scholarly journals Assessing the potential for egg chemoattractants to mediate sexual selection in a broadcast spawning marine invertebrate

2012 ◽  
Vol 279 (1739) ◽  
pp. 2855-2861 ◽  
Author(s):  
Jonathan P. Evans ◽  
Francisco Garcia-Gonzalez ◽  
Maria Almbro ◽  
Oscar Robinson ◽  
John L. Fitzpatrick
Keyword(s):  
Sexual Selection ◽  
Choice Experiment ◽  
Chemical Cues ◽  
Marine Invertebrate ◽  
Species Recognition ◽  
Critical Role ◽  
Experimental Conditions ◽  
Broadcast Spawning ◽  
Fertilization Rates ◽  
Sperm Chemotaxis

In numerous species, egg chemoattractants play a critical role in guiding sperm towards unfertilized eggs (sperm chemotaxis). Until now, the known functions of sperm chemotaxis include increasing the effective target size of eggs, thereby promoting sperm–egg encounters, and facilitating species recognition. Here, we report that in the broadcast spawning mussel, Mytilus galloprovincialis , egg chemoattractants may play an unforeseen role in sexual selection by enabling sperm to effectively ‘choose’ between the eggs of different conspecific females. In an initial experiment, we confirmed that sperm chemotaxis occurs in M. galloprovincialis by showing that sperm are attracted towards unfertilized eggs when given the choice of eggs or no eggs in a dichotomous chamber. We then conducted two cross-classified mating experiments, each comprising the same individual males and females crossed in identical male × female combinations, but under experimental conditions that offered sperm ‘no-choice’ (each fertilization trial took place in a Petri dish and involved a single male and female) or a ‘choice’ of a female's eggs (sperm were placed in the centre of a dichotomous choice chamber and allowed to choose eggs from different females). We show that male-by-female interactions characterized fertilization rates in both experiments, and that there was remarkable consistency between patterns of sperm migration in the egg-choice experiment and fertilization rates in the no-choice experiment. Thus, sperm appear to exploit chemical cues to preferentially swim towards eggs with which they are most compatible during direct sperm-to-egg encounters. These results reveal that sperm differentially select eggs on the basis of chemical cues, thus exposing the potential for egg chemoattractants to mediate mate choice for genetically compatible partners. Given the prevalence of sperm chemotaxis across diverse taxa, our findings may have broad implications for sexual selection in other mating systems.

scholarly journals Ultrafiltration Method for Plasma Protein Binding Studies and Its Limitations

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 382
Author(s):  
Camelia-Maria Toma ◽  
Silvia Imre ◽  
Camil-Eugen Vari ◽  
Daniela-Lucia Muntean ◽  
Amelia Tero-Vescan
Keyword(s):  
Protein Binding ◽  
Plasma Protein Binding ◽  
Plasma Protein ◽  
Specific Binding ◽  
Critical Role ◽  
Volume Ratio ◽  
Binding Studies ◽  
Experimental Conditions ◽  
Key Aspects

Plasma protein binding plays a critical role in drug therapy, being a key part in the characterization of any compound. Among other methods, this process is largely studied by ultrafiltration based on its advantages. However, the method also has some limitations that could negatively influence the experimental results. The aim of this study was to underline key aspects regarding the limitations of the ultrafiltration method, and the potential ways to overcome them. The main limitations are given by the non-specific binding of the substances, the effect of the volume ratio obtained, and the need of a rigorous control of the experimental conditions, especially pH and temperature. This review presents a variety of methods that can hypothetically reduce the limitations, and concludes that ultrafiltration remains a reliable method for the study of protein binding. However, the methodology of the study should be carefully chosen.

scholarly journals Interactions of ants with native and invasive lady beetles and the role of chemical cues in intraguild interference

