Evolutionary Developmental Biology

Differential impact of nutrition on developmental and metabolic gene expression during fruiting body development in Neurospora crassa

by Jeffrey Townsend

Fungal fruiting body size and form are influenced by the ecology of the species, including diverse environmental... more Fungal fruiting body size and form are influenced by the ecology of the species, including diverse environmental stimuli. Accordingly, nutritional resources available to the fungus during development can be vital to successful production of fruiting bodies. To investigate the effect of nutrition, perithecial development of Neurospora crassa was induced on two different media, a chemically sparsely nutritive Synthetic Crossing Medium (SCM) and a natural Carrot Agar (CA). Protoperithecia were collected before crossing, and perithecia were collected at 2, 24, 48, 72, 96, 120, and at full maturity 144h after crossing. No differences in fruiting body morphology were observed between the two media at any time point. A circuit of microarray hybridizations comparing cDNA from all neighboring stages was performed. For a majority of differentially expressed genes, expression was higher in SCM than in CA, and expression of core metabolic genes was particularly affected. Effects of nutrition were highest in magnitude before crossing, lowering in magnitude during early perithecial development. Interestingly, metabolic effects of the media were also large in magnitude during late perithecial development, at which stage the lower expression in CA presumably reflected the continued intake of diverse complex initial compounds, diminishing the need for expression of anabolic pathways. However, for genes with key regulatory roles in sexual development, including pheromone precursor ccg-4 and poi2, expression patterns were similar between treatments. When possible, a common nutritional environment is ideal for comparing transcriptional profiles between different fungi. Nevertheless, the observed consistency of the developmental program across media, despite considerable metabolic differentiation is reassuring. This result facilitates comparative studies that will require different nutritional resources for sexual development in different fungi.

Developmental plasticity and human health

by Debal Deb

Early Evolutionary Trends In Ammonoid Embryonic Development

by Kenneth De Baets

De Baets, K., Klug, C., Korn, D. & Landman, N. H. (2012). Evolution. doi: 10.1111/j.1558-5646.2011.01567.x

During the Devonian Nekton Revolution, ammonoids show a progressive coiling of their shell just like many other... more During the Devonian Nekton Revolution, ammonoids show a progressive coiling of their shell just like many other pelagic mollusk groups. These now extinct, externally shelled cephalopods derived from bactritoid cephalopods with a straight shell in the Early Devonian. During the Devonian, evolutionary trends toward tighter coiling and a size reduction occurred in ammonoid embryonic shells. In at least three lineages, descendants with a closed umbilicus evolved convergently from forms with an opening in the first whorl (umbilical window). Other lineages having representatives with open umbilici became extinct around important Devonian events while only those with more tightly coiled embryonic shells survived. This change was accompanied by an evolutionary trend in shape of the initial chamber, but no clear trend in its size. The fact that several ammonoid lineages independently reduced and closed the umbilical window more or less synchronously indicates that common driving factors were involved. A trend in size decrease of the embryos as well as the concurrent increase in adult size in some lineages likely reflects a fundamental change in reproductive strategies toward a higher fecundity early in the evolutionary history of ammonoids. This must have played an important role in their subsequent success as well as in their demise.

Evolution of ruminant headgear: a review

by K Brakora

Open access / free download of full paper

The horns, ossicones and antlers of ruminants are familiar and diverse examples of cranial appendages. We collectively... more The horns, ossicones and antlers of ruminants are familiar and diverse examples of cranial appendages. We collectively term ruminant cranial appendages ‘headgear’; this includes four extant forms: antlers (in cervids), horns (in bovids), pronghorns (in pronghorn antelope) and ossicones (in giraffids). Headgear evolution remains an open and intriguing question because phylogenies (molecular and morphological), adult headgear structure and headgear development (where data are available) all suggest different pictures of ruminant evolution. We discuss what is known about the evolution of headgear, including the evidence motivating previous hypotheses of single versus multiple origins, and the implications of recent phylogenetic revisions for these hypotheses. Inclusion of developmental data is critical for progress on the question of headgear evolution, and we synthesize the scattered literature on this front. The areas most in need of attention are early development in general; pronghorn and ossicone development in particular; and histological study of fossil forms of headgear. An integrative study of headgear development and evolution may have ramifications beyond the fields of systematics and evolution. Researchers in organismal biology, as well as those in biomedical fields investigating skin, bone and regenerative medicine, may all benefit from insights produced by this line of research.

