Gedanken über die Intelligenz von Tieren

Thoughts about animal intelligence To give a short and clear definition of what means “animal intelligence” it's necessary to find the connection between different methods of “learning” processes: Habituation, trial and error resp. classical and instrumental conditioning, play behavior, imitation, insight learning and imprinting. Some examples try to explain animal intelligence by human mind, and to find out the difference between “ability” as a genetic tool and intelligent behavior far from genetic influence (pressure?). Animals are able to behave independent without any manipulation – they act by fun, they act as free ranging animals.     

Functional and Evolutionary Relationships of Vocal Copying Phenomena in Birds

Vocal copying (vocal imitation, vocal mimicry, and vocal convergence) in birds is reviewed and synthesized by placing these phenomena in a functional and evolutionary framework. Confusion surrounding avian vocal copying has resulted from vague and inconsistently applied terminology, virtually no experimental field work, and a failure to consider vocal copying in an evolutionary perspective. Four categories of vocal copying are recognized herein: vocal appropriation, vocal imitation, vocal mimicry, and vocal convergence or nondivergence. Vocal mimicry, a vocalization that serves to deceive a signalreceiver, is the rarest of the four categories and has not been verified experimentally.     

THE DIVERSITY AND EVOLUTION OF BATESIAN MIMICRY IN PAPILIO SWALLOWTAIL BUTTERFLIES

Papilio swallowtail butterflies exhibit a remarkable diversity of Batesian mimicry, manifested in several sex-limited and polymorphic types. There is little understanding of how this diversity is distributed within Papilio , and how different mimicry types have evolved in relation to each other. To answer these questions, I present a graphical model that connects various mimicry types by hypothetical character state changes within a phylogenetic framework. A maximum likelihood analysis of evolution of mimicry types on the Papilio phylogeny showed that sexually monomorphic mimicry and female-limited mimicry have evolved repeatedly but predominantly independently in different clades. However, transitions between these mimicry types are rarely observed. The frequency distribution of character state changes was skewed in favor of the evolution of mimicry, whereas many theoretically plausible character state changes, especially evolutionary loss of mimicry, were not evident. I discuss these findings in relation to studying the tempo of evolutionary change, loss of traits, and directionality and connectivity among character states. The pathway approach and phylogenetic patterns of mimicry demonstrated in Papilio are useful to test novel hypotheses regarding the diversity and evolutionary directionality of Batesian mimicry in other systems.     

单细胞动物和多细胞动物的激素印迹

激素印迹是单细胞动物和多细胞动物的一种生理现象,也是选择参与信号识别过程分子的工具。激素印迹后,受体记忆将遗传给子孙后代,因此其对进化的作用可能是很大的。同时,激素印迹还有利于物种的维持。另外,激素印迹过程还是具有终身效应的临时开放系统的一部分。没有印迹,就没有完全的受体成熟,而不成熟的受体是不能和适量的激素结合的。在围 期诸如治疗药物和环境污染剂等人工合成的物质分子易致错误或病理印迹。许多研究表明错误印迹对生物体具有重要的影响。当然,单细胞动物的激素印迹过程与多细胞动物并不完全一样。     

A comparative study of the function of heterospecific vocal mimicry in European passerines

Although heterospecific vocal imitation is well documented inpasserines, the evolutionary correlates of this phenomenon arepoorly known. Here, we studied interspecific variation in vocalmimicry in a comparative study of 241 European songbirds. Wetested whether vocal mimicry is a mode of repertoire acquisitionor whether it resulted from imperfect song learning. We alsoinvestigated the effect of the degree of contact with the vocalenvironment (with species having larger ranges, abundance, orbeing long lived having a higher degree of mimicry) and a possiblelink with cognitive capacity (an overall larger brain in specieswith mimicry). Finally, we determined the potential evolutionaryrole of vocal mimicry in different interspecific contexts, predictingthat mimicry may affect the intensity of brood parasitism, predation,or degree of hybridization. While controlling for research effortand phylogenetic relationships among taxa, we found that effectsizes for intersong interval, brain size, breeding dispersal,abundance, age-dependent expression of repertoires, and predationrisk reached a level that may indicate evolutionary importance.Vocal mimicry seems to be a consequence of song continuity ratherthan song complexity, may partially have some cognitive componentbut may also be dependent on the vocal environment, and mayattract the attention of predators. However, estimates of sexualselection and interspecific contacts due to brood parasitismand hybridization varied independently of vocal mimicry. Therefore,mimicry may have no function in female choice for complex songsand may be weakly selected via interspecific associations. Thesefindings provide little evidence for vocal mimicry having evolvedto serve important functions in most birds.     

