Variation in brain size and ecology in Pongo

Numerous hypotheses have been advanced to explain relative increases in brain size in primates and other mammals. However, notably less attention has been directed towards addressing the biological limits to increasing brain size. Here we explore variation in brain size in orangutans. We evaluated both raw and size-adjusted cranial capacity (CC) in adult Pongo pygmaeus pygmaeus (n=147), P. p. wurmbii (n=24), P. p. morio (n=14), and P. abelii (n=36). Results demonstrate significant variation in CC among orangutan taxa. Population differences in raw CC are significant for females (p=0.014) but not males. Post-hoc pairwise comparisons among females further reveal that raw CC is significantly smaller in P. p. morio compared to both P. abelii and P. p. pygmaeus. When evaluated for proportionality, geometric equivalence in CC is not maintained in orangutans, as P. p. morio has a significantly smaller CC when compared to one or more other orangutan groups. Even after statistically partitioning size and size-correlated shape, P. p. morio has a significantly smaller CC compared to most other orangutan groups. These observed differences in relative brain size are consistent with known variation in resource quality and life history amongst orangutan populations. Specifically, P. p. morio is characterized by the least productive habitat, the lowest energy intake during extended lean periods, and the shortest interbirth intervals. Our results, therefore, provide conditional support for the hypothesis that decreased brain size is related to prolonged episodes of food scarcity, and suggest a correlation between brain size, diet quality, and life history at the lowest macroevolutionary level. The association of a relatively small brain and poor diet quality in Pongo further suggests that ecological factors may plausibly account for such a reduction in brain size as observed in the recently recovered Homo floresiensis from Indonesia.     

Feeding behavior, diet, and the functional consequences of jaw form in orangutans, with implications for the evolution of Pongo

Orangutans are amongst the most craniometrically variable of the extant great apes, yet there has been no attempt to explicitly link this morphological variation with observed differences in behavioral ecology. This study explores the relationship between feeding behavior, diet, and mandibular morphology in orangutans. All orangutans prefer ripe, pulpy fruit when available. However, some populations of Bornean orangutans (Pongo pygmaeus morio and P. p. wurmbii) rely more heavily on bark and relatively tough vegetation during periods of low fruit yield than do Sumatran orangutans (Pongo abelii). I tested the hypothesis that Bornean orangutans exhibit structural features of the mandible that provide greater load resistance abilities to masticatory and incisal forces. Compared to P. abelii, P. p. morio exhibits greater load resistance abilities as reflected in a relatively deeper mandibular corpus, deeper and wider mandibular symphysis, and relatively greater condylar area. P. p. wurmbii exhibits most of these same morphologies, and in all comparisons is either comparable in jaw proportions to P. p. morio, or intermediate between P. p. morio and P. abelii. These data indicate that P. p. morio and P. p. wurmbii are better suited to resisting large and/or frequent jaw loads than P. abelii. Using these results, I evaluated mandibular morphology in P. p. pygmaeus, a Bornean orangutan population whose behavioral ecology is poorly known. Pongo p. pygmaeus generally exhibits relatively greater load resistance capabilities than P. abelii, but less than P. p. morio. These results suggest that P. p. pygmaeus may consume greater amounts of tougher and/or more obdurate foods than P. abelii, and that consumption of such foods may intensify amongst Bornean orangutan populations. Finally, data from this study are used to evaluate variation in craniomandibular morphology in Khoratpithecus piriyai, possibly the earliest relative of Pongo from the late Miocene of Thailand, and the late Pleistocene Hoa Binh subfossil orangutan recovered from Vietnam. With the exception of a relatively thicker M(3) mandibular corpus, K. piriyai has jaw proportions that would be expected for an extant orangutan of comparable jaw size. Likewise, the Hoa Binh subfossil does not differ in skull proportions from extant Pongo, independent of the effects of increase in jaw size. These results indicate that differences in skull and mandibular proportions between these fossil and subfossil orangutans and extant Pongo are allometric. Furthermore, the ability of K. piriyai to resist jaw loads appears to have been comparable to that of extant orangutans. However, the similarity in jaw proportions between P. abelii and K. piriyai suggest the latter may have been dietarily more similar to Sumatran orangutans.     

