Deconstructing latitudinal species richness patterns in the ocean: does larval development hold the clue?

Area of Science:

• Marine Biology
• Ecology
• Evolutionary Biology

Background:

• Latitudinal diversity gradients are a fundamental ecological pattern, but exceptions exist for marine organisms.
• Life-history traits, particularly mode of larval development (MLD), are hypothesized to explain these variations.

Purpose of the Study:

• To investigate how different modes of larval development (MLD) influence latitudinal species richness patterns in marine benthic invertebrates.
• To identify the underlying ecological processes driving these contrasting patterns.

Main Methods:

• Deconstruction of latitudinal species richness data for marine benthic invertebrates based on their mode of larval development.
• Statistical analysis to determine the influence of environmental factors, such as temperature and chlorophyll-a concentration, on species richness patterns.

Main Results:

• Species richness patterns were consistent within each MLD but differed significantly between MLDs.
• Planktotrophic species showed decreased richness with increasing latitude (poleward), while direct-developing species exhibited increased richness.
• Temperature was the primary driver of variation in species richness, with secondary influence from chlorophyll-a concentration.

Conclusions:

• Mode of larval development is a critical factor explaining contrasting latitudinal diversity gradients in marine benthic invertebrates.
• Temperature's differential impact on planktotrophic and direct-developing species, likely via effects on larval duration and brooding costs, shapes these patterns.
• Environmental factors interact with life-history traits to determine large-scale biodiversity patterns in marine ecosystems.