Consequences of sex change for effective population size

Waples, Robin S.; Mariani, Stefano; Benvenuto, Chiara

doi:10.1098/rspb.2018.1702

Cited by 15 publications

(17 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indeed, we often tend to oversimplify the complexity of sequential hermaphroditism: not all protogynous species are haremic, as not all protandrous species mate in pairs. A recent study 28,85 has revealed a broader variation in effective population size in protogynous species that differs from the more limited expectations obtained when all protogynous species were considered haremic by default. Instead, some protogynous species were found to be group spawners, altering the expectations that all protogynous species should have low effective population size due to their supposed haremic system.…”

Section: Discussionmentioning

confidence: 81%

A phylogenetic comparative analysis on the evolution of sequential hermaphroditism in seabreams (Teleostei: Sparidae)

Pla

Benvenuto

Capellini

et al. 2020

Sci Rep

Self Cite

View full text Add to dashboard Cite

systems, particularly for both types of sequential hermaphroditism, given that it contains many gonochoristic, protogynous and protandrous species, with differences in sexual systems even between species belonging to the same genus. The main theoretical framework to explain the evolutionary advantage of sequential hermaphroditism based on sex allocation theory is the size-advantage model (SAM) 9,19-21. The SAM proposes that individuals should switch sex when the second sex achieves a greater fitness at a larger body size than the first sex, thus increasing lifetime fitness 22. When larger males have higher reproductive success than smaller males and similar sized females, fish should reproduce initially as female and change later to male (protogyny) 19,23,24. Conversely, protandry is expected when large females have greater fitness than smaller females and similar sized males 19,20. Empirical studies support this model in several fish families, explaining quantitatively the size or age at which an individual should change sex, as well as the overall population sex ratio 25,26. Typically, male-biased sex ratios are observed in populations of protandrous species, while female-biased sex ratios are observed in populations of protogynous species, especially in haremic groups 19,26,27. Mating systems (the number and social dominance of mates involved) and spawning mode (i.e., group spawning, where several males spawn with one or several females, or pair-mating, where a single male spawns with a single female), determine the fitness that a fish of a given size can achieve as a female or as a male 23,28. Fish mating systems range from monogamy or pair-mating, to harem polygyny (one dominant male controls access to multiple females 29), lek-type polygyny (temporary harems 25), and large polygamous or promiscuous aggregations (where group spawning occurs 30). Sperm competition is particularly intense in large aggregations with multiple males 31,32 while it is absent in monogamy and pair-mating, and low in polygynous mating systems. Sperm competition and spawning modes have been used to infer mating systems 33-35 , which are relevant when testing the predictions of SAM since they can generate sex-specific differences in reproductive expectations 23,24,36,37. Thus, the first study that tested the predictions of SAM incorporating the mating system in a phylogenetic context focused on the evolution of protogynous groupers according to pair spawning mode 35. Indeed, protandry should be favored when sperm competition is low (mating occurs between members of monogamous or random pairs 19,22-24), and mate monopolization by large males should occur in protogynous species 23. Even though sperm competition was not included in the original formulation of the model 9,19 , it was subsequently mentioned as absent in protogyny 21,23,24,38 , limited in protandry (considered typical of random pairing and small groups) 22,23 and high in gonochorism (when mating occurs in large groups) 21,23,35,39. The influence of sperm competition on sex c...

show abstract

Section: Discussionmentioning

confidence: 81%

A phylogenetic comparative analysis on the evolution of sequential hermaphroditism in seabreams (Teleostei: Sparidae)

Pla

Benvenuto

Capellini

et al. 2020

Sci Rep

Self Cite

View full text Add to dashboard Cite

show abstract

“…The very high N e /generation values obtained for the white seabream seemingly contradict this prediction (Table 2). This expected lower N e was also challenged in recent studies with protogynous species over historical timescales (Coscia et al, 2016), and in analysis of an eco-evolutionary model with ten hypothetical species (Waples, Mariani & Benvenuto, 2018).…”

