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Pollinator-mediated selection on three deceptive Dactylorhiza Marsh orchids

Rodriguez Otero, Cristina (2021) BION03 20202
Degree Projects in Biology
Abstract
It has been shown that pollinators mediate selection on floral traits of food-deceptive orchids. However, few studies have disentangled the mechanisms linking floral traits to performance and fitness, providing an opportunity to gain a deeper understanding of the process of natural selection.
In this project, we studied trait-performance-fitness relationships on three food-deceptive Dactylorhiza orchids in Sweden.
We built a fitness function linking each phenotypic trait to pollinator visitation, pollen deposition, pollinarium removal, and fruit set. We then used the fitness function to estimate pollination-related selection on each phenotypic trait.
Our results show that advertisement traits, such as height and number of flowers are... (More)
It has been shown that pollinators mediate selection on floral traits of food-deceptive orchids. However, few studies have disentangled the mechanisms linking floral traits to performance and fitness, providing an opportunity to gain a deeper understanding of the process of natural selection.
In this project, we studied trait-performance-fitness relationships on three food-deceptive Dactylorhiza orchids in Sweden.
We built a fitness function linking each phenotypic trait to pollinator visitation, pollen deposition, pollinarium removal, and fruit set. We then used the fitness function to estimate pollination-related selection on each phenotypic trait.
Our results show that advertisement traits, such as height and number of flowers are under strong and positive pollinator-mediated selection in the three orchid species. The strength and direction of selection acting on traits related to the mechanical fit of the pollinator varied among the three species. (Less)
Popular Abstract
To ensure sexual reproduction, plants need to receive pollen on their stigmas. Pollen can be dispersed by wind, water or it can be transported by animals. Plants that depend on animals for their pollination have developed certain strategies to increase the efficiency of pollination. Many animal-pollinated plants provide a reward for the animals that pollinate them. In this mutualistic relationship, plants can reproduce, while pollinators get something in return. However, the relationship is not perfect, it can occur that some animals just take an advantage and feed on the flowers without transferring any pollen. Also, there are plants that can “cheat” and look like they provide some kind of reward for the pollinators, when they in fact do... (More)
To ensure sexual reproduction, plants need to receive pollen on their stigmas. Pollen can be dispersed by wind, water or it can be transported by animals. Plants that depend on animals for their pollination have developed certain strategies to increase the efficiency of pollination. Many animal-pollinated plants provide a reward for the animals that pollinate them. In this mutualistic relationship, plants can reproduce, while pollinators get something in return. However, the relationship is not perfect, it can occur that some animals just take an advantage and feed on the flowers without transferring any pollen. Also, there are plants that can “cheat” and look like they provide some kind of reward for the pollinators, when they in fact do not.

In this project we studied three Dactylorhiza orchid species at two different locations in Sweden. These species are all food-deceptive and bumble-bee pollinated. Since they are cheating orchids, insects might visit a few flowers in the plant, searching for food and then leave, restricting the numbers of flowers becoming pollinated. Without pollen, there is no reproduction, no survival. To optimize the pollination process, we expect to find that some traits are more important than others in the process. However, how do we know that bumble-bees really have an effect on orchids floral traits? We investigated this question by measuring traits related to the attractiveness of the plant and also traits related to how well the pollen is transfer. To understand how natural selection works, we used a fitness function approach, in which we linked floral traits to the different steps of the pollination process, such as pollinator visitation, pollen deposition on the stigmas, pollinarium removal and fruit set. Then, we used the fitness function to estimate pollinator-related selection on each trait.

We found out that there was indeed pollinator-mediated selection acting on visual traits. So, for these three orchid species, bumble-bees prefer vigorous plants which are easier to spot. Whereas the results on selection acting on the traits that are important for the correct transfer of pollen varied among species. (Less)
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author
Rodriguez Otero, Cristina
supervisor
organization
course
BION03 20202
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
9067619
date added to LUP
2021-11-05 10:54:41
date last changed
2021-11-05 10:54:41
@misc{9067619,
  abstract     = {{It has been shown that pollinators mediate selection on floral traits of food-deceptive orchids. However, few studies have disentangled the mechanisms linking floral traits to performance and fitness, providing an opportunity to gain a deeper understanding of the process of natural selection.
In this project, we studied trait-performance-fitness relationships on three food-deceptive Dactylorhiza orchids in Sweden.
We built a fitness function linking each phenotypic trait to pollinator visitation, pollen deposition, pollinarium removal, and fruit set. We then used the fitness function to estimate pollination-related selection on each phenotypic trait. 
Our results show that advertisement traits, such as height and number of flowers are under strong and positive pollinator-mediated selection in the three orchid species. The strength and direction of selection acting on traits related to the mechanical fit of the pollinator varied among the three species.}},
  author       = {{Rodriguez Otero, Cristina}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Pollinator-mediated selection on three deceptive Dactylorhiza Marsh orchids}},
  year         = {{2021}},
}