scholarly journals Divergence in Defence against Herbivores between Males and Females of Dioecious Plant Species

2012 ◽  
Vol 2012 ◽  
pp. 1-16 ◽  
Author(s):  
Germán Avila-Sakar ◽  
Cora Anne Romanow
Keyword(s):  
Plant Species ◽  
Dioecious Plant ◽  
Dioecious Species ◽  
Dioecious Plants ◽  
Current State ◽  
Evolution Of Resistance ◽  
Males And Females ◽  
Minimal Standard ◽  
Dioecious Populations ◽  
Partial View

Defensive traits may evolve differently between sexes in dioecious plant species. Our current understanding of this process hinges on a partial view of the evolution of resistance traits that may result in male-biased herbivory in dioecious populations. Here, we present a critical summary of the current state of the knowledge of herbivory in dioecious species and propose alternative evolutionary scenarios that have been neglected. These scenarios consider the potential evolutionary and functional determinants of sexual dimorphism in patterns of resource allocation to reproduction, growth, and defence. We review the evidence upon which two previous reviews of sex-biased herbivory have concluded that male-biased herbivory is a rule for dioecious species, and we caution readers about a series of shortcomings of many of these studies. Lastly, we propose a minimal standard protocol that should be followed in any studies that intend to elucidate the (co)evolution of interactions between dioecious plants and their herbivores.

Flies (Diptera) as pollinators of two dioecious plants: behaviour and implications for plant mating

2007 ◽  
Vol 139 (2) ◽  
pp. 235-246 ◽  
Author(s):  
Christopher J. Borkent ◽  
Lawrence D. Harder
Keyword(s):  
Plant Species ◽  
Breeding System ◽  
Dioecious Plant ◽  
Dioecious Species ◽  
Dioecious Plants ◽  
Visitation Rate ◽  
Self Pollination ◽  
Shepherdia Canadensis ◽  
Plant Mating

AbstractWe consider the role of generalist Diptera in the pollination of two dioecious plant species, Clematis ligusticifolia Nutt. (Ranunculaceae) and Shepherdia canadensis (L.) Nutt. (Elaeagnaceae). In particular, we assess (i) whether or not generalist pollinators are unable to distinguish between the sexes of dioecious species and so visit the sexes at equivalent rates, and (ii) the number of flowers that generalist flies visit and revisit during a foraging bout, which would affect self-pollination if plants were hermaphroditic. We determined the visitation rate to each plant species during 10 min periods and recorded the number of flowers that individual pollinators visited and revisited per foraging bout. Diptera were the main pollinators, visiting both sexes at similar rates for both plant species. The main visitors to C. ligusticifolia were muscoid flies (small and large), Culicidae, and halictid bees. The number of flowers visited in this species varied with pollinator group, but groups did not differ in the frequency of revisits. Visitors to S. canadensis were primarily Syrphidae and Empididae. Neither the number of flowers visited nor the number of revisits differed between these two pollinator groups. The results for each plant species are discussed and contrasted, particularly with other studies of the behaviour of generalist and specialist pollinators. We compare the observed pollinator behaviours, and their implications for plant mating, with the various theories of the role of pollinators in the evolution of the dioecious breeding system in plants.

scholarly journals Pleiotropic effects of sex-determining genes in the evolution of dioecy in two plant species

2019 ◽  
Vol 286 (1913) ◽  
pp. 20191805 ◽  
Author(s):  
Takashi Akagi ◽  
Deborah Charlesworth
Keyword(s):  
Theoretical Models ◽  
Ancestral State ◽  
Relative Importance ◽  
Sexual Antagonism ◽  
Dioecious Plant ◽  
Dioecious Species ◽  
Dioecious Plants ◽  
Sexual Dimorphisms ◽  
Evolution Of Dioecy ◽  
Plant Sex

