Leo W. Buss

Population biology and evolution of clonal organisms

The best ebooks about Population Biology And Evolution Of Clonal Organisms that you can get for free here by download this Population Biology And Evolution Of Clonal Organisms and save to your desktop. This ebooks is under topic such as population biology and evolution of clonal organisms clonal diversity cell tackling the population genetics of clonal and partially senescence in organisms with clonal reproduction and clonal plants: beyond the patterns—ecological and review: evolution and disease population biology t evolution of a f reproduction webanford overestimating population sizes of rare clonal plants book reviews taylor & francis online the population genetic structure of clonal organisms in the light of evolution ix: clonal reproduction clonal are bacteria? proceedings of the national academy when can a clonal organism escape senescence? jstor from the academy: colloquium introduction in the light of ecology and physiology of herbivoreinduced changes in plants the population genetic structure of clonal organisms oscillations in continuous culture populations of the inà ̄¬‚uence of recombination on the population structure cloncase: estimation of sex frequency and effective clonal organisms and the benefits of sex researchgate ecosystem evolution is about variation and persistence title: spectrum of genetic diversity and networks of 212 the quarterly review of biology university of chicago current topics in clonal plants research: editorial contrasting abundance and contribution of clonal research open access population genetics of cancer cell cryptic speciation in the cosmopolitan and clonal human kinship and the evolution of social behaviours in the sea an evolutionary genetic perspective on cancer biology fitness and evolution in clonal plants: the impact of genetic mosaicism in animals annual reviews chapter 2 the ecology of altruism in a clonal insect the effects of spatial configuration of populations on the reticulation,phylogeography, and population biology fitness and evolution in clonal plants: the impact of review california institute of technology

The Trichoplax genome and the nature of placozoans

As arguably the simplest free-living animals, placozoans may represent a primitive metazoan form, yet their biology is poorly understood. Here we report the sequencing and analysis of the ∼98 million base pair nuclear genome of the placozoan Trichoplax adhaerens. Whole-genome phylogenetic analysis suggests that placozoans belong to a ‘eumetazoan’ clade that includes cnidarians and bilaterians, with sponges as the earliest diverging animals. The compact genome shows conserved gene content, gene structure and synteny in relation to the human and other complex eumetazoan genomes. Despite the apparent cellular and organismal simplicity of Trichoplax, its genome encodes a rich array of transcription factor and signalling pathway genes that are typically associated with diverse cell types and developmental processes in eumetazoans, motivating further searches for cryptic cellular complexity and/or as yet unobserved life history stages.

Molecular evidence for multiple episodes of paedomorphosis in the family Hydractiniidae

Key Word Index--Hydroid; medusae reduction; paedomorphosis; phylogeny; mitochondrial DNA. Abstract--Reduction of complex life cycles in the Hydrozoa is commonly achieved by the hetarochronic reduction of the medusa from a free-living to a sessile stage. Two competing traditions of hydroid taxonomy dating from the last century disagree about whether the degree of medusa reduction is an appropriate generic character. A phylogeny based on a fragment of the sequence encoding mitochondrial large ribosomal subunit RNA is constructed for thirteen representatives of three hydractiniid genera, each defined by its degree of medusa reduction. The minimum length trees found by parsimony and distance methods are not consistent with a monophyletic origin for all three genera. Tree topologies constrained to hold the genera Stylactus and HydracEnia monophyletic were shown by a statistical test to be significantly worse than the minimum length trees. These results support the hypothesis that medusa reduction has happened repeatedly in the family Hydractiniidae, thereby calling into question the tradition of hydroid taxonomy which defines genera based on degree of medusa reduction.

Group Living, Competition, and the Evolution of Cooperation in a Sessile Invertebrate

Competition and cooperation are thought to represent the opposite extremes of organism interactions. I here show that the formation of aggregations in a sessile organism requires cooperation between individuals and that the gregarious pattern of habitat selection generating these aggregations is a response to a density dependence in the outcome of interference competition.

Planktonic food availability and suspension-feeder abundance: Evidence of in situ depletion

Abstract Substrata were arranged in a manner allowing in situ measurement of particle depletion as a function of the abundance of suspension-feeders and time. The abundance of two suspension-feeding groups, bryozoans and sponges, and of two planktonic fractions, naked and bacterial cells, were monitored. In one experiment, organism-cover increased through time and in another it remained low through time. As organism-cover increased, food availability per organism decreased, whereas when it remained low, food availability remained high. High levels of depletion measured suggest the possibility of competition for food in dense assemblages of suspension feeders.

