Direct Evidence of Ancient Symbiosis Using Trace Fossils

2008 ◽  
Vol 14 ◽  
pp. 271-287 ◽  
Author(s):  
Leif Tapanila
Keyword(s):  
Fossil Record ◽  
Direct Evidence ◽  
Spatial Competition ◽  
Adaptive Strategy ◽  
Negative Effects ◽  
Symbiotic Associations ◽  
Negative Change ◽  
Intimate Association ◽  
Host Taxon ◽  
Levels Of Integration

Symbiotic associations are a poorly studied aspect of the fossil record, owing largely to the taphonomic biases that inhibit direct observation that two organisms shared an intimate association in life. A symbiosis between an infesting animal and a skeleton-producing host can form a bioclaustration cavity that directly preserves the association and has a high preservation potential. Identification of ancient mutuals and parasites must reject the null hypothesis of commensalism by demonstrating that the symbiosis correlates with a positive or negative change in host fitness as compared to a non-symbiotic relative of the host taxon. Reviews of the Paleozoic record of marine symbionts show that the majority are hosted by colonial animals, especially corals and calcareous sponges. These hosts include structural forms that have moderate to high levels of integration and can support bioclaustrations between clonal units, mitigating the negative effects of symbionts, and perhaps facilitating the symbiosis.The fossil record is biased toward recording long-lasting, widespread, equilibrated associations. By contrast, parasitisms that are especially negative to the host are expected to be fossilized rarely. The symbiotic associations that form bioclaustrations may also represent an endolithic adaptive strategy in response to biological antagonisms, such as predation and spatial competition. The Late Ordovician rise in symbiotic bioclaustrations joins burrows and borings as trace fossil examples of infaunalization strategies that accompany the Ordovician faunal radiation.

scholarly journals Naticid gastropod and octopodid cephalopod predatory traces: evidence of drill holes on the leucosid crab Ristoria pliocaenica (Ristori, 1891), from the Pliocene of the “La Serra” quarry (Tuscany, Italy)

10.4081/19 ◽  
2012 ◽  
Vol 153 (2) ◽  
pp. 257 ◽  
Author(s):  
Giovanni Pasini ◽  
Alessandro Garassino
Keyword(s):  
Fossil Record ◽  
Direct Evidence ◽  
Central Italy ◽  
Decapod Crustaceans ◽  
Early Pliocene ◽  
First Report ◽  
Predatory Activity ◽  
The Common ◽  
Drill Holes

Garassino<em> et al.</em> (2012) reported on a rich community of decapod crustaceans including axiideans, gebiideans, anomurans, and brachyurans from the Zanclean (Early Pliocene) of the “La Serra” quarry near San Miniato (Pisa, Tuscany, central Italy). In this decapod-rich assemblage some carapaces of the common pebble crab<em> Ristoria pliocaenica</em> (Ristori, 1891) (<em>Leucosiidae Samouelle</em>, 1819) are drilled in characteristic ways, due to the predatory activity of individuals belonging to two different taxa of marine clades, possibly naticids (Gastropoda, Naticoidea), and to octopodids (Cephalopoda, Octopoda). This is the first report of direct evidence of predation by cephalopods on crabs in the fossil record.

scholarly journals Genome-Wide Dissection of the CRF Gene Family in Brassica napus Indicates that BnaCRF8s Specifically Regulate Root Architecture and Phosphate Homeostasis against Phosphate Fluctuation in Plants

2020 ◽  
Vol 21 (10) ◽  
pp. 3660
Author(s):  
Sheliang Wang ◽  
Hao Zhang ◽  
Lei Shi ◽  
Fangsen Xu ◽  
Guangda Ding
Keyword(s):  
Brassica Napus ◽  
Plant Growth ◽  
Root Architecture ◽  
Time Course ◽  
Primary Root ◽  
Adaptive Strategy ◽  
Negative Effects ◽  
Response Factors ◽  
Pi Homeostasis ◽  
Genome Wide

