Predation on snakes of Argentina: Effects of coloration and ring pattern on coral and false coral snakes

The occurrence of coral snake coloration among unrelated venomous and non‐venomous snake species has often been explained in terms of warning coloration and mimicry. In Argentina, no field tests have been conducted to confirm this mimetic association between one venomous coral species (Micrurus phyrrocryptus, Elapidae) and two non‐venomous snake species with a similar color pattern (Lystrophis pulcher and Oxyrhopus rhombifer, Colubridae). The aims of this work were to test for the possible aposematic or cryptic function of the ring pattern and coloration of coral snakes and false coral snakes from central Argentina, and to analyse whether the pattern is effective throughout the year. Predation on snakes was estimated by using non‐toxic plasticine replicas of ringed venomous and non‐venomous snakes and unbanded green snakes placed along transects in their natural habitat during the dry and rainy season. Ringed color pattern was attacked by predators despite the background color. One of the replica types was attacked more than expected during the dry season, suggesting that both shape and width of rings may influence the choice by predators. The reaction of predators towards replicas that mimic snake species with ringed patterns is independent of the geographical region, and we can conclude that mimicry characteristics are quite general when the true models are present in the area.     

The status of Pliocercus and Urotheca (Serpentes: Golubridae), with a review of included species of coral snake mimics

The generic name Urotheca Bibron, 1843 is revived for a group of Neotropical colubrid snakes diagnosed by a long, thickened but fragile tail and the presence of a specialized naked pocket on the asulcate surface of the hemipenial capitulum. Urotheca includes those species previously placed in the lateristriga group of the genus Rhadinaea and the coral snake mimics usually referred to the genus Pliocercus. The many names based upon the coral snake mimics are shown to represent two species at most: Urotheca elapoides, a bicolour (red and black) or tricolour (red, yellow and black) banded or ringed form found in Mexico and northern Central America and U. euryzona, which is usually bicolour (red, yellow or white and black) and ranges from Nicaragua to western Ecuador. Coloration in U. elapoides resembles closely that of sympatric species of venomous coral snakes. Local variation in coloration and a geographic trend in the colour of the light rings (usually red in the north, white to the south) in U. euryzona parallels similar colour variation in the sympatric venomous coral snake Micrurus mipartitus. These patterns of variation add strong support to the idea that the two species are mimics of the highly venomous coral snakes. Urotheca, including the non-mimetic species U. decipiens, U. fulmceps, U. guentheri, U. lateristriga, U. multilineata and U. pachyura, shares the characteristic of a very long and disproportionately thickened and fragile tail with the coral snake mimics of the distantly related genus Scapkiodontophis. Members of both genera have a very high proportion (about 50%) of the tails broken indicating a probable predator escape device. Breakage is intercentral, with a calcified cap developing over the tip of the distal surface of the new terminal vertebra unlike the situation in many lizards where there is an intracentral fracture septum and the tail is regenerated.     

Uncoupling ecological innovation and speciation in sea snakes (Elapidae, Hydrophiinae, Hydrophiini)

The viviparous sea snakes (Hydrophiini) are by far the most successful living marine reptiles, with ～ 60 species that comprise a prominent component of shallow-water marine ecosystems throughout the Indo-West Pacific. Phylogenetically nested within the ～ 100 species of terrestrial Australo-Melanesian elapids (Hydrophiinae), molecular timescales suggest that the Hydrophiini are also very young, perhaps only ～ 8-13 Myr old. Here, we use likelihood-based analyses of combined phylogenetic and taxonomic data for Hydrophiinae to show that the initial invasion of marine habitats was not accompanied by elevated diversification rates. Rather, a dramatic three to six-fold increase in diversification rates occurred at least 3-5 Myr after this transition, in a single nested clade: the Hydrophis group accounts for ～ 80% of species richness in Hydrophiini and ～ 35% of species richness in (terrestrial and marine) Hydrophiinae. Furthermore, other co-distributed lineages of viviparous sea snakes (and marine Laticauda, Acrochordus and homalopsid snakes) are not especially species rich. Invasion of the oceans has not (by itself) accelerated diversification in Hydrophiini; novelties characterizing the Hydrophis group alone must have contributed to its evolutionary and ecological success.     