One reason for studying sex chromosomes of flowering plants is that they have often evolved separate sexes recently, and the genomes of dioecious species may not yet have evolved adaptations to their changes from the ancestral state. An unstudied question concerns the relative importance of such adaptation, versus the effects of the mutations that led to separate sexes in the first place. Theoretical models for such an evolutionary change make the prediction that the mutations that created males must have sexually antagonistic effects, not only abolishing female functions, but also increasing male functions relative to the ancestral functional hermaphrodites. It is important to test this critical assumption. Moreover, the involvement of sexual antagonism also implies that plant sex-determining genes may directly cause some of the sexual dimorphisms observed in dioecious plants. Sex-determining genes are starting to be uncovered in plants, including species in the genera Diospyros and Actinidia (families Ebenaceae and Actinidiaceae, respectively). Here, we describe transgenic experiments in which the effects of the very different male-determining genes of these two dioecious species were studied in a non-dioecious plant, Nicotiana tabacum . The results indeed support the critical assumption outlined above.

scholarly journals Has adaptation occurred in males and females since separate sexes evolved in the plant Silene latifolia ?

2018 ◽  
Vol 285 (1883) ◽  
pp. 20172824 ◽  
Author(s):  
Niklaus Zemp ◽  
Alex Widmer ◽  
Deborah Charlesworth
Keyword(s):  
Sex Differences ◽  
Male Sterility ◽  
Plant Species ◽  
Flowering Plants ◽  
Pleiotropic Effects ◽  
Silene Latifolia ◽  
Dioecious Plant ◽  
Adaptive Changes ◽  
Males And Females

The evolution of separate sexes may involve changed expression of many genes, as each sex adapts to its new state. Evidence is accumulating for sex differences in expression even in organisms that have recently evolved separate sexes from hermaphrodite or monoecious (cosexual) ancestors, such as some dioecious flowering plants. We describe evidence that a dioecious plant species with recently evolved dioecy, Silene latifolia , has undergone adaptive changes that improve functioning in females, in addition to changes that are probably pleiotropic effects of male sterility. The results suggest pervasive adaptations as soon as males and females evolve from their cosexual ancestor.

scholarly journals Multifaceted origins of sex differences in the brain

2016 ◽  
Vol 371 (1688) ◽  
pp. 20150106 ◽  
Author(s):  
Margaret M. McCarthy
Keyword(s):  
Sex Differences ◽  
State Of The Art ◽  
Human Subjects ◽  
Special Issue ◽  
Molecular Analyses ◽  
The Past ◽  
Current State ◽  
Biological Variable ◽  
Males And Females ◽  
The Brain

Studies of sex differences in the brain range from reductionistic cell and molecular analyses in animal models to functional imaging in awake human subjects, with many other levels in between. Interpretations and conclusions about the importance of particular differences often vary with differing levels of analyses and can lead to discord and dissent. In the past two decades, the range of neurobiological, psychological and psychiatric endpoints found to differ between males and females has expanded beyond reproduction into every aspect of the healthy and diseased brain, and thereby demands our attention. A greater understanding of all aspects of neural functioning will only be achieved by incorporating sex as a biological variable. The goal of this review is to highlight the current state of the art of the discipline of sex differences research with an emphasis on the brain and to contextualize the articles appearing in the accompanying special issue.

Cortisol responsiveness and dominance rank, but not baseline cortisol level, are repeatable traits in adult female guinea pigs

2021 ◽  
Author(s):  
Taylor Lynne Rystrom ◽  
Romy C. Prawitt ◽  
S. Helene Richter ◽  
Norbert Sachser ◽  
Sylvia Kaiser
Keyword(s):  
Social Behavior ◽  
Adult Female ◽  
Guinea Pigs ◽  
Dominance Rank ◽  
Dominance Hierarchies ◽  
Current State ◽  
Baseline Cortisol ◽  
Group Members ◽  
Endocrine Mechanism ◽  
Males And Females