Chemoecology ◽  
2021 ◽  
Author(s):  
Roman Bucher ◽  
Laura M. Japke ◽  
Ayse Gül Ünlü ◽  
Florian Menzel
Keyword(s):  
Chemical Cues ◽  
Harmonia Axyridis ◽  
Species Recognition ◽  
Lady Beetle ◽  
Lasius Niger ◽  
Beetle Species ◽  
Beetle Elytra ◽  
Lady Beetles ◽  
Ant Aggression

AbstractThe predator-predator naïveté hypothesis suggests that non-native predators benefit from being unknown to native predators, resulting in reduced intraguild interference with native predators. This novelty advantage should depend on the ability of native predators to recognize cues of non-native predators. Here, we compared ant aggression and lady beetle reaction in four native and the invasive lady beetle species Harmonia axyridis. In addition, we tested whether lady beetle cuticular hydrocarbons (CHCs) are involved in species recognition, which might explain naïveté if the invasive species has a specific CHC profile. To this end, we conducted behavioral assays confronting two native ant species with both living lady beetles and lady beetle elytra bearing or lacking CHCs of different lady beetle species. Finally, we characterized CHC profiles of the lady beetles using GC–MS. In general, the aggression of Lasius niger was more frequent than that of Myrmica rubra and L. niger aggression was more frequent towards most native lady beetle species compared to H. axyridis. The removal of CHCs from lady beetle elytra reduced aggression of both ant species. If CHCs of respective lady beetle species were added on cue-free elytra, natural strength of L. niger aggression could be restored. CHC analyses revealed a distinct cue composition for each lady beetle species. Our experiments demonstrate that the presence of chemical cues on the surface of lady beetles contribute to the strength of ant aggression against lady beetles. Reduced aggression of L. niger towards H. axyridis and reduced avoidance behavior in H. axyridis compared to the equally voracious C. septempunctata might improve the invasive lady beetle’s access to ant-tended aphids.

scholarly journals Autocatalytic and oscillatory reaction networks that form guanidines and products of their cyclization

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Alexander I. Novichkov ◽  
Anton I. Hanopolskyi ◽  
Xiaoming Miao ◽  
Linda J. W. Shimon ◽  
Yael Diskin-Posner ◽  
...  
Keyword(s):  
Chemical Cues ◽  
Native Chemical Ligation ◽  
Reaction Networks ◽  
Oscillatory Reaction ◽  
Experimental Conditions ◽  
Chemical Ligation ◽  
Chemical Systems ◽  
Life On Earth ◽  
Emergence Of Life ◽  
Equilibrium Chemical

AbstractAutocatalytic and oscillatory networks of organic reactions are important for designing life-inspired materials and for better understanding the emergence of life on Earth; however, the diversity of the chemistries of these reactions is limited. In this work, we present the thiol-assisted formation of guanidines, which has a mechanism analogous to that of native chemical ligation. Using this reaction, we designed autocatalytic and oscillatory reaction networks that form substituted guanidines from thiouronium salts. The thiouronium salt-based oscillator show good stability of oscillations within a broad range of experimental conditions. By using nitrile-containing starting materials, we constructed an oscillator where the concentration of a bicyclic derivative of dihydropyrimidine oscillates. Moreover, the mixed thioester and thiouronium salt-based oscillator show unique responsiveness to chemical cues. The reactions developed in this work expand our toolbox for designing out-of-equilibrium chemical systems and link autocatalytic and oscillatory chemistry to the synthesis of guanidinium derivatives and the products of their transformations including analogs of nucleobases.

scholarly journals Effects of parasites upon non-host predator avoidance behaviour in native and invasive gammarids

Parasitology ◽  
2020 ◽  
pp. 1-7
Author(s):  
Sajad Farahani ◽  
Per J. Palsbøll ◽  
Ido Pen ◽  
Jan Komdeur
Keyword(s):  
Invasive Species ◽  
Definitive Host ◽  
Predator Avoidance ◽  
Gasterosteus Aculeatus ◽  
Chemical Cues ◽  
Critical Role ◽  
Fundamental Question ◽  
Intermediate Hosts ◽  
Gammarus Fossarum ◽  
Acanthocephalan Parasite