Reproductive mode may determine geographic distributions in Australian venomous snakes (Pseudechis,Elapidae)

Summary Why are viviparous squamate reptiles more common in cold climates, and oviparous ones in warmer areas? The usual explanation is that (1) oviparous squamates cannot reproduce successfully in cold areas because soil temperatures are too low for embryonic development; and (2) viviparous squamates experience lower survivorship or reproductive success than oviparous taxa in warmer areas. These hypotheses suggest that the boundaries of geographic distributions of congeneric oviparous and viviparous squamates should be predictable from data on thermal tolerances of embryos, and estimated temperatures of soils and gravid female reptiles throughout the potential geographic range of the taxon. In large venomous Australian snakes of the genus Pseudechis, distributional boundaries of oviparous and viviparous taxa can be accurately predicted from such data. This predictive ability, if substantiated by studies of other reproductively biomodal squamate taxa, would support the putative role of reproductive mode as a direct determinant of reptilian geographic distributions.     

Phylogeny of Australasian venomous snakes (Colubroidea, Elapidae, Hydrophiinae) based on phenotypic and molecular evidence

Scanlon, John D. & Lee, Michael S. Y. (2004). Phylogeny of Australasian venomous snakes (Colubroidea, Elapidae, Hydrophiinae) based on phenotypic and molecular evidence. — Zoologica Scripta , 33 , 335–366.
Phylogenetic relationships among Hydrophiinae (Australasian and marine elapid snakes) are inferred using 87 characters from external, skeletal, hemipenial and internal anatomy, ecology, and chromosomes as well as available sequences of two mitochondrial genes (cytochrome b and 16S rRNA). Parsimony analysis of the combined data retrieves many widely accepted clades; while observed bootstrap or branch (Bremer) support for these is often weak, most have never been corroborated previously by a rigorous numerical analysis. Sea kraits ( Laticauda ) and Solomon Islands elapids are basal to the remaining hydrophiines (Australian terrestrial forms and hydrophiin sea snakes). The latter clade includes three main lineages: a large-bodied oviparous lineage, a small-bodied oviparous lineage, and a viviparous lineage (which also includes the hydrophiin sea snakes, strongly reaffirmed as monophyletic). While the Solomons retain a relictual fauna, New Guinea has less endemism and has been invaded multiple times by Australian lineages, so there is no clear 'stepping stone' pattern supporting a northern (Asian, rather than Gondwanan) biogeographical origin.     

First records of sea snakes (Elapidae: Hydrophiinae) diving to the mesopelagic zone (>200 m)

Viviparous sea snakes (Elapidae: Hydrophiinae) are fully marine reptiles distributed in the tropical and subtropical waters of the Indian and Pacific Oceans. Their known maximum diving depth ranges between 50 and 100 m and this is thought to limit their ecological ranges to shallow habitats. We report two observations, from industry‐owned remotely operated vehicles, of hydrophiine sea snakes swimming and foraging at depths of approximately 250 m in the Browse Basin on Australia's North West Shelf, in 2014 and 2017. These observations show that sea snakes are capable of diving to the dim‐lit, cold‐water mesopelagic zone, also known as the ‘twilight’ zone. These record‐setting dives raise new questions about the thermal tolerances, diving behaviour and ecological requirements of sea snakes. In addition to significantly extending previous diving records for sea snakes, these observations highlight the importance of university‐industry collaboration in surveying understudied deep‐sea habitats.     

Primer registro de accidentes ofídicos por mordedura de Micrurus ortoni y Micrurus hemprichii (Serpentes: Elapidae) en Colombia y Perú

We report two snakebites by Micrurus ortoni in Colombia and one by M. hemprichii in Perú. In two of the cases, we observed mild to moderate motor neurological involvement and in all patients, there was a marked sensory effect with hyperesthesia and hyperalgesia radiating from the bite site to the entire ipsilateral hemibody. The only patient who received antivenom, which did not correspond with the type of envenomation, developed equine serum sickness eight days after its administration.The results of the laboratory tests, including an electromyographic study, the photographic record of the clinical manifestations, and the causative agents are presented and discussed.     