Competition within and between encrusting clonal invertebrates.

Colonies of encrusting marine invertebrates are tractable models for the study of competition, because of the relative ease with which observations can be made on the frequency and outcome of overgrowth interactions. Studies of intraspecific competition have found that competition is predicated upon a genetically controlled recognition event, which results in either fusion or rejection. Data are rapidly accumulating in two model systems showing that fusion is associated with somatic cell parasitism and that rejection is associated with overgrowth. Thus, encounters between conspecifics define a choice: to compete at the level of the cell lineage or to compete at the level of the colony. Fusion-rejection genes act to control the units (or targets) of selection.

BIOLOGY OF HYDRACTINIID HYDROIDS. 2. HISTOCOMPATIBILITY EFFECTOR SYSTEM/COMPETITIVE MECHANISM MEDIATED BY NEMATOCYST DISCHARGE

Intraspecific encounters between colonies of the athecate, colonial hydroid Hydractinia echinata result in contact between mat or stolonal tissues. We have monitored colony ontogeny in five clones of H. echinata and initiated experimental encounters between the two tissue types in both isogeneic and allogeneic combinations. All isogeneic interactions result in fusion, all allogeneic interactions in rejection. Transmission electron microscopy shows that fusion results in the establishment of a common gastrovascular system, whereas rejection is characterized by an electrondense, fibrous layer separating the two colonies. Rejection involves either the passive cessation of growth along the contact zone or the development of hypertrophied stolons. These hyperplastic stolons destroy foreign tissues and can develop only from existing stolons. Scanning and transmission electron microscopy demonstrates that stolons become hyperplastic through the differentiation of interstitial cells into nematocytes and that the ...

The Phylum Vendobionta: a sister group of the Eumetazoa?

We offer an alternative interpretation of the Kingdom Vendobionta as a monophyletic sister group to the Eumetazoa. We hypothesize that the Vendobionta are cnidarian-like organisms that lacked cnidae. Cnidarians are held to have arisen by acquisition of cnidae by symbiosis with a microsporidian. Our analysis differs from existing interpretations of the Ediacaran fossils as ancestors of extant cnidarians in that we do not regard any of these forms as either polypoid or medusoid. This interpretation requires the erection of a new metazoan phylum, the Vendobionta.

A Hypervariable Invertebrate Allodeterminant

Colonial marine invertebrates, such as sponges, corals, bryozoans, and ascidians, often live in densely populated communities where they encounter other members of their species as they grow over their substratum. Such encounters typically lead to a natural histocompatibility response in which colonies either fuse to become a single, chimeric colony or reject and aggressively compete for space. These allorecognition phenomena mediate intraspecific competition, support allotypic diversity, control the level at which selection acts, and resemble allogeneic interactions in pregnancy and transplantation. Despite the ubiquity of allorecognition in colonial phyla, however, its molecular basis has not been identified beyond what is currently known about histocompatibility in vertebrates and protochordates. We positionally cloned an allorecognition gene by using inbred strains of the cnidarian, Hydractinia symbiolongicarpus, which is a model system for the study of invertebrate allorecognition. The gene identified encodes a putative transmembrane receptor expressed in all tissues capable of allorecognition that is highly polymorphic and predicts allorecognition responses in laboratory and field-derived strains. This study reveals that a previously undescribed hypervariable molecule bearing three extracellular domains with greatest sequence similarity to the immunoglobulin superfamily is an allodeterminant in a lower metazoan.

Determination of paternity in dragonflies by Random Amplified Polymorphic DNA fingerprinting

We used Random Amplified Polymorphic DNA (RAPD) fingerprinting to address issues of paternity in two odonate species. Amplification artifacts of RAPD markers were controlled by assessing paternity patterns relative to the banding patterns generated by quantitative mixtures of DNA from putative parents (‘synthetic offspring’). In the aeshnid dragonfly Anax parthenope, for which the mating histories of both males and females were unknown, we found strong evidence for complete paternity success for the contact guarding male. In the highly polygamous libellulid dragonfly Orthetrum coerulescens, we detected and quantified mixed paternity in sequentially produced offspring clutches and demonstrated that fertilization success is correlated with the duration of copulation. Our results suggest that RAPD fingerprinting is suitable to address issues of paternity in systems which are genetically uncharacterized and produce large offspring clutches.