scholarly journals Time for a change: patterns of sex expression, health and mortality in a sex-changing tree

2019 ◽  
Vol 124 (3) ◽  
pp. 367-377 ◽  
Author(s):  
Jennifer Blake-Mahmud ◽  
Lena Struwe
Keyword(s):  
Life History ◽  
Sex Determination ◽  
Classification Tree ◽  
Sex Ratios ◽  
Sex Expression ◽  
Life History Trait ◽  
Differential Mortality ◽  
Male And Female ◽  
Female Sex ◽  
Theoretical Predictions

Abstract Background and Aims The ability of individuals to change sex during their lifetime is known as environmental sex determination (ESD). This represents a unique life history trait, allowing plants to allocate resources differentially to male and female functions across lifetimes, potentially maximizing fitness in response to changing environmental or internal cues. In this study, Acer pensylvanicum, a species with an unconfirmed sex determination system, was investigated to see what patterns in sex expression existed across multiple years, if there were sex-based differences in growth and mortality, and whether this species conformed to theoretical predictions that females are larger and in better condition. Methods Patterns of sex expression were documented over 4 years in a phenotypically subdioecious A. pensylvanicum population located in New Jersey, USA, and data on size, mortality, health and growth were collected. A machine-learning algorithm known as a boosted classification tree was used to develop a model to predict the sex of a tree based on its condition, size and previous sex. Results In this study, 54 % of the trees switched sex expression during a 4-year period, with 26 % of those trees switching sex at least twice. Consistently monoecious trees could change relative sex expression by as much as 95 %. Both size and condition were influential in predicting sex, with condition exerting three times more relative influence than size on expressed sex. Contrary to theoretical predictions, the model showed that full female sex expression did not increase with size. Healthy trees were more likely to be male; predicted female sex expression increased with deteriorating health. Growth rate negatively correlated with multiple years of female sex expression. Populations maintained similar male-skewed sex ratios across years and locations and may result from differential mortality: 75 % of dead trees flowered female immediately before death. Conclusions This study shows conclusively that A. pensylvanicum exhibits ESD and that femaleness correlates with decreased health, in contrast to prevailing theory. The mortality findings advance our understanding of puzzling non-equilibrium sex ratios and life history trade-offs resulting from male and female sex expression.

scholarly journals Equality between the sexes in plants for costs of reproduction; evidence from the dioecious Cape genus Leucadendron (Proteaceae)

2017 ◽  
Author(s):  
Jeremy J. Midgley ◽  
Adam G. West ◽  
Michael D. Cramer
Keyword(s):  
Life History ◽  
Fire Ecology ◽  
Sex Ratios ◽  
Costs Of Reproduction ◽  
Male And Female ◽  
Reproductive Synchrony ◽  
Male Function ◽  
Female Function ◽  
Mating Opportunities ◽  
Dimorphic Species

AbstractIt has been argued that sexual allocation is greater for female function than male function in plants in general and specifically for the large dioecious Cape genus Leucadendron. Here, we use new interpretations of published information to support the hypothesis of equality between sexes in this genus. The explanations are based on the fire ecology of the Cape that results in reproductive synchrony, reproductive doubling and competitive symmetry. Firstly, strict post-fire seedling establishment of the reseeder life-history in the Cape results in single-aged populations. Consequently, the reproductive and vegetative schedules of males must synchronously track that of females. This implies equal allocation to sex. Secondly, after fires, dioecious females have double the seedling to adult ratio of co-occurring hermaphrodites. This indicates that being liberated from male function allows females access to resources that double their fitness compared to hermaphrodites. Therefore, male and female costs of reproduction are equal in hermaphrodites. Thirdly, competitive symmetry must occur because males and female plants will frequently encounter each other as close near neighbours. Competitive asymmetry would both reduce mating opportunities and skew local sex ratios. The evidence to date is for 1:1 sex ratios in small plots and this indicates competitive symmetry and a lack of dimorphic niches. Finally, vegetatively dimorphic species must also allocate equally to sex, or else sexual asynchrony, lack of reproductive doubling or competitive asymmetry will occur.

Male and female sex determination in hair roots

2008 ◽  
Vol 2 (2) ◽  
pp. 73-77 ◽  
Author(s):  
J. Francois ◽  
M. Th. Matton-Van Leuven ◽  
J. Acosta
Keyword(s):  
Sex Determination ◽  
Male And Female ◽  
Female Sex ◽  
Hair Roots

scholarly journals Identification of sex-linked markers in the sexually cryptic coco de mer: are males and females produced in equal proportions?

