La casualidad me llevó a descubrir el momento justo de la eclosión de las mantis de una ooteca, salían con las patas pegadas al cuerpo asemejandose a momias extraterrestres, cuando se desperezaban corrian por todas partes atacandose incluso entre ellas, la sorpresa no terminó ahí, una lagartija asomó por la esquina y empezó el tierno festín hasta que se dió cuenta de que era observada, haciendo mutis por el foro. Ir al video.

A much-ballyhooed study on habitat and extinction may mean increased peril for California desert species — not because of the science, but because of how it’s being reported.

The study, entitled “Species-area relationships always overestimate extinction rates from habitat loss” and published May 19 in the prestigious peer-reviewed journal Nature, looked at the way in which ecologists estimate the number of species likely to go extinct as a result of destruction of a given amount of habitat. Leer más.

Non-recombining sex chromosomes, such as the Y chromosome, are expected to degenerate over evolutionary times because they accumulate deleterious mutations that cannot be corrected by recombination with a pristine copy. In most cold-blooded vertebrates, such as frogs, however, sex chromosomes are undifferentiated. Why is that so? On the one hand, the “high-turnover” hypothesis holds that these sex chromosomes are regularly replaced before they had time to decay. On the other hand, the “fountain-of-youth” hypothesis posits that they are regularly rejuvenated by X-Y recombination in sex-reversed XY females. Here, we show that three species of tree frogs that diverged more than 5.4 million years ago share the same pair of undifferentiated sex chromosomes. Although male recombination stopped before species divergence, X and Y alleles show no differentiation, and cluster by species, not gametologs. We conclude that their sex chromosome homomorphy is not due to a recent turnover but is maintained over long evolutionary times by occasional recombination. Such rare episodes of X-Y recombination are expected to have long-lasting consequences on the evolution of sex chromosomes and sex antagonistic genes. Leer más.