Telemetry System for Assessing Jaw-Muscle Function in Free-ranging Primates

In vivo laboratory-based studies describing jaw-muscle activity and mandibular bone strain during mastication provide the empirical basis for most evolutionary hypotheses linking primate masticatory apparatus form to diet. However, the laboratory data pose a potential problem for testing predictions of these hypotheses because estimates of masticatory function and performance recorded in the laboratory may lack the appropriate ecological context for understanding adaptation and evolution. For example, in laboratory studies researchers elicit rhythmic chewing using foods that may differ significantly from the diets of wild primates. Because the textural and mechanical properties of foods influence jaw-muscle activity and the resulting strains, chewing behaviors studied in the laboratory may not adequately reflect chewing behaviors of primates feeding in their natural habitats. To circumvent this limitation of laboratory-based studies of primate mastication, we developed a system for recording jaw-muscle electromyograms (EMGs) from free-ranging primates so that researchers can conduct studies of primate jaw-muscle function in vivo in the field. We used the system to record jaw-muscle EMGs from mantled howlers (Alouatta palliata) at Hacienda La Pacifica, Costa Rica. These are the first EMGs recorded from a noncaptive primate feeding in its natural habitat. Further refinements of the system will allow long-term EMG data collection so that researchers can correlate jaw-muscle function with food mechanical properties and behavioral observations. In addition to furthering understanding of primate feeding biology, our work will foster improved adaptive hypotheses explaining the evolution of primate jaw form.     

Host gene evolution traces the evolutionary history of ancient primate lentiviruses

Simian immunodeficiency viruses (SIVs) have infected primate species long before  human immunodeficiency virus has infected humans. Dozens of species-specific lentiviruses are found in African primate species, including two strains that have repeatedly jumped into human populations within the past century. Traditional phylogenetic approaches have grossly underestimated the age of these primate lentiviruses. Instead, here we review how selective pressures imposed by these viruses have fundamentally altered the evolutionary trajectory of hosts genes and, even in cases where there now remains no trace of the viruses themselves, these evolutionary signatures can reveal the types of viruses that were once present. Examination of selection by ancient viruses on the adaptive evolution of host genes has been used to derive minimum age estimates for modern primate lentiviruses. This type of data suggests that ancestors of modern SIV existed in simian primates more than 10 Ma. Moreover, examples of host resistance and viral adaptation have implications not only for estimating the age and host range of ancient primate lentiviruses, but also the pathogenic potential of their modern counterparts.     

Selection in nature: experimental manipulations of natural populations

Numerous studies have documented evolution by natural selectionin natural populations, but few are genuine selection experimentsthat are designed and then executed in nature. We will focuson these few cases to illustrate what can be learned from fieldselection experiments alone or field and laboratory selectionexperiments together that cannot be learned from laboratoryexperiments alone. Both types of study allow us to evaluatecause and effect relationships because a planned experimentcan be accompanied by a more direct evaluation of the factorsthat cause evolution. A unique benefit of field experimentsis that they give us the opportunity to measure the rate andmagnitude of selection in nature. We have found that this rateis far greater than one might imagine based on observationsof the fossil record. A combination of field and laboratoryselection experiments has revealed the importance of populationsize and structure in shaping the genetics of adaptation. Forexample, laboratory selection experiments on insecticide resistancetend to attain resistance though polygenic inheritance. Theevolution of insecticide resistance in nature often eventuallyyields to single genes of large effect that are rare but, oncethey arise, represent a higher fitness solution to resistanceand spread among populations. Finally, field studies enableus to test evolutionary theory in a context in which all ofthe tradeoffs associated with a trait are realized; in the laboratory,organisms may be shielded from the fitness tradeoffs associatedwith the evolution of a trait. For example, we have comparedthe patterns of senescence in guppies from high and low mortalityrate environments in the laboratory and in the field. In thelaboratory, guppies from high predation environments had delayedsenescence relative to those from low predation environments.In the field the apparent relationship is the opposite. Onehypothesis for this difference is that a tradeoff associatedwith the evolution of the high predation life history is a decreasein the investment in the immune system. Such a sacrifice wouldbe evident in nature where there is exposure to disease andparasites but less so in the laboratory, which is relativelydisease and parasite free.     

