Genomic investigations provide insights into the mechanisms of resilience to heterogeneous habitats of the Indian Ocean in a pelagic fish

The adaptive genetic variation in response to heterogeneous habitats of the Indian Ocean was investigated in the Indian oil sardine using ddRAD sequencing to understand the subpopulation structure, stock complexity, mechanisms of resilience, and vulnerability in the face of climate change. Samples were collected from different ecoregions of the Indian ocean and ddRAD sequencing was carried out. Population genetic analyses revealed that samples from the Gulf of Oman significantly diverged from other Indian Ocean samples. SNP allele-environment correlation revealed the presence of candidate loci correlated with the environmental variables like annual sea surface temperature, chlorophyll-a, and dissolved oxygen concentration which might represent genomic regions allegedly diverging as a result of local adaptation. Larval dispersal modelling along the southwest coast of India indicated a high dispersal rate. The two major subpopulations (Gulf of Oman and Indian) need to be managed regionally to ensure the preservation of genetic diversity, which is crucial for climatic resilience.

EVOLUTION OF PREY POLYMORPHISM INDUCED BY LEARNING PREDATORS

A prey species using crypsis to avoid predators has the opportunity to evolve polymorphic crypsis when it is being exposed to two (or more) habitats with different backgrounds. Here, we investigate when this phenomenon can occur, in a simulation study with a sexually reproducing prey and a predator that can learn to find hiding prey, represented by an artificial neural network. Initially, the prey is well adapted to one habitat, but tries to expand its range by invading another, different, habitat. This can cause the prey to evolve toward an intermediate phenotype, equally cryptic in both habitats. The prey can also fail in adapting to its new environment, and stay the same. Alternatively, it can evolve polymorphic crypsis. We find that the evolutionary outcome depends on the amount of dispersal between the habitats, with polymorphic crypsis evolving for low dispersal rates, an intermediate phenotype will evolve for intermediate dispersal rates and no adaptation to the new habitat will occur for high dispersal rates. The distribution of phenotypes of the prey will also vary for different dispersal rates, with narrow distributions for low and high dispersal rate and a wide distribution for intermediate dispersal rates.