Dental metric assessment of the omo fossils: implications for the phylogenetic position of Australopithecus africanus

The discovery of Australopithecus afarensis has led to new interpretations of hominid phylogeny, some of which reject A. africanus as an ancestor of Homo. Analysis of buccolingual tooth crown dimensions in australopithecines and Homo species by Johanson and White (Science 202:321-330, 1979) revealed that the South African gracile australopithecines are intermediate in size between Laetoli/hadar hominids and South African robust hominids. Homo, on the other hand, displays dimensions similar to those of A. afarensis and smaller than those of other australopithecines. These authors conclude, therefore, that A. africanus is derived in the direction of A. robustus and is not an ancestor of the Homo clade. However, there is a considerable time gap (ca. 800,000 years) between the Laetoli/Hadar specimens and the earliest Homo specimens; "gracile" hominids from Omo fit into this chronological gap and are from the same geographic area. Because the early specimens at Omo have been designated A. afarensis and the later specimens classified as Homo habilis, Omo offers a unique opportunity to test hypotheses concerning hominid evolution, especially regarding the phylogenetic status of A. africanus. Comparisons of mean cheek teeth breadths disclosed the significant (P less than or equal to 0.05) differences between the Omo sample and the Laetoli/Hadar fossils (P4, M2, and M3), the Homo fossils (P3, P4, M1, M2, and M1), and A. africanus (M3). Of the several possible interpretations of these data, it appears that the high degree of similarity between the Omo sample and the South African gracile australopithecine material warrants considering the two as geographical variants of A. africanus. The geographic, chronologic, and metric attributes of the Omo sample argue for its lineal affinity with A. afarensis and Homo. In conclusion, a consideration of hominid postcanine dental metrics provides no basis for removing A. africanus from the ancestry of the Homo lineage.     

Size variation in early human mandibles and molars from Klasies River,South Africa: Comparison with other middle and late Pleistocene assemblages and with modern humans

Previous studies of the Middle Stone Age human remains from Klasies River have concluded that they exhibited more sexual dimorphism than extant populations, but these claims have not been assessed statistically. We evaluate these claims by comparing size variation in the best‐represented elements at the site, namely the mandibular corpora and M₂s, to that in samples from three recent human populations using resampling methods. We also examine size variation in these same elements from seven additional middle and late Pleistocene sites: Skhūl, Dolní Věstonice, Sima de los Huesos, Arago, Krapina, Shanidar, and Vindija. Our results demonstrate that size variation in the Klasies assemblage was greater than in recent humans, consistent with arguments that the Klasies people were more dimorphic than living humans. Variation in the Skhūl, Dolní Věstonice, and Sima de los Huesos mandibular samples is also higher than in the recent human samples, indicating that the Klasies sample was not unusual among middle and late Pleistocene hominins. In contrast, the Neandertal samples (Krapina, Shanidar, and Vindija) do not evince relatively high mandibular and molar variation, which may indicate that the level of dimorphism in Neandertals was similar to that observed in extant humans. These results suggest that the reduced levels of dimorphism in Neandertals and living humans may have developed independently, though larger fossil samples are needed to test this hypothesis. Am J Phys Anthropol, 2009. © 2009 Wiley‐Liss, Inc.     

Captive breeding of squirrel monkeys,Saimiri sciureus and Saimiri boliviensis: The problem of hybrid groups

The electrophoretic variability of blood proteins coding for up to 32 genetic loci was analyzed in 108 squirrel monkeys (Saimiri sciureus, Saimiri boliviensis, hybrids) from two captive colonies. Twelve polymorphic loci with 31 alleles are reported. The biallelic Ada* locus, G-statistics and Hardy-Weinberg genotype equilibria are useful for recognizing hybrids between S. sciureus and S. boliviensis. Backcrosses in hybrid stocks and gene flow in a natural hybrid belt, however, complicate the taxonomic diagnosis of captive specimens: S. sciureus phenotypes imported from Peru possessed the allele Ada*132, which generally characterizes S. boliviensis (or species hybrids). The complex taxonomy of Saimiri spp. Requires careful planning of captive breeding. We suggest a genetic analysis of the founder individuals before their inclusion in the European studbook population and to breed S. sciureus from Guyana separately from Peruvian imports, because the latter bear a greater risk of being taxonomically heterogeneous. Zoo Biol 17:95–109, 1998. © 1998 Wiley-Liss, Inc.     

