Most other shell forming organisms appear during the Cambrian period, with the Bryozoans being the only calcifying phylum to appear later, in the Ordovician.

Bryozoans form colonies consisting of clones called zooids that are typically about long.

Bryozoans are small and the skeletons of crinoids disintegrate.

Bryozoans, phoronids and brachiopods strain food out of the water by means of a lophophore, a " crown " of hollow tentacles.

Bryozoans have spread diseases to fish farms and fishermen.

Bryozoans and crinoids, common contributors to marine sediments during the Mississippian ( for example ), produced a very different kind of mound.

The origins and evolutionary relationships between the three main groups of amphibians is a matter of debate.

Future molecular studies should provide further insights into their evolutionary relationships.

Botany covers a wide range of scientific disciplines including structure, growth, reproduction, metabolism, development, diseases, chemical properties, and evolutionary relationships among taxonomic groups.

The ideas of natural selection as a mechanism for evolution required adaptations to the Candollean system, which started the studies on evolutionary relationships and phylogenetic classifications of plants.

Attempts to work out the evolutionary relationships of the chordates have produced several hypotheses.

Note: lines show evolutionary relationships.

The outcome of a cladistic analysis is a cladogram – a tree-shaped diagram ( dendrogram ) that represents a phylogenetic hypothesis, a hypothesis on evolutionary relationships.

Examination of the pol genes that encode the DNA dependent DNA polymerase in various groups of viruses suggests a number of possible evolutionary relationships.

In determining the relationships between " phylogenetic linkages " and " evolutionary laws of form ," both Gegenbaur and Haeckel relied on a method of comparison.

The study of fossils across geological time, how they were formed, and the evolutionary relationships between taxa ( phylogeny ) are some of the most important functions of the science of paleontology.

Research is ongoing into the genetic relationships among killer whale types, and whether these types represent deep evolutionary trends.

Representing presumptive evolutionary relationships, especially given the wide acceptance of cladistic methodology and numerous molecular phylogenies that have challenged long-accepted classifications, within the framework of Linnaean taxonomy, is sometimes seen as problematic.

* Evolutionary tree — a way to express insights into evolutionary relationships

The overall goal of National Science Foundation's Assembling the Tree of Life activity ( AToL ) is to resolve evolutionary relationships for large groups of organisms throughout the history of life, with the research often involving large teams working across institutions and disciplines.

Phenetics has largely been superseded by cladistics for research into evolutionary relationships among species.

In general, phenetics is today recognized to provide too much unreliable information about the evolutionary relationships among taxa to remain a mainstay method.

But there is no reason why e. g. species identified using phenetics cannot subsequently be subjected to cladistic analysis, to determine their evolutionary relationships.

Traditionally there was a great deal of heated debate between pheneticists and cladists, as both methods were initially proposed to resolve evolutionary relationships.

The evolutionary relationships of the tree of life were refined using genetic data by the American microbiologist Carl Woese, the discoverer of the domain Archaea and a pioneer in molecular ( genetic ) methods in evolutionary biology.

Taxa in virology are not necessarily monophyletic, as the evolutionary relationships of the various virus groups remain unclear.

Future studies of molecular genetics should provide further insights into the evolutionary relationships among anuran families.

The origins and evolutionary relationships between the three main groups of amphibians is hotly debated.

The use of techniques such as DNA-DNA hybridization to study evolutionary relationships was pioneered by Charles Sibley and Jon Edward Ahlquist resulting in what is called the Sibley-Ahlquist taxonomy.

Group selection theory has criticized by many other evolutionary scientists.

However, this theory is undermined by the disproportional fear of spiders in comparison to other, potentially dangerous creatures that were present during Homo sapiens environment of evolutionary adaptiveness.

Wallace was one of the leading evolutionary thinkers of the 19th century and made a number of other contributions to the development of evolutionary theory besides being co-discoverer of natural selection.

This accompanied or facilitated other important evolutionary developments: the bilaterian body plan ; the coelom, an internal cavity that provided space for a circulatory system and, in some animals, formed a hydrostatic skeleton which enables worm-like animals to burrow ; metamerism, in which the body was built of repeated " modules " which could later specialize, for example the heads of most arthropods are composed of fused, specialized segments.

These individuals and the work of other biostatisticians, mathematical biologists, and statistically inclined geneticists helped bring together evolutionary biology and genetics into a consistent, coherent whole that could begin to be quantitatively modeled.

Scientists currently think that cnidarians, ctenophores and bilaterians are more closely related to calcareous sponges than these are to other sponges, and that anthozoans are the evolutionary " aunts " or " sisters " of other cnidarians, and the most closely related to bilaterians.

In " Intimate Behaviour " Morris studies the human side of intimate behaviour by comparing mans earlier evolutionary psychology to that of modern man and how man copes with an increasingly rigid society empty of physical interaction in public by enacting intimate behaviour in other forms in private or deviant behaviour in public.

Darwinism also is used neutrally by historians to differentiate his theory from other evolutionary theories current around the same period.

This stems from Gould's long-running public debate with E. O. Wilson and other evolutionary biologists over human sociobiology and its descendant evolutionary psychology, which Gould and Richard Lewontin opposed, but which Dennett advocated, together with Dawkins and Steven Pinker.

In many of his writings, Mayr rejected reductionism in evolutionary biology, arguing that evolutionary pressures act on the whole organism, not on single genes, and that genes can have different effects depending on the other genes present.

Proponents of EP suggest that it seeks to integrate psychology into the other natural sciences, rooting it in the organizing theory of biology ( evolutionary theory ), and thus understanding psychology as a branch of biology.

Domain-general mechanisms, on the other hand, are proposed to deal with evolutionary novelty.

Human evolutionary genetics studies how one human genome differs from the other, the evolutionary past that gave rise to it, and its current effects.

In other words, H. floresiensis shares a common ancestor with modern humans, but split from the modern human lineage and followed a distinct evolutionary path.

Other reported evolutionary trends in other populations include a lengthening of the reproductive period, reduction in cholesterol levels, blood glucose and blood pressure.

Gaia concept draws a connection between the survivability of a species ( hence its evolutionary course ) and its usefulness to the survival of other species.

Some evolutionary biologists, on the other hand, view it as an undirected emergent property of the ecosystem: as each individual species pursues its own self-interest, their combined actions tend to have counterbalancing effects on environmental change.

* " The Hound of Heaven " was mentioned in the suicide note of George R. Price, a geneticist who pioneered the evolutionary theory of altruism and suicide ( among other things ), before becoming a committed Christian and giving away all his possessions to the poor.

It can be seen as one form of altruism for which there are also several other evolutionary explanations.