Abstract The acanthocephalan parasite, Polymorphus minutus, manipulates its intermediate hosts' (gammarids) behaviour, presumably to facilitate its transmission to the definitive hosts. A fundamental question is whether this capability has evolved to target gammarids in general, or specifically sympatric gammarids. We assessed the responses to chemical cues from a non-host predator (the three-spined sticklebacks Gasterosteus aculeatus) in infected and non-infected gammarids; two native (Gammarus pulex and Gammarus fossarum), and one invasive (Echinogammarus berilloni) species, all sampled in the Paderborn Plateau (Germany). The level of predator avoidance was assessed by subjecting gammarids to choice experiments with the presence or absence of predator chemical cues. We did not detect any behavioural differences between uninfected and infected G. pulex and E. berilloni, but an elevated degree of predator avoidance in infected G. fossarum. Avoiding non-host predators may ultimately increase the probability of P. minutus' of predation by the definitive host. Our results suggested that P. minutus' ability to alter the host's behaviour may have evolved to specifically target sympatric gammarid host species. Uninfected gammarids did not appear to avoid the non-host predator chemical cues. Overall the results also opened the possibility that parasites may play a critical role in the success or failure of invasive species.

Influence of prey diet quality on predator-induced traits in wood frog tadpoles (Lithobates sylvaticus)

2021 ◽  
pp. 1-11
Author(s):  
Catherine Chuirazzi ◽  
Melissa Ocampo ◽  
Mizuki K. Takahashi
Keyword(s):  
Predation Risk ◽  
Diet Quality ◽  
Growth And Development ◽  
Chemical Cues ◽  
Wood Frog ◽  
Experimental Conditions ◽  
Lithobates Sylvaticus ◽  
Phenotypic Changes ◽  
Intestinal Length ◽  
Frog Tadpoles

Abstract Diet quality and predation are two critical factors in determining the growth and development of organisms. Various anurans are susceptible to phenotypic changes influenced by these factors. Yet, few studies examined prey diet quality as potential influence over predator-induced traits. Using wood frog tadpoles (Lithobates sylvaticus) as a model species, we investigated the effects of three diet compositions (plant-based, animal-based, omnivorous) crossed with presence or absence of chemical cues from predatory dragonfly larvae (Aeshnidae). After 35 days, we recorded 11 morphological measurements, Gosner stage, and intestinal length of tadpoles to assess phenotypic changes under the six different experimental conditions. Our results showed the additive effects of both diet quality and predator chemical cue without detection of interactions between the two. Tadpoles receiving the omnivorous diet grew and developed faster with wider denticle rows than those receiving the plant or animal diets. The growth and development of tadpoles receiving only the animal diet were significantly hindered. These results emphasize the importance of diet quality in the growth and development of larval wood frogs. Chemical cues from predators significantly reduced tadpole body size but, in contrast to previous findings, did not affect tail size. Our experimental procedure of providing water containing predator and injured conspecific chemical cues on a weekly basis likely provided relatively weak predation risk perceived by tadpoles compared to previous studies using caged predators. The predator environment in our experiment, however, represents one ecologically relevant scenario in which predation risk is not urgent.

Sexual Selection, Timing and an X–Y Homologous Gene: Did Homo Sapiens Speciate on the Y Chromosome?

2004 ◽  
Author(s):  
Tim J. Crow
Keyword(s):  
Sexual Selection ◽  
Sex Chromosome ◽  
Homo Sapiens ◽  
Single Gene ◽  
Critical Role ◽  
Hominid Evolution ◽  
Homologous Gene ◽  
Chromosomal Change ◽  
Species Specific ◽  
Sex Chromosome Aneuploidies