Ecological and evolutionary factors of intraspecific variation in inducible defenses: Insights gained from Daphnia experiments

Phenotypic variation among individuals and species is a fundamental principle of natural selection. In this review, we focus on numerous experiments involving the model species Daphnia (Crustacea) and categorize the factors, especially secondary ones, affecting intraspecific variations in inducible defense. Primary factors, such as predator type and density, determine the degree to which inducible defense expresses and increases or decreases. Secondary factors, on the other hand, act together with primary factors to inducible defense or without primary factors on inducible defense. The secondary factors increase intraspecies variation in inducible defense, and thus, the level of adaptation of organisms varies within species. Future research will explore the potential for new secondary factors, as well as the relative importance between factors needs to be clarified.     

Molecular analysis of genetic variation in angiotensin I-converting enzyme identifies no association with sporting ability: First report from Indian population

INTRODUCTION:

A polymorphism in the angiotensin-converting enzyme (ACE) gene was the first performance enhancing polymorphisms (PEPs) to be identified and correlated with athletic abilities. This polymorphism (rs. 5186) is the absence (deletion; D allele), rather than the presence (insertion, I allele) of 287bp Alu repeat element in intron 16. However, the association of ACE I/D polymorphism in sports abilities have been contradicted and debated. No study has evaluated the ACE gene polymorphism in Indian athletes so far. Hence, the genotype distribution and allelic frequency of ACE gene in selected Indian athletic and non-athletic population was studied.

MATERIALS AND METHODS:

A total of 147 athletes and 131 controls were genotyped for the ACE gene polymorphism using PCR.

RESULTS:

No significant association was observed between the allelic frequencies of ACE gene in controls and athletes on a whole, as well as after sub-categorizing the athletes based on the type of sport they played (P > 0.1). However, a higher representation of I allele was observed in the athletes.

CONCLUSION:

ACE genotyping studies need to focus on truly elite athletes of a single sporting discipline, to be able to find an association. The ACE I/D polymorphism may not be considered a marker for human performance, but can be further studied in combination with other potent performance enhancing polymorphisms.     

Molecular and morphometric data provide evidence of intraspecific variation in shape and pigmentation pattern in Otocinclus cocama (Siluriformes: Loricariidae) across major river drainages

Otocinclus cocama, a uniquely colored species of the loricariid catfish genus Otocinclus described solely from the type locality in the lower Ucayali River in northern Peru, is reported occurring in the Tigre River, a tributary to the Marañón River that drains a different section of the Andean Mountain range in the western Amazon. Both populations differ in the number of dark bars spanning the flanks of the body, and we investigated whether these morphotypes constitute distinct species. The body shapes of populations from the Tigre and Ucayali rivers were compared using geometric morphometrics. Although principal component analysis detected a broad overlap between populations, multivariate analysis of variance and linear driscriminat analysis revealed a subtle differentiation between the populations of the two hydrographic basins. Average body shape of the Ucayali River population tend to be slightly higher than that of the Tigre River, with the caudal peduncle stretched vertically in the Ucayali population. Multivariate regression of shape and centroid size revealed an allometric effect of 10.7% (p < 0.001), suggesting that the variation between Tigre and Ucayali populations was purely shape variation. Molecular data of coI, cytb, nd2, and 16S mitochondrial genes indicated a nucleotide diversity range from 0.001 to 0.003, and haplotypic diversity range from 0.600 ± 0.11 to 0.79 ± 0.07. The median-joining haplotype network for the concatenated matrix exhibited two divergent haplogroups related to the geographic area and separated by <10 mutational steps. The molecular species delimitation methods based on distance (automatic barcode gap discovery and assemble species by automatic partitioning) recovered two molecular lineages evolving independently, being one of the lineages formed by individuals from both populations. Tree-based methods (generalized mixed Yule coalescent and Bayesian implementation of the Poisson tree process) recovered similar topologies and supported single lineage recognition. Methods of molecular delimitation of species disclosed the high similarity between the two populations of Otocinclus cocama, further supported by the presence of old haplotypes common to both groups which could indicate that the populations still maintain gene flow. Although the morphological data reveal a subtle variation between both river basins, the molecular data suggest a weak population structuration based on hydrographic areas, but not different species lineages, therefore Otocinclus cocama is composed of a single lineage with two distinct morphotypes.     