What kind of signals do mimetic tiger moths send? A phylogenetic test of wasp mimicry systems (Lepidoptera: Arctiidae: Euchromiini).

Mimicry has been examined in field and laboratory studies of butterflies and its evolutionary dynamics have been explored in computer simulations. Phylogenetic studies examining the evolution of mimicry, however, are rare. Here, the phylogeny of wasp-mimicking tiger moths, the Sphecosoma group, was used to test evolutionary predictions of computer simulations of conventional Müllerian mimicry and quasi-Batesian mimicry dynamics. We examined whether mimetic traits evolved individually, or as suites of characters, using concentrated change tests. The phylogeny of these moth mimics revealed that individual mimetic characters were conserved, as are the three mimetic wasp forms: yellow Polybia, black Polybia and Parachartergus mimetic types. This finding was consistent with a 'supergene' control of linked loci and the Nicholson two-step model of mimicry evolution. We also used a modified permutation-tail probability approach to examine the rate of mimetic-type evolution. The observed topology, hypothetical Müllerian and Batesian scenarios, and 1000 random trees were compared using Kishino-Hasegawa tests. The observed phylogeny was more consistent with the predicted Müllerian distribution of mimetic traits than with that of a quasi-Batesian scenario. We suggest that the range of discriminatory abilities of the predator community plays a key role in shaping mimicry dynamics.     

A central role for p38 MAPK in the early transcriptional response to stress

A study using phylogenetic hypothesis testing, published in BMC Evolutionary Biology, suggests that non-mimetic forms of the North American white admiral butterfly evolved from a mimetic ancestor. This case might provide one of the first examples in which mimicry was gained and then lost again, emphasizing the evolutionary lability of Batesian mimicry. See research article http://www.biomedcentral.com/1471-2148/10/239     

Coding behavioural data for cladistic analysis: using dynamic homology without parsimony

Many of the controversies around the concept of homology rest on the subjectivity inherent to primary homology propositions. Dynamic homology partially solves this problem, but there has been up to now scant application of it outside of the molecular domain. This is probably because morphological and behavioural characters are rich in properties, connections and qualities, so that there is less space for conflicting character delimitations. Here we present a new method for the direct optimization of behavioural data, a method that relies on the richness of this database to delimit the characters, and on dynamic procedures to establish character state identity. We use between‐species congruence in the data matrix and topological stability to choose the best cladogram. We test the methodology using sequences of predatory behaviour in a group of spiders that evolved the highly modified predatory technique of spitting glue onto prey. The cladogram recovered is fully compatible with previous analyses in the literature, and thus the method seems consistent. Besides the advantage of enhanced objectivity in character proposition, the new procedure allows the use of complex, context‐dependent behavioural characters in an evolutionary framework, an important step towards the practical integration of the evolutionary and ecological perspectives on diversity. © The Willi Hennig Society 2010.     

Stepwise molecular evolution of bacterial photosynthetic energy conversion

The concept of continuity in molecular evolution implies a stepwise formation of metabolic systems and processes. In this manner, chemical and biological evolution have given rise, step by step, to such complicated systems as the photosynthetic apparatus and thus, such elaborate processes as photosynthesis in the living cell. Among currently living organisms, the bacteria contain a much less complex photosynthetic system than the algae and higher plants, which uniquely are capable fo splitting H2O. But also the bacterial system is a very highly evolved and sophisticated, membrane-bound apparatus for the transformation of light energy to other biologically useful energy forms. The study of its molecular evolution is here undertaken by the method of attempting to break down the system into its main components and functions in order to elucidate how they had originated and evolved, and how, by divergent and convergent evolutionary steps, the stage was set for the arrival of bacterial photophosphorylation.     