Autumn colouration and herbivore resistance in mountain birch (Betula pubescens)

We explored Hamilton and Brown's autumn signalling hypothesis in mountain birch (Betula pubescens). As predicted by the hypothesis, early autumn colour change (i.e. high degree of autumn colouration in September) was negatively correlated with insect damage the following season. Furthermore, as expected, indices of physiological stress (i.e. leaf fluctuating asymmetry) and reproductive investment (i.e. catkin production) were positively correlated with insect damage the following season. Indirectly, we also found support for the idea that the proposed handicap signal (i.e. early autumn senescence) might be associated with an honesty ensuring cost in terms of lost primary production. Further work is, however, required to determine whether the link between autumn colours and insect damage observed in this study is causal.     

Garotenoids and colouration of poplar hawkmoth caterpillars (Laothoe populi)

Carotcnoids and chlorophylls a and b were extracted from final instar caterpillars of the poplar hawkmoth ( Laothoe populi ) and the eyed hawkmoth ( Smerinthus ocellata ), as well as from their food plants. Both species of caterpillar absorb the two chlorophylls and the carotenoids lutein, cis -lutein and β-carotene in the gut and deposit lutein and cis -lutein in the integument. It is the lutein, together with pterobilin, that is largely responsible for the colour of the insect: yellow-green poplar hawkmoth caterpillars have more lutein in the integument than dull green ones which in turn have more than white ones. Yellow-green and dull green caterpillars both sequester lutein and cis -lutein in the gut wall, but the yellow-greens translocate more of these pigments to the integument than the dull greens. The white caterpillars absorb very little lutein and cis -lutein into the gut, and so they have much less also in the integument. The mechanism by which the reflected light perceived by the caterpillar is translated into differential absorption of pigment by the gut and deposition in the integument is not known.     

Ecological and evolutionary components of body size: geographic variation of venomous snakes at the global scale

Biogeographical patterns of animal body size and the environmental and evolutionary mechanisms that may be driving them have been broadly investigated in macroecology, although just barely in ectotherms. We separately studied two snake clades, Viperidae and Elapidae, and used phylogenetic eigenvector regression and ordinary least squares multiple regression methods to perform a global grid-based analysis of the extent at which the patterns of body size (measured for each species as its log₁₀-transformed maximum body length) of these groups are phylogenetically structured or driven by current environment trends. Phylogenetic relatedness explained 20% of the across-species size variation in Viperidae, and 59% of that of Elapidae, which is a more recent clade. Conversely, when we analysed spatial trends in mean body size values (calculated for each grid-cell as the average size of its extant species), an environmental model including temperature, precipitation, primary productivity (as indicated by the global vegetation index) and topography (range in elevation) explained 37.6% of the variation of Viperidae, but only 4.5% of that of Elapidae. These contrasted responses of body size patterns to current environment gradients are discussed, taking into consideration the dissimilar evolutionary histories of these closely-related groups. Additionally, the results obtained emphasize the importance of the need to start adopting deconstructive approaches in macroecology.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 94–109.     

The colubrid radiation in Africa (Serpentes: Golubridae): phylogenetic relationships and evolutionary patterns based on immunological data

Phylogenetic relationships among genera of African colubrids were evaluated using estimates of divergence among serum albumins compared by microcomplement fixation. Representatives of about half of the extant genera of African colubrids, as well as the Elapidae, Atractaspis and the Madagascan colubrid Leioheterodon, were analysed. The tree of best fit to the data has an unresolved basal polychotomy comprising at least five lineages of colubrids, as well as Elapidae and Atractaspis; thus, colubrids were not demonstrably monophyletic with these data. Two cosmopolitan clades, colubrines and natricines, are represented in Africa by series of closely related genera, but divergence among other genera is relatively great. Rate tests show that this is apparently not due to higher rates of albumin evolution in these, relative to other colubrids. Among the other associations supported by the immunological data are: (1) Psammophis-(Rhamphiophis-Dipsina)-Malpolon-Psammophylax; (2) Amblyodipsas-Macrelaps; (3) (Lycodonomorphus-Lamprophis)-Mehelya; and (4) Colubrinae-Natricinae. Grayia is questionably associated with the colubrine-natricine lineage. Prosymna and Lycodon are clearly members of the colubrine clade, and Amplorhinus possibly associates with Leioheterodon. Gonionotophis, Duherria, Lycophidion and Pseudaspis show no strong association with any other genera, and represent other basal or near-basal clades within the colubrid/elapid radiation. The immunological data do not support a clade comprising the Elapidae, Atractaspis and some ‘aparallactines’ relative to Viperidae and other colubrids. The basal colubrid-elapid-Atractaspis divergence occurred more than 30 Myr ago, and the fossil record of colubrids in Africa greatly underestimates both the age and clade diversity of this group. In contrast to the pattern of radiation in the neotropics, where most colubrids belong to one of three major clades, in Africa only the colubrine lineage comprises a substantial portion of the extant generic diversity; most other genera stem from relatively ancient cladogenetic events and have few living representatives.     

