Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

The sea level seasonal cycle was assessed in the San Andrés, Providencia and Santa Catalina Archipelago in the Caribbean Sea using 22 years of absolute dynamic topography. Large spatial variability was found in the sea level seasonal spectrum in the 9 most important geographical features that constitute the archipelago, depending on their meridional position and as consequence of different forcings for this cycle present in the Colombian Basin. The sea level annual variation has a minimal range of 2.7 cm in Quitasueño and a maximum range of 9.5 cm in Roncador. The seasonal cycle is maximum in July-August and minimum in January-March toward the north of the archipelago; on the contrary, the seasonal cycle is maximum in February-March and minimum in August-September toward the south of the archipelago. The seasonal cycle explains between the 3 and 23% of the monthly sea level variation in the archipelago and it is not steady in time; changes up to 3.6 cm were found in the amplitude and 83° in the phase lag when the annual cycle was assessed fractionating the time series in 5-year segments. The seasonal cycle contribution must be included in the archipelago’s risk assessment associated to sea level extreme values

The Spanish fishing fleet is one of the most important in the European Union and is exploiting marine resources in the FAO area 27 (North-eastern Atlantic Ocean). The Galician Region has a relevant role in the fishing industry. The number of boats decreased significantly between 1980 and 2012. But the landing quantities of the main marine species exploited (small pelagic fishes and tuna species mainly) decreased faster that the fleet during the same period. In contrast, landing quantities of Elasmobranchs (sharks and rays) and Cephalopods increased. This analysis shows the overexploitation of the Atlantic fishing grounds.

Viviparity is so advantageous that it has evolved at least 140 times in the invertebrates, but some Australian and New Zealand onychophorans have gone back, abandoning ovoviviparity to return to eggs. Why? Here we propose that it is an adaptation to climatically inhospitable habitats and low food availability.

In the only onychophorans mating that has been photographed, instead of fleeing, the couple remained together despite being manipulated. Why? The duration of copulation in onychophorans is possibly controlled by the female, larger and stronger than the male, probably with the participation of dopamine and γ-aminobutyric acid. Insemination through the body wall can be a male mechanism to overcome female defenses.

After more than a century of studying a phylum that has over 200 species, we only have three reports of the mating itself. Insemination can occur vaginally or through the skin, and it is suspected that the male simply places its genital opening against the vulva and inserts the spermatophore. However, in the particular case of a few Australian onychophorans, males insert it with a specialized head structure, and the spermatophore also serves as a vaginal plug, preventing insemination by other males.

Males of some Australian onychophorans transfer their spermatophores with spectacular structures in their head, such as pits with palps and spines. No one has explained why these structures allow this species to be identified. Here we propose that, when its head is the genital apparatus, natural selection treats it as a genital apparatus. Probably these fantastic heads of Australian onychophorans are just another case of divergent sexual evolution by sexual selection.

One of the many mysteries surrounding onychophorans, is why, despite their small body size, they have gestation periods that are as long as gestation in some mammals. Here we propose that the causes are infrequent feeding and the Mandatory Minimum Size model, according to which they must be born sufficiently developed to hunt their own food and survive adverse microclimates.

The sperm of many onychophorans must cross body walls and swim for years before fertilizing an egg. We propose that the cause for such obstacles is the high cost of reproduction in these animals, which leads females to select eggs early in their development; and to invest heavily in their atypically large Golgi apparatus and in the production of glycogen. Velvet worm spermatozoa are subjected to a marathon that selects the most resistant.

There are two ways to be a velvet worm. One is to mate vaginally at a young age, give birth in any month and have small, scarce males. The other is to periodically inseminate through the body wall, with sexual equality in size and abundance. The second way seems to be an evolutionary adaptation to habitats that are colder and drier than the habitats of neotropical velvet worms.

Pérdida de la diversidad biológica, destrucción de hábitats, sobreexplotación, descargas ilegales de substancias en el medio, calentamiento global y crisis ambiental, son solo algunos de los temas ambientales que han cobrado relevancia a nivel mundial en los últimos años, y con ello la opción de viajar a paraísos turísticos con una buena calidad ambiental se ha puesto de moda. Seguramente en algún punto de tú vida has pensado en viajar y conocer lugares nuevos alrededor del mundo. No obstante, ¿alguna vez has pensado en el impacto ambiental que se genera a través del turismo convencional? Turismo convencional vs. Turismo de naturaleza La saturación de ecosistemas estratégicos, deterioro del paisaje, privatización de recursos naturales y por ende una desvinculación de la comunidad local con el desarrollo de la zona, son traducidos en áreas de miseria alrededor de los sitios turísticos, afectación de la seguridad alimentaria en comunidades locales, contaminación, erosión, deforestación, consumo irracional de recursos naturales, monopolio por parte de empresas multinacionales, entre muchos otros efectos. Estos efectos son producto de un turismo regido por intereses únicamente monetarios, en el cual se hace caso omiso a las circunstancias ambientales y sociales1.--LEER MÁS--