Source-sink dynamics assists the maintenance of a pollinating wasp

Area of Science:

• Ecology
• Evolutionary Biology
• Conservation Biology

Background:

• Metapopulation dynamics, particularly source-sink systems, are critical for species persistence in fragmented environments.
• Understanding pollinator population dynamics is essential due to the global pollination crisis.

Purpose of the Study:

• To investigate the population structure and source-sink dynamics of the pollinating wasp (Wiebesia sp. 3) of Ficus pumila.
• To assess the impact of a superior competitor wasp (Wiebesia sp. 1) on population structure and dispersal patterns.

Main Methods:

• Analysis of pairwise migrant numbers on historical and contemporary timescales.
• Assessment of genetic diversity and differentiation (Fst) across islands.
• Clustering analysis and isolation-by-distance pattern evaluation.
• Estimation of effective population sizes across timescales.

Main Results:

• Significant historical asymmetry in migrant numbers, but limited contemporary asymmetry.
• A single island acted as a consistent net exporter of migrants, supplying sink populations.
• Low genetic differentiation and comparable genetic diversity across islands.
• Negligible isolation-by-distance pattern, except for migration from the competition-free island.

Conclusions:

• The pollinating wasp metapopulation is likely organized as a patchy population with complex, time-variable source-sink dynamics.
• Effective population sizes remained comparable across historical and contemporary timescales.
• The source-sink dynamics within a well-connected network facilitate the persistence of Wiebesia sp. 3 despite competitive disadvantage.