Detecting local adaptation in a natural plant-pathogen metapopulation: a laboratory vs. field transplant approach

Antagonistic coevolution between hosts and parasites in spatially structured populations can result in local adaptation of parasites. Traditionally parasite local adaptation has been investigated in field transplant experiments or in the laboratory under a constant environment. Despite the conceptual importance of local adaptation in studies of (co)evolution, to date no study has provided a comparative analysis of these two methods. Here, using information on pathogen population dynamics, I tested local adaptation of the specialist phytopathogen, Podosphaera plantaginis, to its host, Plantago lanceolata at three different spatial scales: sympatric host population, sympatric host metapopulation and allopatric host metapopulations. The experiment was carried out as a field transplant experiment with greenhouse-reared host plants from these three different origins introduced into four pathogen populations. In contrast to results of an earlier study performed with these same host and parasite populations under laboratory conditions, I did not find any evidence for parasite local adaptation. For interactions governed by strain-specific resistance, field studies may not be sensitive enough to detect mean parasite population virulence. Given that parasite transmission potential may be mediated by the abiotic environment and genotype-by-environment interactions, I suggest that relevant environmental variation should be incorporated into laboratory studies of parasite local adaptation.     

Anatomies and lifestyles,morphometrics and niche metrics: Tools for studying primate evolution

In recent years, comparative observations of primate anatomies have been extended using measurements and computer analyses: morphometrics. A question then follows. Can we extend field observations of animal lifestyles using measurement and computer analysis, using, in other words, a new «niche metrics», for comparison with the morphometrics of animal anatomies? This has been attempted (Oxnard, Crompton & Lieberman, 1990) by «measuring» 17 lifestyle variables (on locomotion, environment and diet) for 28 prosimian primate species. These data have been analysed by multivariate statistical methods entirely similar to those used in morphometrics. The results define groups of prosimian species that seem not to be related directly with taxonomy and evolution, but with functional adaptation to lifestyle. Comparisons between the morphometric and niche metric results reveal a degree of similarity of species grouping in each that is apparently related to adaptation and remarkably detailed. But further study of both the morphometric and niche metric results suggests that questions pertaining to evolution may also be asked. Thus, both morphometric investigations seeking clusterings of anatomical variables and niche metric studies seeking clustering of higher taxonomic groups of species produce results that seem to be of developmental and phylogenetic rather than directly adaptive import. Through the combination of these two approaches, it may eventually be possible to partition both evolutionary and adaptive components, even though, of course, there must always be overlap between them.     

Optimization, constraint, and history in the evolution of eyes

Several features of the evolution of eyes and photoreceptors are examined in an effort to explore the relative roles of adaptation and historical and developmental constraints. Optical design shows clear evidence of adaptation, which in some respects approaches optima predictable from physics. The primate fovea, on the other hand, illustrates how adaptation can be channeled by developmental heritage. The primary structures of opsins reveal multiple evolutionary lineages within both Drosophila and humans. The pigments of vertebrae rods comprise a subset of opsins whose evolutionary relationships map onto the phylogeny of the parent species. The evolutionary reasons for why most rod pigments absorb maximally at 500 +/- 10 nm are obscure, as there is no convincing explanation based on adaptation alone. Rods are appropriately distinguished from cones on the basis of which opsin gene is expressed. This criterion is likely to be in conflict with other definitions in phyletic lines (e.g., geckos, snakes) that have long diurnal or nocturnal histories accompanied by loss of one or more opsin genes, followed by a secondary adaptation to life in a different photic environment. Color vision--a generalizable perception associated with the spectral composition of light--is usefully distinguished from wavelength-specific behaviors. The latter are also based on multiple visual pigments and more than one spectral class of receptors but cannot be altered by learning. The distinction is particularly forceful in bees, which exhibit both kinds of behavior. The evolution of primate color vision has been shaped by historical factors involving an extensive period of early mammalian nocturnality. Birds, by contrast, have more elaborate cones and a richer set of visual pigments. Avian color space can be represented in a tetrahedron.     

