Male pygmy hippopotamus influence offspring sex ratio

Pre-determining fetal sex is against the random and equal opportunity that both conceptus sexes have by nature. Yet, under a wide variety of circumstances, populations shift their birth sex ratio from the expected unity. Here we show, using fluorescence in situ hybridization, that in a population of pygmy hippopotamus (Choeropsis liberiensis) with 42.5% male offspring, males bias the ratio of X- and Y-chromosome-bearing spermatozoa in their ejaculates, resulting in a 0.4337±0.0094 (mean±s.d.) proportion of Y-chromosome-bearing spermatozoa. Three alternative hypotheses for the shifted population sex ratio were compared: female counteract male, female indifferent, or male and female in agreement. We conclude that there appears little or no antagonistic sexual conflict, unexpected by prevailing theories. Our results indicate that males possess a mechanism to adjust the ratio of X- and Y-chromosome-bearing spermatozoa in the ejaculate, thereby substantially expanding currently known male options in sexual conflict

ANAK LELAKI ATAU PEREMPUAN?: Bagaimana Memilih Jenis Kelamin Bayi Anda

XVII; 109 hlm;21 x 14,5 c

Examination of uncertainty in per unit area estimates of above ground biomass using terrestrial LiDAR and ground data

In estimating aboveground forest biomass (AGB), three sources of error that interact and propagate include: (1) measurement error, the quality of the tree-level measurement data used as inputs for the individual-tree equations; (2) model error, the uncertainty about the equations of the individual trees; and (3) sampling error, the uncertainty due to having obtained a probabilistic or purposive sample, rather than a census, of the trees on a given area of forest land. Monte Carlo simulations were used to examine measurement, model and sampling error, and to compare total uncertainty between models, and between a phase-based terrestrial laser scanner (TLS) and traditional forest inventory instruments. Input variables for the equations were diameter at breast height, total tree height and height to crown base; these were extracted from the terrestrial LiDAR data. Relative contributions for measurement, model and sampling error were 5%, 70% and 25%, respectively when using TLS, and 11%, 66% and 23%, respectively when using the traditional inventory measurements as inputs into the models. We conclude that the use of TLS can reduce measurement errors of AGB compared to traditional measurement approaches