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Kämpfer P 《Antonie van Leeuwenhoek》2012,101(1):3-11
The term taxonomy is often used synonymously with systematics but it should be regarded more as a specific part of the latter
and comprises the orderly arrangements of (defined) units in addition to the nomenclature, i.e. labelling of these units defined
by classification, and also identification of these units defined by classification and labeled by nomenclature. Similar to
all biological disciplines, taxonomic approaches in microbiology aim at the establishment of a system that mirrors the “order
in nature” as closely as possible with the ultimate goal to describe the whole evolutionary order back to the origin of life.
With the recognition of molecular markers present in all organisms (here in particular the small subunit rRNAs, ssRNSs), the
achievement of this goal has become more and more feasible and the generation of gene and increasing numbers of genome sequences
allow nowadays the generation of large amounts of data and often a very detailed insight into the genetic potential of prokaryotes.
The possibility to generate whole genome sequences in a very short period of time leads to a strong tendency to base the taxonomic
system more and more on sequence data. However, a comprehensive understanding of all the information behind sequence data
is lagging far behind their accumulation. Genes and genomes may (or may not) function only in a given “environment”, with
the cell as basic entity for the display of this potential. Prokaryotic taxonomy still has its focus on the whole organism.
In this context, natural selection drives evolution selecting the existing phenotypes and it is the phenotype that “exhibits”
this process both in a given cellular and also environmental context. The term polyphasic taxonomy, which was coined almost
40 years ago and aimed at the integration of many levels of information (from molecular to ecological data) thereby allowing
a more holistic view, should be revisited in the light of the enormous potential of the novel information associated with
large data sets. 相似文献
3.
Extending Darwin’s analogy: Bridging differences in concepts of selection between farmers, biologists, and plant breeders 总被引:1,自引:0,他引:1
Darwin developed his theory of evolution based on an analogy between artificial selection by breeders of his day and “natural
selection.” For Darwin, selection included what biologists came to see as being composed of (1) phenotypic selection of individuals
based on phenotypic differences, and, when these are based on heritable genotypic differences, (2) genetic response between
generations, which can result in (3) evolution (cumulative directional genetic response over generations). The use of the
term “selection” in biology and plant breeding today reflects Darwin’s assumption—phenotypic selection is only biologically
significant when it results in evolution. In contrast, research shows that small-scale, traditionally-based farmers select
seed as part of an integrated production and consumption system in which selection is often not part of an evolutionary process,
but is still useful to farmers. Extending Darwin’s analogy to farmers can facilitate communication between farmers, biologists,
and plant breeders to improve selection and crop genetic resource conservation. 相似文献
4.
Stuart A. Newman 《Journal of biosciences》1992,17(3):193-215
Early embryos of metazoan species are subject to the same set of physical forces and interactions as any small parcels of
semi-solid material, living or nonliving. It is proposed that such “generic” properties of embryonic tissues have played a
major role in the evolution of biological form and pattern by providing an array of morphological templates, during the early
stages of metazoan phylogeny, upon which natural selection could act. The generic physical mechanisms considered include sedimentation,
diffusion, and reaction-diffusion coupling, all of which can give rise to chemical nonuniformities (including periodic patterns)
in eggs and small multicellular aggregates, and differential adhesion, which can lead to the formation of boundaries of non-mixing
between adjacent cell populations. Generic mechanisms that produce chemical patterns, acting in concern with the capacity
of cells to modulate their adhesivity (presumed to be a primitive, defining property of metazoa), could lead to multilayered
gastrulae of various types, segmental organization, and many of the other distinguishing characteristics of extant and extinct
metazoan body plans. Similar generic mechanisms, acting on small tissue primordia during and subsequent to the establishment
of the major body plans, could have given rise to the forms of organs, such as the vertebrate limbs. Generic physical processes
acting on a single system of cells and cell products can often produce a widely divergent set of morphological phenotypes,
and these are proposed to be the raw material of the evolution of form. The establishment of any ecologically successful form
by these mechanisms will be followed, under this hypothesis, by a period of genetic evolution, in which the recruitment of
gene products to produce the “generically templated” morphologies by redundant pathways would be favoured by intense selection,
leading to extensive genetic change with little impact on the fossil record. In this view, the stabilizing and reinforcing
functions of natural selection are more important than its ability to effect incremental change in morphology. Aspects of
evolution which are problematic from the standard neo-Darwinian viewpoint, or not considered within that framework, but which
follow in a straightforward fashion from the view presented here, include the beginnings of an understanding of why organisms
have the structure and appearance they’ do, why homoplasy (the recurrent evolution of certain forms) is so prevalent, why
evolution has the tempo and mode it does (“punctuated equilibrium”), and why a “rapid” burst of morphological evolution occurred
so soon after the origin of the metazoa. 相似文献
5.
