A longirostrine Temnodontosaurus (Ichthyosauria) with comments on Early Jurassic ichthyosaur niche partitioning and disparity

Abstract: We describe an almost complete ichthyosaur skeleton from the middle Toarcian (Lower Jurassic) of the Beaujolais foothills near Lyon, France, and assign it to Temnodontosaurus azerguensis sp. nov. This new species exhibits cranial peculiarities such as a thin, elongated and possibly edentulous rostrum, as well as a reduced quadrate. These characters indicate dietary preferences that markedly differ from other species referred to Temnodontosaurus, a genus previously considered as the top predator of the Early Jurassic seas. Despite a conservative postcranial skeleton, we propose that Temnodontosaurus is one of the most ecologically disparate genera of ichthyosaurs, including apex predators and now a soft prey longirostrine hunter. Ammonites collected from the same stratigraphic level as the described specimen indicate that the new species is somewhat younger (bifrons ammonite zone) than the most known Toarcian ichthyosaurs and therefore slightly postdates the interval of severe environmental changes and marine invertebrate extinctions known as the Toarcian Oceanic Anoxic Event. The present study therefore raises the question of whether postcrisis recovery of vertebrate faunas, including the radiation of Temnodontosaurus into a new ecological niche, may have been a consequence of marine ecosystem reorganization across this event.     

Population Indices Versus Correlated Density Estimates of Black-Footed Ferret Abundance

ABSTRACT Estimating abundance of carnivore populations is problematic because individuals typically are elusive, nocturnal, and dispersed across the landscape. Rare or endangered carnivore populations are even more difficult to estimate because of small sample sizes. Considering behavioral ecology of the target species can drastically improve survey efficiency and effectiveness. Previously, abundance of the black-footed ferret (Mustela nigripes) was monitored by spotlighting and generating indices of relative abundance because reintroduced populations were slow to establish. Indices, however, lack variance estimates and are costly to generate for the black-footed ferret. We therefore used spotlight surveys and live-trapping in conjunction with a robust mark-recapture estimator to improve abundance monitoring for the black-footed ferret, one of North America's most endangered carnivores. We estimated abundance of the black-footed ferret at Shirley Basin, Wyoming, USA, using correlated density estimates and Program MARK. We compared our results to 2 indices of relative abundance, minimum number alive and predicted number of ferrets from litter counts. The correlated density estimate for the black-footed ferret (N̂_R = 229; 95% CI = 161–298) was similar to minimum number alive (N̂_R = 192) and predicted number of ferrets from litter counts (N̂_R= 235). The efficiency and effectiveness of survey methods we used for the black-footed ferret were high by carnivoran standards. Our results suggest that the sampling approach we utilized can be implemented for a fraction of the cost and effort required to generate 2 indices of relative abundance for the black-footed ferret. Although we recommend managers implement a similar survey approach to monitor abundance of reintroduced populations of the black-footed ferret, analysis with sparse data sets will be problematic. Until the black-footed ferret becomes widespread and abundant at a reintroduction site, spotlighting will remain preferable as a means to generate indices of distribution and relative abundance for the black-footed ferret.     

Acoustic differentiation reflects mitochondrial lineages in Blyth's leaf warbler and white-tailed leaf warbler complexes (Aves: Phylloscopus reguloides, Phylloscopus davisoni)

The present study evaluated the degree of differentiation between closely-related species of Blyth's leaf warbler complex ( Phylloscopus reguloides s.l. ) and white-tailed leaf warbler complex ( Phylloscopus davisoni s.l. ) by molecular (cytochrome b and 16S rRNA) and bioacoustic markers (sonagraphic analysis of songs). Molecular phylogenetic results corroborate the recently suggested splittings of the two former taxa into three and two species, respectively. By contrast to previous opinion, differentiation of territorial songs parallels the genetic diversification in both groups. In the P. reguloides group, all recently established species can be distinguished by a characteristic song pattern. Regularly structured songs composed of repeated two- or three-note syllables were found in all species of the group, whereas trill songs with single notes repeated are unique to Phylloscopus claudiae . The phylogenetic relationships of Phylloscopus occipitalis are ambiguous among different molecular trees, but song pattern clearly corroborates a close relationship to the P. reguloides group. In the white-tailed leaf warbler group, songs are irregularly structured and often descending in frequency with exception of P. davisoni and Phylloscopus ogilviegranti disturbans . Song pattern corroborates the genetic affiliation of Phylloscopus hainanus and Phylloscopus xanthoschistos to the molecular white-tailed leaf warbler clade. All target species correspond to distinct acoustic clusters resulting from discriminant analysis of several spectral and structural song parameters. Linear correlation between genetic and acoustic differentiation (pairwise p -distances versus difference of discriminant functions) is significant within both groups, except for one case, in which discriminant function 1 was correlated with a spectral parameter (minimum frequency) only.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 584–600.     

