The genesis of size hierarchies in seedling populations of impatiens capensis meerb.
TLDR
In this article, the authors used path analysis to summarize the interactions among the continuous variables and to disentangle direct from indirect causal effects, concluding that seed weight enhanced performance primarily through its effects on emergence date and cotyledon area.Abstract:
Summary
In 1978 and 1980 I planted 660 and 900 seeds of Impatiens capensis Meerb. at four densities in the greenhouse to examine how variation in plant performance is generated. I noted seed weight, seed type (cleistogamous or chasmogamous), maternal parent, and population of origin, and monitored emergence date, cotyledon area, the biomass of competitors within the same flat, and the final size reached by the seedlings after 63 to 80 d of growth. Larger seeds tended to germinate sooner, as did seeds derived from chasmogamous flowers. Seeds from northern populations took longer to germinate. Seeds from different maternal parents also germinated at different rates. Cotyledon area strongly depended on seed weight, and, to a lesser extent, germination date. Maternal parent and seed type significantly affected cotyledon area in 1980.
Plant density and cotyledon area influenced final size the most, but almost every factor proved to be statistically significant. As expected, earlier emerging seedlings with larger cotyledons growing at the lowest density grew into the largest plants. I applied path analysis to summarize the interactions among the continuous variables and to disentangle direct from indirect causal effects. This technique revealed that seed weight enhanced performance primarily through its effects on emergence date and cotyledon area. Chasmogamous seedlings outperformed cleistogamous seedlings, and their advantage was expressed during most phases of growth. Together, the predictor variables accounted for over four-fifths of the total variation in final size.
The inequality of plant sizes, as measured by the Gini coefficient, increased appreciably during the course of the experiment. There was no simple relation to density, however, suggesting that both intrinsic differences in growth rate, and competitive dominance and supression fuel the establishment of size hierarchies.read more
Citations
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Do Plant Populations Purge Their Genetic Load? Effects of Population Size and Mating History on Inbreeding Depression
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Reproductive Allocation in Plants
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Enhancement of inbreeding depression by dominance and suppression in Impatiens capensis
TL;DR: Plant density may influence patterns of natural selection both on mating system and on juvenile traits in natural Impatiens populations, indicating that larger plants competitively suppressed smaller plants in the high‐density treatments.
References
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Book
On Economic Inequality
Amartya Sen,James E. Foster +1 more
TL;DR: In this paper, Amartya Sen relates the theory of welfare economics to the study of economic inequality and presents a systematic treatment of the conceptual framework as well as the practical problems of measurement of inequality.
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Correlation and Causation
Victor R. Martuza,David A. Kenny +1 more
TL;DR: Causality is the area of statistics that is most commonly misused, and misinterpreted, by nonspecialists as discussed by the authors, who fail to understand that, just because results show a correlation, there is no proof of an underlying causality.