Mating system variation in the eelgrass, Zostera marina

Genetic diversity can modulate a population’s response to a changing environment and plays a critical role in its ecological function. While multiple processes act to maintain genetic diversity, sexual reproduction remains the primary driving force. The eelgrass (Zostera marina) is an important habitat forming species found in temperate coastal ecosystems across the globe. Recent increases in sea surface temperatures have resulted in shifts from a perennial to a largely annual life-history strategy at its southern edge-of-range. Given that mating systems are intimately linked to standing levels of genetic variation, understanding the scope of sexual reproduction can illuminate the processes that shape genetic diversity. To describe and characterize edge-of-range eelgrass mating systems, developing seeds on flowering Z. marina shoots were genotyped from three meadows in Topsail, North Carolina. In all meadows, levels of multiple mating were high, with shoots pollinated by an average of 8...,

Study Organism  

During Zostera marina’s reproductive season, reproductive shoots (i.e., flowering shoots) extend from a basal node and form multiple flowering branches (rhipidia). Each rhipidium contains additional branches with several spathes (i.e., inflorescences) containing flowers (De Cock 1981; Thayer et al. 1984, Kuo & Den Hartog 2006). Spathes contain a spadix with rows of both male and female flowers clustered in ratios of 2:1. Flowering occurs in two stages: (1) the flowering and exposure of ovaries and (2) the opening of anthers and release of pollen, each separated by approximately 5 days (De Cock 1980). Past studies describe sequential flowering of spathes (i.e., temporal dichogamy) within Z. marina reproductive shoots beginning with basal structures (De Cock 1980, 1981). Specifically, one spathe per rhipidium flowers at a time, during which the next spathe of the same rhipidium is not yet entirely developed. The second spathe starts flowering a few days following ..., , # Mating system variation in the eelgrass, Zostera marina

[https://doi.org/10.5061/dryad.dfn2z358x](https://doi.org/10.5061/dryad.dfn2z358x)

## Description of the data

Microsatellite genotypes of sampled offspring are available in the `Seed Genotypes` file. Parent genotypes were reconstructed using the program COLONY (Jones & Wang 2010) and are available in the `Parent Genotypes` file. Offspring genotypes were then associated to their respective seed on each parent plant and organized in the `Paternity` file. This file contains data organized on spatial scales corresponding to varying degrees of seagrass morphological structures - on a 'per shoot,' 'per rhipidium,' 'per spathe,' and 'per sire' basis. Data exploration was performed, in which outliers in both dependent and independent variables were identified and the appropriate distribution was assigned to each dependent variable (`Mating System Data Exploration Results`). Data were then quality controlled to remove any outliers...