THE UTILITY OF MOLECULAR MARKERS FROM NON-LETHAL DNA SAMPLES OF THE CITES II PROTECTED ‘‘TARANTULA’’ BRACHYPELMA VAGANS (ARANEAE, THERAPHOSIDAE)
ABSTRACT. Tarantula spiders of the genus Brachypelma Simon 1891 are the only complete genus of arachnids protected from international trade under CITES law. To better understand the genetic cohesion of spiders within this genus, we evaluated multiple genetic fragments (totalling about 2200 bp) for their ability to recover population sub-structure among wild-caught Brachypelma vagans (Ausserer 1875) from
Belize. We used a novel non-lethal method of tissue sampling, by inducing autospasy of the medial leg. This method allowed us to release wild-caught individuals of this protected species after DNA sampling. We used arachnid specific PCR primers to amplify targeted regions of B. vagans DNA, testing various combinations for consistency. We compared mitochondrial fragments from two populations of B. vagans
(50 km apart) for variation in mitochondrial 16S lrRNA (plus 5 ND1), CO1, and the nuclear ITS-2 spacer. Both lrRNA-ND1 and CO1 provided congruent estimates of population subdivision, and indicated that lrRNA-ND1 contained the greatest variation. The nuclear ITS-2 was surprisingly short (193 bp) and relatively invariant across B. vagans. While both mitochondrial fragments appear suitable to elucidate population subdivision and historical processes in B. vagans, we suggest that mitochondrial markers may overestimate population division in B. vagans. We conclude that along with valuable inferences from mitochondrial regions, the characterization of population sub-structure in tarantula spiders will be enhanced
by other estimates from alternate nuclear fragments.
Keywords: Belize, forced autospasy, molecular divergence
RESPIRATORY REFINEMENTS IN THE MYGALOMORPH SPIDER GRAMMOSTOLA ROSEA WALCKENAER 1837 (ARANEAE, THERAPHOSIDAE)
ABSTRACT. In this study we hypothesized that Grammostola rosea Walckenaer 1837, an active predator of large size that depends on its two paired book lungs for respiration, would have a refined low energy strategy based on its thin air-hemolymph barrier. The morphology of book lungs and the oxygen consumption at 20u and 30u C under normal and starvation conditions were studied. The oxygen consumption was low compared to that expected for spiders from the allometric relationship, 0.027 6 0.01 ml O2 g21 h21 (average 6 standard deviation), and it was depressed at 30u C under starvation. The harmonic mean thickness of the airhemolymph barrier was 0.14 6 0.03 mm, the respiratory surface density was 122.99 6 35.84 mm21, and the book lung volume ranged from 12.2 to 37.5 mm3. With these parameters a high oxygen diffusion capacity was estimated. The combination of low resting oxygen consumption and high pulmonary oxygen conductance results in very low gradients of partial oxygen pressures across the air-hemolymph barrier (0.12–0.16 kPa)required to satisfy the resting oxygen demands.
Keywords: Oxygen consumption, book lungs, mygalomorph spider
SOCIAL ENCOUNTERS BETWEEN MALE BROWN SPIDERS, LOXOSCELES GAUCHO (ARANEAE, SICARIIDAE)
ABSTRACT. Twenty-two interactions between males of Loxosceles gaucho Gertsch 1967 were investigated in order to study its intrasexual interactions and level of aggressiveness. Aggression by lunges or bites was observed in just 22.7% of the trials and three behaviors were identified as aggression-attenuating mechanisms: a hug; fleeing, and a postural pattern (POS). Interactions took place in 59.1% of the trials and the pairs interacted using one or two behavioral patterns (vibratory and/or postural). The vibratory pattern (VIB) consisted of foreleg vibration, palpal drumming, and abdominal pulsation and was used by both resident and intruder opponents. The postural pattern (POS) was used exclusively by resident males and it was similar to the behavioral pattern of sexually receptive L. gaucho females; in these cases the intruder male responded using the VIB. In conclusion, the interaction between adult L. gaucho males is usually non-aggressive. The behaviors described in this study possibly promote group-living and help to explain the gregarious populations of recluse spiders. Intra-specific sexual mimicry can occur in these interactions, but this hypothesis requires further investigation.
Keywords: Aggression, gregariousness, male-male interaction, sexual mimicry
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