Social interactions among group members often lead to the formation of stable dominance hierarchies. Glucocorticoids (i.e. cortisol) have been proposed as an endocrine mechanism underlying social behavior, and previous studies have linked baseline as well as challenge glucocorticoid concentrations to dominance rank. Since the importance of rank on fitness differs between males and females, selection pressures acting on the underlying endocrine mechanisms may differ between the sexes. In male guinea pigs, for example, it is known that cortisol responsiveness mediates social behavior and that dominance rank and cortisol responsiveness are stable within individuals over time. It is unclear whether this is also the case for female guinea pigs. Thus the aim of this study was to investigate whether cortisol concentrations are repeatable in female guinea pigs and whether female rank is correlated to baseline cortisol concentrations or cortisol responsiveness. We show that cortisol responsiveness and dominance rank were significantly repeatable but not correlated in female guinea pigs. Furthermore, baseline cortisol was not repeatable and also did not correlate to dominance rank. Our results demonstrate that baseline cortisol and cortisol responsiveness represent different biological processes; cortisol responsiveness reflects a stable trait while baseline cortisol likely fluctuates with current state. Furthermore, cortisol responsiveness as a mediator of aggressive behavior and dominance acquisition might not be important for maintaining dominance hierarchies in stable groups of females displaying minimal aggression. Overall, this study reveals the remarkable stability of cortisol responsiveness and dominance rank in an adult female rodent and lays the groundwork for future investigations into the causes and consequences of this individual variation.

Male sex-specific DNA in Silene latifolia and other dioecious plant species

2004 ◽  
pp. 73-87
Author(s):  
S.Donnison Iain ◽  
G.Grant Sarah
Keyword(s):  
Plant Species ◽  
Silene Latifolia ◽  
Dioecious Plant ◽  
Male Sex

scholarly journals Outbreeding and inbreeding strategies in herbaceous-shrubby communities in the Venezuelan Gran Sabana Plateau

AoB Plants ◽  
2019 ◽  
Vol 11 (4) ◽  
Author(s):  
Nelson Ramírez ◽  
Omaira Hokche
Keyword(s):  
Plant Species ◽  
Carbon Metabolism ◽  
Life Form ◽  
Sex Expression ◽  
Perennial Herb ◽  
Sexual System ◽  
Dioecious Species ◽  
Successional Stage ◽  
Sexual Systems ◽  
Perennial Herbs

Abstract Breeding system, sexual system, temporal variation in sex expression and herkogamy were evaluated in seven herbaceous-shrubby communities from the Gran Sabana Plateau, Venezuela. This analysis was conducted considering the life form, substrate type, succulence, carbon metabolism, nutritional relation, successional stage, pollination system specificity and endemism of plant species. Of the 348 plant species studied, 73.8 % were hermaphrodite, 16.9 % were monoecious and 9.2 % were dioecious. Plant sexual systems such as dichogamy and herkogamy were associated with life form, nutritional relations, carbon metabolism and pollination systems. Most species were adichogamous, followed by protandrous and protogynous. Protandry was high for perennial herbs, annual herbs and trees, and protogyny was most frequent in perennial herbs. Protandrous and protogynous species were frequently anemophilous. Herkogamy was higher than non-herkogamy. Herkogamy was higher for trees, shrubs and liana; higher in monophilous and lower in anemophilous species. Most of the hermaphrodites were herkogamous and adichogamous species. In contrast, monoecy were commonly perennial herb and dichogamous species and frequently associated with anemophily. Dioecious species were trees and shrubs and with polyphilous pollination. Dioecy was the most frequent sexual system for endemic species. Hermaphrodite species were similarly distributed across plant communities. Monoecy was slightly higher for savanna and fallow than the other communities, and dioecy was higher for shrublands and secondary bushland. Most plant species were non-agamospermous, non-spontaneous self-pollinated and xenogamous. Partially self-incompatible dominated, followed by self-incompatible, partially cross-incompatible and the lowest frequency corresponded to cross-incompatible species. All these results are discussed in the context of evolutionary and ecological trends.