A molecular phylogeny of living primates

Comparative genomic analyses of primates offer considerable potential to define and understand the processes that mold, shape, and transform the human genome. However, primate taxonomy is both complex and controversial, with marginal unifying consensus of the evolutionary hierarchy of extant primate species. Here we provide new genomic sequence (~8 Mb) from 186 primates representing 61 (~90%) of the described genera, and we include outgroup species from Dermoptera, Scandentia, and Lagomorpha. The resultant phylogeny is exceptionally robust and illuminates events in primate evolution from ancient to recent, clarifying numerous taxonomic controversies and providing new data on human evolution. Ongoing speciation, reticulate evolution, ancient relic lineages, unequal rates of evolution, and disparate distributions of insertions/deletions among the reconstructed primate lineages are uncovered. Our resolution of the primate phylogeny provides an essential evolutionary framework with far-reaching applications including: human selection and adaptation, global emergence of zoonotic diseases, mammalian comparative genomics, primate taxonomy, and conservation of endangered species.     

Molecular Mechanisms of Stress Adaptation in Plant Natural Populations

Recent advances in studies of genetic variation at protein and DNA levels in plant natural populations and its relationship with environmental changes were reviewed with special reference to the works on the wild barley ( Hordeum spontaneum C. Koch.). On one side, adaptation was shown in statistic data, on the other side, the fact that a considerable part of genetic variation does exist within populations (subpopulations) under same ecological condition indicated its maintainability of neutral or near-neutral mutations in natural populations. The researches on adaptive populations of plants, especially on wild soybean ( Glycine soja Sieb. et Zucc.) mainly conducted in author's laboratory, have shown that the most part of molecular variation within and among populations can not be explained by selection particularly as far as the individual uniqueness was concerned. There are some data shown that adaptation may be caused by accumulation of a few near-neutral mutations. Recent publications on molecular mechanisms of morphological evolution has been received special attention to elucidate the discrepancy between molecular evolution and morphological adaptive evolution. A frame on the unified evolution theory has been built. Finally some related viewpoints of philosophy were discussed.     

Experimental evolution of Bacillus subtilis

The endospore‐forming bacteria have persisted on earth perhaps 3Ga, leveraging the flexibility of their distinctive lifestyle to adapt to a remarkably wide range of environments. This process of adaptation can be investigated through the simple but powerful technique of laboratory evolution. Evolved strains can be analyzed by whole genome sequencing and an array of omics technologies. The intensively studied, genetically tractable endospore‐former, Bacillus subtilis, is an ideal subject for laboratory evolution experiments. Here, we describe the use of the B. subtilis model system to study the adaptation of these bacteria to reduced and stringent selection for endospore formation, as well as to novel environmental challenges of low atmospheric pressure, high ultraviolet radiation, and unfavourable growth temperatures. In combination with other approaches, including comparative genomics and environmental field work, laboratory evolution may help elucidate how these bacteria have so successfully adapted to life on earth, and perhaps beyond.     

Primates got personality,too: Toward an integrative primatology of consistent individual differences in behavior

In recent years, research on animal personality has exploded within the field of behavioral ecology. Consistent individual differences in behavior exist in a wide range of species, and these differences can have fitness consequences and influence several aspects of a species' ecology. In comparison to studies of other animals, however, there has been relatively little research on the behavioral ecology of primate personality. This is surprising given the large body of research within psychology and biomedicine showing that primate personality traits are heritable and linked to health and life history outcomes. In this article, I bring together theoretical perspectives on the ecology and evolution of animal personality with an integrative review of what we know about primate personality from studies conducted on captive, free‐ranging, and wild primates. Incorporating frameworks that emphasize consistency in behavior into primate behavioral ecology research holds promise for improving our understanding of primate behavioral evolution.     

The sexual behavior of the primates]

The article presents the review of modern data of the field and laboratory investigations of primate sexual behavior, cyclicity, reproductive strategies and copulation in different primates taxa: strepsirrhini, platyrrhyni, catarrhini. The specific character, progressiveness and adaptation of some reproductive models are discussed by the authors. A problem of connection between dominance and reproductive success is also discussed, the role of sexual teaching in postnatal ontogenesis, age and hormonal status for expression of sexual behavior are analysed. Some forms of sexual declinations in primates are considered.     

