Evidence of venom variability associated with venom extraction interval in the monocled cobra (Naja kaouthia)

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  Evidence of venom variability associated with venom extraction interval in the monocled cobra (Naja kaouthia) Abstract Snake venom variability is a critical factor in antivenom production. Although several influencing factors have been studied, the impact of extraction interval on venom properties remains poorly understood. This study evaluated the effects of various extraction intervals on venom yield, the percentage of dry weight (%Dw), and composition in the monocled cobra ( Naja kaouthia ). Twenty-five captive snakes were randomly allocated to five groups, each undergoing a control extraction followed by a repeated extraction at 1, 4, 7, 10, or 14 days. Venom profiles were characterized using reversed-phase high-performance liquid chromatography (RP-HPLC) and Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS). Results indicated that while fresh venom yield remained stable across all intervals, %Dw significantly decreased in extractions performed between 1 and 10 days, ...

Hypothesis-driven biogeography to estimate rates and dates when fossil evidence is scarce: a case study using an ancient, Holarctic genus of spider (Araneae, Antrodiaetidae, Antrodiaetus)

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Hypothesis-driven biogeography to estimate rates and dates when fossil evidence is scarce: a case study using an ancient, Holarctic genus of spider (Araneae, Antrodiaetidae, Antrodiaetus)

Abstract

Understanding when lineages diverged is a common inquiry within the field of biogeography and often requires a rate of evolution and a means to calibrate the phylogeny to absolute time. While fossil evidence is the most common means regarding calibration, estimated molecular rates specific to the group in question are not as widespread. Furthermore, geological events can also be employed to calibrate a phylogeny, especially when lineages have a poor fossil record. In this paper, the effectiveness of employing biogeographic hypotheses to overcome a depauperate fossil record is tested in a group of spiders whose evolution is strongly affected by abiotic forces. Using a known biogeographic break, the fit of two competing biogeographic hypotheses (Ancient Vicariance vs. Inland Dispersal) is tested as calibration points for estimating an evolutionary rate and dates elsewhere across the tree. An optimized dataset of ultraconserved element (UCE) phylogenomic loci, which have been shown to be highly informative in mygalomorph spider systematics (i.e., tarantulas and trapdoor spiders), is employed. Hypothesis testing strongly supports Ancient Vicariance over Inland Dispersal, and phylogenetic inferences recover topological patterns predicted by Ancient Vicariance. Significantly, subsequent modeling proposes a novel estimate of ancient vicariance older than that of any other system observed across this biogeographic break. Finally, the modeling proposes divergence estimates among other Antrodiaetus species that correlate with previous hypotheses. This research broadens knowledge of mygalomorph evolutionary rates, answers questions about the evolutionary history of a relatively old lineage of folding-door spiders, Antrodiaetus (Antrodiaetidae, Mygalomorphae), and proposes a novel hypothesis for divergence times in the Pacific Northwest.

Ciaccio E, Hamilton CA (2026) Hypothesis-driven biogeography to estimate rates and dates when fossil evidence is scarce: a case study using an ancient, Holarctic genus of spider (Araneae, Antrodiaetidae, Antrodiaetus). Frontiers of Biogeography 19: e182722. https://doi.org/10.21425/fob.19.182722