Factors influencing intraspecific variation and polymorphism in marine podocopid Ostracoda,with particular reference to Tertiary species from southeastern Australia

Work on intraspecific variation in ornate ostracods over the last 30 years is reviewed. Polymorphism (discontinuous variation) due to environmental and genetic factors (and combinations thereof) is discussed. Specimens of the ornate marine genera Cletocythereis, Hermanites, Notocarinovalva, Neobuntonia, Chapmanella, Actinocythereis, Spinobradleya and Loxoconcha, from Tertiary deposits of southeastern Australia, are examined for examples of significant intraspecific morphological variation. Variations in the degree of spinosity, the nature of spines, the degree and type of aggradation (celation), the occurrence of microreticulation, the shape of fossae, the form of eye tubercles and subcentral tubercles, combinations of reticulation and nodules, and the relationships between punctation, reticulation and spinosity, are described and illustrated. These variations are considered in relation to location, time, facies, inferred palaeoenvironment and assemblage. It is shown that the complex of factors connecting these variations with their expression by the phenotype does not allow their unqualified use in establishing palaeoecological parameters, especially where strict polymorphism is not established, or where the timescale of the variations may be several orders of magnitude out of step with the palaeoecological changes inferred from them. The necessity of high magnification illustrations is stressed. The entire range of research into intraspecific variation must be accessed if robust palaeoecological inferences are to be drawn.     

The cellular slime mold guild and its bacterial prey: growth rate variation at the inter- and intraspecific levels

Summary A guild of cellular slime molds (CSM) consisting of two isolates from each of five species, representing two genera, and obtained from the same square meter of forest soil exhibited extensive growth rate variation when tested on a suite of 18 bacteria isolated from the same soil. Significant growth rate differences were found at each taxonomic level examined: among species of different genera, between genera, among species within genera, and between isolates (=clones) within species. The type of bacteria used as prey determined the relative rank of the growth rates in different CSM isolates, as well as the taxonomic level at which significant differences were found. We suggest a possible reconciliation between a previous hypothesis, based on competition, and contradictory experimental work on resource partitioning in this guild of bacterial predators. Our results raise a question about the efficacy of using single genotypes to represent a species when ecological ideas are developed through laboratory investigations.     

The St. Lawrence Island Eskimos: genetic variation and genetic distance

The Eskimos of St. Lawrence Island have been typed for genetic variation at 44 discrete genetic loci. Three private polymorphisms, at the 2,3-diphosphoglycerate mutase, peptidase B, and purine nucleoside phosphorylase loci, have been observed, which may be useful in future studies of genetic relationships between Eskimos and other circumpolar populations. Genetic distance analysis reveals a close relationship between the St. Lawrence Island Eskimos and other Eskimo populations and that the Eskimo populations form a distinct cluster from Amerindian populations. The St. Lawrence Island Eskimos appear to be more similar to Asiatic Eskimos than to other groups. Caucasian admixture in this population is estimated to be between 2 and 7%.     

The hidden history of the snowshoe hare,Lepus americanus: extensive mitochondrial DNA introgression inferred from multilocus genetic variation

Hybridization drives the evolutionary trajectory of many species or local populations, and assessing the geographic extent and genetic impact of interspecific gene flow may provide invaluable clues to understand population divergence or the adaptive relevance of admixture. In North America, hares (Lepus spp.) are key species for ecosystem dynamics and their evolutionary history may have been affected by hybridization. Here we reconstructed the speciation history of the three most widespread hares in North America – the snowshoe hare (Lepus americanus), the white‐tailed jackrabbit (L. townsendii) and the black‐tailed jackrabbit (L. californicus) – by analysing sequence variation at eight nuclear markers and one mitochondrial DNA (mtDNA) locus (6240 bp; 94 specimens). A multilocus–multispecies coalescent‐based phylogeny suggests that L. americanus diverged ~2.7 Ma and that L. californicus and L. townsendii split more recently (~1.2 Ma). Within L. americanus, a deep history of cryptic divergence (~2.0 Ma) was inferred, which coincides with major speciation events in other North American species. While the isolation‐with‐migration model suggested that nuclear gene flow was generally rare or absent among species or major genetic groups, coalescent simulations of mtDNA divergence revealed historical mtDNA introgression from L. californicus into the Pacific Northwest populations of L. americanus. This finding marks a history of past reticulation between these species, which may have affected other parts of the genome and influence the adaptive potential of hares during climate change.     