Variability in Floral Scent in Rewarding and Deceptive Orchids: The Signature of Pollinator-imposed Selection?

BACKGROUND AND AIMS: A comparative investigation was made of floral scent variation in the closely related, food-rewarding Anacamptis coriophora and the food-deceptive Anacamptis morio in order to identify patterns of variability of odour compounds in the two species and their role in pollinator attraction/avoidance learning. METHODS: Scent was collected from plants in natural populations and samples were analysed via quantitative gas chromatography and mass spectrometry. Combined gas chromatography and electroantennographic detection was used to identify compounds that are detected by the pollinators. Experimental reduction of scent variability was performed in the field with plots of A. morio plants supplemented with a uniform amount of anisaldehyde. KEY RESULTS: Both orchid species emitted complex odour bouquets. In A. coriophora the two main benzenoid compounds, hydroquinone dimethyl ether (1,4-dimethoxybenzene) and anisaldehyde (methoxybenzaldehyde), triggered electrophysiological responses in olfactory neurons of honey-bee and bumble-bee workers. The scent of A. morio, however, was too weak to elicit any electrophysiological responses. The overall variation in scent was significantly lower in the rewarding A. coriophora than in the deceptive A. morio, suggesting pollinator avoidance-learning selecting for high variation in the deceptive species. A. morio flowers supplemented with non-variable scent in plot experiments, however, did not show significantly reduced pollination success. CONCLUSIONS: Whereas in the rewarding A. coriophora stabilizing selection imposed by floral constancy of the pollinators may reduce scent variability, in the deceptive A. morio the emitted scent seems to be too weak to be detected by pollinators and thus its high variability may result from relaxed selection on this floral trait.     

A new species of harvestman of the genus Mitopus in Britain

A new species of Mitopus , found in upland regions of Britain, is described. It occurs sympatrically with M. morio in the upper altitudinal parts of the latter's range. The two species are distinguished by their differences in morphology, biometrics and phenology. The new species of Mitopus is larger and longer-legged than M. morio , and develops faster, reaching maturity at an earlier date.     

Structural basis for altered activity of M- and H-isozyme forms of human lactate dehydrogenase

Lactate dehydrogenase (LDH) interconverts pyruvate and lactate with concomitant interconversion of NADH and NAD(+). Although crystal structures of a variety of LDH have previously been described, a notable absence has been any of the three known human forms of this glycolytic enzyme. We have now determined the crystal structures of two isoforms of human LDH-the M form, predominantly found in muscle; and the H form, found mainly in cardiac muscle. Both structures have been crystallized as ternary complexes in the presence of the NADH cofactor and oxamate, a substrate-like inhibitor. Although each of these isoforms has different kinetic properties, the domain structure, subunit association, and active-site regions are indistinguishable between the two structures. The pK(a) that governs the K(M) for pyruvate for the two isozymes is found to differ by about 0.94 pH units, consistent with variation in pK(a) of the active-site histidine. The close similarity of these crystal structures suggests the distinctive activity of these enzyme isoforms is likely to result directly from variation of charged surface residues peripheral to the active site, a hypothesis supported by electrostatic calculations based on each structure. Proteins 2001;43:175-185.     

Flies and concealed nectar sources: morphological innovations in the proboscis of Bombyliidae (Diptera)

Bee-flies (Bombyliidae) have morphological adaptations of the mouthparts to particular floral traits. To investigate this the short, plesiomorphic proboscis of Hemipenthes morio was compared with the long, apomorphic proboscis of Bombylius major . A novel feeding position enables B. major to use flowers that open to the side as additional nectar sources. The new horizontal feeding position is enabled by the prolonged ventral base of the proboscis. Bombylius major exploits deep corolla tubes with an elongate proboscis, and an increased efficiency in both the suction pumps and the sealing mechanisms of the proboscis. The exploitation of narrow corolla tubes is made possible by the shift from a sponging feeding mode, exhibited by H. morio , to the exclusively sucking mode in B. major . Besides quantitative changes in the proportions of the different proboscis components, labellar movements as well as the structures of saliva distribution are changed along with this shift. The labial musculature of B. major does not significantly differ from the plesiomorphic state, since both examined species do not only feed on nectar, but also on pollen.     