Variable Food Begging Calls Are Harbingers of Vocal Learning

Vocal learning has evolved in only a few groups of mammals and birds. The developmental and evolutionary origins of vocal learning remain unclear. The imitation of a memorized sound is a clear example of vocal learning, but is that when vocal learning starts? Here we use an ontogenetic approach to examine how vocal learning emerges in a songbird, the chipping sparrow. The first vocalizations of songbirds, food begging calls, were thought to be innate, and vocal learning emerges later during subsong, a behavior reminiscent of infant babbling. Here we report that the food begging calls of male sparrows show several characteristics associated with learned song: male begging calls are highly variable between individuals and are altered by deafening; the production of food begging calls induces c-fos expression in a forebrain motor nucleus, RA, that is involved with the production of learned song. Electrolytic lesions of RA significantly reduce the variability of male calls. The male begging calls are subsequently incorporated into subsong, which in turn transitions into recognizable attempts at vocal imitation. Females do not sing and their begging calls are not affected by deafening or RA lesion. Our results suggest that, in chipping sparrows, intact hearing can influence the quality of male begging calls, auditory-sensitive vocal variability during food begging calls is the first step in a modification of vocal output that eventually culminates with vocal imitation.     

Understanding Mimicry – with Special Reference to Vocal Mimicry

The term mimicry was introduced to biology in 1862 by Henry Walter Bates in his evolutionary explanation of deceptive communication in nature, based on a three‐part interaction system of a mimicked organism or object (called model), a mimicking organism (called mimic), and one or more organisms as selecting agents. Bates gave two incongruous definitions of mimicry: one from the viewpoint of a natural agent that selects for, and in consequence is deceived by, the close resemblance of a toxic model's warning signal and the similar appearance of a palatable mimic, and another one from the viewpoint of a human taxonomist who under an evolutionary aspect focuses on convergent resemblance between model and mimic. Later definitions of Müllerian (F. Müller), arithmetic (A. Wallace) and social (M. Moynihan) mimicry abolish deception in the natural selecting agent, rely on the convergence criterion alone, fuse the roles of model and mimic but have to accept a mix of homologous and convergent resemblance amongst them for a functional explanation. The definition of vocal mimicry (E. Armstrong) refers to a learned resemblance between mimic and heterospecific model by character duplication (no convergence), so far without known (deceived or not deceived) natural selecting agents. It excludes Batesian vocal mimicry. The functional ethological understanding of mimicry as a tripartite communication system (W. Wickler) is consistent with Bates' concept and accepts deception as key element of Batesian mimicry beyond homologous and convergent resemblances. Deception is seen as caused by the divergence between a sign and its meaning for the natural selecting agent. This understanding covers mimicry in all behaviour domains, provides a generally applicable definition of mimic and model so far missing in any mimicry concept, and it distinguishes – still in line with Henry Bates – cultural from genetically determined model‐mimic‐resemblance; this applies to vocal mimicry in particular. Convergently evolved model‐mimic‐resemblance, not essential in Batesian mimicry but mandatory for its alternatives, marks a fundamental distinction between Batesian mimicry (including Mimesis) and all other conceptualized mimicries and accounts for the non‐existence of a unified meaning of the term mimicry. However, character convergence does not help to explain the mere existence of mimicry phenomena and is irrelevant for their permanence in nature. I therefore propose to remove the convergence argument from any mimicry definition.     

Mimicry: developmental genes that contribute to speciation

Despite renewed interest in the role of natural selection as a catalyst for the origin of species, the developmental and genetic basis of speciation remains poorly understood. Here we describe the genetics of Müllerian mimicry in Heliconius cydno and H. melpomene (Lepidoptera: Nymphalidae), sister species that recently diverged to mimic other Heliconius. This mimetic shift was a key step in their speciation, leading to pre- and postmating isolation. We identify 10 autosomal loci, half of which have major effects. At least eight appear to be homologous with genes known to control pattern differences within each species. Dominance has evolved under the influence of identifiable "modifier" loci rather than being a fixed characteristic of each locus. Epistasis is found at many levels: phenotypic interaction between specific pairs of genes, developmental canalization due to polygenic modifiers so that patterns are less sharply defined in hybrids, and overall fitness through ecological selection against nonmimetic hybrid genotypes. Most of the loci are clustered into two genomic regions or "supergenes," suggesting color pattern evolution is constrained by preexisting linked elements that may have arisen via tandem duplication rather than having been assembled by natural selection. Linkage, modifiers, and epistasis affect the strength of mimicry as a barrier to gene flow between these naturally hybridizing species and may permit introgression in genomic regions unlinked to those under disruptive selection. Müllerian mimics in Heliconius use different genetic architectures to achieve the same mimetic patterns, implying few developmental constraints. Therefore, although developmental and genomic constraints undoubtedly influence the evolutionary process, their effects are probably not strong in comparison with natural selection.     

