An annotated checklist of sea snakes of Vietnam, with notes on a new record of the yellow-lipped sea krait, Laticauda colubrina (Schneider, 1799) (Laticaudidae, Hydrophiidae)

The yellow-lipped sea krait, Laticauda colubrina (Schneider, 1799), is recorded in the waters of Vietnam for the second time. The morphological characteristics of this species are described. Identification keys, a checklist, and distribution data for sea snakes of Vietnam are provided, proceeding from museum collections and extensive analysis of the available literature. Thalassophis anomalus P. Schmidt, 1852 and Leioselasma melanocephala (Gray, 1849) are registered for the first time for Vietnamese waters.     

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.     

Comparison of freshwater discrimination ability in three species of sea kraits (Laticauda semifasciata, L. laticaudata and L. colubrina)

Three species of amphibious sea kraits (Laticauda spp.) require drinking freshwater to regulate water balance. The extent of terrestriality is known to differ among them. Species with higher extent of terrestriality would drink freshwater accumulated on land, whereas less terrestrial species would rely totally on freshwater that runs into the sea. Consequently, we predicted that the latter species might have a better ability to follow the flow of freshwater or lower salinity water in the sea than the former. We investigated the freshwater discrimination ability of three sea krait species, using a Y-maze apparatus. We found that Laticauda semifasciata and Laticauda laticaudata, less terrestrial species, followed freshwater significantly more frequently than seawater, whereas Laticauda colubrina, more terrestrial species, unbiasedly selected freshwater and seawater. This result supports our prediction and suggests that less terrestrial sea kraits more efficiently access freshwater sources in the sea than highly terrestrial sea kraits. It is likely that behavioral rehydration systems vary among sea kraits in relation to their terrestrial tendency.     

Molecular phylogeny and divergence dates for Australasian elapids and sea snakes (hydrophiinae): evidence from seven genes for rapid evolutionary radiations

One of the most prolific radiations of venomous snakes, the Australo-Melanesian Hydrophiinae includes approximately 100 species of Australasian terrestrial elapids plus all approximately 60 species of viviparous sea snakes. Here, we estimate hydrophiine relationships based on a large data set comprising 5800 bp drawn from seven genes (mitochondrial: ND4, cytb, 12S, 16S; nuclear: rag1, cmos, myh). These data were analysed using parsimony, likelihood and Bayesian methods to better resolve hydrophiine phylogeny and provide a timescale for the terrestrial and marine radiations. Among oviparous forms, Cacophis, Furina and Demansia are basal to other Australian elapids (core oxyuranines). The Melanesian Toxicocalamus and Aspidomorphus group with Demansia, indicating multiple dispersal events between New Guinea and Australia. Oxyuranus and Pseudonaja form a robust clade. The small burrowing taxa form two separate clades, one consisting of Vermicella and Neelaps calanotus, and the other including Simoselaps, Brachyurophis and Neelaps bimaculatus. The viviparous terrestrial elapids form three separate groups: Acanthophis, the Rhinoplocephalus group and the Notechis-Hemiaspis group. True sea snakes (Hydrophiini) are robustly united with the Notechis-Hemiaspis group. Many of the retrieved groupings are consistent with previous molecular and morphological analyses, but the polyphyly of the viviparous and burrowing groups, and of Neelaps, are novel results. Bayesian relaxed clock analyses indicate very recent divergences: the approximately 160 species of the core Australian radiation (including sea snakes) arose within the last 10 Myr, with most inter-generic splits dating to between 10 and 6 Ma. The Hydrophis sea snake lineage is an exceptionally rapid radiation, with > 40 species evolving within the last 5 Myr.     

Increased drag, and thus lower speed: a cost for morphological defence in Bosmina (Eubosmina) (Crustacea: Cladocera)

1. The swimming speed of two forms, an extreme and a typical, within the cladoceran subgenus Eubosmina were examined using a three-dimensional video-technique. The extreme form has a very high carapax and extremely long antennule, features probably involved in predator defence.
2. It was found that the extreme form swam almost 40% slower than the typical form.
3. Calculations show that the extreme form had to work at least 12% harder to swim at the same speed, or if it used the same amount of energy to swim, the extreme form would swim 6% slower. Increased drag, because of its distinguishing carapax and antennule, is thus the most likely explanation for the slower swimming speed of the extreme form, assuming it selects the same power output.
4. Swimming speed can be correlated to food intake either by the frequency of hits to edible food particles or by the time to swim from a poor food patch to a good one. So the reduced speed is probably a great cost for the extreme form.     

