The Evolution of Allomothering Behavior Among Colobine Monkeys: Function and Opportunism in Evolution

The great majority of Old World monkey females are interested in infants, particularly very young ones. Characteristically, females will approach infants cradled by their mothers and subsequently attempt to touch or hold them. For Cercopithecine monkeys, the subfamily that includes the baboons and macaques, caretaking attempts by females other than the mother are ordinarily unsuccessful, at least during the first two or three weeks of life. Mothers are highly possessive of their offspring and will not surrender them to substitute infant-caretakers. In striking contrast, among the other major subfamily of Old World monkeys, the Colobines, mothers readily allow extensive and sometimes prolonged infant carrying and handling by other females (allomothering), even on the first day of life. This paper reviews the traditional functional explanations for these different maternal systems. Stressing opportunism in evolution, the paper suggests that the social and/or genetic benefits alone are not adequate to account for the origins of allomothering behavior among Colobines. Instead, emphasis is given to the kind of ancestral social structure and its environmental context that might allow such a behavioral system to begin. It is hypothesized that, relative to the Cercopithecines, who do not exhibit infant-sharing, the dental morphology and digestive system of the Colobines produced food-acquiring and food-processing advantages that, in effect, reduced intragroup feeding competition and, concomitantly, reduced the importance of status differences between females. Such a social structure could permit the emergence of allomothering behavior since, for all the participants in this activity pattern, there are varying benefits that contribute to individual fitness. [Colobine, allomothering, functions, opportunism, dietary adaptations, social structure]     

The Vertebrate Body Axis: Evolution and Mechanical Function

The body axis of vertebrates is an integrated cylinder of bones,connective tissue, and muscle. These structures vary among livingand extinct vertebrates in their orientation, composition, andfunction in ways that render useless simplistic models of theselective pressures that may have driven the evolution of theaxis. Instead, recent experimental work indicates that the vertebrateaxis serves multiple mechanical functions simultaneously: bendingthe body, storing elastic energy, transmitting forces from limbs,and ventilating the lungs. On the biochemical level, researchon human intervertebral discs has shown that collagens resisttension and torsion while proteoglycans bind water to resistcompression. This molecular behavior predicts mechanical behaviorof the entire joint, which, in turn helps determine the mechanicalbehavior of the vertebral column. The axial skeleton, in turn,is reconfigured by axial muscles that work by way of three-dimensionalconnective tissues that derive mechanical advantage for themuscle force by using the skin to increase leverage. Modelsmay eventually help determine which evolutionary changes inthe vertebrate body axis have had important functional and possiblyadaptational consequences. Current reconstruction of the hypotheticalstem lineage of early chordates and vertebrates suggests thatthe gradual mineralization of the vertebral elements, appearanceof fin rays and new median fins, and transverse and then horizontalsegmentation of the axial musculature are all features correlatedwith increases in swimming speed, maneuverability, and bodysize.     

Experiment and Comprehending the Evolution of Function

Experimentation involves the manipulation of variables in vertebrateform-functionsystems. Two general experimental approaches areused most often in attempts at defining the relationship ofform and function in animals: holding the form constant whilevarying the experimental regime, and the reverse. Either realor abstract forms and experimental regimes canbe productive,though all variations have limitations. The place of such experimentsin the understanding of the evolution of form-function is exploredin a narrative tracing the change in our conception of functionand evolution for the tetrapod ear over the past twenty years.Combining experimental functional anatomy and studies of structuralevolution and phylogeny creates an environment of reciprocalillumination. The experimental determination of function illuminatesdetails of structure otherwise not noticed—creating newcharacters or suggesting reinterpretations for those alreadyknown. Attempts to understand the evolution of structure andfunction in a clade can suggest experiments or key taxa forexperimental study. This combinedapproach is relatively newand is being led by vertebrate morphologists.     

The Classification and Evolution of Enzyme Function

Enzymes are the proteins responsible for the catalysis of life. Enzymes sharing a common ancestor as defined by sequence and structure similarity are grouped into families and superfamilies. The molecular function of enzymes is defined as their ability to catalyze biochemical reactions; it is manually classified by the Enzyme Commission and robust approaches to quantitatively compare catalytic reactions are just beginning to appear. Here, we present an overview of studies at the interface of the evolution and function of enzymes.     

The Evolution of Thyroidal Function in Fishes

Although the thyroid gland evolved from the gut, there is noevidence that thyroxine functions as part of the gastro-intestinalendocrine system nor does it have any major function analogousto the control of glucose by the pancreatic islets. The controlof the thyroid evolved from the pituitary control of the gonadsuggesting that an early role of thyroxine was in reproduction.This idea is supported by the presence of cycles of thyroidactivity associated with reproduction in both elasmobranchsand teleosts. In teleosts thyroxine is necessary for gonadalmaturation. The numerous other effects of thyroxine in teleostsmay have evolved from this maturational effect or have beenadded to it during the course of teleost evolution.     