Morphological variation in <Emphasis Type="Italic">Laboulbenia polymorpha</Emphasis> (Laboulbeniales)

Specimens of the type collection of Laboulbenia polymorpha Sugiyama (1978) were reexamined. The holotype, M. Ishikawa 673, is composed of three slides and includes three morphologically different forms of thalli, of which two forms were illustrated (Sugiyama 1978, fig. 1-D, 1-E). On the other hand, one of the paratypes, M. Ishikawa 674, has now been lost but photographs were made earlier from this slide, in which one mature individual illustrated as fig. 1-C (Sugiyama 1978) is included. This individual was not correctly shown in Sugiyamas illustration, but actually has a strong resemblance to a form in slide 673-b that was not illustrated by Sugiyama (1978). Thus, three different forms have been recognized as variations of L. polymorpha. In the present article, each variation was termed C-form, D-form, and E-form because Sugiyama (1978) used the same notation in his figures. A mature specimen of C-form in slide 673-b has been selected as a lectotype. Slide 673-d includes only young thalli, one of which was illustrated as fig. 1-G (Sugiyama 1978). This young thallus undoubtedly belongs to another species; mature thalli of the same species were also found in slide 673-b. Another paratype, K. Sugiyama 2101, includes C- and D-forms of L. polymorpha. Infection sites of the C- and D-forms have been determined: the C-form grows mainly on the lateral margins of the elytra of the host, and the D-form occurs mainly on the basal part of the elytra and the mesothorax.     

大麦虫不同虫态甲醇粗提物化学成分的分析和比较

为了探寻大麦虫Zophobas morio变态发育过程中化学成分的变化, 本研究利用薄层色谱技术对大麦虫的3个虫态(幼虫、 蛹和成虫)甲醇粗提物中的化学成分进行分析和比较, 利用柱色谱技术、 核磁共振氢谱技术（¹H MR）和气相色谱-质谱联用技术（GC-MS）对蛹甲醇粗提物进行重点分析。结果表明： 虫蛹甲醇粗提物中含有幼虫和成虫甲醇粗提物中不存在的化学成分。对虫蛹甲醇粗提物进行针对性的结构研究, 共鉴定出10个脂肪酸。其中, 存在于大麦虫虫蛹中的10-十六碳酮酸、 10-十八碳酮酸为首次从自然界昆虫中获得; (8E, 11E)-8, 11-十八碳烯酸、 (9Z, 12Z)-9, 12-十八碳烯酸、 (9Z, 12Z, 15Z)-9, 12, 15-十八碳烯酸、 8-(3-辛基-2-环氧乙烷基)辛酸和8-(2-辛基环丙烷基)辛酸为首次从大麦虫中发现。以上研究结果为针对大麦虫不同生物阶段的开发利用提供新的理论依据。     

C-heterochromatin polymorphism and variation in chiasma localization in Euchorthippus pulvinatus gallicus (Acrididae,Orthoptera)

Eight populations of the grasshopper Euchorthippus pulvinatus gallicus have been analyzed by means of C-banding. Chromosome pairs M6, M7 and S8 show both quantitative and qualitative variation in their C-heterochromatin. There are at least four different types of M6, three of M7 and two of S8. Differences in the frequencies of these chromosome types have been found between populations. Within a given population the frequencies of the different M7 and S8 chromosomes fit a Hardy-Weinberg distribution and they remain constant within and between generations. The possible adaptative role of supernumerary heterochromatin as leading to a redistribution of chiasmata in the heterochromatin carrier chromosomes is discussed.     

Role of phase variation in the resistance of Myxococcus xanthus fruiting bodies to Caenorhabditis elegans predation

The phenomenon of phase variation between yellow and tan forms of Myxococcus xanthus has been recognized for several decades, but it is not known what role this variation may play in the ecology of myxobacteria. We confirm an earlier report that tan variants are disproportionately more numerous in the resulting spore population of a M. xanthus fruiting body than the tan vegetative cells that contributed to fruiting body formation. However, we found that tan cells may not require yellow cells for fruiting body formation or starvation-induced sporulation of tan cells. Here we report three differences between the yellow and tan variants that may play important roles in the soil ecology of M. xanthus. Specifically, the yellow variant is more capable of forming biofilms, is more sensitive to lysozyme, and is more resistant to ingestion by bacteriophagous nematodes. We also show that the myxobacterial fruiting body is more resistant to predation by worms than are dispersed M. xanthus cells.     