Horn growth rate and longevity: implications for natural and artificial selection in thinhorn sheep (Ovis dalli)

We used horn measurements from natural and hunted mortalities of male thinhorn sheep Ovis dalli from Yukon Territory, Canada, to examine the relationship between rapid growth early in life and longevity. We found that rapid growth was associated with reduced longevity for sheep aged 5 years and older for both the hunted and natural mortality data sets. The negative relationship between growth rate and longevity in hunted sheep can at least partially be explained by morphologically biased hunting regulations. The same trend was evident from natural mortalities from populations that were not hunted or underwent very limited hunting, suggesting a naturally imposed mortality cost directly or indirectly associated with rapid growth. Age and growth rate were both positively associated with horn size at death for both data sets, however of the two growth rate appeared to be a better predictor. Large horn size can be achieved both by individuals that grow horns rapidly and by those that have greater longevity, and the trade-off between growth rate and longevity could limit horn size evolution in this species. The similarity in the relationship between growth rate and longevity for hunted and natural mortalities suggests that horn growth rate should not respond to artificial selection. Our study highlights the need for the existence and study of protected populations to properly assess the impacts of selective harvesting.     

Cheetahs of the deep sea: deep foraging sprints in short-finned pilot whales off Tenerife (Canary Islands)

1. Empirical testing of optimal foraging models for breath-hold divers has been difficult. Here we report data from sound and movement recording DTags placed on 23 short-finned pilot whales off Tenerife to study the foraging strategies used to catch deep-water prey. 2. Day and night foraging dives had a maximum depth and duration of 1018 m and 21 min. Vocal behaviour during dives was consistent with biosonar-based foraging, with long series of echolocation clicks interspersed with buzzes. Similar buzzes have been associated with prey capture attempts in other echolocating species. 3. Foraging dives seemed to adapt to circadian rhythms. Deep dives during the day were deeper, but contained fewer buzzes (median 1), than night-time deep dives (median 5 buzzes). 4. In most deep (540-1019 m) daytime dives with buzzes, a downward directed sprint reaching up to 9 m s(-1) occurred just prior to a buzz and coincided with the deepest point in the dive, suggestive of a chase after escaping prey. 5. A large percentage (10-36%) of the drag-related locomotion cost of these dives (15 min long) is spent in sprinting (19-79 s). This energetic foraging tactic focused on a single or few prey items has not been observed previously in deep-diving mammals but resembles the high-risk/high-gain strategy of some terrestrial hunters such as cheetahs. 6. Deep sprints contrast with the expectation that deep-diving mammals will swim at moderate speeds optimized to reduce oxygen consumption and maximize foraging time at depth. Pilot whales may have developed this tactic to target a deep-water niche formed by large/calorific/fast moving prey such as giant squid.     

Kleptothermy: an additional category of thermoregulation,and a possible example in sea kraits (Laticauda laticaudata,Serpentes)

Lacking the capacity for thermogenesis, most ectotherms inhabiting thermally heterogeneous environments rely instead upon exploiting that ambient heterogeneity. In many cases they maintain body temperatures within a narrow range despite massive spatial and temporal variation in ambient conditions. Reliance on diverse thermal opportunities is reflected in specific terms for organisms that bask in sunlight to regulate their temperature (heliotherms), or that press their bodies against warm substrates to facilitate heat flow (thigmotherms), or that rely on large body mass to maintain thermal constancy (gigantothermy). We propose an additional category of thermoregulators: kleptotherms, which regulate their own temperature by ‘stealing’ heat from other organisms. This concept involves two major conditions: the thermal heterogeneity created by the presence of a warm organism in a cool environment and the selective use of that heterogeneity by another animal to maintain body temperatures at higher (and more stable) levels than would be possible elsewhere in the local area. Kleptothermy occurs in endotherms also, but is usually reciprocal (rather than unilateral as in ectotherms). Thermal monitoring on a small tropical island documents a possible example of kleptothermy, based on high stable temperatures of a sea snake (Laticauda laticaudata) inside a burrow occupied by seabirds.     