AoB Plants ◽  
2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Emma J Morgan ◽  
Christopher N Kaiser-Bunbury ◽  
Peter J Edwards ◽  
Mathias Scharmann ◽  
Alex Widmer ◽  
...  
Keyword(s):  
Sex Ratios ◽  
Differential Mortality ◽  
Sexually Dimorphic ◽  
Male And Female ◽  
Determination System ◽  
Males And Females ◽  
Heterogametic Sex ◽  
Sex Determination System ◽  
Male Specific ◽  
Genetically Determined

Abstract Lodoicea maldivica (coco de mer) is a long-lived dioecious palm in which male and female plants are visually indistinguishable when immature, only becoming sexually dimorphic as adults, which in natural forest can take as much as 50 years. Most adult populations in the Seychelles exhibit biased sex ratios, but it is unknown whether this is due to different proportions of male and female plants being produced or to differential mortality. In this study, we developed sex-linked markers in Lodoicea using ddRAD sequencing, enabling us to reliably determine the gender of immature individuals. We screened 589 immature individuals to explore sex ratios across life stages in Lodoicea. The two sex-specific markers resulted in the amplification of male-specific bands (Lm123977 at 405 bp and Lm435135 at 130 bp). Our study of four sub-populations of Lodoicea on the islands of Praslin and Curieuse revealed that the two sexes were produced in approximately equal numbers, with no significant deviation from a 1:1 ratio before the adult stage. We conclude that sex in Lodoicea is genetically determined, suggesting that Lodoicea has a chromosomal sex determination system in which males are the heterogametic sex (XY) and females are homogametic (XX). We discuss the potential causes for observed biased sex ratios in adult populations, and the implications of our results for the life history, ecology and conservation management of Lodoicea.

Environmental Sex Determination in Southern Brook Lamprey, Ichthyomyzon gagei

1993 ◽  
Vol 50 (6) ◽  
pp. 1299-1307 ◽  
Author(s):  
F. William H. Beamish
Keyword(s):  
United States ◽  
Sex Determination ◽  
Sex Ratios ◽  
Southeastern United States ◽  
Larval Density ◽  
Larval Growth ◽  
Age Groups ◽  
Differential Mortality ◽  
Environmental Sex Determination ◽  
Brook Lamprey

Sex ratios were determined for 20 populations of southern brook lamprey larvae, Ichthyomyzon gagei, collected from throughout much of their range in the southeastern United States. Ratios varied between 9 and 49% males. Differential mortality was an unlikely factor, as sex ratios were similar among age groups within each population. Environmental sex determination is suggested. Sex ratio varied with growth (expressed as length of larvae at specific ages), larval density, pH, and annual mean temperature of the natal stream. Generally, under conditions promoting rapid growth, the percentage of males varied directly with density and inversely with temperature. Where growth was slow, the percentage of males declined as larval density increased, the response being less at low than at high pH. Temperature had little effect when larval growth was slow. The percentage of males declined when growth was rapid under otherwise similar environmental conditions.

scholarly journals Missing Piece Connecting Male and Female Sex Determination

Endocrinology ◽  
2017 ◽  
Vol 158 (11) ◽  
pp. 3713-3715
Author(s):  
Gregor Majdic
Keyword(s):  
Sex Determination ◽  
Male And Female ◽  
Female Sex

scholarly journals Epigenetic Regulation and Environmental Sex Determination in Cichlid Fishes

2021 ◽  
Vol 15 (1-3) ◽  
pp. 93-107
Author(s):  
Suzy C.P. Renn ◽  
Peter L. Hurd
Keyword(s):  
Life History ◽  
Sex Determination ◽  
Female Offspring ◽  
Epigenetic Mechanism ◽  
Life History Strategies ◽  
Comparative Approach ◽  
Environmental Sex Determination ◽  
Reproductive Tactics ◽  
Male And Female ◽  
Underlying Mechanisms

Studying environmental sex determination (ESD) in cichlids provides a phylogenetic and comparative approach to understand the evolution of the underlying mechanisms, their impact on the evolution of the overlying systems, and the neuroethology of life history strategies. Natural selection normally favors parents who invest equally in the development of male and female offspring, but evolution may favor deviations from this 50:50 ratio when environmental conditions produce an advantage for doing so. Many species of cichlids demonstrate ESD in response to water chemistry (temperature, pH, and oxygen concentration). The relative strengths of and the exact interactions between these factors vary between congeners, demonstrating genetic variation in sensitivity. The presence of sizable proportions of the less common sex towards the environmental extremes in most species strongly suggests the presence of some genetic sex-determining loci acting in parallel with the ESD factors. Sex determination and differentiation in these species does not seem to result in the organization of a final and irreversible sexual fate, so much as a life-long ongoing battle between competing male- and female-determining genetic and hormonal networks governed by epigenetic factors. We discuss what is and is not known about the epigenetic mechanism behind the differentiation of both gonads and sex differences in the brain. Beyond the well-studied tilapia species, the 2 best-studied dwarf cichlid systems showing ESD are the South American genus <i>Apistogramma</i> and the West African genus <i>Pelvicachromis</i>. Both species demonstrate male morphs with alternative reproductive tactics. We discuss the further neuroethology opportunities such systems provide to the study of epigenetics of alternative life history strategies and other behavioral variation.

scholarly journals wnt4a promotes female development and reproductive duct elongation in zebrafish