Phosphorus (P) is an essential macronutrient required for plant growth and development. The involvement of cytokinin response factors (CRFs) in phosphate (Pi) homeostasis and lateral root (LR) initiation in Arabidopsis has been revealed. However, little is known in oil crops. Here, we performed genome-wide dissection of the CRF family in Brassica napus to identify 44 members, which were evolutionally classified into 6 subgroups. Among them, four BnaCRF8 genes were strongly upregulated by P deprivation, and were selected to be further investigated. Time course qRT-PCR analyses showed that four BnaCRF8 genes were enhanced dramatically after 12 h of P stress. Analyses of the subcellular localization in tobacco leaves indicated that BnaA7.CRF8 and BnaC2.CRF8 were localized in the nucleus. The expression of BnaCRF8 genes had constant negative effects on primary root growth and LR initiation and growth, and it reduced Pi acquisition and plant growth in Arabidopsis. Moreover, the expression of Pi homeostasis-related genes was modulated in BnaA7.CRF8 overexpression plants. These results suggest that BnaCRF8 genes might negatively regulate root architecture and plant growth through transcriptional modification of Pi homeostasis-related components. Overall, this study suggests that upregulation of BnaCRF8 genes might be a smart adaptive strategy to cope with continuous Pi deficiency in the environment.

Asymmetry in the fossil record

2005 ◽  
Vol 13 (S2) ◽  
pp. 135-143 ◽  
Author(s):  
LOREN E. BABCOCK
Keyword(s):  
Fossil Record ◽  
Direct Evidence ◽  
Directional Asymmetry ◽  
Fundamental Aspect ◽  
Lateral Asymmetry ◽  
Morphological Asymmetry ◽  
Fossil Evidence ◽  
Behavioural Asymmetries ◽  
Life On Earth ◽  
Body Fossil

Asymmetry is a fundamental aspect of the biology of all organisms, and has a deep evolutionary history. The fossil record contains evidence of both morphological and behavioural asymmetries. Morphological asymmetry is most commonly expressed as conspicuous, directional asymmetry (either lateral asymmetry or spiral asymmetry) in body fossils. Few examples of fluctuating asymmetry, a form of subtle asymmetry, have been documented from fossils. Body fossil evidence indicates that morphological asymmetry dates to the time of the appearance of the first life on Earth (Archaean Eon). Behavioural asymmetry can be assumed to have been concomitant with conspicuous morphological asymmetry, but more direct evidence is in the form of trace fossils. Trace fossil evidence suggests that behavioural asymmetry, including nervous system lateralization, was in existence by the beginning of the Palaeozoic Era.

New mixosaurid ichthyosaur specimen from the Middle Triassic of SW China: further evidence for the diapsid origin of ichthyosaurs

2011 ◽  
Vol 85 (1) ◽  
pp. 32-36 ◽  
Author(s):  
Jun Liu ◽  
Jonathan C. Aitchison ◽  
Yuan-Yuan Sun ◽  
Qi-Yue Zhang ◽  
Chang-Yong Zhou ◽  
...  
Keyword(s):  
Fossil Record ◽  
Direct Evidence ◽  
Middle Triassic ◽  
Evolutionary Stage ◽  
Temporal Region ◽  
Sw China ◽  
Anterior Process ◽  
Cladistic Analyses

Recent cladistic analyses have all suggested a diapsid origin of ichthyosaurs. However, an intermediate evolutionary stage of the lower temporal region of ichthyosaurian skull between basal diapsids and derived ichthyosaurs has been absent from the fossil record. Here we describe the cranial skeleton of a new mixosaurid ichthyosaur specimen with a well-preserved lower temporal region from the Anisian Guanling Formation of eastern Yunnan. It is characterized by the most primitive lower temporal region within known ichthyosaurs. The primitive characters of the lower temporal region include both external and internal separation between the jugal and the quadratojugal, an anterior process of the quadratojugal, an apparent posteroventral process of the jugal, and a large lower temporal opening surrounded by the jugal, the postorbital, the squamosal, and the quadratojugal. The lower temporal region of this specimen provides the most direct evidence to the diapsid origin of ichthyosaurs. It also suggests that the disappearance of the lower temporal fenestra is caused initially by the reduction of the lower temporal arcade rather than the enlargement of the surrounding bones.

scholarly journals Identification of NRPS gene families from Neotyphodium/Epichloe endophytic fungi that form mutualistic associations with cool season grasses