Genetic architecture for normal and novel host-plant use in two local populations of the herbivorous ladybird beetle, Epilachna pustulosa

Trade-offs in host-plant use are thought to promote the evolution of host specificity. However, usually either positive or no genetic correlations have been found. Whereas factors enhancing variation in overall viability have been claimed to mask negative genetic correlations, alternative hypotheses emphasize the sequential changes in genetic correlation in the course of host-range evolution. In this study, the genetic architectures of performances on different hosts were compared in two populations of the herbivorous ladybird beetle, Epilachna pustulosa, using three host plants, one being normal for both, one novel for only one population, and the other novel for both populations. The genetic correlations between larval periods on normal hosts were significantly positive whereas those between normal and novel hosts were not different from zero. There was no evidence for reduced genetic variation on the normal host-plants. These results suggest that the host-range is not restricted by the antagonistic genetic associations among exploitation abilities on different plant species, but rather that selection of different host-plants may improve the coordination between genes responsible for the use of different plants.     

Nematocysts of sea anemones (Actiniaria,Ceriantharia and Corallimorpharia: Cnidaria): nomenclature

A brief historical review of nematocyst terminology is given and three nomenclatural problems are discussed. It is proposed to combine the terms initiated by Weill (1934) with those of Schmidt (1969). A new mesobasic grade, intermediate between microbasic and macrobasic is proposed for amastigophores and p-mastigophores possessing a short Faltstück. A more liberal interpretation of Weill's (1934) terminology for nematocysts than that proposed by Cutress (1955) is suggested in respect of microbasic amastigophores and p-mastigophores. Basitrichs and b-mastigophores continue to be recognized as separate categories.deceased     

Increase in song frequency decreases spermatophore size: correlative evidence of a macroevolutionary trade-off in katydids (Orthoptera: Tettigoniidae)

In many katydids, the male feeds his mate with a large gelatinous spermatophore. Males of most species also produce elaborate calling songs. We predicted a negative relationship between spermatophore size and call frequency because of trade-offs between these two costly traits. Our comparative analysis controlling phylogeny and body size supported this prediction. Although call frequency is expected to decrease with increasing body size, after controlling for phylogeny, both variables were not related. Finally, given that song frequency and spermatophore size are likely targets of sexual selection, we examined the relationship between these variables and sexual size dimorphism (SSD) which can be influenced by sexual selection on body size. We found that only female body size was positively related to SSD, suggesting that natural and/or sexual selection on female body size may be stronger than sexual selection on male and spermatophore size.     

Sperm competition games: Sperm size (mass) and number under raffle and displacement, and the evolution of P2

We examine models for evolution of sperm size (i.e. mass m) and number (s) under three mechanisms of sperm competition at low ‘risk’ levels: (i) raffle with no constraint on space available for competing sperm, (ii) direct displacement mainly by seminal fluid, and (iii) direct displacement mainly by sperm mass. Increasing sperm mass increases a sperm's ‘competitive weight’ against rival sperm through a diminishing returns function, r(m). ESS total ejaculate expenditure (the product m^?s^?) increases in all three models with sperm competition risk, q. If r(m), or ratio r′(m)/r(m), is independent of ESS sperm numbers, ESS sperm mass remains constant, and the sperm mass/number ratio (m^?/s^?) therefore decreases with risk. Dependency of sperm mass on risk can arise if r(m) depends on competing sperm density (sperm number / space available for sperm competition). Such dependencies generate complex relationships between sperm mass and number with risk, depending both on the mechanism and how sperm density affects r(m). While numbers always increase with risk, mass can either increase or decrease, but m^?/s^? typically decreases with risk unless sperm density strongly influences r(m). Where there is no extrinsic loading due to mating order, ESS paternity of the second (i.e. last) male to mate (P₂) under displacement always exceeds 0.5, and increases with risk (in the raffle P₂=0.5). Caution is needed when seeking evidence for a sperm size-number trade off. Although size and number trade-off independently against effort spent on acquiring matings, their product, m^?s^?, is invariant or fixed at a given risk level, effectively generating a size-number trade off. However, unless controlled for the effects of risk, the relation between m^? and s^? can be either positive or negative (a positive relation is usually taken as evidence against a size-number trade off).     

