Sex is matter of life, then death for male marsupials

A new study suggests that some species of marsupials mate with such vigour and intensity that it quite literally kills them.

The scientists say that males die in large numbers after mating with as many partners as possible in sex sessions lasting up to 14 hours at a time.

A key factor in this costly coitus is the promiscuous behaviour of females who all breed at the same time of year.

The study is published in the journal PNAS.

Suicidal reproduction or semelparity is well known in many species of plants and fish but is rare in mammals.

This new study looks at the mating behaviour of 52 different species of small, insect eating marsupials in Australia, South America and Papua New Guinea.

They found that in some of these animals, such as the antechinus, the phascogale and the dasykaluta, male attempts to father offspring cost them their lives.

Lust for life?

This "dying-off" trait is more likely to be found in species living in regions where food was plentiful in one period of the year.

This makes the females of the species more likely to shorten their mating seasons so they only give birth when there is plenty to eat.

In these marsupials, the females have also synchronised their reproductive cycles.

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Exposure to pesticides can kill frogs

Pesticides, fully authorised by the relevant authorities, and used in recommended amounts can lead to mortality rates of up to 100 percent on amphibians according to a new study in Germany.

January 2013. A recent study has revealed that even the use of the recommended amount of agrochemicals can lead to mortality rates of 20 to 100 percent in common frogs (Rana temporaria). The study tested the risk of seven different chemicals; fungicides, herbicides and insecticides, and all were found to be damaging or lethal to frogs. However, the chemicals are still allowed because the testing methods did not check their effects on amphibians. The study was commissioned by the Federal Environment Agency and conducted by the Institute of Environmental Sciences Landau at the University of Koblenz-Landau.

"It's hard to comprehend that the pesticides have gone through the current authorization process but are still a direct threat to amphibians," said Carsten Brühl, who led the study. "Our laboratory tests show the effect on fully formed frogs, rather than tadpoles".

The tests that were conducted on these chemicals were undertaken on amphibians in the aquatic habitat, and mostly on tadpoles. The serious effects that are found mostly effect the land-based frog and toad populations were not taken into account.

The moist skin of frogs absorb pesticides in large quantities
Amphibians are the most threatened vertebrates worldwide. Possible causes of the decline of amphibians worldwide are thought to be competition with invasive species, increased ultraviolet radiation, global warming, infectious diseases and the loss of habitat. However, the impact of pesticides has not previously been suspected. This is because the evaluation of possible effects of pesticides had been inadequately tested and was not part of the authorization procedure for agrochemical products. Currently, only the effects on birds and mammals and aquatic organisms are tested.

Dangerous to birds and mammals
Even in birds and mammals, there has long been a discussion of whether pesticides are absorbed through the skin and how big the consequent risk is. The moist skin of frogs absorbs substances in much greater quantities, as it is in direct contact with the environment. So the danger of so-called dermal exposure is high.

Continued:  http://www.wildlifeextra.com/go/news/frog-pesticide.html