LTR retrotransposons in the dioecious plant Silene latifolia

Genome ◽  
2002 ◽  
Vol 45 (4) ◽  
pp. 745-751 ◽  
Author(s):  
Sachihiro Matsunaga ◽  
Fumi Yagisawa ◽  
Maki Yamamoto ◽  
Wakana Uchida ◽  
Shunsuke Nakao ◽  
...  
Keyword(s):  
Sex Chromosomes ◽  
Evolutionary Dynamics ◽  
Sex Chromosome ◽  
Silene Latifolia ◽  
Ltr Retrotransposons ◽  
Dioecious Plant ◽  
Dioecious Species ◽  
Y Chromosomes ◽  
Genus Silene ◽  
Silene Species

Conserved domains of two types of LTR retrotransposons, Ty1–copia- and Ty3–gypsy-like retrotransposons, were isolated from the dioecious plant Silene latifolia, whose sex is determined by X and Y chromosomes. Southern hybridization analyses using these retrotransposons as probes resulted in identical patterns from male and female genomes. Fluorescence in situ hybridization indicated that these retrotransposons do not accumulate specifically in the sex chromosomes. These results suggest that recombination between the sex chromosomes of S. latifolia has not been severely reduced. Conserved reverse transcriptase regions of Ty1–copia-like retrotransposons were isolated from 13 different Silene species and classified into two major families. Their categorization suggests that parallel divergence of the Ty1–copia-like retrotransposons occurred during the differentiation of Silene species. Most functional retrotransposons from three dioecious species, S. latifolia, S. dioica, and S. diclinis, fell into two clusters. The evolutionary dynamics of retrotransposons implies that, in the genus Silene, dioecious species evolved recently from gynodioecious species.Key words: retrotransposon, dioecious plant, sex chromosome.

Y chromosome specific markers and the evolution of dioecy in the genus Silene

Genome ◽  
1998 ◽  
Vol 41 (2) ◽  
pp. 141-147 ◽  
Author(s):  
Y Hi Zhang ◽  
Veronica S Stilio ◽  
Farah Rehman ◽  
Amy Avery ◽  
David Mulcahy ◽  
...  
Keyword(s):  
Y Chromosome ◽  
Sex Chromosomes ◽  
Silene Latifolia ◽  
Dioecious Species ◽  
Sequence Characterized Amplified Region ◽  
Y Chromosomes ◽  
Heteromorphic Sex Chromosomes ◽  
Males And Females ◽  
Genus Silene ◽  
Evolution Of Dioecy

Sex determination in plants has been most thoroughly investigated in Silene latifolia, a dioecious species possessing heteromorphic sex chromosomes. We have identified several new Y chromosome linked RAPD markers and converted these to more reliable sequence characterized amplified region (SCAR) markers by cloning the RAPD fragments and developing longer primers. Of the primer pairs for seven SCARs, five amplify a single, unique fragment from the DNA of male S. latifolia. Two sets of primers also amplify additional fragments common to males and females. Homology between the X and Y chromosomes is sufficient to allow the amplification of fragments from females under less stringent PCR conditions. Five of the SCARs also distinguish between the sexes of closely related dioecious taxa of the section Elisanthe, but not between the sexes of distantly related dioecious species. These markers will be useful for continued investigations into the evolution of sex, phylogenetic relationships among taxa, and population dynamics of sex ratios in the genus Silene.Key words: Melandrium, RAPDs, sex chromosomes, SCARs.

Resistance economics: social cost and the evolution of antibiotic resistance

1996 ◽  
Vol 1 (3) ◽  
pp. 349-355 ◽  
Author(s):  
Gardner Brown ◽  
David F. Layton
Keyword(s):  
Antibiotic Resistance ◽  
Social Cost ◽  
Selective Pressure ◽  
Human Beings ◽  
Resistance To Antibiotics ◽  
Current State ◽  
Evolution Of Resistance

Daily and Ehrlich have described the current state of our epidemiological environment in chilling detail. While their point is that human beings interact and affect the epidemiological environment in a variety of ways, the development of antibiotic resistance in bacteria strikes us as one aspect that we can begin to analyse immediately. The evolution of resistance to antibiotics is a function of their use by humans. The more we use, the more selective pressure is placed upon bacteria to develop resistance. This is further complicated by how they are used. Both the duration and the amounts used affect the change in the level of resistance. Finally, the primary feature driving the concern over the use of these drugs is that the evolution of resistance makes these ‘miracle’ drugs exhaustible. We can try to develop new and better antibiotics, but it is uncertain how successful we will be and how expensive they will be if we are successful.

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