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<p>Density-dependent selection, especially if <i>r</i> and<i>K</i> are inversely related, is one of the most plausible suggested mechanisms for the evolution of population stability. However, experimental support for this explanation has been both meagre and mixed. One study with <i>Drosophila melanogaster</i> yielded no evidence for populations adapted to chronic larval crowding at high food levels having also evolved greater population stability in terms of constancy; a later study showed the evolution of persistence but not constancy in populations experiencing crowding in a similar manner. Another study, on <i>D</i>. <i>ananassae</i>, suggested that populations adapted to larval crowding evolved both greater constancy and persistence stability, and the data also suggested a possible inverse relationship between <i>r</i> and <i>K</i> in those populations. Moreover, simulations suggested that density-dependent selection could mediate the evolution of greater population stability, even if <i>r</i> and <i>K</i> were not inversely related. Here, we show that populations of <i>D</i>. <i>melanogaster</i>, selected for adaptation to larval crowding at very low food amounts per vial, evolve enhanced constancy and persistence stability. Enhanced population stability in the crowding-adapted populations seems to be due to increased equilibrium population size (<i>K</i>) and reduced sensitivity of realized population growth rates to density (<i>α</i>). Intrinsic population growth rate (<i>r</i>) was not reduced in the more stable crowding-adapted populations. Our study provides clear support to the hypothesis that population stability can evolve in response to density-dependent selection through certain life-history traits that are associated with higher <i>K</i> and less negative <i>α</i>. We discuss our results in the light of previous work, and suggest that an empirically driven framework might be of great heuristic value in understanding the evolution of population stability through changes in the density-sensitivity of life-history traits, whether or not these changes result from density-dependent selection.</p>

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Density-dependent selection at low food levels leads to the evolution of population stability in Drosophila melanogaster even without an inverse r-K relationship

  • 期刊论文

  • 发表日期：

    2026年1月2日

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  • Neha Pandey,
  • Amitabh Joshi

摘要

Density-dependent selection, especially if r andK are inversely related, is one of the most plausible suggested mechanisms for the evolution of population stability. However, experimental support for this explanation has been both meagre and mixed. One study with Drosophila melanogaster yielded no evidence for populations adapted to chronic larval crowding at high food levels having also evolved greater population stability in terms of constancy; a later study showed the evolution of persistence but not constancy in populations experiencing crowding in a similar manner. Another study, on D. ananassae, suggested that populations adapted to larval crowding evolved both greater constancy and persistence stability, and the data also suggested a possible inverse relationship between r and K in those populations. Moreover, simulations suggested that density-dependent selection could mediate the evolution of greater population stability, even if r and K were not inversely related. Here, we show that populations of D. melanogaster, selected for adaptation to larval crowding at very low food amounts per vial, evolve enhanced constancy and persistence stability. Enhanced population stability in the crowding-adapted populations seems to be due to increased equilibrium population size (K) and reduced sensitivity of realized population growth rates to density (α). Intrinsic population growth rate (r) was not reduced in the more stable crowding-adapted populations. Our study provides clear support to the hypothesis that population stability can evolve in response to density-dependent selection through certain life-history traits that are associated with higher K and less negative α. We discuss our results in the light of previous work, and suggest that an empirically driven framework might be of great heuristic value in understanding the evolution of population stability through changes in the density-sensitivity of life-history traits, whether or not these changes result from density-dependent selection.