Marine insects: genital morphology, phylogeny and evolution of sea skaters, genus Halobates (Hemiptera: Gerridae)

Five species of sea skaters, genus Halobates Eschscholtz, are the only insects to have successfully colonized the open ocean. In addition, 36 species are found in sheltered coastal waters throughout tropical Indo-Pacific. The taxonomy of the genus is relatively well known, but reliable hypotheses about phylogenetic relationships are required if the biogeography and evolution of sea skaters is to be discussed in a meaningful way. This work presents the results of a study of new characters from the genital segments, especially those of the male phallus and the female gynatrial complex, and a reinterpretation for several other characters. In total 64 characters were scored for 26 species of Halobates , two species ofAsclepios and one species of Metrocoris. With Asclepios and Metrocoris species as outgroups, the character state sets were analysed cladistically using the computer program Hennig86. After critical evaluations of both characters and clades, a phylogeny for Halobates is presented and its taxonomic implications are discussed. A number of monophyletic species groups are delimited. One genus-level synonymy and three species-level synonymies are suggested. The evolution of Halobates is discussed in the light of the reconstructed phylogeny and present knowledge of the ecology and behaviour of sea skaters. A hypothesis of ecological evolution in halobatine water striders is proposed and tested.     

Reproduction in the yellow-bellied sea snake (Pelamis platurus) from Panama: Field and laboratory observations

Little is known of the reproductive biology of the yellow-bellied sea snake (Pelamis platurus), a species widely distributed in the Indo-Pacific and eastern Pacific Oceans. We observed mating, birth, and free-ranging neonates of P. platurus while collecting this snake once a month over 19 months in the Gulf of Chiriquí, Panama. A pair of copulating snakes was netted on the water surface during February. Neonates, which were identified by size, were observed from September to December. Captive females gave birth during September. Neonates born in captivity emerged head- or tailfirst, shed the remnants of the fetal membranes by coiling their body in a circular loop, and then surfaced to breathe. © 1996 Wiley-Liss, Inc.     

Integrating phylogeny,environment and space to explore variation in macroecological traits of Viperidae and Elapidae (Squamata: Serpentes)

We used eigenvector mapping in space and phylogeny to investigate the relationships among space, phylogeny and environment on body size and range size variation across two groups of venomous snakes – Viperidae and Elapidae – from the New World. Data on species geographic range sizes, maximum body sizes and phylogenetic relationships were compiled from the available literature. The distributional data were also used to calculate the latitudinal and longitudinal midpoint and the environmental centroids for each species. The eigenvectors extracted from the pair wise spatial and phylogenetic distance matrices were integrated with environmental variables into a method of variation partitioning where the variation in each trait was quantitatively attributed to ‘pure’ and/or shared effects of phylogeny, environment and space. Our results showed that variation in body size was predominantly determined by phylogeny in both groups of snakes. For Viperidae, we found that pure ‘effects’ of phylogeny were the strongest, indicating that most of the body size evolution that was phylogenetically determined in this group occurred independently of environment and geographical proximity. Regarding range sizes, pure phylogenetic influences were very low in both groups, whereas the largest single fraction of explained variation corresponded to overlapped influences of the three sets of predictors, especially for Elapidae. Along with this, we found evidence that niche conservatism is an important processes underlying variation in body size and range size in both groups of snakes.     

The growth, development and reproduction of a deep sea cumacean (Crustacea: Peracarida)

A single sample of over 1000 individuals of Leuconjonesi Bishop, 1982, taken at a depth of about 1500 m on the continental slope off Surinam, was studied. The carapace length of individuals in the first postmarsupial instar was already about half that of brooding females. Growth increments at early moults were of 20–25. Males reached the final morphological form in the sixth postmarsupial instar. A prepuberty moult was recognized between the third and fourth male instars. Females reached the preparatory stage in the fourth postmarsupial instar. Brooding condition occurred for the first time after the next moult. The brooding form could then alternate at successive moults with an inter-brood form, resembling the preparatory female, with small, non-overlapping oostegites. Preparatory and inter-brood females were morphologically separable; vitellogenesis was restricted to these instars. Broods were of 6–12 young. The individuals in each brood probably completed marsupial development, and were released, one by one. The copepod parasite Sphaeronella infested 10, of brooding-form females.