Homeotic transformations and number changes in the vertebral column of Triturus newts

We explored intraspecific variation in vertebral formulae, more specifically the variation in the number of thoracic vertebrae and frequencies of transitional sacral vertebrae inTriturusnewts (Caudata: Salamandridae). Within salamandrid salamanders this monophyletic group shows the highest disparity in the number of thoracic vertebrae and considerable intraspecific variation in the number of thoracic vertebrae.Triturusspecies also differ in their ecological preferences, from predominantly terrestrial to largely aquatic. Following Geoffroy St. Hilaire’s and Darwin’s rule which states that structures with a large number of serially homologous repetitive elements are more variable than structures with smaller numbers, we hypothesized that the variation in vertebral formulae increases in more elongated species with a larger number of thoracic vertebrae. We furthermore hypothesized that the frequency of transitional vertebrae will be correlated with the variation in the number of thoracic vertebrae within the species. We also investigated potential effects of species hybridization on the vertebral formula. The proportion of individuals with a number of thoracic vertebrae different from the modal number and the range of variation in number of vertebrae significantly increased in species with a larger number of thoracic vertebrae. Contrary to our expectation, the frequencies of transitional vertebrae were not correlated with frequencies of change in the complete vertebrae number. The frequency of transitional sacral vertebra in hybrids did not significantly differ from that of the parental species. Such a pattern could be a result of selection pressure against transitional vertebrae and/or a bias towards the development of full vertebrae numbers. Although our data indicate relaxed selection for vertebral count changes in more elongated, aquatic species, more data on different selective pressures in species with different numbers of vertebrae in the two contrasting, terrestrial and aquatic environments are needed to test for causality.

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Homeotic transformations and number changes in the vertebral column of Triturus newts

10.7287/peerj.preprints.1443v1 ◽

2015 ◽

Author(s):

Maja Slijepčević ◽

Frietson F Galis ◽

Jan W Arntzen ◽

Ana Ivanović

Keyword(s):

Intraspecific Variation ◽

Selection Pressure ◽

Parental Species ◽

Aquatic Environments ◽

Thoracic Vertebrae ◽

Modal Number ◽

Selective Pressures ◽

Selection For ◽

Species Hybridization ◽

Range Of Variation

We explored intraspecific variation in vertebral formulae, more specifically the variation in the number of thoracic vertebrae and frequencies of transitional sacral vertebrae in Triturus newts (Caudata: Salamandridae). Within salamandrid salamanders this monophyletic group shows the highest disparity in the number of thoracic vertebrae and considerable intraspecific variation in the number of thoracic vertebrae. Triturus species also differ in their ecological preferences, from predominantly terrestrial to largely aquatic. Following Geoffroy St. Hilaire’s and Darwin’s rule which states that structures with a large number of serially homologous repetitive elements are more variable than structures with smaller numbers, we hypothesized that the variation in vertebral formulae increases in more elongated species with a larger number of thoracic vertebrae. We furthermore hypothesized that the frequency of transitional vertebrae will be correlated with the variation in the number of thoracic vertebrae within the species. We also investigated potential effects of species hybridization on the vertebral formula. The proportion of individuals with a number of thoracic vertebrae different from the modal number and the range of variation in number of vertebrae significantly increased in species with a larger number of thoracic vertebrae. Contrary to our expectation, the frequencies of transitional vertebrae were not correlated with frequencies of change in the complete vertebrae number. The frequency of transitional sacral vertebra in hybrids did not significantly differ from that of the parental species. Such a pattern could be a result of selection pressure against transitional vertebrae and/or a bias towards the development of full vertebrae numbers. Although our data indicate relaxed selection for vertebral count changes in more elongated, aquatic species, more data on different selective pressures in species with different numbers of vertebrae in the two contrasting, terrestrial and aquatic environments are needed to test for causality.

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Homeotic transformations and number changes in the vertebral column of Triturus newts

10.7287/peerj.preprints.1443 ◽

2015 ◽

Author(s):

Maja Slijepčević ◽

Frietson F Galis ◽

Jan W Arntzen ◽

Ana Ivanović

Keyword(s):