Polymorphic mimicry in Papilio dardanus: mosaic dominance, big effects, and origins

The mocker swallowtail, Papilio dardanus, has a female-limited polymorphic mimicry. This polymorphism is controlled by allelic variation at a single locus with at least 11 alleles. Many of the alternative morphs are accurate mimics of different species of distasteful butterflies. Geneticists have long been interested in the mechanism by which a single gene can have such diverse and profound effects on the phenotype and in the process by which these complex phenotypic effects could have evolved. Here we present the results of a morphometric analysis of the pleiotropic effects of the mimicry gene on the array of elements that makes up the overall pattern. We show that the patterns controlled by mimicking alleles are more variable and less internally correlated than those controlled by nonmimicking alleles, suggesting the two are subject to different degrees of selection and mutational variance. Analysis of the pleiotropic dominance of the alleles reveals a consistent pattern of dominance within a coevolved genetic background and a mosaic pattern of dominant and recessive effects (including overdominance) in a heterologous genetic background. The alleles of the mimicry gene have big effects on some pattern elements and small effects on others. When the array of big phenotypic effects of the mimicry gene is applied to the presumptive ancestral color pattern, it produces a reasonable resemblance to distasteful models and suggests the initial steps that may have produced the mimicry as well as the polymorphism.     

Is Psammophily an Evolutionary Dead End? A Phylogenetic Test in the Genus Willemia (Collembola: Hypogastruridae)

The law of the unspecialized states that specialized taxa have evolved from more generalized ancestors. Moreover, it is usually assumed that ecological specialization is irreversible and hence leads to extinction. This study aims to test these assumptions using a phylogenetic framework in a case study within the springtail genus Willemia and its diverse life habits. This genus is represented mostly by loam-dwelling species (generalized condition), but some species are psammophilous, living in sandy habitats (specialized condition). Fifty-two morphological characters were examined in 34 of the 36 species of the genus and in three outgroups. The cladistic analysis yielded two most parsimonious trees (tree length 124 steps; consistency index 0.56; retention index 0.86). The evolution of psammophily versus loam-confined life is compared to the cladogram: unexpectedly, psammophily is not an evolutionary innovation that occurred once in a monophyletic group; the evolutionary scenario that parsimoniously fits the phylogeny suggests that psammophily is ancestral to the genus Willemia and reversed twice to loam-confined life. These results demonstrate that habitat generalists can evolve from habitat specialists and therefore that habitat specializations are not necessarily an evolutionary dead end. Many other seemingly specialized characters may be shown to be equally malleable.     

Analysis of the platypus genome suggests a transposon origin for mammalian imprinting

Background  

Genomic imprinting is an epigenetic phenomenon that results in monoallelic gene expression. Many hypotheses have been advanced to explain why genomic imprinting evolved in mammals, but few have examined how it arose. The host defence hypothesis suggests that imprinting evolved from existing mechanisms within the cell that act to silence foreign DNA elements that insert into the genome. However, the changes to the mammalian genome that accompanied the evolution of imprinting have been hard to define due to the absence of large scale genomic resources between all extant classes. The recent release of the platypus genome has provided the first opportunity to perform comparisons between prototherian (monotreme; which appear to lack imprinting) and therian (marsupial and eutherian; which have imprinting) mammals.     

A rheostat model for a rapid and reversible form of imprinting-dependent evolution

The evolutionary advantages of genomic imprinting are puzzling. We propose that genomic imprinting evolved as a mechanism that maximizes the interindividual variability in the rates of gene expression for dosage-sensitive loci that, with minimal unrelated deleterious effects, can alter the phenotype over a wide continuum. We hypothesize (1) that genomic imprinting provides a previously suggested haploid selective advantage (HSA); (2) that many imprinted genes have evolved mechanisms that facilitate quantitative hypervariability (QH) of gene expression; (3) that the combination of HSA and QH makes possible a rapid and reversible form of imprinting-dependent evolution (IDE) that can mediate changes in phenotype; and (4) that this enhanced adaptability to a changing environment provides selective advantage to the population, as an assisted form of evolution. These mechanisms may have provided at least one of the driving forces for the evolution of genomic imprinting in mammals. The rheostat model suggests that both genetic and epigenetic variants can contribute to an integrated mechanism of mixed Mendelian and non-Mendelian inheritance and suggests the possibility that the majority of variants are not intrinsically deleterious but, depending on the environment, are each potentially advantageous. Moreover, this would be a reversible form of evolution, with the ability not only to protect a silent allele from selection for many generations but to reactivate and expand it in the population quickly.     

