IB Biology Topic D3.1.11 Self-incompatibility Mechanisms to Increase Genetic Variation Within a Species Revision Notes (SL/HL)

IB Biology Topic D3.1.11 Self-incompatibility Mechanisms to Increase Genetic Variation Within a Species Revision Notes (SL/HL) | RevisionDojo

Written by official IB examiners

Self-Incompatibility Blocks Self-Pollination to Keep a Species Genetically Varied

If every flower in a garden only pollinated itself, the population would slowly lose its genetic diversity and resilience.
To avoid this, many plants have evolved self-incompatibility, a system that prevents self-pollination and forces cross-pollination.

Definition

Self-incompatibility

A genetic mechanism in plants that prevents self-pollination by rejecting pollen from the same plant or genetically similar individuals.

Self-Pollination Causes Inbreeding, Which Weakens Offspring

Self-pollination occurs when pollen from a flower fertilises the ovules of the same plant.
This guarantees reproduction but leads to inbreeding, which has two main drawbacks.
1. Reduced genetic diversity: offspring are genetically similar to the parent, limiting variation.
2. Inbreeding depression: harmful recessive alleles are more likely to pair up, producing weaker plants.

Analogy

Picture a sports team where every player has identical skills.
They may do well in one situation but struggle to adapt to new challenges.
Self-pollinating plants lack the genetic flexibility to thrive when conditions change.

Cross-Pollination Adds Variation and Hybrid Vigour

Increased genetic variation: offspring inherit diverse traits, improving adaptability.

Nice try, unfortunately this paywall isn't as easy to bypass as you think. Want to help devleop the site? Join the team at https://revisiondojo.com/join-us. exercitation voluptate cillum ullamco excepteur sint officia do tempor Lorem irure minim Lorem elit id voluptate reprehenderit voluptate laboris in nostrud qui non Lorem nostrud laborum culpa sit occaecat reprehenderit

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Duis aute irure dolor in reprehenderit

Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia consequuntur magni dolores eos qui ratione voluptatem sequi nesciunt. Neque porro quisquam est, qui dolorem ipsum quia dolor sit amet, consectetur, adipisci velit.

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

Unlock the rest of this chapter with a free account

Self-Incompatibility Blocks Self-Pollination to Keep a Species Genetically Varied

If every flower in a garden only pollinated itself, the population would slowly lose its genetic diversity and resilience.
To avoid this, many plants have evolved self-incompatibility, a system that prevents self-pollination and forces cross-pollination.

Definition

Self-incompatibility

A genetic mechanism in plants that prevents self-pollination by rejecting pollen from the same plant or genetically similar individuals.

Self-Pollination Causes Inbreeding, Which Weakens Offspring

Self-pollination occurs when pollen from a flower fertilises the ovules of the same plant.
This guarantees reproduction but leads to inbreeding, which has two main drawbacks.
1. Reduced genetic diversity: offspring are genetically similar to the parent, limiting variation.
2. Inbreeding depression: harmful recessive alleles are more likely to pair up, producing weaker plants.

Analogy

Picture a sports team where every player has identical skills.
They may do well in one situation but struggle to adapt to new challenges.
Self-pollinating plants lack the genetic flexibility to thrive when conditions change.

Cross-Pollination Adds Variation and Hybrid Vigour

Increased genetic variation: offspring inherit diverse traits, improving adaptability.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic D3.1.11: Self-incompatibility Mechanisms to Increase Genetic Variation Within a Species Notes

Self-Incompatibility Blocks Self-Pollination to Keep a Species Genetically Varied

Self-Pollination Causes Inbreeding, Which Weakens Offspring

Cross-Pollination Adds Variation and Hybrid Vigour

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

Self-Incompatibility Blocks Self-Pollination to Keep a Species Genetically Varied

Self-Pollination Causes Inbreeding, Which Weakens Offspring

Cross-Pollination Adds Variation and Hybrid Vigour

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics