Rare Sage Plant Adapts to Pollinator Shortage Through Self-Pollination

Greg Howard
2nd March, 2024

Rare Sage Plant Adapts to Pollinator Shortage Through Self-Pollination

Image Source: Natural Science News, 2024

Key Findings

  • In the eastern Adriatic, the endangered sage Salvia brachyodon has seen a recent, significant range reduction
  • One population is nearly isolated, while two others still share genes moderately
  • The plant can self-pollinate or cross-pollinate, adapting to scarce pollinators
Understanding the survival mechanisms of plant populations in the face of environmental changes is crucial for conservation efforts. A recent study by researchers at the Natural History Museum Rijeka sheds light on how range contraction and habitat fragmentation can lead to biodiversity loss, particularly by affecting plant-pollinator interactions[1]. Salvia brachyodon, an endangered sage species found in the eastern Adriatic, serves as the focal point for this investigation. The study reveals that this plant has experienced a significant and recent reduction in its range. Among the three remaining populations of S. brachyodon, one is nearly reproductively isolated, while the other two still maintain moderate gene flow. The concept of gene flow is integral to understanding species survival. It refers to the transfer of genetic material between populations, which can help maintain genetic diversity and resilience. However, when habitats are fragmented, this flow can be disrupted, leading to isolated populations that may suffer from reduced genetic diversity and increased vulnerability to environmental changes. The study also finds that S. brachyodon has a mixed mating system, as indicated by its high pollen-to-ovule ratio and the outcomes of controlled hand pollination experiments. A mixed mating system means that the plant can reproduce both through self-pollination and cross-pollination with other individuals. This flexibility can be an adaptive response to unpredictable pollinator availability, a situation that is exacerbated by habitat fragmentation. Pollinators play a pivotal role in the reproduction of many plant species. The study notes quantitative and qualitative differences in the community and behavior of flower visitors among the S. brachyodon populations. In one population, effective pollinators were scarce, and the plants were primarily visited by pollen and nectar robbers—organisms that consume these resources without contributing to pollination. Consequently, this population relied more on self-pollination. This finding resonates with previous research[2], which explored reproductive isolation mechanisms in two sympatric Salvia species. It was found that microhabitat and pollinator isolation were significant factors in maintaining the coexistence of closely related species by preventing gene flow. Similarly, the current study suggests that environmental factors and plant-pollinator interactions have led to genetic and phenotypic differentiation among S. brachyodon populations. The implications of these findings extend beyond the individual species. They contribute to a broader understanding of how plants adapt to changing environments. For instance, a study on Salvia officinalis revealed how Pleistocene climate fluctuations shaped its evolutionary history[3]. It highlighted the importance of refugia—areas where species survive through unfavorable conditions—and microrefugia for maintaining genetic diversity during periods of climate change. Furthermore, the research on gene flow patterns in Ziziphus lotus, a semiarid shrub, demonstrated that even in highly altered landscapes, an active pollinator assemblage could maintain efficient mating and prevent genetic isolation[4]. This underscores the resilience of plant-pollinator systems and their ability to adapt to environmental disturbances. In conclusion, the study by the Natural History Museum Rijeka not only provides insights into the reproductive strategies of Salvia brachyodon in fragmented habitats but also contributes to our understanding of the evolutionary processes that enable plant species to cope with habitat changes. These findings are vital for developing conservation strategies that ensure the survival of endangered species in a rapidly changing world.

EcologyPlant ScienceEvolution

References

Main Study

1) Lack of pollinators selects for increased selfing, restricted gene flow and resource allocation in the rare Mediterranean sage Salvia brachyodon.

Published 29th February, 2024

https://doi.org/10.1038/s41598-024-55344-7

Related Studies

2) Microhabitat and Pollinator Differentiation Drive Reproductive Isolation between Two Sympatric Salvia Species (Lamiaceae).

https://doi.org/10.3390/plants11182423

3) Phylogeographic structure of common sage (Salvia officinalis L.) reveals microrefugia throughout the Balkans and colonizations of the Apennines.

https://doi.org/10.1038/s41598-022-20055-4

4) Extensive pollen-mediated gene flow across intensively managed landscapes in an insect-pollinated shrub native to semiarid habitats.

https://doi.org/10.1111/mec.15950


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