scholarly journals Nonlinear acoustic complexity in a fish ‘two-voice’ system

2011 ◽  
Vol 278 (1725) ◽  
pp. 3762-3768 ◽  
Author(s):  
Aaron N. Rice ◽  
Bruce R. Land ◽  
Andrew H. Bass
Keyword(s):  
Social Communication ◽  
Selection Pressure ◽  
Motor System ◽  
Sound Production ◽  
Nonlinear Characteristics ◽  
Strong Selection ◽  
Vocal Signals ◽  
Nonlinear Acoustic ◽  
Selection For ◽  
Mathematical Analyses

Acoustic signals play essential roles in social communication and show a strong selection for novel morphologies leading to increased call complexity in many taxa. Among vertebrates, repeated innovations in the larynges of frogs and mammals and the syrinx of songbirds have enhanced the spectro-temporal content, and hence the diversity of vocalizations. This acoustic diversification includes nonlinear characteristics that expand frequency profiles beyond the traditional categorization of harmonic and broadband calls. Fishes have remained a notable exception to evidence for such acoustic innovations among vertebrates, despite their being the largest group of living vertebrates that also exhibit widespread evolution of sound production. Here, we combine rigorous acoustic and mathematical analyses with experimental silencing of the vocal motor system to show how a novel swim bladder mechanism in a toadfish enables it to generate calls exhibiting nonlinearities like those found among frogs, birds and mammals, including primates. By showing that fishes have evolved nonlinear acoustic signalling like all other major lineages of vocal vertebrates, these results suggest strong selection pressure favouring this mechanism to enrich the spectro-temporal content and complexity of vocal signals.

scholarly journals Selection for Reinforcement-Free Learning Ability as an Organizing Factor in the Evolution of Cognition

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Solvi Arnold ◽  
Reiji Suzuki ◽  
Takaya Arita
Keyword(s):  
Selection Pressure ◽  
Learning Ability ◽  
Environmental Complexity ◽  
Baldwin Effect ◽  
Neural Structure ◽  
Neural Organization ◽  
Environmental Structure ◽  
Selection For ◽  
Efficient Learning ◽  
Complexity Thesis

This research explores the relation between environmental structure and neurocognitive structure. We hypothesize that selection pressure on abilities for efficient learning (especially in settings with limited or no reward information) translates into selection pressure on correspondence relations between neurocognitive and environmental structure, since such correspondence allows for simple changes in the environment to be handled with simple learning updates in neurocognitive structure. We present a model in which a simple form of reinforcement-free learning is evolved in neural networks using neuromodulation and analyze the effect this selection for learning ability has on the virtual species' neural organization. We find a higher degree of organization than in a control population evolved without learning ability and discuss the relation between the observed neural structure and the environmental structure. We discuss our findings in the context of the environmental complexity thesis, the Baldwin effect, and other interactions between adaptation processes.

scholarly journals The return to water in ancestral Xenopus was accompanied by a novel mechanism for producing and shaping vocal signals

2018 ◽  
Author(s):  
Ursula Kwong-Brown ◽  
Martha L. Tobias ◽  
Damian O. Elias ◽  
Ian C. Hall ◽  
Coen P.H. Elemans ◽  
...  
Keyword(s):  
Sound Production ◽  
Neuromuscular Control ◽  
Current Theory ◽  
Species Divergence ◽  
Species Identity ◽  
Rapid Separation ◽  
Resonance Modes ◽  
Acoustic Signature ◽  
Vocal Signals ◽  
Species Specific

AbstractSpecies-specific vocal signals allow listeners to locate potential mates. During the tetrapod transition from water to land, lungs replaced gills, allowing expiration to drive sound production. Several groups, e.g. cetaceans and some frogs, then returned to water. Here we explore how air-driven sound production changed upon re-entry and how essential acoustic information on species identity was preserved in the secondarily aquatic frog Xenopus. We filmed movements of cartilage and muscles during evoked sound production in isolated larynges. Our results refute the current theory for Xenopus vocalization, cavitation, and instead favor sound production by mechanical excitation of laryngeal resonance modes following rapid separation of laryngeal arytenoid discs. The resulting frequency resonance modes (dyads) are intrinsic to the larynx rather than due to neuromuscular control. We show that dyads are a distinctive acoustic signature across species. While dyad component frequencies overlap across species, their ratio is shared within each Xenopus clade and thus provide information on species identity, potentially facilitating both conspecific localization and ancient species divergence.