Seventy-five years ago, the geneticist Richard Goldschmidt hypothesized that single mutations affecting development could
result in major phenotypic changes in a single generation to produce unique organisms within animal populations that he called
“hopeful monsters”. Three decades ago, Sarah P. Gibbs proposed that photosynthetic unicellular micro-organisms like euglenoids
and dinoflagellates are the products of a process now called “secondary endosymbiosis” (i.e., the evolution of a chloroplast
surrounded by three or four membranes resulting from the incorporation of a eukaryotic alga by a eukaryotic heterotrophic
host cell). In this article, we explore the evidence for Goldschmidt’s “hopeful monster” concept and expand the scope of this
theory to include the macroevolutionary emergence of organisms like Euglena and Chlorarachnion from secondary endosymbiotic events. We argue that a Neo-Goldschmidtian perspective leads to the conclusion that cell chimeras
such as euglenids and dinoflagellates, which are important groups of phytoplankton in freshwater and marine ecosystems, should
be interpreted as “successful monsters”. In addition, we argue that Charles Darwin had euglenoids (infusoria) in mind when
he speculated on the “primordial intermediate form”, although his Proto-Euglena-hypothesis for the origin of the last common
ancestor of all forms of life is no longer acceptable. 相似文献
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Summary While many developmental processes (e. g., gene networks or signaling pathways) are astonishingly conserved during evolution,
they may be employed differently in different metazoan taxa or may be used multiply in different contexts of development.
This suggests that these processes belong to building blocks or modules, viz., highly integrated parts of the organism, which
develop and/or function relatively independent from other parts. Such modules may be relatively easy to dissociate from other
modules and, therefore, could also serve as units of evolution. However, in order to further explore the implications of modularity
for evolution, the vague notion of “modularity” as well as its relation to concepts like “unit of evolution” need to be more
precisely specified. Here, a module is characterized as a certain type of dynamic pattern of couplings among the constituents of a process. It may or may not
form a spatially contiguous unit. A unit of selection is defined as a unit of those constituents of a reproducing process/system, which exists in different variants and acts as
a non-decomposable unit of fitness and variant reproduction during a particular selection process. The more general notion
of a unit of evolution is characterized as a nondecomposable unit of constituents with reciprocal fitness dependence, be it due to fitness epistasis
or due to the lack of independent variability. Because such fitness dependence may only be observed for some combinations
of variants, several constituents may act as a unit of evolution only with a certain probability (coevolution probability).
It is argued, that under certain conditions modules are likely to act as units of evolution with high coevolution probabilities,
because there is likely to be a close tie between the pattern of couplings of the constituents of a reproducing system and
their interdependent fitness contributions. Moreover and contrary to the traditional dichotomy of genes versus organisms as
units of selection, modules tend to be more important in delimiting actual units of selection than either organisms or genes,
because they are less easily disrupted by recombination than organisms, while having less contextsensitive fitness values
than genes. Finally, it is suggested that the evolution of modularity is self-reinforcing, because the flexibility of intermodular
connections facilitates the recombination among modules and their multiple employment in new contexts. 相似文献
8.
The genetic composition of present day human populations is determined largely by the interaction between the human host
and infective agents. Therefore, theoretical analysis of the host-infective-agent system is required in order for us to be
able to understand human evolution. Classical population genetics has been confined largely to analysing the interplay of
various mechanisms, such as selection, mutation and drift, in one species at a time. Unfortunately, there have been few studies
of such interactive systems. In the present investigation, these studies have been enlarged, with problems of human genetics
in mind, by mathematical examination of a model in which a diploid host with three alleles interacts with a haploid infective
agent with two alleles. The results are compared with those obtained from simpler models analysed in the past. The assumptions
inherent in such “gene for gene” models and our results are discussed. An increase in the number of alleles appears to enhance
the chances for the establishment of permanent genetic polymorphisms, improving genetic “elasticity” of a population for coping
with changing challenges by various infective agents. Interaction between two haploid species leads to a loss of polymorphism
in both of them and, hence, to a severe loss of evolutionary elasticity. The hypothesis that the evolution of diploidy might
have been favoured by a selective advantage of diploid organisms interacting with environmental challenges, such as infective
agents, is supported.