Prey specificity, comparative lethality and compositional differences of coral snake venoms

Toxicities of crude venoms from 49 coral snake (Micrurus sp.) populations, representing 15 nominal taxa, were examined in both laboratory mice and in native prey animals and compared with data gathered from two non-micrurine elapids and a crotalid, which served as outgroups. These venoms were further compared on the basis of 23 enzymatic activities. Both toxicities and enzymatic activities were analyzed with respect to natural prey preferences, as determined from stomach content analyses and literature reports. Venoms of nearly all Micrurus for which prey preferences are known, are more toxic to natural prey than to non-prey species. Except for amphisbaenians, prey are more susceptible to venoms of Micrurus that feed upon them, than to venoms of those that eat other organisms. All venoms were more toxic i.v.>i.p.>i.m. Route-specific differences in toxicity are generally greatest for preferred prey species. Cluster analyses of venom enzymatic activities resulted in five clusters, with the fish-eating M. surinamensis more distant from other Micrurus than even the crotalid, Bothrops moojeni. Ophiophagous and amphisbaenian-eating Micrurus formed two close subclusters, one allied to the outgroup species Naja naja and the other to the fossorial, ophiophagous Bungarus multicinctus. Prey preference is shown to be the most important determinant of venom composition in Micrurus.     

The environmental control of colouration in a bushcricket, Mygalopsis marki Bailey (Orthoptera: Tettigoniidae)

The environmental factors proximately influencing variable colouration in the bushcricket, Mygalopsis marki , were studied in natural populations and under controlled laboratory conditions. Two major components of variable colouration were identified; a green/brown dimorphism in ground colour hue (dominant wave length) and continuous variation in the darkness of brown insects, representing a contrast between ground colour value (brightness) and the intensity of overlying black pattern. Ground colour hue differed between natural populations in different seasons and at different localities. The proportion of brown individuals was greater in populations developing over late summer than over spring at the same locality, and in populations from drier localities, as indicated by vegetation type, in the same season. Experimental studies showed that colour change occurred at moults, with green colouration promoted by increased water intake in developing nymphs. Ground colour value and pattern differed between natural populations at different localities, but not in different seasons. Ground colour value was less, and pattern was greater, in populations from localities with a dense cover of forbs and grasses. Experimental studies showed that ground colour value and pattern were influenced by the intensity of incident radiation received by developing nymphs, with decreased intensity promoting lower value and greater pattern.     

The salivary glands of Aparallactinae (Golubridae) and the venom glands of Elaps (Elapidae) in relation to the taxonomic status of this genus

The venom glands of four specimens of Elaps lacteus were examined and found to be structurally similar to the glands of other Elapidae and consequently different from the variable glands of the colubrid Aparallactinae, Lycophidinae and Dispholidinae. The recently proposed removal of Elaps from the Elapidae and its inclusion in the Aparallactinae (McDowell, 1968) is discussed, and the conclusion is reached that Elaps should remain within the Elapidae.     

The morphometrics and colouration of the European pond turtle Emys orbicularis in Lubuskie province (West Poland)

The European pond turtle Emys orbicularis, is an endangered species in Poland. The region of the Ilanka River, in the western part of the country (Lubuskie province), is the most densely inhabited area by the species. Several populous sites are dispersed over the whole area of the province. Over the past 10 years, 279 turtles were captured at 11 sites. In 218 individuals, those with a straight carapace length (SCL) between 2.10–12.10 cm, sex was not determined; the remaining 61 with SCL 13.33–19.85 cm were sexed. Females had bigger bodies and were heavier than males. The SCL of females was 17.10 ± 1.7 cm (average ± SD, n = 33), their body mass (BM) was 790.6 ± 228.7 g (n = 27), and in the case of males SCL was 15.44 ± 1.5 cm and BM was 554.2 ± 138.8 g (n = 28). SCL of the smallest egg laying female was 15.30 cm, and SCL of the smallest mating male was 13.33 cm. The colouration of the turtles which undergoes change with age can be varied.