The Role of Copy Number Variation in Psychiatric Disorders

2018 ◽  
pp. 84-95
Author(s):  
Elliott Rees ◽  
George Kirov
Keyword(s):  
Autism Spectrum Disorders ◽  
Copy Number ◽  
Selection Pressure ◽  
Copy Number Variants ◽  
Autism Spectrum ◽  
High Odds ◽  
Strong Selection ◽  
Increase Risk ◽  
Number Variation

Copy number variants (CNVs) are deletions, duplications, inversions, or translocations of large DNA segments. They can play a significant role in human disease. Thirteen CNVs have received strong statistical support for involvement in schizophrenia. They are all rare in cases (<1%), much rarer among controls, and have high odds ratios (ORs) for causing disease. The same CNVs also increase risk for autism spectrum disorders, developmental delay, and medical/physical comorbidities. The penetrance of these CNVs for any disorder is relatively high, ranging from 10% for 15q11.2 deletions to nearly 100% for deletions at 22q11.2. Strong selection pressure operates against carriers of these CNVs. Most of these are formed by non-allelic homologous recombination (NAHR), which leads to high mutation rates, thus maintaining the rates of these CNVs in the general population, despite the strong selection forces.

scholarly journals Phenotypic, genotypic and biochemical changes during pyrethroid resistance selection in Anopheles gambiae mosquitoes

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Maxwell G. Machani ◽  
Eric Ochomo ◽  
Daibin Zhong ◽  
Guofa Zhou ◽  
Xiaoming Wang ◽  
...  
Keyword(s):  
Public Health ◽  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Selection Pressure ◽  
Pyrethroid Resistance ◽  
Natural Populations ◽  
Biochemical Changes ◽  
Moderate Intensity ◽  
Agricultural System ◽  
Selection For

Abstract The directional selection for insecticide resistance due to indiscriminate use of insecticides in public health and agricultural system favors an increase in the frequency of insecticide-resistant alleles in the natural populations. Similarly, removal of selection pressure generally leads to decay in resistance. Past investigations on the emergence of insecticide resistance in mosquitoes mostly relied on field survey of resistance in vector populations that typically had a complex history of exposure to various public health and agricultural pest control insecticides in nature, and thus the effect of specific insecticides on rate of resistance emergency or resistance decay rate is not known. This study examined the phenotypic, genotypic, and biochemical changes that had occurred during the process of selection for pyrethroid resistance in Anopheles gambiae, the most important malaria vector in Africa. In parallel, we also examined these changes in resistant populations when there is no selection pressure applied. Through repeated deltamethrin selection in adult mosquitoes from a field population collected in western Kenya for 12 generations, we obtained three independent and highly pyrethroid-resistant An. gambiae populations. Three susceptible populations from the same parental population were generated by removing selection pressure. These two lines of mosquito populations differed significantly in monooxygenase and beta-esterase activities, but not in Vgsc gene mutation frequency, suggesting metabolic detoxification mechanism plays a major role in generating moderate-intensity resistance or high-intensity resistance. Pre-exposure to the synergist piperonyl butoxide restored the susceptibility to insecticide among the highly resistant mosquitoes, confirming the role of monooxygenases in pyrethroid resistance. The rate of resistance decay to become fully susceptible from moderate-intensity resistance took 15 generations, supporting at least 2-years interval is needed when the rotational use of insecticides with different modes of action is considered for resistance management.

scholarly journals Characteristics of survivors: growth and nutritional condition of early stages of the hake species Merluccius paradoxus and M. capensis in the southern Benguela ecosystem

2012 ◽  
Vol 69 (4) ◽  
pp. 553-562 ◽  
Author(s):  
Britta Grote ◽  
Werner Ekau ◽  
Erling K. Stenevik ◽  
Catriona Clemmesen ◽  
Hans M. Verheye ◽  
...  
Keyword(s):  
Selection Pressure ◽  
Larval Mortality ◽  
Larval Growth ◽  
Threshold Level ◽  
Nutritional Condition ◽  
Complex Relationship ◽  
Early Stages ◽  
Benguela Upwelling ◽  
Selection For ◽  
High Selection

Abstract Grote, B., Ekau, W., Stenevik, E. K., Clemmesen, C., Verheye, H. M., Lipinski, M. R., and Hagen, W. 2012. Characteristics of survivors: growth and nutritional condition of early stages of the hake species Merluccius paradoxus and M. capensis in the southern Benguela ecosystem. – ICES Journal of Marine Science, 69: 553–562. Larval mortality in marine fish is strongly linked to characteristic traits such as growth and condition, but the variability in these traits is poorly understood. We tried to identify the variability in growth in relation to conditions leading to greater survival chances for early stages of Cape hake, Merluccius paradoxus and M. capensis, in the Benguela upwelling ecosystem. During two cruises in 2007 and one cruise in 2008, hake larvae and juveniles were caught. Otolith microstructures revealed a larval age ranging from 2 to 29 days post-hatching (dph), whereas juvenile age was 67–152 dph. RNA:DNA ratios, used to evaluate nutritional condition, were above the relevant threshold level for growth. No strong coupling between growth and condition was detected, indicating a complex relationship between these factors in the southern Benguela ecosystem. Merluccius paradoxus juveniles caught in 2007 (the surviving larvae of 2006) had significantly higher larval growth rates than larvae hatched in 2007 and 2008, possibly indicating selection for fast growth in 2006. High selection pressure on growth could be linked to predation avoidance, including cannibalism.

