger than expected sperm dispersal led to high multiple paternity, regardless of the distance to the nearest neighbour. Our results have important implications for understanding selection on dispersal distance: in this system, there are few disadvantages to the limited larval dispersal that does occur and limited advantages for larvae to disperse further than a few 10s of metres.
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- Award ID(s):
- 1948788
- PAR ID:
- 10584887
- Editor(s):
- Hunt, John; Ravinet, Mark
- Publisher / Repository:
- Oxford University Press
- Date Published:
- Journal Name:
- Journal of Evolutionary Biology
- Volume:
- 38
- ISSN:
- 1420-9101
- Page Range / eLocation ID:
- 28–40
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript
- Journal Article:
- https://doi.org/10.1093/jeb/voae125