2007 ◽  
Vol 13 ◽  
pp. 495-499
Author(s):  
R.D. Johnson ◽  
C.R. Voisey ◽  
J.M. Pratt ◽  
L.J. Johnson ◽  
G.T. Bryan
Keyword(s):  
Gene Family ◽  
Endophytic Fungi ◽  
Gene Families ◽  
Grass Species ◽  
Negative Effects ◽  
Cool Season ◽  
Nrps Gene ◽  
Diverse Range ◽  
Symbiotic Associations ◽  
Niche Adaptation

Neotyphodium and Epichloë species are closely related asexual and sexual endophytic fungi, respectively, that form symbiotic associations with cool season grasses of the sub family Pooideae, including several important forage and turf grass species. The endophytes confer a number of advantages to their hosts, but also can cause animal toxicosis. These positive and negative effects are, in many cases, due to the production of fungal secondary metabolites. In filamentous fungi secondary metabolite genes are commonly clustered and are well documented to often contain non-ribosomal peptide synthetases (NRPSs) at their core. Members of this gene family encode large multifunctional proteins that synthesise a diverse range of bioactive compounds, many of which have been shown to serve as pathogenicity or virulence factors, in addition to suggested roles in niche adaptation. We have used a degenerate PCR approach to identify members of the NRPS gene family from Neotyphodium and Epichloë species, and have shown that at least 13 NRPS genes exist among these genomes. The distribution of these genes among different Neotyphodium/Epichloë lineages suggests that a common ancestor contributed most of the complement of NRPS genes, which have been either retained or lost during the evolution of these fungi. Keywords: Neotyphodium, Epichloë, non-ribosomal peptide synthetase, NRPS

scholarly journals The impact of the spatial heterogeneity of resistant cells and fibroblasts on treatment response

2021 ◽  
Author(s):  
Masud M.A ◽  
Jae-Young Kim ◽  
Cheol-Ho Pan ◽  
Eunjung Kim
Keyword(s):  
Cancer Cell ◽  
Spatial Competition ◽  
Adaptive Strategy ◽  
Maximum Tolerated Dose ◽  
Resistant Cell ◽  
Drug Resistant ◽  
Continuous Therapy ◽  
The Impact ◽  
Adaptive Therapy ◽  
Resistant Cells

A long-standing practice in the treatment of cancer is that of hitting hard with the maximum tolerated dose to eradicate tumors. This continuous therapy, however, selects for resistant cells, leading to the failure of the treatment. A different type of treatment strategy, adaptive therapy, has recently been shown to have a degree of success in both preclinical xenograft experiments and clinical trials. Adaptive therapy is used to maintain a tumor's volume by exploiting the competition between drug-sensitive and drug-resistant cells with minimum effective drug doses or timed drug holidays. To further understand the role of competition in the outcomes of adaptive therapy, we developed a 2D on-lattice agent-based model. Our simulations show that the superiority of the adaptive strategy over continuous therapy depends on the local competition shaped by the spatial distribution of resistant cells. Cancer cell migration and increased carrying capacity accelerate the progression of the tumor under both types of treatments by reducing the spatial competition. Intratumor competition can also be affected by fibroblasts, which produce microenvironmental factors that promote cancer cell growth. Our simulations show that the spatial architecture of fibroblasts modulates the benefits of adaptive therapy. Finally, as a proof of concept, we simulated the outcomes of adaptive therapy in multiple metastatic sites composed of different spatial distributions of fibroblasts and drug-resistant cell populations.

scholarly journals Prey choice and cannibalistic behaviour in the theropod Coelophysis

2006 ◽  
Vol 2 (4) ◽  
pp. 611-614 ◽  
Author(s):  
Sterling J Nesbitt ◽  
Alan H Turner ◽  
Gregory M Erickson ◽  
Mark A Norell
Keyword(s):  
Histological Examination ◽  
Fossil Record ◽  
Direct Evidence ◽  
Stomach Contents ◽  
Gut Contents ◽  
Prey Choice ◽  
Cannibalistic Behaviour ◽  
Coelophysis Bauri