2018 ◽  
Author(s):  
Michelle E. Kossack ◽  
Samantha K. High ◽  
Rachel E. Hopton ◽  
Yi-lin Yan ◽  
John H. Postlethwait ◽  
...  
Keyword(s):  
Sex Determination ◽  
Sex Chromosome ◽  
Ovary Development ◽  
Last Common Ancestor ◽  
Loss Of Function ◽  
Female Development ◽  
Male And Female ◽  
Female Sex ◽  
Somatic Gonad ◽  
Duct Development

ABSTRACTIn laboratory strains of zebrafish, sex determination occurs in the absence of a typical sex chromosome and it is not known what regulates the proportion of animals that develop as male or female. Many sex determination and differentiation genes that act downstream of a sex chromosome are well conserved among vertebrates, but studies that test their contribution to this process have mostly been limited to mammalian models. In mammals, WNT4 is a signaling ligand that is essential for ovary and Müllerian duct development, where it function, in part, to antagonize the male-promoting FGF9 signal. Wnt4 is highly conserved in non-mammalian vertebrates, but it is not known if Wnt4 plays a role in sex determination and/or the differentiation of sex organs outside of mammals. This is an especially interesting question in teleost, such as zebrafish, because they lack an Fgf9 ortholog. Here we show that wnt4a is the ortholog of mammalian Wnt4, and that wnt4b was present in the last common ancestor of humans and zebrafish, but was lost in mammals. We found that wnt4a is expressed in the somatic cells of juvenile gonads during the time sex determination likely occurs. We show that wnt4a loss-of-function mutants develop predominantly as males and conclude that wnt4a activity promotes female sex determination in zebrafish. Additionally, both male and female wnt4a mutants are sterile because their reproductive ducts do not connect to the vent, where wnt4a is normally expressed. Yet when dissected from homozygous wnt4a mutant gonads, both sperm and eggs can produce fertile offspring. Together these results strongly argue that Wnt4a is a conserved regulator of female sex determination and reproductive duct development in non-mammalian vertebrates.SUMMARYWnt4 is a key regulator of ovary development in mammals, but it is not known if it plays a similar role in other vertebrates. Here we show that zebrafish wnt4a is the ortholog of mammalian Wnt4. We show that wnt4a is expressed in zebrafish somatic gonad cells during the time sex determination likely occurs. Through analysis of wnt4a mutants, we show that Wnt4a promotes female sex determination and the development of the male and female reproductive. We conclude that Wnt4/Wnt4a is likely a conserved regulator of ovarian and reproductive duct development in all vertebrates

scholarly journals Gonadal Development and Tumor Formation at the Crossroads of Male and Female Sex Determination

2011 ◽  
Vol 5 (4) ◽  
pp. 167-180 ◽  
Author(s):  
M. Cools ◽  
K.P. Wolffenbuttel ◽  
S.L.S. Drop ◽  
J.W. Oosterhuis ◽  
L.H.J. Looijenga
Keyword(s):  
Sex Determination ◽  
Gonadal Development ◽  
Tumor Formation ◽  
Male And Female ◽  
Female Sex

scholarly journals Mapping the adaptive landscape of a major agricultural pathogen reveals evolutionary constraints across heterogeneous environments

2021 ◽  
Author(s):  
Anik Dutta ◽  
Fanny E. Hartmann ◽  
Carolina Sardinha Francisco ◽  
Bruce A. McDonald ◽  
Daniel Croll
Keyword(s):  
Life History ◽  
Large Scale ◽  
Life History Traits ◽  
Genetic Correlations ◽  
Stress Factors ◽  
Life History Trait ◽  
Adaptive Landscape ◽  
Heterogeneous Environments ◽  
Growth Responses ◽  
Trade Offs

AbstractThe adaptive potential of pathogens in novel or heterogeneous environments underpins the risk of disease epidemics. Antagonistic pleiotropy or differential resource allocation among life-history traits can constrain pathogen adaptation. However, we lack understanding of how the genetic architecture of individual traits can generate trade-offs. Here, we report a large-scale study based on 145 global strains of the fungal wheat pathogen Zymoseptoria tritici from four continents. We measured 50 life-history traits, including virulence and reproduction on 12 different wheat hosts and growth responses to several abiotic stressors. To elucidate the genetic basis of adaptation, we used genome-wide association mapping coupled with genetic correlation analyses. We show that most traits are governed by polygenic architectures and are highly heritable suggesting that adaptation proceeds mainly through allele frequency shifts at many loci. We identified negative genetic correlations among traits related to host colonization and survival in stressful environments. Such genetic constraints indicate that pleiotropic effects could limit the pathogen’s ability to cause host damage. In contrast, adaptation to abiotic stress factors was likely facilitated by synergistic pleiotropy. Our study illustrates how comprehensive mapping of life-history trait architectures across diverse environments allows to predict evolutionary trajectories of pathogens confronted with environmental perturbations.

Sign in / Sign up

Export Citation Format

Share Document