Evolutionary and biogeographical history of an ancient and global group of arachnids (Arachnida: Opiliones: Cyphophthalmi) with a new taxonomic arrangement

We investigate the phylogeny, biogeography, time of origin and diversification, ancestral area reconstruction and large‐scale distributional patterns of an ancient group of arachnids, the harvestman suborder Cyphophthalmi. Analysis of molecular and morphological data allow us to propose a new classification system for the group; Pettalidae constitutes the infraorder Scopulophthalmi new clade , sister group to all other families, which are divided into the infraorders Sternophthalmi new clade and Boreophthalmi new clade . Sternophthalmi includes the families Troglosironidae, Ogoveidae, and Neogoveidae; Boreophthalmi includes Stylocellidae and Sironidae, the latter family of questionable monophyly. The internal resolution of each family is discussed and traced back to its geological time origin, as well as to its original landmass, using methods for estimating divergence times and ancestral area reconstruction. The origin of Cyphophthalmi can be traced back to the Carboniferous, whereas the diversification time of most families ranges between the Carboniferous and the Jurassic, with the exception of Troglosironidae, whose current diversity originates in the Cretaceous/Tertiary. Ancestral area reconstruction is ambiguous in most cases. Sternophthalmi is traced back to an ancestral land mass that contained New Caledonia and West Africa in the Permian, whereas the ancestral landmass for Neogoveidae included the south‐eastern USA and West Africa, dating back to the Triassic. For Pettalidae, most results include South Africa, or a combination of South Africa with the Australian plate of New Zealand or Sri Lanka, as the most likely ancestral landmass, back in the Jurassic. Stylocellidae is reconstructed to the Thai‐Malay Penisula during the Jurassic. Combination of the molecular and morphological data results in a hypothesis for all the cyphophthalmid genera, although the limited data available for some taxa represented only in the morphological partition negatively affects the phylogenetic reconstruction by decreasing nodal support in most clades. However, it resolves the position of many monotypic genera not available for molecular analysis, such as Iberosiro, Odontosiro, Speleosiro, Managotria or Marwe, although it does not place Shearogovea or Ankaratra within any existing family. The biogeographical data show a strong correlation between relatedness and formerly adjacent landmasses, and oceanic dispersal does not need to be postulated to explain disjunct distributions, especially when considering the time of divergence. The data also allow testing of the hypotheses of the supposed total submersion of New Zealand and New Caledonia, clearly falsifying submersion of the former, although the data cannot reject the latter. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 92–130.     

Synchrony in capture dates suggests cryptic social organization in sea snakes (Emydocephalus annulatus,Hydrophiidae)

Abstract Complex sociality is widespread in lizards, but the difficulties of directly observing social interactions in free‐ranging snakes have precluded such studies for most snake species. However, a type of data already available from mark‐recapture studies (dates of capture and recapture of individually marked animals) can reveal social substructure within snake populations. If individuals associate with each other in social groups, we expect synchrony in the dates of capture and recapture of those animals. A field study of turtle‐headed sea snakes (Emydocephalus annulatus) in New Caledonia reveals exactly this phenomenon. For example, animals that were captured on the same day in one year often were recaptured on the same day the following year. Analysis rejects non‐social interpretations of these data (such as spatial‐temporal confounding in sampling, intrapopulation heterogeneity in cues for activity), suggesting instead that many individual sea snakes belong to ‘social’ groups that consistently move about together. The phenomenon of capture synchrony during mark‐recapture studies can provide new insights into the occurrence and correlates of cryptic social aggregations.     

Terrestrial Passive Integrated Transponder Antennae for Tracking Small Animal Movements

ABSTRACT Measuring terrestrial movements of small animals poses a substantial technological challenge. We developed very long (up to 130 m) passive integrated transponder (PIT) detectors with which we tracked salamanders (Caudata) migrating from breeding ponds to their upland habitat >200 m away. In all 60 trials, salamanders were detected when released near the antennae. In a second test, we tracked 7 of 14 tagged marbled salamanders (Ambystoma opacum) migrating >65 m, well beyond the area protected by existing wetland buffer regulations in Massachusetts, USA. The mean rate of movement for these salamanders (x̄ = 0.9 m/min; SE = 0.1 m/min) was substantially higher than rates of movement reported for related salamanders with radio-implants. These PIT antennae offer researchers a means to study small animal movements with less disruption of the animals’ natural movement patterns than is caused by other available techniques.     

Poleward shifts in breeding bird distributions in New York State

Like other regions of the northern hemisphere, the northeastern United States has experienced a general increase in regional temperatures over the past 20 years. Quantifying the ecological implications of these changing temperatures has been severely constrained by a lack of multispecies distributional data by which to compare long-term changes. We used the New York State Breeding Bird Atlas, a statewide survey of 5332 25 km² blocks surveyed in 1980–1985 and 2000–2005, to test several predictions that the birds of New York State are responding to climate change. Our objective was to use an information-theoretic approach to analyze changes in three geographic range characteristics, the center of occurrence, range boundaries, and states of occurrence to address several predictions that the birds of New York State are moving polewards and up in elevation. As expected, we found all bird species ( n =129) included in this analysis showed an average northward range shift in their mean latitude of 3.58 km [ Prob ( H _a|data)=0.87)]. Past studies have found that northern range boundaries are more likely to be influenced by climatic factors than southern range boundaries. Consequently, we predicted that northward shifts would be more evident in northern as opposed to southern range boundaries. We found, however, that the southern range boundaries of northerly birds moved northward by 11.4 km [ n =43, Prob ( H _a|data)=0.92], but this pattern was less evident in northern range boundaries of southerly birds. In addition, we found that bird species demonstrated a general shift downhill in their mean elevation, but demonstrated little change in their elevational boundaries. The repeated pattern of a predicted northward shift in bird ranges in various geographic regions of the world provides compelling evidence that climate change is driving range shifts.     

