In marine systems, many species have at least one highly dispersive life stage, often a drifting larval form, which has led to the prevailing paradigm that populations across large geographic regions should be well mixed, and exhibit little genetic differentiation. However, evidence of small, but significant, patterns of genetic structure occurring over small spatial scales (referred to as chaotic genetic patchiness) has been found in numerous marine species, and challenges the traditional expectation of highly mixed populations. By seeking to understand the biological mechanisms that drive this pattern we can deepen our understanding of the ecology and evolution of complex marine populations.
Several mechanisms could create a pattern of chaotic genetic patchiness across populations of marine organisms, including: local habitat differences, temporal variability in ocean currents affecting dispersal, habitat selection at settlement, and the formation of kin-aggregations just to name a few. In particular, kin-aggregations, or the clustering of highly related individuals within a species, has received little attention.
To fill this gap, new research on the tropical goby, Coryphopterus personatus by Three Seas Alumnus Jason Selwyn and MSC PhD Candidate Alan Downey-Wall offers new insight into how close kin-aggregations could be driving observed genetic patterns.
In the study, recently published in the journal PLoS ONE, Downey-Wall and colleagues found the pattern of chaotic genetic patchiness in tropical gobies could be the result of clusters of highly related individuals living in close proximity. Analysis of these related clusters revealed that aggregations were not likely the result of random chance, suggesting the observed aggregations might be driven by some aspect of the gobies’ life history or behavior.
The authors suggested these findings could result from a limited larval dispersal phase, leading to new individuals settling in close proximity to where they spawned. Alternately, siblings may stay together for safety as drifting larvae and settle collectively as a large group. They concluded that kin-aggregations may play an important role in determining the genetic variation both within and between populations, and offers a possible explanation for the phenomenon of chaotic genetic patchiness.
