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

It seems that many people report poor PS recruitment in their ponds.

If PS and BG are in the same pond, might this partly explain the apparent poor recruitment of pure PS?

PS are NOT colony spawners like BG, so to keep a population going in a pond you need a lot of spawning real estate for PS. At least that is how they spawn in a local lake. Also, a PS male makes a nest that is MUCH larger than a BG nest. I would say the PS nest diameter is around 8x to 12x the body length of the male PS.

for those of us who are ignorant of technical bluegill jargon, can someone please explain the concept of a cuckolder BG? Is this always a male or can there be a female cuckolder? Is the term cuckolder based on the GB appearance or is it a term that describes a behavior of the BG? Can you pick out who might be a cuckolder or be acting like one by appearance only?

Is the article above stating that PS behavior fitting the cuckolder description is less than BG cuckolder behavior and that explains the hybrid rates? I apologize for not being able to understand the summary of the article.

Are BG the only fish that act like (or look like??) cuckolders?

Very strange the person who coined the term...

It's a male BG that has the body color/characteristics of a female. That way it can sneak into a nest with another male BG and also fertilize the eggs when a female is in the nest. The male BG that "owns" the nest won't chase the cuckolder out.

Very sneaky!

Yes, they are also referred to as sneaker males. BG and PS have them. Neff has done a lot of work on the subject, and it can be found online.

Fascinating info.