Abstract Direct evidence of prey choice in carnivorous dinosaurs is rare in the fossil record. The most celebrated example pertains to purported stomach contents in the carnivorous dinosaur Coelophysis bauri , which besides revealing prey choice, also points to cannibalistic behaviour as being commonplace ( Colbert 1989 , 1995). Here, we test this hypothesis by conducting the first comprehensive anatomical and histological examination of the famed Coelophysis ‘cannibals’. The results unequivocally show that the gut contents derive from early crocodylomorphs rather than juveniles of Coelophysis . These findings suggest that this taxon is not cannibalistic and bring into question the commonality of this behaviour among non-avian dinosaurs.

scholarly journals Humble origins for a successful strategy: complete enrolment in early Cambrian olenellid trilobites

2013 ◽  
Vol 9 (5) ◽  
pp. 20130679 ◽  
Author(s):  
Javier Ortega-Hernández ◽  
Jorge Esteve ◽  
Nicholas J. Butterfield
Keyword(s):  
Environmental Conditions ◽  
Fossil Record ◽  
Direct Evidence ◽  
Morphological Features ◽  
Early Cambrian ◽  
Defence Mechanism ◽  
Successful Strategy ◽  
New Information ◽  
Adverse Environmental Conditions ◽  
Morphological Ability

Trilobites are typified by the behavioural and morphological ability to enrol their bodies, most probably as a defence mechanism against adverse environmental conditions or predators. Although most trilobites could enrol at least partially, there is uncertainty about whether olenellids—among the most phylogenetically and stratigraphically basal representatives—could perform this behaviour because of their poorly caudalized trunk and scarcity of coaptative devices. Here, we report complete—but not encapsulating—enrolment for the olenellid genus Mummaspis from the early Cambrian Mural Formation in Alberta, the earliest direct evidence of this strategy in the fossil record of polymerid trilobites. Complete enrolment in olenellids was achieved through a combination of ancestral morphological features, and thus provides new information on the character polarity associated with this key trilobite adaptation.

Testing the time axis of phylogenies

1995 ◽  
Vol 349 (1327) ◽  
pp. 5-10 ◽  
Keyword(s):  
Phylogenetic Analysis ◽  
Fossil Record ◽  
Direct Evidence ◽  
Phylogeny Reconstruction ◽  
Time Axis ◽  
Historical Events ◽  
Subsequent Evolution ◽  
The Past ◽  
Fossil Data

Fossils are not perfect materials for phylogenetic analysis because of problems of missing characters and missing taxa. However, fossils have three major advantages: (1) they give the only direct evidence of the order of acquisition of characters, (2) they frequently present character combinations not found in modern forms, and (3) they may allow the coding of characters that have been overwritten by subsequent evolution within a clade. There are three independent sources of evidence about sequences of historical events in evolution - morphological, molecular and stratigraphic - and these may be mutually cross- tested. Tests of the quality of the fossil record against morphological cladistic data show that (1) age and clade data on branching sequences generally agree, (2) knowledge of the fossil record has improved by 5% over the past 26 years of research, and (3) the fossil record of continental vertebrates is as good as that of (marine) echinoderms. Hence, systematists and evolutionary biologists may use fossil data with confidence in phylogeny reconstruction and to calibrate the time axis of phylogenies.

scholarly journals Early Cambrian record of failed durophagy and shell repair in an epibenthic mollusc

2007 ◽  
Vol 3 (3) ◽  
pp. 314-317 ◽  
Author(s):  
Christian B Skovsted ◽  
Glenn A Brock ◽  
Anna Lindström ◽  
John S Peel ◽  
John R Paterson ◽  
...  
Keyword(s):  
Fossil Record ◽  
Direct Evidence ◽  
Driving Forces ◽  
South Australia ◽  
Early Cambrian ◽  
Metazoan Evolution ◽  
Flinders Ranges ◽  
Shell Repair ◽  
Early Metazoan

Predation is arguably one of the main driving forces of early metazoan evolution, yet the fossil record of predation during the Ediacaran–Early Cambrian transition is relatively poor. Here, we present direct evidence of failed durophagous (shell-breaking) predation and subsequent shell repair in the Early Cambrian (Botoman) epibenthic mollusc Marocella from the Mernmerna Formation and Oraparinna Shale in the Flinders Ranges, South Australia. This record pushes back the first appearance of durophagy on molluscs by approximately 40 Myr.

Sign in / Sign up

Export Citation Format

Share Document