Effects of competition,cannibalism and intra‐guild predation on larval development of the European coccinellid Adalia bipunctata and the invasive species Harmonia axyridis

Abstract 1. Resource competition and intra‐guild predation (IGP) are important determinants of the structure of aphidophagous guilds. The likelihood and outcome of IGP is influenced by the density of extra‐guild prey and the characteristics of the species involved. 2. The nature of intra‐guild interactions between alien and indigenous coccinellids often determines the success of coccinellid invasions, as exemplified by Adalia bipunctata in Japan and Harmonia axyridis in North America and Europe. 3. Harmonia axyridis has negatively impinged on indigenous species in its introduced range, and its recent arrival in Britain poses a threat for members of native aphidophagous guilds. IGP and inter‐specific competition between H. axyridis and British coccinellids are predicted to occur. However, the results of such interactions have been little studied. 4. Here we investigate the effects of different diets, designed to mimic possible conditions in the wild, on the survival, development, and adult size of H. axyridis and A. bipunctata. Results demonstrate a skew in the consequences of IGP between the two species: the supplementation of a limited aphid diet with non‐conspecific eggs leads to a significant advantage for H. axyridis in respect of all parameters assessed, but gives no benefit to A. bipunctata. 5. We conclude that IGP of A. bipunctata by H. axyridis will contribute to the spread and increase of H. axyridis in Britain. 6. We further conclude that the skewed nature of IGP between A. bipunctata and H. axyridis at least in part explains the limited spread of A. bipunctata in Japan.     

Cascading effects of herbivore protective symbionts on hyperparasitoids

1. Microbial symbionts can play an important role in defending their insect hosts against natural enemies. However, researchers have little idea how the presence of such protective symbionts impacts food web interactions and species diversity. 2. This study investigated the effects of a protective symbiont (Hamiltonella defensa) in pea aphids (Acyrthosiphon pisum) on hyperparasitoids, which are a trophic level above the natural enemy target of the symbiont (primary parasitoids). 3. Pea aphids, with and without their natural infections of H. defensa, were exposed first to a primary parasitoid against which the symbiont provides partial protection (either Aphidius ervi or Aphelinus abdominalis), and second to a hyperparasitoid known to attack the primary parasitoid species. 4. It was found that hyperparasitoid hatch rate was substantially affected by the presence of the symbiont. This effect appears to be entirely due to the removal of potential hosts by the action of the symbiont: there was no additional benefit or cost experienced by the hyperparasitoids in response to symbiont presence. The results were similar across the two different aphid–parasitoid–hyperparasitoid interactions we studied. 5. It is concluded that protective symbionts can have an important cascading effect on multiple trophic levels by altering the success of natural enemies, but that there is no evidence for more complex interactions. These findings demonstrate that the potential influence of protective symbionts on the wider community should be considered in future food web studies.     

A native dasyurid predator (common planigale,Planigale maculata) rapidly learns to avoid a toxic invader

Abstract Interactions between invasive species and native fauna afford a unique opportunity to examine interspecific encounters as they first occur, without the complications introduced by coevolution. In northern Australia, the continuing invasion of the highly toxic cane toad Bufo marinus poses a threat to many frog‐eating predators. Can predators learn to distinguish the novel toxic prey item from native prey (and thus, avoid being poisoned), or are longer‐term genetically based changes to attack behaviour needed before predators can coexist with toads? To predict the short‐term impact of cane toads on native predators, we need to know the proportion of individuals that will attack toads, the proportion surviving the encounter, and whether surviving predators learn to avoid toads. We quantified these traits in a dasyurid (common planigale, Planigale maculata) that inhabits tropical floodplains across northern Australia. Although 90% of naïve planigales attacked cane toads, 83% of these animals survived because they either rejected the toad unharmed, or killed and consumed the prey snout‐first (thereby avoiding the toxin‐laden parotoid glands). Most planigales showed one‐trial learning and subsequently refused to attack cane toads for long time periods (up to 28 days). Toad‐exposed planigales also avoided native frogs for up to 9 days, thereby providing an immediate benefit to native anurans. However, the predators gradually learnt to use chemical cues to discriminate between frogs and toads. Collectively, our results suggest that generalist predators can learn to distinguish and avoid novel toxic prey very rapidly – and hence, that small dasyurid predators can rapidly adapt to the cane toad invasion. Indeed, it may be feasible to teach especially vulnerable predators to avoid cane toads before the toads invade, by deploying low‐toxicity baits that stimulate taste‐aversion learning.