Habitat partitioning in native Geranium species through reproductive interference

Area of Science:

• Ecology
• Evolutionary Biology
• Plant Science

Background:

• Reproductive interference, where pollen from one species harms another's fitness, can influence species distributions.
• Theoretical models predict species distributions (syntopic, allotopic, exclusive) based on the strength of reproductive interference.
• Testing these predictions is crucial for understanding community assembly rules.

Purpose of the Study:

• To test theoretical predictions of reproductive interference on species distribution.
• To investigate the interaction between two sympatric wild Geranium species: G. thunbergii and G. wilfordii.

Main Methods:

• Assessed reproductive interference by analyzing seed set in relation to counterpart species abundance and heterospecific pollen deposition.
• Examined hybridization potential and fertility of hybrids through genotyping and seed set analysis.
• Conducted a transect study to analyze spatial partitioning and environmental influences (canopy openness, soil moisture).

Main Results:

• Neither counterpart species abundance nor heterospecific pollen significantly affected focal species seed set.
• Hybridization between G. thunbergii and G. wilfordii was symmetrical, with putative hybrids exhibiting low fertility.
• The two Geranium species showed exclusive small-scale distribution, despite similar environmental conditions.

Conclusions:

• Weak, bidirectional reproductive interference through hybridization may maintain the observed allotopy (spatial partitioning) between the Geranium species.
• Re-evaluating hybridization can reveal past or ongoing reproductive interference and inform distributional relationships between interacting plant species.