The Protohermes fruhstorferi species group (Megaloptera: Corydalidae: Corydalinae), with description of a new species from Vietnam

A new species group, the Protohermes fruhstorferi group of the dobsonfly genus Protohermes, is recognised. Three species belonging to the new species group are described and illustrated, including one new species from northern Vietnam.     

Foraging characteristics and intraspecific behaviour of the exotic species Monomorium sydneyense (Hymenoptera: Formicidae) in New Zealand,with implications for its management

Abstract

We attempt to evaluate the biosecurity risk posed by the newly established exotic ant species Monomorium sydneyense Forel, in New Zealand. Aggression was observed between workers from different M. sydneyense nests, indicating that unicoloniality is unlikely. Nests had multiple queens, and nest foundation is apparently via winged queens. The foraging behaviour corresponded to multicoloniality, with workers foraging in close proximity to the nest. In trials during December (2003) and March (2004), workers had a >50% probability of finding food at a distance of 0.8–1 m from their nest, but on cooler study dates (October 2004) our logistic regression model indicated that they would not reach this threshold irrespective of how close the food was to the nest. Although M. sydneyense forage during both night and day, they appeared to be relatively inefficient at locating food. We conclude that under the conditions assessed here, the environmental damage likely to be caused by M. sydneyense is modest compared with other invasive ant species.     

中国毛缘小蜂属Lasiochalcidia Masi及二新种记述（膜翅目：小蜂科）

首次报道了中国毛缘小蜂属Lasiochalcidia Masi种类,描述了该属细角毛缘小蜂L. gracilantenna sp. Nov.和赤亮毛缘小蜂L. rufipolita sp. Nov.2个新种,并记述1新记录种披绒毛缘小蜂L. pilosella。文中提供了毛缘小蜂属中国已知种检索表。     

The genus Apsiphortica from China with DNA barcoding information (Diptera: Drosophilidae)

Two new species of the genus Apsiphortica are described from China: A. orthophallos n. sp. and A. sinuatipenis n. sp. Species delimitations are improved by integrating morphological and DNA barcoding information. The intra- and interspecific pairwise p-distances (proportional distance) are summarized for five Apsiphortica species from China. Furthermore, nucleotide sites with fixed status in the alignment of the COI sequences (639 nucleotide sites in length) are used as “pure” molecular diagnostic characters to delineate the five species. A key to all the Chinese species of the genus Apsiphortica is provided.     

Phylogenies from amino acid sequences aligned with gaps: The problem of gap weighting

Summary The common but generally overlooked problem of how best to construct phylogenies from orthologous amino acid sequences, when their alignment requires the placement therein of gaps denoting insertions/deletions in the evolutionary history of their genes since their common ancestor, has been studied. Three diverse methods were examined: 1. each missing residue in a gap is weighted as equivalent to the average number of minimum nucleotide replacements in known conjugate amino acid pairs of those same two sequences, which weight necessarily differs for each pair of sequences; 2. each missing residue in a gap is weighted as equivalent to a fixed number of nucleotide replacements; and 3. each gap, regardless of length, is weighted as equivalent to a fixed number of nucleotide replacements. For the flavodoxins, each method yielded a different best tree and suggests that the choice of method may be crucial. For the plant ferredoxins, all methods give results inconsistent with botanical classification and suggests the sequences may not all be orthologous. For the bacterial ferredoxins, the method was less germane than the actual weight used, five different best trees being obtained depending upon the weight. The best tree for all ferredoxins (prokaryotic plus eukaryotic) combined proved to be greatly dependent upon the gap locations with several reasonable alignments yielding different best trees. They also suggest that functional equivalence may well prove to be a poor guide to which residues have a common ancestral codon. The rubredoxin sequences show that a partial internal gene duplication occurred in thePseudomonas line, probably very soon after its divergence from the other genera. Together, the results clearly indicate that the phylogenetic answer one gets may greatly depend upon how one treats the gaps but they fail to indicate what treatment may be best. This results partly from the fact that the phylogenies of the taxa represented are not known with sufficient confidence to be sure when the procedures are performing best.