Intraspecific Variation ◽

Selection Pressure ◽

Parental Species ◽

Aquatic Environments ◽

Thoracic Vertebrae ◽

Modal Number ◽

Selective Pressures ◽

Selection For ◽

Species Hybridization ◽

Range Of Variation

We explored intraspecific variation in vertebral formulae, more specifically the variation in the number of thoracic vertebrae and frequencies of transitional sacral vertebrae in Triturus newts (Caudata: Salamandridae). Within salamandrid salamanders this monophyletic group shows the highest disparity in the number of thoracic vertebrae and considerable intraspecific variation in the number of thoracic vertebrae. Triturus species also differ in their ecological preferences, from predominantly terrestrial to largely aquatic. Following Geoffroy St. Hilaire’s and Darwin’s rule which states that structures with a large number of serially homologous repetitive elements are more variable than structures with smaller numbers, we hypothesized that the variation in vertebral formulae increases in more elongated species with a larger number of thoracic vertebrae. We furthermore hypothesized that the frequency of transitional vertebrae will be correlated with the variation in the number of thoracic vertebrae within the species. We also investigated potential effects of species hybridization on the vertebral formula. The proportion of individuals with a number of thoracic vertebrae different from the modal number and the range of variation in number of vertebrae significantly increased in species with a larger number of thoracic vertebrae. Contrary to our expectation, the frequencies of transitional vertebrae were not correlated with frequencies of change in the complete vertebrae number. The frequency of transitional sacral vertebra in hybrids did not significantly differ from that of the parental species. Such a pattern could be a result of selection pressure against transitional vertebrae and/or a bias towards the development of full vertebrae numbers. Although our data indicate relaxed selection for vertebral count changes in more elongated, aquatic species, more data on different selective pressures in species with different numbers of vertebrae in the two contrasting, terrestrial and aquatic environments are needed to test for causality.

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

Advances in Artificial Intelligence ◽

10.1155/2013/841646 ◽

2013 ◽

Vol 2013 ◽

pp. 1-13 ◽

Cited By ~ 2

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.

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Penis size and sperm quality, are all bats grey in the dark?

Current Zoology ◽

10.1093/cz/zoy094 ◽

2018 ◽

Vol 65 (6) ◽

pp. 697-703 ◽

Cited By ~ 2

Author(s):

Nicolas Jean Fasel ◽

Marta Kołodziej-Sobocińska ◽

Ewa Komar ◽

Marcin Zegarek ◽

Ireneusz Ruczyński

Keyword(s):

Sperm Quality ◽

Copulatory Behavior ◽

Scaling Relations ◽

Head Width ◽

Sperm Velocity ◽

Selective Pressures ◽

Penis Size ◽

Penis Length ◽

Selection For ◽

Myotis Nattereri

Abstract Penises play a key role in sperm transport and in stimulating female genitals. This should impact post-copulatory competition, and expose penis characteristics to sexual selective pressures. Studies of male genitalia have repeatedly reported negative static allometries, which mean that, within species, large males have disproportionally small genitals when compared with smaller individuals. Males of some sperm-storing bat species may stand as an exception to such a pattern by arousing from hibernation to copulate with torpid females. The selection for large penises might take place, if a long organ provides advantages during post-copulatory competition and/or if females have evolved mechanisms allowing the choice of sire, relying on characters other than pre-copulatory traits (e.g., penis size). In this study, we measured dimensions of the erected penis in 4 sperm-storing bat species. Furthermore, we collected sperm and evaluated the link between penis dimensions and sperm velocity. Our results revealed steep allometric slopes of the erected penis length in Barbastella barbastellus and an inverse allometry of penis head width in Myotis nattereri. More detailed studies of copulatory behavior are urgently needed to explain the range of observed scaling relations. Furthermore, penis head width correlates with sperm velocity in Plecotus auritus. For this last species, we propose that penis shape might act as a marker of male fertility.

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

Scientific Reports ◽

10.1038/s41598-020-75865-1 ◽

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.

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Lateralization correlates with individual differences in inhibitory control in zebrafish

Biology Letters ◽

10.1098/rsbl.2020.0296 ◽

2020 ◽

Vol 16 (8) ◽

pp. 20200296

Author(s):

Tyrone Lucon-Xiccato ◽

Giulia Montalbano ◽

Marco Dadda ◽

Cristiano Bertolucci

Keyword(s):

Inhibitory Control ◽

Cognitive Differences ◽

Cerebral Lateralization ◽

Brain Hemisphere ◽

Selective Pressures ◽

Individual Fitness ◽

Left Brain ◽

Selection For ◽

The Right ◽

Selection Mechanisms

Individual fitness often depends on the ability to inhibit behaviours not adapted to a given situation. However, inhibitory control can vary greatly between individuals of the same species. We investigated a mechanism that might maintain this variability in zebrafish ( Danio rerio ). We demonstrate that inhibitory control correlates with cerebral lateralization, the tendency to process information with one brain hemisphere or the other. Individuals that preferentially observed a social stimulus with the right eye and thus processed social information with the left brain hemisphere, inhibited foraging behaviour more efficiently. Therefore, selective pressures that maintain lateralization variability in populations might provide indirect selection for variability in inhibitory control. Our study suggests that individual cognitive differences may result from complex multi-trait selection mechanisms.

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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 ◽

10.1093/icesjms/fss020 ◽

2012 ◽

Vol 69 (4) ◽

pp. 553-562 ◽

Cited By ~ 17

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.

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

Canadian Journal of Animal Science ◽

10.4141/cjas92-048 ◽

1992 ◽

Vol 72 (2) ◽

pp. 403-408 ◽

Cited By ~ 3

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

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SELECTION PRESSURE IN CELL POPULATIONS OF VICIA HAJASTANA CULTURED IN VITRO

Canadian Journal of Genetics and Cytology ◽

10.1139/g72-008 ◽

1972 ◽

Vol 14 (1) ◽

pp. 65-70 ◽

Cited By ~ 41

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.

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