2019 REUs presented at the CERF Conference in Mobile, AL
Consequences of diversification among Acartia tonsa in the Chesapeake Bay
ASLO Aquatic Sciences Meeting, Granada, Spain
Acartia tonsa is an ecologically important copepod in many of the world's coastal oceans. Previous studies have revealed two divergent, cryptic lineages of A. tonsa in Chesapeake Bay that sort by salinity preference but are found to be sympatric at moderate salinities (6-12) ppt. The main objective of this study was to examine mating success within and between the two Acartia lineages (Fresh-F, and Salt-S) and any possible fitness consequences to hybrid matings. A protocol was developed to isolate copepods early in development, identify their lineage with a PCR-RFLP assay, and make known-lineage pair crosses. Egg production was similar across cross types (range of 16-90 eggs produced) but hatching success differed significantly between hybrid and parental crosses, with an average of just 3.75 % for hybrids vs. 60% in the parental crosses. Our results indicate that the two lineages can mate, but that hybrid inviability acts early in the life cycle and no viable progeny are produced. Our results confirm previous genetic data suggesting long-term reproductive isolation between the clades, however the ecological consequences of this cryptic divergence remains unexplored.