Form and Function of Lungs: The Evolution of Air Breathing Mechanisms

SYNOPSIS. Structural evolution of the vertebrate lung illustratesthe principle that the emergence of seemingly new structuressuch as the mammalian lung is due to intensification of oneof the functions of the original piscine lung. The configurationof the mechanical support of the lung in which elastic and collagenfibers form a continuous framework is well matched with thefunctional demands. The design of the mammalian gas exchangecells is an ingenious solution to meet the functional demandsof optimizing maintenance pathways from nucleus to the cytoplasmwhile simultaneously providing minimal barrier thickness. Surfactantis found in the most primitive lungs providing a protectivecontinuous film of fluid over the delicate epithelium. As thelung became profusely partitioned, surfactant became a functionallynew surface-tension reduction device to prevent the collapseof the super-thin foam-like respiratory surface. Experimentalanalyses have established that in lower vertebrates lungs areventilated with a buccal pulse pump, which is driven by identicalsets of muscles acting in identical patterns in fishes and frogs.In the aquatic habitats suction is the dominant mode of feedinggenerating buccal pressure changes far exceeding those recordedduring air ventilation. From the perspective of air ventilationthe buccal pulse pump is overdesigned. However in terrestrialhabitats vertebrates must operate with higher metabolic demandsand the lung became subdivided into long narrow airways andprogressively smaller air spaces, rendering the pulse pump inefficient.With the placement of the lungs inside a pump, the aspirationpump was established. In mammals, the muscular diaphragm representsa key evolutionary innovation since it led to an energeticallymost efficient aspiration pump. Apparently the potential energycreated by contraction of the diaphragm during inhalation isstored in the elastic tissues of the thoracic unit and lung.This energy is released when lung and thorax recoil to bringabout exhalation. It is further determined experimentally thatrespiratory and locomotory patterns are coupled, further maximizingthe efficiency of mammalian respiration. Symmorphosis is exhibitedin the avian breathing apparatus, which is endowed with a keyevolutionary innovation by having the highly specialized lungcontinuously ventilated by multiple air sacs that function asbellows. Functional morphologists directly deal with these kindsof functional and structural complexities that provide an enormouspotential upon simple changes in underlying mechanisms.     

Animal Cognition: Function,Mechanisms, Evolution,and Development

The manner in which any animal,including a human,behaves depends on the information it receives from its environment.The capacity to use this information depend...     

Germin and Germin-like Proteins: Evolution,Structure, and Function

Germin and germin-like proteins (GLPs) are encoded by a family of genes found in all plants. They are part of the cupin superfamily of biochemically diverse proteins, a superfamily that has a conserved tertiary structure, though with limited similarity in primary sequence. The subgroups of GLPs have different enzyme functions that include the two hydrogen peroxide–generating enzymes, oxalate oxidase (OxO) and superoxide dismutase. This review summarizes the sequence and structural details of GLPs and also discusses their evolutionary progression, particularly their amplification in gene number during the evolution of the land plants. In terms of function, the GLPs are known to be differentially expressed during specific periods of plant growth and development, a pattern of evolutionary subfunctionalization. They are also implicated in the response of plants to biotic (viruses, bacteria, mycorrhizae, fungi, insects, nematodes, and parasitic plants) and abiotic (salt, heat/cold, drought, nutrient, and metal) stress. Most detailed data come from studies of fungal pathogenesis in cereals. This involvement with the protection of plants from environmental stress of various types has led to numerous plant breeding studies that have found links between GLPs and QTLs for disease and stress resistance. In addition the OxO enzyme has considerable commercial significance, based principally on its use in the medical diagnosis of oxalate concentration in plasma and urine. Finally, this review provides information on the nutritional importance of these proteins in the human diet, as several members are known to be allergenic, a feature related to their thermal stability and evolutionary connection to the seed storage proteins, also members of the cupin superfamily.     

Homepeptide Repeats:Implications for Protein Structure,Function and Evolution

Analysis of protein sequences from Mycobacterium tuberculosis H37Rv(Mtb H37Rv) was performed to identify homopeptide repeatcontaining proteins(HRCPs).Functional annotation of the HRCPs showed that they are preferentially involved in cellular metabolism.Furthermore,these homopeptide repeats might play some specific roles in protein-protein interaction.Repeat length differences among Bacteria,Archaea and Eukaryotes were calculated in order to identify the conservation of the repeats in these divergent kingdoms.From the results,it was evident that these repeats have a higher degree of conservation in Bacteria and Archaea than in Eukaryotes.In addition,there seems to be a direct correlation between the repeat length difference and the degree of divergence between the species.Our study supports the hypothesis that the presence of homopeptide repeats influences the rate of evolution of the protein sequences in which they are embedded.Thus,homopeptide repeat may have structural,functional and evolutionary implications on proteins.     

