02056nas a2200241 4500008004100000022001400041245014300055210006900198260001600267300001100283520124300294653003801537653002201575653001801597653001801615653001501633653002801648100002401676700001801700700002301718700002401741856004901765 2024 eng d a0380-133000aBiogeographic barriers are differentially permeable based on traits: Movement of hypoxia tolerant mormyrid fish in the Lake Victoria basin0 aBiogeographic barriers are differentially permeable based on tra cNov-01-2024 a1024853 a

Lake Nabugabo is a small satellite lake separated from Lake Victoria by hypoxic swamps that impose a biogeographic barrier to fish assemblages. Some species occur exclusively in Nabugabo while others show high differentiation across this barrier, yet air-breathing fishes show nearly zero genetic differentiation between the two lakes. We hypothesize that hypoxia-tolerant fishes, unlike other non-air-breathing species, would have similarly low genetic differentiation across the barrier. We used pooled RAD-seq to examine the degree of genetic differentiation in two species of non-air-breathing but hypoxia-tolerant mormyrid fishes, Marcusenius victoriae and Petrocephalus degeni. Other non-air-breathing fishes have been shown to have FST values as low as 0.05 but mostly between 0.10 and 0.20; however, we discovered that the genetic differentiation in our focal species was very low, with FST values between 0.02 and 0.04, making them much more comparable to air-breathing fishes with FST values of near zero. We conclude that this and other analogous barriers should be understood as differentially permeable depending on the traits of the organisms crossing them, such as hypoxia tolerance in this case.

10aDifferentially permeable barriers10aHypoxia tolerance10aLake Nabugabo10aLake Victoria10aMormyridae10aPopulation connectivity1 aHunt, David, A.G.A.1 aThomas, Quinn1 aClarke, Shelby, B.1 aChapman, Lauren, J. uhttp://dx.doi.org/10.1016/j.jglr.2024.10248502363nas a2200145 4500008004100000022001400041245013300055210006900188260001600257300001200273490000800285520184500293100002202138856005702160 2016 eng d a0022-094900aDifferences in electrosensory anatomy and social behavior in an area of sympatry between two species of mormyrid electric fishes0 aDifferences in electrosensory anatomy and social behavior in an  cApr-11-2016 a31 - 430 v2193 a

Sensory systems play a key role in social behavior by mediating the detection and analysis of communication signals. In mormyrid fishes, electric signals are processed within a dedicated sensory pathway, providing a unique opportunity to relate sensory biology to social behavior. Evolutionary changes within this pathway led to new perceptual abilities that have been linked to increased rates of signal evolution and species diversification in a lineage called ‘clade A’. Previous field observations suggest that clade-A species tend to be solitary and territorial, whereas non-clade-A species tend to be clustered in high densities suggestive of schooling or shoaling. To explore behavioral differences between species in these lineages in greater detail, I studied population densities, social interactions, and electric signaling in two mormyrid species, Gnathonemus victoriae (clade A) and Petrocephalus degeni (non-clade A), from Lwamunda Swamp, Uganda. Petrocephalus degeni was found at higher population densities, but intraspecific diversity in electric signal waveform was greater in G. victoriae. In the laboratory, G. victoriae exhibited strong shelter-seeking behavior and competition for shelter, whereas P. degeni were more likely to abandon shelter in the presence of conspecifics as well as electric mimics of signaling conspecifics. In other words, P. degeni exhibited social affiliation whereas G. victoriae exhibited social competition. Further, P. degeni showed correlated electric signaling behavior whereas G. victoriae showed anti-correlated signaling behavior. These findings extend previous reports of social spacing, territoriality, and habitat preference among mormyrid species, suggesting that evolutionary divergence in electrosensory processing relates to differences in social behavior.

1 aCarlson, Bruce, A uhttp://jeb.biologists.org/cgi/doi/10.1242/jeb.127720