This chapter provides a theory of the speciation of modern Homo sapiens, that a single gene played a critical role in the transition from a precursor species. The theory is founded upon the following: firstly, the premise that hemispheric asymmetry is the defining feature of the human brain and the only plausible correlate of language; secondly, an argument for a specific candidate region (the Xq21.3/Yp11.2 region of homology) based upon the reciprocal deficits associated with the sex chromosome aneuploidies, and the course of chromosomal change in hominid evolution; and thirdly, a particular evolutionary mechanism (sexual selection acting on an X-Y-linked gene) to account for species-specific modification of what initially was a saltational change. These postulates relate to the case of modern Homo sapiens. On the basis of the recent literature, the discussion argues that the third premise has general significance as a mechanism of speciation.

scholarly journals Sexual selection after gamete release in broadcast spawning invertebrates

2020 ◽  
Vol 375 (1813) ◽  
pp. 20200069 ◽  
Author(s):  
Jonathan P. Evans ◽  
Rowan A. Lymbery
Keyword(s):  
Sexual Selection ◽  
Mate Choice ◽  
Sperm Competition ◽  
Sexual Conflict ◽  
Gamete Release ◽  
Theme Issue ◽  
Animal Kingdom ◽  
External Fertilization ◽  
Broadcast Spawning ◽  
Males And Females

Broadcast spawning invertebrates offer highly tractable models for evaluating sperm competition, gamete-level mate choice and sexual conflict. By displaying the ancestral mating strategy of external fertilization, where sexual selection is constrained to act after gamete release, broadcast spawners also offer potential evolutionary insights into the cascade of events that led to sexual reproduction in more ‘derived’ groups (including humans). Moreover, the dynamic reproductive conditions faced by these animals mean that the strength and direction of sexual selection on both males and females can vary considerably. These attributes make broadcast spawning invertebrate systems uniquely suited to testing, extending, and sometimes challenging classic and contemporary ideas in sperm competition, many of which were first captured in Parker's seminal papers on the topic. Here, we provide a synthesis outlining progress in these fields, and highlight the burgeoning potential for broadcast spawners to provide both evolutionary and mechanistic understanding into gamete-level sexual selection more broadly across the animal kingdom. This article is part of the theme issue ‘Fifty years of sperm competition’.

Larger leeches attack from higher ground – size-dependent preferences for ambush sites in the Bornean terrestrial leech Haemadipsa picta

2019 ◽  
Vol 35 (03) ◽  
pp. 140-143
Author(s):  
Krzysztof Miler ◽  
Aleksandra Gurgul ◽  
Maja Peryga ◽  
Marcin Czarnoleski
Keyword(s):  
Body Length ◽  
Rain Forest ◽  
Choice Experiment ◽  
Biodiversity Hotspot ◽  
South East Asia ◽  
Natural Conditions ◽  
Experimental Conditions ◽  
Size Dependent ◽  
Foraging Tactics ◽  
The Vertical Distribution

AbstractThe rain forests of South-East Asia represent a biodiversity hotspot of terrestrial leeches, but we have only fragmentary and often anecdotal information on this component of tropical communities. To address the foraging tactics of terrestrial leeches, we studied the vertical distribution of Haemadipsa picta on foliage in a Bornean tropical rain forest. We investigated the links between leech body length and the above-ground height of their ambush positions under natural conditions and in a choice experiment performed under semi-natural conditions. We studied 167 leeches, which varied considerably with respect to body length (4–29 mm). On average, the leeches ambushed at lower heights under natural conditions than under experimental conditions (47.7 cm vs. 67.5 cm), though the heights of ambush positions overlapped considerably. Leeches that chose higher ambush positions under natural conditions consistently chose higher ambush positions in the experiment (Pearson r = 0.29). Under both natural and experimental conditions, leech body length was positively correlated with the height of ambush positions (Pearson r = 0.48); on average, a 1-mm increase in body length corresponded to a 2–3 cm higher ambush position. Our findings suggest that H. picta individuals actively choose hunting locations according to their above-ground height, shifting their ambush sites over ontogeny to higher foliage. We hypothesize that growing leeches might target different prey following ontogenetic shifts in the foraging optima, ultimately decreasing intraspecific competition.

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