Patterns of haplotype diversity within the serpin gene cluster at 14q32.1: insights into the natural history of the α1-antitrypsin polymorphism

The levels of haplotype diversity associated with different alpha1-antitrypsin (PI) alleles were assessed by the analysis of three microsatellites located within or close to corticosteroid-binding globulin (CBG), alpha1-antitrypsin [PI-(TG)n] and protein C inhibitor [PCI-(TG)n] loci in three populations with different historic backgrounds: Portugal, the Basque Country and S?o Tomé Príncipe (Gulf of Guinea). Unlike the more distant PCI-(TG)n repeat, allelic variation at PI-(TG)n reflected distinct phases of mutational recovery of microsatellite diversity around different founder alleles and showed a considerable differentiation between alpha1-antitrypsin protein variants. In accordance with population history, the Basque sample presented overall reduced levels of microsatellite variation. The African sample, although presenting the highest PCI-(TG)n diversity, showed a lineage-specific reduction in PI-(TG)n heterozygosity within the oldest M1Ala213 variant that could have been caused by (1) selection at a closely linked locus or (2) biases in the microsatellite mutation process leading to a stable equilibrium distribution. Age estimates of alpha1-antitrypsin variants based on microsatellite variation suggest that the Z deficiency allele appeared 107-135 generations ago and could have been spread in Neolithic times. The S mutation has an older 279- to 470-generation age, indicating that its high frequencies in Iberia did not result from a recent bottleneck and that PI*S could have originated in this region. M2 and M3 types had lower age estimates than would be expected from their wide geographical distributions, suggesting that their dispersion in Europe might have been preceded by important bottlenecks.     

Hydrogen exchange demonstrates three domains in aldolase unfold sequentially.

Rabbit muscle aldolase is a homotetramer in which the subunits have a classical alpha/beta-barrel structure and Mr 39,212 Da. We have previously reported that aldolase incubated in 3 M urea has three unfolding domains distinguished by their different unfolding rates. The unfolding rates of these domains were determined from isotope patterns in the mass spectra of peptic fragments derived from aldolase incubated in 3 M urea and pulse labeled in (2)H2O. The present study extends this investigation to more thoroughly characterize the structures of these unfolding intermediates. Mass spectra of intact monomers had four envelopes of isotope peaks corresponding to four structural forms of aldolase. Analysis of the present results suggests that these structural forms consist of native aldolase and three forms that have one to three domains unfolded. The molecular masses of these four structural forms indicate that there are 107 residues in each of the three unfolding domains of aldolase. Present results also show that aldolase remains a tetramer in 4 M urea, even though hydrogen exchange and circular dichroism indicate that it has lost most of its secondary and tertiary structure. The abundances of unfolded domains, which were determined from mass spectra of either intact aldolase or its peptic fragments, were used to determine the abundances of specific, partially unfolded forms of aldolase. Kinetic modeling of the abundances of these structures suggests that these structures are formed sequentially as aldolase unfolds in urea.     

Flowering dynamics of Orchis morio L. and Herminium monorchis (L.) R.Br, at two sites in eastern England

Information taken from two long-term demographic studies on Orchis morio L. and Herminium monorchis (L.) R.Br, is used to explore some of the factors which influence flowering. The proportion of plants which flowered each year varied considerably between species, flowering in O. morio exceeding 40% in all years except one over an 18 year period; over a 30 year period (1966–95), the number of plants of Herminium in flower never exceeded 36% of the population and no inflorescences were produced in 1977 and 1991. The relationship between flowering in Herminium in a given year and the monthly rainfall and temperature for the current and 3 previous years was analysed using logistic regression. Best fits were obtained using data for the summer months in the previous year, with an increasing flowering rate with rainfall and a decline with temperature. It is hypothesized that drought and high temperatures in the summer reduce leaf area and cause premature senescence and the death of leaves, with the result that not enough carbohydrates are stored to enable plants to support or initiate inflorescences the following year. For species such as Orchis morio which produce leaves in the autumn and remain green, summer drought causes no problems as they have no above ground organs. Factors which influence flowering in this species are as yet unknown.     

