Eleutherodactylus zygodactylus

Number of Pages: 2Integrative BiologyGeological Science

No relationship between fecundity and annual reproductive rate in bony fish

Background. There is still a widespread notion that bony fishes with high fecundities are more productive and therefore more resistant to overexploitation. The purpose of this study was to formally explore the relationship between fecundity and reproductive success expressed as maximum annual reproductive rate, i.e. the number of new spawners produced by existing spawners at low population densities. Material and methods. We used maximum annual reproductive rate from a recent study covering 49 species of bony fish; we used fecundity estimates from the published literature. Results. We found no significant relationship between fecundity (ranging from 368 to 10 million eggs) and maximum annual reproductive rate (ranging from 0.4 to 13.5 replacement spawners). Conclusion. Fecundity in oviparous bony fish without parental care has no relation with reproductive success. Apparently high fecundity in bony fish has evolved to counterbalance pre-adult mortality, as indicated by the fact that variance in fecundity is 3 orders of magnitude larger than variance in annual reproductive rate

Nuclear matter properties and relativistic mean-field theory

Nuclear matter properties are calculated in the relativistic mean field theory by using a number of different parameter sets. The result shows that the volume energy $a_1$ and the symmetry energy $J$ are around the acceptable values 16MeV and 30MeV respectively; the incompressibility $K_0$ is unacceptably high in the linear model, but assumes reasonable value if nonlinear terms are included; the density symmetry $L$ is around $100MeV$ for most parameter sets, and the symmetry incompressibility $K_s$ has positive sign which is opposite to expectations based on the nonrelativistic model. In almost all parameter sets there exists a critical point $(\rho_c, \delta_c)$, where the minimum and the maximum of the equation of state are coincident and the incompressibility equals zero, falling into ranges 0.014fm$^{-3}<\rho_c<0.039$fm$^{-3}$ and $0.74<\delta_c\le0.95$; for a few parameter sets there is no critical point and the pure neutron matter is predicted to be bound. The maximum mass $M_{NS}$ of neutron stars is predicted in the range 2.45M$_\odot\leq M_{NS}\leq 3.26$M$_\odot$, the corresponding neutron star radius $R_{NS}$ is in the range 12.2km$\leq R_{NS}\leq 15.1$km.Comment: 10 pages, 5 figure