Autumn-winter energetics of Holarctic tree squirrels:a review

Similarities in general size, geometry, lifestyle, and environment mean that certain energetic constraints are common and peculiar to Holarctic tree squirrels as a group. Holarctic tree squirrels are relatively small, diurnal mammals which, in association with their food niche, maintain activity throughout the autumn-winter period. Despite this, they exhibit no major morphological or physiological adaptations to minimize energy expenditure at low temperatures; on the contrary, both basal metabolism and conductance are higher than expected on the grounds of physical size. When they are active energy expenditure is therefore strongly influenced by effective ambient temperature for these species when active in their natural autumn-winter environments. Nest use allows near-basal metabolism at most natural ambient temperatures. The balance of economical inactivity against feeding rewards offset by cold exposure must therefore be a crucial aspect of the lifestyle of these squirrels.     

Unravelling a tangle of Mexican serpents: a systematic revision of highland pitvipers

As most recently recognized, the name Cerrophidion barbouri Dunn, 1919, refers to a highland species of pitviper endemic to Guerrero, Mexico, of which Agkistrodon browni Shreve, 1938, is considered a junior synonym. This species is rarely collected and prior to recent decades it was known from only a few specimens. A careful re‐examination of nearly all known specimens of C. barbouri and the type series of A. browni reveals that both names represent valid species and we therefore resurrect A. browni. Both species are extremely variable with respect to cephalic scalation and colour pattern, which has previously confounded efforts to identify them. We provide phylogenetic analyses using both Bayesian and maximum parsimony criteria of New World pitvipers to investigate the phylogenetic position of A. browni and C. barbouri. Our phylogenetic tree, based on 2235 bp of mitochondrial data [12S, 16S, cytochrome b (cyt b), NADH dehydrogenase subunit 4 (ND4)], strongly supports a clade consisting of A. browni, C. barbouri, and Ophryacus melanurus, which has a distant sister relationship to Ophryacus undulatus. Based on the deep phylogenetic divergences amongst these species and distinctive morphology we recommend that a new genus be recognized for A. browni, C. barbouri, and O. melanurus. Finally, we revise the genera Cerrophidion and Ophryacus in accordance with our new classification. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011, 163 , 943–958.     

A NEW OVOVIVIPAROUS SPECIES OF TECTARIUS (GASTROPODA: LITTORINIDAE) FROM NIUE, SOUTH PACIFIC, WITH A MOLECULAR PHYLOGENY OF THE GENUS

A new ovoviviparous littorinid gastropod, Tectarius (Echininiopsis)niuensis, from Niue, west of the Cook Islands, is described.This is distinguished from the only other ovoviviparous memberof the genus, T. (E.) viviparus (Rosewater, 1982) from the MarianaIslands, here redescribed in detail. The new species is remarkabletor its high-level habitat in the littoral fringe on wave-exposedkarstic limestone cliffs, for its variation in shell shape accordingto tidal level, shell colour polymorphism, calcified operculumand penis with a single mamilliform penial gland. In a cladisticanalysis of morphological characters, including single representativesof each of the three other subgenera of Tectarius (Tectarius,Echininus, Tectininus), these two ovoviviparous species appearas sister-taxa. This is confirmed by a molecular phylogeneticanalysis of the same species, based on the sequence of a portionof the 16S ribosomal RNA mitochondrial gene. Neither analysisunequivocally confirms the monophyly of Tectarius. The divergenceof DNA sequences within Tectarius suggests that the genus arosein the Upper Cretaceous, much earlier than the oldest (UpperEocene) fossils. Only 4 of the 175 species of Littorinidae areknown to be ovoviviparous (with brooding through metamorphosis)and the possible adaptive significance of this type of developmentis discussed. Hitherto, its rarity had been explained by earlyextinction of poorly-dispersed brooding taxa. However, ovoviviparitymay have persisted in Echininiopsis for at least 35 millionyears, and has not precluded colonization of islands 6300kmapart. (Received 17 September 1996; accepted 15 November 1996)     

Functional analysis of fenestellid bryozoan colonies

True colonies are more than aggregated individuals, they are integrated operational units which can be explained in functional terms. At the same time each constituent individual is fully functional. Paleobiological hypotheses about colonies must withstand testing on both individual and colonial levels. We illustrate our argument by analysis of fenestellid bryozoans. We propose that ciliary feeding currents swept through the fenestrules from frontal side to reverse, with the fenestrules as operational filtering units manned by co-operating zooids. We reconstruct viable current systems applicable to most fenestellids. For the amazing spiral structure of Archimedes we suggest a downward current spiralling about the central axis, since at each 'deck' the fenestrules filtered water downwards.     

Selection of candidate coding DNA barcoding regions for use on land plants

An in silico screen of 41 of the 81 coding regions of the Nicotiana plastid genome generated a shortlist of 12 candidates as DNA barcoding loci for land plants. These loci were evaluated for amplification and sequence variation against a reference set of 98 land plant taxa. The deployment of multiple primers and a modified multiplexed tandem polymerase chain reaction yielded 85–94% amplification across taxa, and mean sequence differences between sister taxa of 6.1 from 156 bases of accD to 22 from 493 bases of matK. We conclude that loci should be combined for effective diagnosis, and recommend further investigation of the following six loci: matK, rpoB, rpoC1, ndhJ, ycf5 and accD. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 159 , 1–11.     

Regulation of Pregerminative Rates of Respiration in Seeds of Various Weed Species by Potassium Nitrate

The effects of potassium nitrate (KNO₃) on germination and O₂uptake in seeds of various weed species were compared and contrastedwith water controls. When KNO₃ promoted germination, rates ofO₃ uptake were increased, when it was inhibitory, rates weredecreased, and when it had no effect there were no appreciabledifferences between the rates of O₂ uptake of KNO₃-and water-imbibedseeds. These effects were clearly the result of early metabolicevents for differences in O₂ uptake were detectable soon afterthe seeds were placed in the liquid media and for some considerabletime prior to germination (i.e. the protrusion of the radicle).The results are discussed in relation to a published hypothesisof other workers concerning the mechanism of seed dormancy breakage. Key words: Potassium nitrate, respiration, seeds     

Geological subsidence, river capture, and cladogenesis of galaxiid fish lineages in central New Zealand

We used mtDNA and isozyme analysis of a freshwater fish, Galaxias divergens (Osmeriformes: Galaxiidae), to test a hypothesis of drainage evolution in South Island, New Zealand. Geological evidence indicates that the presently north-flowing Kaituna River branch of the Pelorus River system once flowed south into the Wairau River system. The subsequent flow-reversal is thought to have resulted from Pleistocene subsidence in central New Zealand. mtDNA sequence data corroborated this geological hypothesis: rivers draining into Pelorus Sound were found to retain a genetic lineage of G. divergens that is otherwise restricted to the Wairau River system and adjacent coastal drainages (based on current sampling). Other sampled drainages in northern South Island and southern North Island were found to house lineages that were highly divergent from the Wairau–Pelorus clade. Isozyme data yielded groupings based on fixed differences that were largely congruent with mtDNA clades. Standard molecular calibrations suggest that vicariant isolation of Pelorus and Wairau systems (drainage reversal) occurred in the mid-Pleistocene rather than the late Pleistocene as suggested by geology. Future multidisciplinary analyses will aim to improve our understanding of geological and molecular evolutionary rates.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 88 , 367–376.