Who would have thought?

Alternative male reproductive tactics drive
asymmetrical hybridization between
sunfishes (Lepomis spp.)

Shawn R. Garner and Bryan D. Neff
Department of Biology, Western University, 1151 Richmond Street, London, Ontario, Canada N6A 5B7

The potential role of alternative reproductive tactics in circumventing premating isolating mechanisms and driving hybridization between species
has long been recognized, but to date there is little empirical support from
natural systems. Hybridization occurs between bluegill (Lepomis macrochirus)
and pumpkinseed sunfish (Lepomis gibbosus) and it is known to be asymmetrical (male bluegill  female pumpkinseed). Here, we test whether this
pattern is driven by a recognition failure by pumpkinseed females or by
an alternative cuckolder reproductive tactic in bluegill males. Using genetic
parentage data, we found that bluegill cuckolders fathered 24.9% of the
larvae in bluegill nests, but no evidence that pumpkinseed females spawned
in bluegill nests. Pumpkinseed cuckolders fathered 8.7% of the larvae in
pumpkinseed nests, whereas bluegill cuckolders fathered 13.6% of the
larvae in those nests. Bluegill cuckolders thus frequently spawn in pumpkinseed nests and are responsible for the asymmetrical hybridization between
the species. We discuss the evolutionary consequences of interactions
between bluegill and pumpkinseed and the role of alternative reproductive
tactics in adaptation and introgression