Outbreeding Devices
Mechanisms developed by flowering plants to discourage self-pollination and encourage cross-pollination.
What is Outbreeding Devices?
Pollination by pollen grains from the same flower.
Key points
- Identify and explain various outbreeding devices in flowering plants.
- Understand the significance of outbreeding for genetic diversity and plant vigour.
- Differentiate between different types of dichogamy and herkogamy.
- Explain the genetic basis of self-incompatibility.
Common exam trap
Confusing dichogamy types (protandry vs. protogyny).
Definitions
- Term
Autogamy
- Meaning
Pollination by pollen grains from the same flower.
- Term
Allogamy
- Meaning
Pollination by pollen grains from a different flower on another plant.
- Term
Dichogamy
- Meaning
The temporal separation of male and female reproductive organ maturation in a flower.
- Term
Protandry
- Meaning
Condition where anthers mature and release pollen before the stigma of the same flower becomes receptive.
- Term
Protogyny
- Meaning
Condition where the stigma of a flower becomes receptive before the anthers mature and release pollen.
- Term
Herkogamy
- Meaning
A spatial arrangement of anthers and stigma that prevents self-pollination.
- Term
Self-incompatibility
- Meaning
A genetic mechanism in plants that prevents pollen from germinating on the stigma of the same plant.
- Term
Inbreeding Depression
- Meaning
The reduced vigour and fertility of offspring resulting from inbreeding.
Learning objectives
Identify and explain various outbreeding devices in flowering plants.
Understand the significance of outbreeding for genetic diversity and plant vigour.
Differentiate between different types of dichogamy and herkogamy.
Explain the genetic basis of self-incompatibility.
Relate outbreeding devices to evolutionary advantages.
Prerequisites
Structure of a flower
Pollination types (autogamy, allogamy, geitonogamy)
Gametogenesis
Fertilization
Common mistakes
Confusing dichogamy types (protandry vs. protogyny).
Overlooking the genetic basis of self-incompatibility.
Assuming all unisexual flowers are dioecious.
Not understanding how cleistogamy can sometimes be an outbreeding device.
Keywords
Outbreeding
Cross-pollination
Self-pollination
Dichogamy
Protandry
Protogyny
Herkogamy
Self-incompatibility
Genetic diversity
Inbreeding depression
Angiosperms
Practice preview
Which of the following is NOT an outbreeding device?…
easy
Which of the following is a device to prevent self-pollination in plants?…
easy
What is the term for the physical separation of anthers and stigma within a flower, which acts as an outbreeding device?…
easy