Effect of index selection for reduced backfat thickness and increased growth rate on sow weight changes through two parities in swine

1992 ◽  
Vol 72 (2) ◽  
pp. 403-408 ◽  
Author(s):  
R. M. McKay
Keyword(s):  
Growth Rate ◽  
Key Words ◽  
Selection Pressure ◽  
Backfat Thickness ◽  
Index Selection ◽  
Weight Changes ◽  
Selection For ◽  
The Impact

The impact of continued selection for reduced backfat thickness and improved growth rate on weight changes in Yorkshire and Hampshire sows, from breeding as gilts to weaning their second litter, was studied. Results suggest that some sow weight changes may have been influenced by selection pressure exerted. Key words: Sows, Canadian Yorkshire, Hampshire, liveweight change

A note on the voluntary intake of Andropogon gayanus hay by cattle, as affected by level of feeding

1972 ◽  
Vol 15 (1) ◽  
pp. 85-88 ◽  
Author(s):  
G. Zemmelink ◽  
R. J. Haggar ◽  
J. H. Davies
Keyword(s):  
Protein Content ◽  
Feed Intake ◽  
Linear Effect ◽  
Low Level ◽  
Strong Selection ◽  
Andropogon Gayanus ◽  
The Mean ◽  
Voluntary Intake ◽  
Selection For ◽  
White Fulani

SUMMARYUnchaffed Andropogon gayanus hays, harvested in July, September, early-October, late-October and November, and the July to November regrowth, were offered to White Fulani heifers at three levels of feeding.Animals on all hays selected for protein and the mean intake of the different hays was closely related to the protein content of the consumed forage. At the low level of feeding all animals, except those on the July hay, left more than 15% residue. Nevertheless, higher levels of feeding had a marked linear effect on feed intake. This effect was largely independent of the effect of level of feeding on the protein content of the consumed ration and was associated with a strong selection for leaves.

scholarly journals Impact of strong selection for the PrP major gene on genetic variability of four French sheep breeds (Open Access publication)

2008 ◽  
Vol 40 (6) ◽  
pp. 663
Author(s):  
Isabelle Palhiere ◽  
Mickaël Brochard ◽  
Katayoun Moazami-Goudarzi ◽  
Denis Laloë ◽  
Yves Amigues ◽  
...  
Keyword(s):  
Open Access ◽  
Genetic Variability ◽  
Major Gene ◽  
Strong Selection ◽  
Sheep Breeds ◽  
Open Access Publication ◽  
Selection For

SELECTION PRESSURE IN CELL POPULATIONS OF VICIA HAJASTANA CULTURED IN VITRO

1972 ◽  
Vol 14 (1) ◽  
pp. 65-70 ◽  
Author(s):  
B. D. Singh ◽  
B. L. Harvey ◽  
K. N. Kao ◽  
R. A. Miller
Keyword(s):  
Frequency Distribution ◽  
Selection Pressure ◽  
Low Frequency ◽  
Cell Populations ◽  
Tissue Cultures ◽  
Very Low Frequency ◽  
Selection For ◽  
Diploid Cells ◽  
Mature Seeds

Tissue cultures from mature seeds of Vicia hajastana Grossh (2n = 10) were maintained in liquid B5 medium with 4.5 × 10−6 M 2,4-D. Initially the cultures had a very low frequency of diploid cells, which increased to 91.7% after 295 days in culture, indicating a strong selection for diploid cells. Chromosomes with changed morphology were observed and anaphase analysis showed various abnormalities. The frequency distribution of different chromosomes of the genome in aneuploid cells was nonrandom.

Dynamics of Microbial Populations and Strong Selection for Cycloclasticus pugetii following the Nakhodka Oil Spill

2003 ◽  
Vol 46 (4) ◽  
pp. 442-453 ◽  
Author(s):  
A. Maruyama ◽  
H. Ishiwata ◽  
K. Kitamura ◽  
M. Sunamura ◽  
T. Fujita ◽  
...  
Keyword(s):  
Oil Spill ◽  
Microbial Populations ◽  
Strong Selection ◽  
Selection For
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