Section: Estimates Of Contemporary Effective Population Sizementioning

confidence: 97%

Time matters: genetic composition and evaluation of effective population size in temperate coastal fish species

Francisco

Robalo

2020

PeerJ

View full text Add to dashboard Cite

Background Extensive knowledge on the genetic characterization of marine organisms has been assembled, mainly concerning the spatial distribution and structuring of populations. Temporal monitoring assesses not only the stability in genetic composition but also its trajectory over time, providing critical information for the accurate forecast of changes in genetic diversity of marine populations, particularly important for both fisheries and endangered species management. We assessed fluctuations in genetic composition among different sampling periods in the western Portuguese shore in three fish species. Methods White seabream Diplodus sargus, sand smelt Atherina presbyter and shanny Lipophrys pholis were chosen, because of their genetic patterns in distinct ecological environments, insight into historical and contemporary factors influencing population effective size (Ne), and degree of commercial exploitation. Samples were obtained near Lisbon between 2003 and 2014 and screened for genetic variation with mitochondrial and nuclear markers. Analyses included genealogies, genetic diversities, temporal structures and contemporary Ne. Results For mtDNA no temporal structure was detected, while for nDNA significant differences were recorded between some sampling periods for the shanny and the sand smelt. Haplotype networks revealed deep genealogies, with various levels of diversification. The shanny revealed a smaller Ne/generation when compared to the other species, which, in turn, revealed no evidence of genetic drift for most study periods. These results highlight the fact that temporal variations in genetic pool composition should be considered when evaluating the population structure of fish species with long distance dispersal, which are more vulnerable to recruitment fluctuations.

show abstract

“…[ 59 ] A recent study shows that biased sex ratios in sequential hermaphrodites have surprisingly little effect on their population effective size and thus evolvability. [ 60 ] We can speculate that similar processes concern ESD species as well. Their biased sex ratios might not be optimal for the individual fitness but advantageous for long‐term survival of the lineage, a situation that creates an interesting case of conflict between individual selection and selection at higher levels.…”

Section: Adaptive Values Of Gsd and Esd: Is Esd A Short‐lived Strategy?mentioning

confidence: 98%

Evolution of Sex Determination in Amniotes: Did Stress and Sequential Hermaphroditism Produce Environmental Determination?

et al. 2020

View full text Add to dashboard Cite

Frequent independent origins of environmental sex determination (ESD) are assumed within amniotes. However, the phylogenetic distribution of sex-determining modes suggests that ESD is likely very ancient and may be homologous across ESD groups. Sex chromosomes are demonstrated to be old and stable in endothermic (mammals and birds) and many ectothermic (non-avian reptiles) lineages, but they are mostly non-homologous between individual amniote lineages. The phylogenetic pattern may be explained by ancestral ESD with multiple transitions to later evolutionary stable genotypic sex determination. It is pointed out here that amniote ESD shares several key aspects with sequential hermaphroditism of fishes such as a lack of sex differences in genomes, biased population sex ratios, and potentially also molecular mechanism related to general stress responses. Here, it is speculated that ESD evolves via a heterochronic shift of the sensitive period of sex change from the adult to the embryonic stage in a hermaphroditic amniote ancestor. Also see the video abstract here https://youtu.be/q2mjtlCefu4.

show abstract

Consequences of sex change for effective population size

Cited by 15 publications

References 35 publications

A phylogenetic comparative analysis on the evolution of sequential hermaphroditism in seabreams (Teleostei: Sparidae)

A phylogenetic comparative analysis on the evolution of sequential hermaphroditism in seabreams (Teleostei: Sparidae)

Time matters: genetic composition and evaluation of effective population size in temperate coastal fish species

Evolution of Sex Determination in Amniotes: Did Stress and Sequential Hermaphroditism Produce Environmental Determination?

Contact Info

Product

Resources

About