The Role of Notch Signalling and Numb Function In Mechanosensory Organ Formation In the Spider Cupiennius Salei

by Katrina Gold

Evolution and Anarchism in International Relations: The Challenge of Kropotkin's Biological Ontology

by Adam Goodwin

Millennium - Journal of International Studies 2010 39: 417

This article will utilise Peter Kropotkin’s theory of Mutual Aid to reconsider ontology in International Relations... more This article will utilise Peter Kropotkin’s theory of Mutual Aid to reconsider ontology in International Relations (IR). Mutual Aid Theory holds that the evolution of organisms is shaped by cooperation within a group of species against a variable ecology; thus giving rise to a sociality instinct. This is contrasted with the Malthusian assumption that evolution takes place at the individual level according to their intraspecific fitness. Mutual Aid Theory, applied to the realm of politics, overturns collective-action-problem-grounded theories that hold that the egoistic and competitive drive of humans must be overcome to promote cooperation. Bradley Thayer applied the orthodox individual-fitness interpretation of evolution in an attempt to shore up realist arguments. I argue that such reductionist approaches to studying politics are archaic and not congruent with current scientific understanding. A Critical Realist (CR) approach, placing analytical priority on ontological investigations over epistemological/methodological commitments, is employed to assist in the criticism of orthodox reductionist ontologies. However, equally in line with Kropotkin’s Anarchist ideas, I argue that this critical realist approach also provokes ontologically-driven inquiries into post-sovereignty global politics and can inform the emancipatory intent of Critical IR theory, along side the basic Anarchist ontological claim: society precedes the State.

Testing the phylogenetic position of fossil pancrustacean larvae: a semaphoront-based coding system

by Jo Wolfe

Wolfe JM, Hegna TA

Working title, in prep Working title, in prep

Effaced preservation in the Ediacara biota and its implications for the early macofossil record

by Martin Brasier

With Alex Liu, Duncan McIlroy and Jonathan Antcliffe

Evolutionary reduction of the first thoracic limb in butterflies

by Jo Wolfe

Wolfe JM, Oliver JC, Monteiro A. 2011. Journal of Insect Science 11: 66 (available online: insectscience.org/11.66).

Members of the diverse butterfly families Nymphalidae (brush-footed butterflies) and Riodinidae (metalmarks) have... more Members of the diverse butterfly families Nymphalidae (brush-footed butterflies) and Riodinidae (metalmarks) have reduced first thoracic limbs and only use two pairs of legs for walking. In order to address questions about the detailed morphology and evolutionary origins of these reduced limbs, the three thoracic limbs of 13 species of butterflies representing all six butterfly families were examined and measured, and ancestral limb sizes were reconstructed for males and females separately. Differences in limb size across butterflies involve changes in limb segment size rather than number of limb segments. Reduction of the first limb in both nymphalids and riodinids appears particularly extensive in the femur but the evolution of these reduced limbs is suggested to be a convergent evolutionary event. Possible developmental differences as well as ecological factors driving the evolution of reduced limbs are discussed.

Degeneracy at Multiple Levels of Complexity

by Paul Mason

"published in 'Biological Theory: Integrating Development, Evolution and Cognition', 2010, 5(3), 277-288."

Degeneracy is a poorly understood process, essential to natural selection. In the 18th and 19th centuries, the concept... more Degeneracy is a poorly understood process, essential to natural selection. In the 18th and 19th centuries, the concept of degeneracy was commandeered by the colonial imagination. A rigid understanding of species, race, and culture grew to dominate the normative thinking that persisted well into the burgeoning new industrial age. A 20th-century reconfiguration of the concept by George Gamow highlighted a form of intraorganismic variation that is still underexplored. Degeneracy exists in a population of variants where structurally different components perform a similar, but not necessarily identical, function with respect to context. The presence of degeneracy increases a system's complexity and robustness against perturbations. The loss of a genetic component in biological systems, for example, can be compensated by redundant elements (the presence of isomorphic and isofunctional components), or by degenerate elements (heteromorphic variants that are isofunctional). A historical survey of the use of the term “degeneracy” reveals how and why the processes it once designated, and the mechanisms it now represents, have largely escaped the purview of contemporary science. Despite confusion and general oversight, degeneracy has been characterized by select researchers at the molecular, genetic, and neuronal levels. The concept is a potent analytical tool to understand selection, variation, and transmission.