The effects of predator learning, forgetting, and recognition errors on the evolution of warning coloration

This paper demonstrates that the specifics of predator avoidance learning, information loss, and recognition errors may heavily influence the evolution of aposematism. I establish a mathematical model of the change in frequency over time of bright individuals of a distasteful prey species. Warning color spreads through green beard selection as reformulated by Guilford (1990); bright colored forms gain an advantage due to their phenotypic resemblance to other bright forms, which have been sampled by the predator. I use a general classical conditioning model to examine gradual predator learning and forgetting, and then consider the extreme of one-trial learning and no forgetting over time that may occur with very toxic prey. The advantage of conspicuous coloration under these latter conditions depends upon its role in lowering a constant probability of the prey being misidentified and thus mistakenly attacked by a predator, a rarely emphasized factor in the evolution of warning coloration. This constant probability of mistaken attacks can also be interpreted as a constant probability that forgetting has occurred (forgetting does not increase with time) or a periodic decision by the predator to resample avoided prey. I show that when predators learn and forget gradually, as under the general classical conditioning model, it is very difficult for aposematic coloration to become established unless bright individuals cross an often high threshold frequency through chance factors. In contrast, the conditions expected with highly toxic prey promote the evolution of warning coloration more easily, by means from the fixation of very bright mutations to the fixation of successive mutations each of which causes a small increase in a prey's conspicuousness. The results therefore predict that aposematic coloration may have evolved in a different manner in different predator and prey systems. They also suggest that it may be extremely difficult for warning coloration to evolve in more mildly toxic or distasteful prey outside of a mimicry system.     

A maternal-offspring coadaptation theory for the evolution of genomic imprinting

Imprinted genes are expressed either from the maternally or paternally inherited copy only, and they play a key role in regulating complex biological processes, including offspring development and mother–offspring interactions. There are several competing theories attempting to explain the evolutionary origin of this monoallelic pattern of gene expression, but a prevailing view has emerged that holds that genomic imprinting is a consequence of conflict between maternal and paternal gene copies over maternal investment. However, many imprinting patterns and the apparent overabundance of maternally expressed genes remain unexplained and may be incompatible with current theory. Here we demonstrate that sole expression of maternal gene copies is favored by natural selection because it increases the adaptive integration of offspring and maternal genomes, leading to higher offspring fitness. This novel coadaptation theory for the evolution of genomic imprinting is consistent with results of recent studies on epigenetic effects, and it provides a testable hypothesis for the origin of previously unexplained major imprinting patterns across different taxa. In conjunction with existing hypotheses, our results suggest that imprinting may have evolved due to different selective pressures at different loci.     

A Maternal–Offspring Coadaptation Theory for the Evolution of Genomic Imprinting

Imprinted genes are expressed either from the maternally or paternally inherited copy only, and they play a key role in regulating complex biological processes, including offspring development and mother–offspring interactions. There are several competing theories attempting to explain the evolutionary origin of this monoallelic pattern of gene expression, but a prevailing view has emerged that holds that genomic imprinting is a consequence of conflict between maternal and paternal gene copies over maternal investment. However, many imprinting patterns and the apparent overabundance of maternally expressed genes remain unexplained and may be incompatible with current theory. Here we demonstrate that sole expression of maternal gene copies is favored by natural selection because it increases the adaptive integration of offspring and maternal genomes, leading to higher offspring fitness. This novel coadaptation theory for the evolution of genomic imprinting is consistent with results of recent studies on epigenetic effects, and it provides a testable hypothesis for the origin of previously unexplained major imprinting patterns across different taxa. In conjunction with existing hypotheses, our results suggest that imprinting may have evolved due to different selective pressures at different loci.