Despite a great diversity of reproductive behaviors in fishes, few studies have examined the genetic consequences of alternative reproductive tactics. Here we develop and employ microsatellite markers to assess genetic paternity and maternity of progeny cohorts in a population of redbreast sunfish (Lepomis auritus), a species in which males build and tend nests. Nearly 1000 progeny from 25 nests, plus nest-attendant males and nearby adults, were genotyped at microsatellite loci that displayed more than 18 alleles each. The genetic data demonstrate that multiple females (at least two to six) spawned in each nest, their offspring were spatially dispersed across a nest, and more than 90% of the young were sired by the attendant male. However, about 40% of the nests also showed genetic evidence of low-level reproductive parasitism, and two nests were tended by males that had fathered none of the sampled offspring. Genetically deduced reproductive behaviors in this population of redbreast sunfish contrast with those reported previously in bluegill sunfish (L. macrochirus) wherein heteromorphic males specialized for parasitism or for parental care coexist in high frequency. Thus, nest-parasitic reproductive behaviors in fishes appear to be evolutionary labile.

Despite a great diversity of reproductive behaviors in fishes, few studies have examined the genetic consequences of alternative reproductive tactics. Here we develop and employ microsatellite markers to assess genetic paternity and maternity of progeny cohorts in a population of redbreast sunfish (Lepomis auritus), a species in which males build and tend nests. Nearly 1000 progeny from 25 nests, plus nest-attendant males and nearby adults, were genotyped at microsatellite loci that displayed more than 18 alleles each. The genetic data demonstrate that multiple females (at least two to six) spawned in each nest, their offspring were spatially dispersed across a nest, and more than 90% of the young were sired by the attendant male. However, about 40% of the nests also showed genetic evidence of low-level reproductive parasitism, and two nests were tended by males that had fathered none of the sampled offspring. Genetically deduced reproductive behaviors in this population of redbreast sunfish contrast with those reported previously in bluegill sunfish (L. macrochirus) wherein heteromorphic males specialized for parasitism or for parental care coexist in high frequency. Thus, nest-parasitic reproductive behaviors in fishes appear to be evolutionary labile.

In nest-building fish species, mature males often exhibit one of two alternative reproductive behaviours. Bourgeois males build nests, court females, and guard their eggs. Parasitic cuckolders attempt to steal fertilizations from bourgeois males and do not invest in parental care. Previous evidence from the bluegill sunfish (Lepomis macrochirus) suggests that adult males are morphologically specialized for these two tactics. Here, we used microsatellite markers to determine genetic parentage in a natural population of the spotted sunfish (L. punctatus) that also displayed both bourgeois and parasitic male morphs. As gauged by relative investments in gonadal vs. somatic tissues, between 5 and 15% of the mature adult males were parasites. Multi-locus genotypes were generated for more than 1400 embryos in 30 nests, their nest-guardian males, and for other adults in the population. Progeny in approximately 57% of the nests were sired exclusively by the guardian male, but the remaining nests contained embryos resulting from cuckoldry as well. Overall, the frequency of offspring resulting from stolen fertilizations was only 1.3%, indicating that the great majority of paternity is by bourgeois nesting males. With regard to maternity, 87% of the nests had at least three dams, and computer simulations estimate that about 7.2 dams spawned per nest.

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Cannibalism is widespread in natural populations of fishes, where the stomachs of adults frequently contain conspecific juveniles. Furthermore, field observations suggest that guardian males routinely eat offspring from their own nests. However, recent genetic paternity analyses have shown that fish nests often contain embryos not sired by the nest-tending male (because of cuckoldry events, egg thievery, or nest piracy). Such findings, coupled with the fact that several fish species have known capabilities for distinguishing kin from nonkin, raise the possibility that cannibalism by guardian males is directed primarily or exclusively toward unrelated embryos in their nests. Here, we test this hypothesis by collecting freshly cannibalized embryos from the stomachs of several nest-tending darter and sunfish males in nature and determining their genetic parentage by using polymorphic microsatellite markers. Our molecular results clearly indicate that guardian males do indeed consume their own genetic offspring, even when unrelated (foster) embryos are present within the nest. These data provide genetic documentation of filial cannibalism in nature. Furthermore, they suggest that the phenomenon may result, at least in part, from an inability of guardians to differentiate between kin and nonkin within their own nests.

We employ microsatellite markers to assess mating tactics in Lepomis marginatus. Genetic assignments for 1015 progeny in 23 nests indicate that about 95% of the offspring were sired by their respective nest-guardians, a finding consistent with the apparent absence of a brood parasitic morphotype in this species. Allopaternal care was documented in two nests, one resulting from a nest takeover, the other from cuckoldry by an adjoining nest-tender. Clustered de novo mutations also were identified. About 2.5 females (range 1-7) contributed to the offspring pool within a typical nest. Results are compared to those for other Lepomis species.

We assessed fish escapement from two South Carolina reservoirs, Par Pond and L Lake, from spring 2002 through summer 2003. Escapement was greatest in the spring and early summer, with lake chubsucker Erimyzon sucetta dominating the escapement catch in early spring and several sunfishes Lepomis spp. dominating in late spring and early summer. Most of the escaping centrarchids were bluegill L. macrochirus, warmouth L. gulosus, and redbreast sunfish L. auritus in L Lake and warmouths, bluegills, dollar sunfish L. marginatus, and spotted sunfish L. punctatus in Par Pond. Escapement was enhanced by high reservoir water levels and surface discharge over the spillway. Escapement declined during periods of hypolimnetic release from bottom discharge gates. Location of the Par Pond discharge structure in the littoral zone rather than the pelagic zone as in L Lake contributed to greater escapement of littoral species in Par Pond. Species composition in the escapement catches and reservoirs was not significantly correlated. Relatively low escapement from L Lake and Par Pond compared with that in other reservoirs may have been related to the configuration of the discharge structures, low water levels during 2002, fish habitat preferences, species composition and abundance in the reservoirs, and low rates of discharge.