Sperm release and use at fertilization by yellow dung fly females (Scathophaga stercoraria)

Females of many species mate multiple times and store transferred sperm in storage organs. The mechanisms underlying sperm release from the stores at fertilization remain poorly understood, although they are central to an understanding of the female influence on post-copulatory male competition. Using double-mated females of the yellow dung fly, we counted the sperm sticking to the surface of deposited eggs of two successive clutches to obtain insight into the physiological processes associated with fertilization. The number of sperm released to fertilize an egg decreased between the first and second clutches, as well as within clutches from early to late eggs. These results indicate that: (1) sperm are lost from the stores over time independent of egg laying and (2) the number of sperm released depends on the amount of sperm stored. The lower number of sperm on eggs of the second clutches was accompanied by a strong increase of the proportion of sperm adhering to the micropyle region, suggesting that sperm use is more efficient and sperm release better controlled when sperm supply is substantially reduced. Finally, our approach indicates that sperm storage capacity of the female is higher than assumed from counts of spermathecal sperm.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 98 , 511–518.     

Developmental patterns of the crocodilian and avian columella auris: reappraisal of interpretations of the derivation of the dorsal hyoid arch in archosaurian tetrapods

The morphogenesis of the crocodilian and avian columella auris is analysed, using Alligator and Struthio as models that are studied in detail, and Crocodylus, Gallus, and Coturnix as models for comparative purposes. This investigation was undertaken to address controversies emanating from previous studies concerning the identity of archosaurian hyal elements, and to clarify confounding nomenclature that has been used for both topographic and phylogenetic purposes. We found that confusion in the identification of the reptilian and avian hyoid arch derivatives is attributable to: (1) redundant and/or inconsistently applied topographical terminology; (2) mixing of topographical and phylogenetic terminology; (3) interpretation in a recapitulatory framework; and (4) failure to consider that developmental pathways of recent archosaurians (reptilians and birds) might be divergently modified. Our analysis identifies errors in previous interpretations, misinterpretations of prior work, and histological observations that have been idealized. The most controversial issues are addressed – the derivation of the supracolumellar process; the concept of the laterohyal component; and segmentation of the distal part of the reptilian and avian columella auris. Based on new data, we suggest that the osteichthyan infrapharyngohyal, suprapharyngohyal, epihyal, and ceratohyal are not applicable terms for reptilian and avian columellar components from a phylogenetic perspective, and should not be used as topographical terms either. We further propose that the original morphogenetic program of the hyoid arch has been overwritten in newly derived evolutionary pathways of crocodilians and birds, in which a new functional and morphological patterning of the hyoid arch, as a specific sound‐transmitting apparatus, have evolved. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 156 , 384–410.     

Phylogeography of lions (Panthera leo ssp.) reveals three distinct taxa and a late Pleistocene reduction in genetic diversity

Lions were the most widespread carnivores in the late Pleistocene, ranging from southern Africa to the southern USA, but little is known about the evolutionary relationships among these Pleistocene populations or the dynamics that led to their extinction. Using ancient DNA techniques, we obtained mitochondrial sequences from 52 individuals sampled across the present and former range of lions. Phylogenetic analysis revealed three distinct clusters: (i) modern lions, Panthera leo ; (ii) extinct Pleistocene cave lions, which formed a homogeneous population extending from Europe across Beringia (Siberia, Alaska and western Canada); and (iii) extinct American lions, which formed a separate population south of the Pleistocene ice sheets. The American lion appears to have become genetically isolated around 340 000 years ago, despite the apparent lack of significant barriers to gene flow with Beringian populations through much of the late Pleistocene. We found potential evidence of a severe population bottleneck in the cave lion during the previous interstadial, sometime after 48 000 years, adding to evidence from bison, mammoths, horses and brown bears that megafaunal populations underwent major genetic alterations throughout the last interstadial, potentially presaging the processes involved in the subsequent end-Pleistocene mass extinctions.