植物自然群体适应逆境的分子机理

Recent advances in studies of genetic variation at protein andDNA levels in plant natural populations and its relationship with environmental changes were reviewed with special reference to the works on the wild barley (Hordeum spontaneum C. Koch.). On one side, adaptation was shown in statistic data, on the other side, the fact that a considerable part of genetic variation does exist within populations (subpopulations) under same ecological condition indicated its maintainability of neutral or near-neutral mutations in natural populations. The researches on adaptive populations of plants, especially on wild soybean (Glycine soja Sieb. et Zucc.) mainly conducted in author's laboratory, have shown that the most part of molecular variation within and among populations can not be explained by selection particularly as far as the individual uniqueness was concerned. There are some data shown that adaptation may be caused by accumulation of a few near-neutral mutations. Recent publications on molecular mechanisms of morphological evolution has been received special attention to elucidate the discrepancy between molecular evolution and morphological adaptive evolution. A frame on the unified evolution theory has been built. Finally some related viewpoints of philosophy were discussed.     

HERV-K(OLD): ancestor sequences of the human endogenous retrovirus family HERV-K(HML-2)

Sequences homologous to the human endogenous retrovirus (HERV) family HERV-K(HML-2) are present in all Old World primate species. A previous study showed that a central region of the HERV-K(HML-2) gag genes in Hominoidea species displays a 96-bp deletion compared to the gag genes in lower Old World primates. The more ancient HERV-K(HML-2) sequences present in lower Old World primates were apparently not conserved during hominoid evolution, as opposed to the deletion variants. To further clarify the evolutionary origin of the HERV-K(HML-2) family, we screened GenBank with the 96-bp gag-sequence characteristic of lower Old World primates and identified, to date, 10 human sequence entries harboring either full-length or partially deleted proviral structures, probably representing remnants of a more ancient HERV-K(HML-2) variant. The high degree of mutations demonstrates the long-time presence of these HERV-K(OLD) proviruses in the genome. Nevertheless, they still belong to the HML-2 family as deduced from dot matrix and phylogenetic analyses. We estimate, based on the family ages of integrated Alu elements and on long terminal repeat (LTR) divergence data, that the average age of HERV-K(OLD) proviruses is ca. 28 million years, supporting an integration time before the evolutionary split of Hominoidea from lower Old World primates. Analysis of HERV-K(OLD) LTR sequences led to the distinction of two subgroups, both of which cluster with LTRs belonging to an evolutionarily older cluster. Taken together, our data give further insight into the evolutionary history of the HERV-K(HML-2) family during primate evolution.     

Signal convergence in fruits: a result of selection by frugivores?

The Dispersal Syndrome hypothesis remains contentious, stating that apparently nonrandom associations of fruit characteristics result from selection by seed dispersers. We examine a key assumption under this hypothesis, i.e. that fruit traits can be used as reliable signals by frugivores. We first test this assumption by looking at whether fruit colour allows birds and primates to distinguish between fruits commonly dispersed by birds or primates. Second, we test whether the colours of fruits dispersed by primates are more contrasting to primates than the colours of bird‐dispersed fruits, expected if fruit colour is an adaptation to facilitate the detection by seed dispersers. Third, we test whether fruit colour has converged in unrelated plant species dispersed by similar frugivores. We use vision models based on peak sensitivities of birds’ and primates’ cone cells. We base our analyses on the visual systems of two types of birds (violet and ultraviolet based) and three types of primates (trichromatic primates from the Old and the New Worlds, and a dichromatic New World monkey). Using a Discriminant Function Analysis, we find that all frugivore groups can reliably discriminate between bird‐ and primate‐dispersed fruits. Fruit colour can be a reliable signal to different seed dispersers. However, the colours of primate‐dispersed fruits are less contrasting to primates than those of bird‐dispersed fruits. Fruit colour convergence in unrelated plants is independent of phylogeny and can be better explained by disperser type, which supports the hypothesis that frugivores are important in fruit evolution. We discuss adaptive and nonadaptive hypotheses that can potentially explain the pattern we found.     

