Natures wonders: Australia's most toxic spider (Introduction)

by David Turell , Tuesday, September 22, 2020, 01:07 (1522 days ago) @ David Turell

Evolved well before an advanced primate they are very dangerous to humans:

https://cosmosmagazine.com/nature/animals/funnelweb-venom/?utm_source=Cosmos+-+Master+M...

"Australia’s funnel-web spiders are deadly to humans – particularly the males from the species Atrax robustus that calls Sydney home – but how they evolved to do this has been a mystery.

"Primates – including humans – weren’t around when these spiders originated around 150 to 200 million years ago, so wouldn’t have featured as predators or prey in their evolution.

"Now, research published in the journal Proceedings of the National Academy of Sciences suggests the adult male funnel-webs repurposed toxins used to kill insect prey to defend themselves against vertebrate predators.

***

“'If we could find common patterns across the full range of funnel-web spiders,” he says, “that would provide big inroads into understanding the evolutionary processes that have shaped their venoms into such potent chemical cocktails.”

"It took 20 years for the researchers to find a broad range of species and raise juveniles to adulthood so they could investigate venom changes, which they did by investigating their molecular evolution.

"The peptides that make funnel-web spider venom so deadly are a group of neurotoxins called delta-hexatoxins. Previously, only eight of these peptides from five species had been analysed. Fry and team nearly tripled that by profiling 22 from the venom of 10 species.

"They found the toxins had originally evolved to kill insects, such as cockroaches and flies, and were used by juvenile males and females of all ages.

"The males, once they reach adulthood, venture far and wide to find females, which exposes them to predators. They feed very little during this mating season, and the study supports theories that their venom evolved long ago via natural selection to protect them against hungry vertebrates such as dunnarts, birds, rats and geckos.

***

“'The defensive toxins are gene duplicates of the toxins used for insect feeding, but these gene duplicates are more potent for vertebrates than to insects. So the spiders have genes for a myriad of toxins, but they turn different ones on at different life stages.'”

Comment: How did the spider figure out it could produce a neurotoxin to stun predators and protect itself. This reeks of design, not chance evolution.