Experimental Hydrodynamics and Evolution: Function of Median Fins in Ray-finned Fishes

The median fins of fishes consist of the dorsal, anal, and caudal fins and have long been thought to play an important role in generating locomotor force during both steady swimming and maneuvering. But the orientations and magnitudes of these forces, the mechanisms by which they are generated, and how fish modulate median fin forces have remained largely unknown until the recent advent of Digital Particle Image Velocimetry (DPIV) which allows empirical analysis of force magnitude and direction. Experimental hydrodynamic studies of median fin function in fishes are of special utility when conducted in a comparative phylogenetic context, and we have examined fin function in four ray-finned fish clades (sturgeon, trout, sunfish, and mackerel) with the goal of testing classical hypotheses of fin function and evolution. In this paper we summarize two recent technical developments in DPIV methodology, and discuss key recent findings relevant to median fin function. High-resolution DPIV using a recursive local-correlation algorithm allows quantification of small vortices, while stereo-DPIV permits simultaneous measurement of x, y, and z flow velocity components within a single planar light sheet. Analyses of median fin wakes reveal that lateral forces are high relative to thrust force, and that mechanical performance of median fins (i.e., thrust as a proportion of total force) averages 0.35, a surprisingly low value. Large lateral forces which could arise as an unavoidable consequence of thrust generation using an undulatory propulsor may also enhance stability and maneuverability. Analysis of hydrodynamic function of the soft dorsal fin in bluegill sunfish shows that a thrust wake is generated that accounts for 12% of total thrust and that the thrust generation by the caudal fin may be enhanced by interception of the dorsal fin wake. Integration of experimental studies of fin wakes, computational approaches, and mechanical models of fin function promise understanding of instantaneous forces on fish fins during the propulsive cycle as well as exploration of a broader locomotor design space and its hydrodynamic consequences.     

Function and the Evolution of Phenotypic Stability: Connecting Pattern to Process

Phenotypes manifest a balance between the inherited tendencyto remain the same (phenotypic stability) and the tendency tochange in response to current environmental conditions (adaptation).This paper explores the role of functional integration and functionaltrade-offs in generating phenotypic stability by limiting theresponses of individual characters to environmental selection.Evolutionarily stable configurations (ESCs) are systems of functionallyinteracting characters within which characters are "judged"by their contribution to system-level functionality. This "internal"component of selection differs from traditional "external" selectionin that it travels with the organism wherever it goes and ismaintained across a wide range of environments. External selection,in contrast, is by definition environment-dependent. The temporaland geographic constancy of internal selection therefore actsto maintain phenotypic stability even as environments change.Functional trade-offs occur when one character participatesin more than one function, but can only be optimized for one.Participation of certain ("keystone") characters in a trade-offpotentially causes stabilization of an entire system owing toa cascade of functional dependencies on that character. Phylogeneticcharacter analysis is an essential part of elucidating theseprocesses, but patterns cannot be used as prima facie evidenceof particular processes.     

Rab蛋白的结构、功能及进化

Rab蛋白是小分子GTP结合蛋白家族(small GTP-binding proteins)中最大的亚家族,大约由200个氨基酸组成,由保守的G结构域与高度可变的N端和C端组成。Rab蛋白作为细胞内囊泡运输的分子开关,与其上游调控子和下游特定的效应子相互作用,并与GTP的结合和水解过程相偶联,在囊泡运输的不同阶段发挥作用。对不同Rab蛋白调控囊泡运输的研究有利干全面理解细胞内各类囊泡定向运输的分子动力学机制。     

Structure, Function, and Evolution of Proton-ATPases

Proton-ATPases are among the most important primary ion pumps in nature. There are three classes of these enzymes which are distinguished by their structure, function, mechanism of action, and evolution. They function in ATP formation at the expense of a protonmotive force generated by oxidative and photosynthetic electron transports, maintaining a constant pH in the cytoplasm, and forming acidic spaces in special compartments inside and outside the cell. The three classes of proton-ATPases evolved in a way that prevents functional assembly in the wrong compartment. This was achieved by a triple genetic system located in the nucleus, mitochondria and chloroplast, as well as delicate control of the proton pumping activity of the enzymes.     

Loss of Olfactory Receptor Function in Hominin Evolution

The mammalian sense of smell is governed by the largest gene family, which encodes the olfactory receptors (ORs). The gain and loss of OR genes is typically correlated with adaptations to various ecological niches. Modern humans have 853 OR genes but 55% of these have lost their function. Here we show evidence of additional OR loss of function in the Neanderthal and Denisovan hominin genomes using comparative genomic methodologies. Ten Neanderthal and 8 Denisovan ORs show evidence of loss of function that differ from the reference modern human OR genome. Some of these losses are also present in a subset of modern humans, while some are unique to each lineage. Morphological changes in the cranium of Neanderthals suggest different sensory arrangements to that of modern humans. We identify differences in functional olfactory receptor genes among modern humans, Neanderthals and Denisovans, suggesting varied loss of function across all three taxa and we highlight the utility of using genomic information to elucidate the sensory niches of extinct species.     

Linking Fold, Function and Phylogeny: A Comparative Genomics View on Protein (Domain) Evolution

Domains are the building blocks of all globular proteins and present one of the most useful levels at which protein function can be understood. Through recombination and duplication of a limited set of domains, proteomes evolved and the collection of protein superfamilies in an organism formed. As such, the presence of a shared domain can be regarded as an indicator of similar function and evolutionary history, but it does not necessarily imply it since convergent evolution may give rise to similar gene functions as well as architectures.