The relationships among physical,geometrical and mechanical properties of bone,with a note on the properties of nonhuman primate bone

Since bone reacts to imposed loads by formation and resorption of tissue, analysis of tissue distribution within a bone provides evidence of the adaptation of that bone to a given mechanical function. Definition of these structure-function relationships permits the physical anthropologist to clarify the wide variety of behavioral/morphological adaptations to specific ecological niches in extant primates. From this information, behavior and locomotor function can ultimately be inferred in fossil primates. This paper reviews research which shows the relationships between the physical, geometrical and mechanical properties of bone, so that researchers who are investigating the properties of bone are aware of the numerous interpretations which may be made about structure and function from basic data. In addition, this paper is an attempt to apprise investigators working with primates that comparative data on the properties of primate bone are available, though sparse.     

Primate vocal communication: a useful tool for understanding human speech and language evolution?

Language is a uniquely human trait, and questions of how and why it evolved have been intriguing scientists for years. Nonhuman primates (primates) are our closest living relatives, and their behavior can be used to estimate the capacities of our extinct ancestors. As humans and many primate species rely on vocalizations as their primary mode of communication, the vocal behavior of primates has been an obvious target for studies investigating the evolutionary roots of human speech and language. By studying the similarities and differences between human and primate vocalizations, comparative research has the potential to clarify the evolutionary processes that shaped human speech and language. This review examines some of the seminal and recent studies that contribute to our knowledge regarding the link between primate calls and human language and speech. We focus on three main aspects of primate vocal behavior: functional reference, call combinations, and vocal learning. Studies in these areas indicate that despite important differences, primate vocal communication exhibits some key features characterizing human language. They also indicate, however, that some critical aspects of speech, such as vocal plasticity, are not shared with our primate cousins. We conclude that comparative research on primate vocal behavior is a very promising tool for deepening our understanding of the evolution of human speech and language, but much is still to be done as many aspects of monkey and ape vocalizations remain largely unexplored.     

Chewing on the trees: Constraints and adaptation in the evolution of the primate mandible

Chewing on different food types is a demanding biological function. The classic assumption in studying the shape of feeding apparatuses is that animals are what they eat, meaning that adaptation to different food items accounts for most of their interspecific variation. Yet, a growing body of evidence points against this concept. We use the primate mandible as a model structure to investigate the complex interplay among shape, size, diet, and phylogeny. We find a weak but significant impact of diet on mandible shape variation in primates as a whole but not in anthropoids and catarrhines as tested in isolation. These clades mainly exhibit allometric shape changes, which are unrelated to diet. Diet is an important factor in the diversification of strepsirrhines and platyrrhines and a phylogenetic signal is detected in all primate clades. Peaks in morphological disparity occur during the Oligocene (between 37 and 25 Ma) supporting the notion that an adaptive radiation characterized the evolution of South American monkeys. In all primate clades, the evolution of mandible size is faster than its shape pointing to a strong effect of allometry on ecomorphological diversification in this group.     

HOW REPEATABLE IS ADAPTIVE EVOLUTION? THE ROLE OF GEOGRAPHICAL ORIGIN AND FOUNDER EFFECTS IN LABORATORY ADAPTATION

The importance of contingency versus predictability in evolution has been a long-standing issue, particularly the interaction between genetic background, founder effects, and selection. Here we address experimentally the effects of genetic background and founder events on the repeatability of laboratory adaptation in Drosophila subobscura populations for several functional traits. We found disparate starting points for adaptation among laboratory populations derived from independently sampled wild populations for all traits. With respect to the subsequent evolutionary rate during laboratory adaptation, starvation resistance varied considerably among foundations such that the outcome of laboratory evolution is rather unpredictable for this particular trait, even in direction. In contrast, the laboratory evolution of traits closely related to fitness was less contingent on the circumstances of foundation. These findings suggest that the initial laboratory evolution of weakly selected characters may be unpredictable, even when the key adaptations under evolutionary domestication are predictable with respect to their trajectories.