椰心叶甲天敌垫跗螋的生物学研究

垫跗螋Chelisoches morio (Fabricius)是入侵害虫椰心叶甲Brontispa longissima (Gestro)的一种本地天敌.为了了解垫跗螋的生物学习性和控害潜能,本文对垫跗螋的形态特征、生长发育、重要生物学习性以及对椰心叶甲的捕食选择性和捕食量进行了观察研究.垫跗螋雌成虫将产的卵堆积在一起,抱孵在体下,且不时用口器翻动重排卵,受到惊扰时会吃掉卵,甚至初孵的若虫.在室温条件下(20±2)℃,以椰心叶甲2龄幼虫为食料,垫跗螋从卵至成虫的平均发育历期为(107.9±15.2)d;平均每头雌虫产卵量为(138.7±59.5)粒;垫跗螋成虫对椰心叶甲2龄幼虫的日平均捕食量为(6.7±1.1)头.寄主龄期选择性实验表明,垫跗螋成虫和4龄若虫喜欢取食椰心叶甲的2龄幼虫;3龄和2龄若虫喜欢取食椰心叶甲的1龄幼虫.     

The effects of nectar addition on pollen removal and geitonogamy in the non-rewarding orchid Anacamptis morio

It has been suggested that the absence of floral rewards in many orchid species causes pollinators to probe fewer flowers on a plant, and thus reduces geitonogamy, i.e. self-pollination between flowers, which may result in inbreeding depression and reduced pollen export. We examined the effects of nectar addition on pollinator visitation and pollen transfer by tracking the fate of colour-labelled pollen in Anacamptis morio, a non-rewarding orchid species pollinated primarily by queen bumble-bees. Addition of nectar to spurs of A. morio significantly increased the number of flowers probed by bumble-bees, the time spent on an inflorescence, pollinarium removal and the proportion of removed pollen involved in self-pollination through geitonogamy, but did not affect pollen carryover (the fraction of a pollinarium carried over from one flower to the next). Only visits that exceeded 18 s resulted in geitonogamy, as this is the time taken for removed pollinaria to bend into a position to strike the stigma. A mutation for nectar production in A. morio would result in an initial 3.8-fold increase in pollinarium removal per visit, but also increase geitonogamous self-pollination from less than 10% of pollen depositions to ca. 40%. Greater efficiency of pollen export will favour deceptive plants when pollinators are relatively common and most pollinaria are removed from flowers or when inbreeding depression is severe. These findings provide empirical support both for Darwin's contention that pollinarium bending is an anti-selfing mechanism in orchids and for the idea that floral deception serves to maximize the efficiency of pollen export.     

Patterns of polymorphism and gene flow of gender-associated mitochondrial DNA lineages in European mussel populations

Mussels of the genus Mytilus have two types of mitochondrial DNA (mtDNA). The M type is transmitted paternally and the F type is transmitted maternally. RFLP analysis is used to assess phylogenetic relationships and nucleotide diversity and divergence for both mtDNA genomes in European populations of M. edulis and Atlantic and Mediterranean forms of M. galloprovincialis. Ten restriction endonucleases were used to assay variation in regions of the ND2 and COIII genes for a total of 77 individuals. F and M genomes show a concordant phylogenetic split into two major divergent clades, one specific to Mediterranean M. galloprovincialis and the other containing haplotypes from the three taxa. For both genomes, the geographical distribution of mtDNA variation suggests: (i) extensive levels of mtDNA introgression; (ii) asymmetric mtDNA gene flow from Atlantic to Mediterranean populations; and (iii) recurrent historical hybridization events. Significantly higher mtDNA diversity and divergence are observed for the M than F genome in all three Mytilus taxa, although the evolutionary forces responsible for these differences cannot be resolved. The extensive mtDNA gene flow between European Mytilus taxa conflicts with the restricted mtDNA introgression observed in American mussels , implying geographical variation in the nature of nuclear/mtDNA interactions regulating biparental inheritance.     