Received: 6 October 1997 / Accepted: 26 November 1997 相似文献
9.
Protein evolution is not a random process. Views which attribute randomness to molecular change, deleterious nature to single-gene
mutations, insufficient geological time, or population size for molecular improvements to occur, or invoke “design creationism”
to account for complexity in molecular structures and biological processes, are unfounded. Scientific evidence suggests that
natural selection tinkers with molecular improvements by retaining adaptive peptide sequence. We used slot-machine probabilities
and ion channels to show biological directionality on molecular change. Because ion channels reside in the lipid bilayer of
cell membranes, their residue location must be in balance with the membrane’s hydrophobic/philic nature; a selective “pore”
for ion passage is located within the hydrophobic region. We contrasted the random generation of DNA sequence for KcsA, a
bacterial two-transmembrane-domain (2TM) potassium channel, from Streptomyces lividans, with an under-selection scenario, the “jackprot,” which predicted much faster evolution than by chance. We wrote a computer
program in JAVA APPLET version 1.0 and designed an online interface, The Jackprot Simulation
, to model a numerical interaction between mutation rate and natural selection during a scenario of polypeptide evolution.
Winning the “jackprot,” or highest-fitness complete-peptide sequence, required cumulative smaller “wins” (rewarded by selection)
at the first, second, and third positions in each of the 161 KcsA codons (“jackdons” that led to “jackacids” that led to the
“jackprot”). The “jackprot” is a didactic tool to demonstrate how mutation rate coupled with natural selection suffices to
explain the evolution of specialized proteins, such as the complex six-transmembrane (6TM) domain potassium, sodium, or calcium
channels. Ancestral DNA sequences coding for 2TM-like proteins underwent nucleotide “edition” and gene duplications to generate
the 6TMs. Ion channels are essential to the physiology of neurons, ganglia, and brains, and were crucial to the evolutionary
advent of consciousness. The Jackprot Simulation illustrates in a computer model that evolution is not and cannot be a random
process as conceived by design creationists. 相似文献
10.
Karel Kleisner 《Biosemiotics》2011,4(2):223-241
Organic appearances are largely neglected by contemporary biology; partly because they are regarded as superficial effects
of causes concealed beneath the surface. The persuasion that everything what does exist is existent for some immediately non-apparent
reasons belongs to a general belief of modern science. All organisms are of the same evolutionary origin and of the same world
wherein appearance coincides with existence. In this study, living beings are approached as appearing centers of experience
that reflects their evolutionary history. From biohermeneutic point of view the evolution of organisms, interactions between
organisms, and their relationships to environment is understood as “evolution of interpretations”. I use simple conceptual
framework of perception, semiotic co-option, and modification to explain the evolution of semantic organs, i.e. organs that
operate through the meaning that was given to them by an animal interpreter. 相似文献
11.
Patrik Krebs Gianni B. Pezzatti Stefano Mazzoleni Lee M. Talbot Marco Conedera 《Theorie in den Biowissenschaften》2010,129(1):53-69
“Fire regime” has become, in recent decades, a key concept in many scientific domains. In spite of its wide spread use, the
concept still lacks a clear and wide established definition. Many believe that it was first discussed in a famous report on
national park management in the United States, and that it may be simply defined as a selection of a few measurable parameters
that summarize the fire occurrence patterns in an area. This view has been uncritically perpetuated in the scientific community
in the last decades. In this paper we attempt a historical reconstruction of the origin, the evolution and the current meaning
of “fire regime” as a concept. Its roots go back to the 19th century in France and to the first half of the 20th century in
French African colonies. The “fire regime” concept took time to evolve and pass from French into English usage and thus to
the whole scientific community. This coincided with a paradigm shift in the early 1960s in the United States, where a favourable
cultural, social and scientific climate led to the natural role of fires as a major disturbance in ecosystem dynamics becoming
fully acknowledged. Today the concept of “fire regime” refers to a collection of several fire-related parameters that may
be organized, assembled and used in different ways according to the needs of the users. A structure for the most relevant
categories of parameters is proposed, aiming to contribute to a unified concept of “fire regime” that can reconcile the physical
nature of fire with the socio-ecological context within which it occurs. 相似文献
12.
V. Sommer 《Human Evolution》1988,3(4):261-278
During a 15 month study on free ranging langurs (Presbytis entellus) at Jodhpur, Rajasthan, India, 5 adult male replacements were observed as a result of nontroop male invasions into the home
ranges of 3 neighbouring one-male troops comprising 16–28 members each. Jodhpur langurs have no breeding season. Periods of
instability during resident male changes lasted 11–119 days. Linear dominance hierarchies could be detected within the 3 main
rival male bands of 2, 5, and 28–35 members. The respective alphas drove their allies away after their bands succeeded cooperatively
at occupying a troop. During gradual replacements interim residencies alternated with multi-male stages. A large band's alpha
may have had better chances to win the competition, since adult and nonadult allies functioned as “buffers” in agonistic encounters.
The role of kin selection in structuring the composition of male bands and male coalitional behaviour cannot yet be quantified.
Tactical “deceit” of powerful males to cause unrealistic expectations and in this way agonistic engagement of less strong
males can be ruled out. “Sneaking copulations” is a proximate advantage for subordinate supporters, since they participated
in 61.9% of all sexual interactions. Female promiscuity might reflect a strategy to induce male-male competition and thus
select for a strong resident. 相似文献
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14.
Peter Alpert 《Biological invasions》2006,8(7):1523-1534
Introduced species, those dispersed outside their natural ranges by humans, now cause almost all biological invasions, i.e.,
entry of organisms into habitats with negative effects on organisms already there. Knowing whether introduction tends to give
organisms specific ecological advantages or disadvantages in their new habitats could help understand and control invasions.
Even if no specific species traits are associated with introduction, introduced species might out-compete native ones just
because the pool of introduced species is very large (“global competition hypothesis”). Especially in the case of intentional
introduction, high initial propagule pressure might further increase the chance of establishment, and repeated introductions
from different source populations might increase the fitness of introduced species through hybridization. Intentional introduction
screens species for usefulness to humans and so might select for rapid growth and reproduction or carry species to suitable
habitats, all which could promote invasiveness. However, trade offs between growth and tolerance might make introduced species
vulnerable to extreme climatic events and cause some invasions to be transient (“reckless invader hypothesis”). Unintentional
introduction may screen for species associated with human-disturbed habitats, and human disturbance of their new habitats
may make these species more invasive. Introduction and natural long-distance dispersal both imply that species have neither
undergone adaptation in their new habitats nor been adapted to by other species there. These two characteristics are the basis
for many well-known hypotheses about invasion, including the “biotic resistance”, “enemy release”, “evolution of increased
competitive ability” and “novel weapon” hypotheses, each of which has been shown to help explain some invasions. To the extent
that biotic resistance depends upon local adaption by native species, altering selection pressures could reduce resistance
and promote invasion (“local adaptation hypothesis”), and restoring natural regimes could reverse this effect. 相似文献
15.
A great number of research papers in the English literature of science education present difficulties pupils have in understanding
natural selection. Studies show that children have essentialist and teleological intuitive ideas when dealing with organisms
and that these biases hinder their ability to understand the theory of evolution by natural selection. Consequently, it is
interesting to ascertain if and how the school education offered today deals with the problem, i.e., helps the children confront
these biases. To that purpose, this study answered the two following research questions: (a) How is biological evolution presented—from
the past to the present day—in the official documentation of primary school education, namely the science curricula and the
textbooks of Greece? and (b) what are the conceptions held by Greek primary school teachers of the concepts of evolutionary
theory and relevant issues that they have to teach? Our research found that not only are the intuitive ideas not “confronted”
but they are also “affirmed” in Greek primary education. This phenomenon, as some other international studies have shown,
must not be only a Greek one. A drastic change in the content and structure of primary school curricula and the training of
educators is necessary in order to improve and facilitate the teaching of biological evolution. 相似文献
16.
Shuzhen Yang Rui Zhang Changchao Hu Jie Xie Jingquan Zhao 《Photosynthesis research》2009,99(2):99-106
Light state transition is a physiological function of oxygenic organisms to balance the excitation of photosystem II (PSII)
and photosystem I (PSI), hence a prerequisite of oxygen-evolving photosynthesis. For cyanobacteria, phycobilisome (PBS) movement
during light state transition has long been expected, but never observed. Here the dynamic behavior of PBS movement during
state transition in cyanobacterium Synechocystis PCC6803 is experimentally detected via time-dependent fluorescence fluctuation. Under continuous excitation of PBSs in the
intact cells, time-dependent fluorescence fluctuations resemble “damped oscillation” mode, which indicates dynamic searching
of a PBS in an “overcorrection” manner for the “balance” position where PSII and PSI are excited equally. Based on the parallel
model, it is suggested that the “damped oscillation” fluorescence fluctuation is originated from a collective movement of
all the PBSs to find the “balance” position. Based on the continuous fluorescence fluctuation during light state transition
and also variety of solar spectra, it may be deduced that light state transition of oxygen-evolution organisms is a natural
behavior that occurs daily rather than an artificial phenomenon at extreme light conditions in laboratory. 相似文献
17.