The variability of orchid population size

Orchid population size has long been believed to be highly variable in time and space. Here we present the first quantitative assessment of the variability of orchid population sizes and compare them with plant and animal population data from the literature. Three measures of temporal variation were used (standard deviation of log₁₀ (population size), Hurst exponent and variance in the intrinsic rate of increase). Eight unfertilized plots of Orchis morio in a factorial fertilizer experiment were assessed for variability in population size over a 26 year period. The Hurst exponent across the eight plots gave measures consistent with pink noise well into black noise (0.86 to 1.87). The variation in the intrinsic rate of increase suggested that the expected time to extinction in the plots differed by an order of magnitude. Standard deviation of log₁₀ (population size) across plots was greater than the corresponding temporal variation within plots. Standard deviation of log₁₀ (population size) reached an asymptote between 10 and 20 years. The range of temporal variation between plots in this and other orchid populations was as great as the mean values reported for birds, insects and mammals. These results have highlighted the importance of spatial variation: until we know the relative importance of spatial and temporal variation for more plant species we will be unable to assess whether orchid populations are more variable in size than other species.     

The "far-west" of Anopheles gambiae molecular forms

The main Afrotropical malaria vector, Anopheles gambiae sensu stricto, is undergoing a process of sympatric ecological diversification leading to at least two incipient species (the M and S molecular forms) showing heterogeneous levels of divergence across the genome. The physically unlinked centromeric regions on all three chromosomes of these closely related taxa contain fixed nucleotide differences which have been found in nearly complete linkage disequilibrium in geographic areas of no or low M-S hybridization. Assays diagnostic for SNP and structural differences between M and S forms in the three centromeric regions were applied in samples from the western extreme of their range of sympatry, the only area where high frequencies of putative M/S hybrids have been reported. The results reveal a level of admixture not observed in the rest of the range. In particular, we found: i) heterozygous genotypes at each marker, although at frequencies lower than expected under panmixia; ii) virtually all possible genotypic combinations between markers on different chromosomes, although genetic association was nevertheless detected; iii) discordant M and S genotypes at two X-linked markers near the centromere, suggestive of introgression and inter-locus recombination. These results could be indicative either of a secondary contact zone between M and S, or of the maintenance of ancestral polymorphisms. This issue and the perspectives opened by these results in the study of the M and S incipient speciation process are discussed.     

'Cebiche'--a potential source of human anisakiasis in Mexico?

Five fish species used for preparation of a popular dish (cebiche) made with raw fish flesh in Mexico were obtained from five localities of the coast of Yucatan. Lutjanus synagris, Gerres cinereus, Sphyraena barracuda, Epinephelus morio and Haemulon plumieriwere examined for the presence of larvae of anisakid nematodes, causative agents of human anisakiasis. The nematode Pseudoterranova sp. was found in E. morio and S. barracuda with a total prevalence of 83% and 6.5 +/- 6.2 worms per fish for E. morio, and a prevalence of 33% and 10.2 +/- 30.0 worms per fish for S. barracuda. Contracaecumsp. was found to infect G. cinereus with a prevalence of 57% and 7.6 +/- 11.4 worms per fish. The relatively high prevalence of Pseudoterranova sp. indicates that this parasite is a potential causal agent of anisakiasis on the coast of Yucatan. Although all larvae were found only in the mesentery of the fish host, their importance as a potential source of human infection cannot be excluded as larval migration to the muscles in dead fish is possible.     

Pollination Flow in Hybrid Formation between Orchis morio and Orchis papilionacea (Orchidaceae) in Two Different Habitats

Two geographically separated natural populations of Orchis xgennarii, a hybrid between Orchis morio and Orchis papilionacea, were examined to establish the parental lineages using nuclear ribosomal DNA and chloroplast DNA length polymorphisms. Results indicate that O. morio more frequently provides the maternal lineage in the population from the volcano Mount Vesuvius (central Campania, Italy) than in the one from Cilento (southern Campania, Italy); in the latter locality maternal genomes are preferentially provided by O. papilionacea. The possible causes of this difference in reproductive behavior are discussed in the light of the pollination biology of parental species and of environmental influences.