Günter Theißen 《Theorie in den Biowissenschaften》2009,128(1):43-51
Since 150 years it is hypothesized now that evolution always proceeds in a countless number of very small steps (Darwin in
On the origin of species by means of natural selection or the preservation of favoured races in the struggle of life, Murray,
London, 1859), a view termed “gradualism”. Few contemporary biologists will doubt that gradualism reflects the most frequent mode of evolution,
but whether it is the only one remains controversial. It has been suggested that in some cases profound (“saltational”) changes
may have occurred within one or a few generations of organisms. Organisms with a profound mutant phenotype that have the potential
to establish a new evolutionary lineage have been termed “hopeful monsters”. Recently I have reviewed the concept of hopeful
monsters in this journal mainly from a historical perspective, and provided some evidence for their past and present existence.
Here I provide a brief update on data and discussions supporting the view that hopeful monsters and saltational evolution
are valuable biological concepts. I suggest that far from being mutually exclusive scenarios, both gradual and saltational
evolution are required to explain the complexity and diversity of life on earth. In my view, gradual changes represent the
usual mode of evolution, but are unlikely to be able to explain all key innovations and changes in body plans. Saltational
changes involving hopeful monsters are probably very exceptional events, but since they have the potential to establish profound
novelties sometimes facilitating adaptive radiations, they are of quite some importance, even if they would occur in any evolutionary
lineage less than once in a million years. From that point of view saltational changes are not more bizarre scenarios of evolutionary
change than whole genome duplications, endosymbiosis or impacts of meteorites. In conclusion I argue that the complete dismissal
of saltational evolution is a major historical error of evolutionary biology tracing back to Darwin that needs to be rectified. 相似文献
18.
Steven R. Jakobi 《Evolution》2010,3(3):416-419
In an informal survey, only five percent of 306 college freshmen students in an introductory biology course provided a correct
scientific definition for the theory of evolution. The other respondents provided answers that ranged from “organisms improving
themselves” (42 percent) to “monkeys becoming humans” (seven percent). Some of the potential reasons for the lack of understanding
of the concept of evolution are explored. 相似文献
19.
Evolutionary biology owes much to Charles Darwin, whose discussions of common descent and natural selection provide the foundations
of the discipline. But evolutionary biology has expanded well beyond its foundations to encompass many theories and concepts
unknown in the 19th century. The term “Darwinism” is, therefore, ambiguous and misleading. Compounding the problem of “Darwinism”
is the hijacking of the term by creationists to portray evolution as a dangerous ideology—an “ism”—that has no place in the
science classroom. When scientists and teachers use “Darwinism” as synonymous with evolutionary biology, it reinforces such
a misleading portrayal and hinders efforts to present the scientific standing of evolution accurately. Accordingly, the term
“Darwinism” should be abandoned as a synonym for evolutionary biology. 相似文献
20.
Niles Eldredge 《Evolution》2008,1(1):10-15
Evolutionary biology presents a bewildering array of phenomena to scientists and students alike—ranging from molecules to
species and ecosystems; and embracing 3.8 billion years of life’s history on earth. Biological systems are arranged hierarchically,
with smaller units forming the components of larger systems. The evolutionary hierarchy, based on replication of genetic information
and reproduction, is a complex of genes/organisms/demes/species and higher taxa. The ecological hierarchy, based on patterns
of matter–energy transfer, is a complex of proteins/organisms/avatars/local ecosystems/regional ecosystems. All organisms
are simultaneously parts of both hierarchical systems. Darwin’s original formulation of natural selection maps smoothly onto
a diagram where the two hierarchical systems are placed side-by-side. The “sloshing bucket” theory of evolution emerges from
empirical cases in biological history mapped onto this dual hierarchy scheme: little phenotypically discernible evolution
occurs with minor ecological disturbance; conversely, greatest concentrations of change in evolutionary history follow mass
extinctions, themselves based on physical perturbations of global extent. Most evolution occurs in intermediate-level regional
“turnovers,” when species extinction leads to rapid evolution of new species. Hierarchy theory provides a way of integrating
all fields of evolutionary biology into an easily understood—and taught—rubric.
相似文献
Niles EldredgeEmail: |