scholarly journals Evolution of sperm morphology in Daphnia

2020 ◽  
Author(s):  
Duneau David ◽  
Markus Möst ◽  
Dieter Ebert
Keyword(s):  
Sexual Selection ◽  
Convergent Evolution ◽  
Sperm Morphology ◽  
Sperm Length ◽  
Reproductive Feature

AbstractSperm, the male most fundamental reproductive feature allowing egg fertilization, evolves under sexual selection. Two components of sperm are mainly under selection, their number and their morphology (including the associated quality). Here we study the evolution of sperm morphology in the genus Daphnia. Based on microscopic observations of sperm morphologies mapped on a Daphnia phylogeny, we found that increase in sperm length evolved at least twice in Daphnia, once in the Daphnia sensus lato clade and once in the Ctenodaphnia clade. Furthermore, Daphnia s.l. lost the ability of cell compaction by losing extracellular encapsulation and exposing large filaments. We discuss the potential reasons for such convergent evolution in sperm morphology.

Brain size evolution in anurans: a review

2019 ◽  
Vol 69 (3) ◽  
pp. 265-279 ◽  
Author(s):  
Chun Lan Mai ◽  
Wen Bo Liao
Keyword(s):  
Sexual Selection ◽  
Life History ◽  
Life History Traits ◽  
Developmental Stages ◽  
Brain Size ◽  
Ecological Factors ◽  
Brain Regions ◽  
Sperm Length ◽  
Testis Size ◽  
Size Evolution

Abstract Selection pressure is an important force in shaping the evolution of vertebrate brain size among populations within species as well as between species. The evolution of brain size is tightly linked to natural and sexual selection, and life-history traits. In particular, increased environmental stress, intensity of sexual selection, and slower life history usually result in enlarged brains. However, although previous studies have addressed the causes of brain size evolution, no systematic reviews have been conducted to explain brain size in anurans. Here, we review whether brain size evolution supports the cognitive buffer hypothesis (CBH), the expensive tissue hypothesis (ETH), or the developmental cost hypothesis (DCH) by analyzing the intraspecific and/or interspecific patterns in brain size and brain regions (i.e., olfactory nerves, olfactory bulbs, telencephalon, optic tectum, and cerebellum) associated with ecological factors (habitat, diet and predator risk), sexual selection intensity, life-history traits (age at sexual maturity, mean age, longevity, clutch size and egg size, testis size and sperm length), and other energetic organs. Our findings suggest that brain size evolution in anurans supports the CBH, ETH or DCH. We also suggest future directions for studying the relationships between brain size evolution and crypsis (i.e., ordinary mucous glands in the skin), and food alteration in different developmental stages.

Sperm morphology of the Rattini – are the interspecific differences due to variation in intensity of intermale sperm competition?

2018 ◽  
Vol 30 (11) ◽  
pp. 1434 ◽  
Author(s):  
Tessa Pahl ◽  
Hanna J. McLennan ◽  
Yun Wang ◽  
Anang S. Achmadi ◽  
Kevin C. Rowe ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Sperm Competition ◽  
Sperm Morphology ◽  
Tail Length ◽  
Sperm Head ◽  
Apical Hook ◽  
Interspecific Differences ◽  
Murine Rodent ◽  
Murine Rodents ◽  
Sperm Size

It is widely accepted that in mammals a causal relationship exists between postcopulatory sexual selection and relative testes mass of the species concerned, but how much it determines sperm size and shape is debatable. Here we detailed for the largest murine rodent tribe, the Rattini, the interspecific differences in relative testes mass and sperm form. We found that residual testes mass correlates with sperm head apical hook length as well as its angle, together with tail length, and that within several lineages a few species have evolved highly divergent sperm morphology with a reduced or absent apical hook and shorter tail. Although most species have a relative testes mass of 1–4%, these derived sperm traits invariably co-occur in species with much smaller relative testes mass. We therefore suggest that high levels of intermale sperm competition maintain a sperm head with a long apical hook and long tail, whereas low levels of intermale sperm competition generally result in divergent sperm heads with a short or non-existent apical hook and shorter tail. We thus conclude that sexual selection is a major selective force in driving sperm head form and tail length in this large tribe of murine rodents.

scholarly journals Sperm morphology, adenosine triphosphate (ATP) concentration and swimming velocity: unexpected relationships in a passerine bird

2016 ◽  
Vol 283 (1837) ◽  
pp. 20161558 ◽  
Author(s):  
Clair Bennison ◽  
Nicola Hemmings ◽  
Lola Brookes ◽  
Jon Slate ◽  
Tim Birkhead
Keyword(s):  
Sperm Morphology ◽  
Passerine Bird ◽  
Negative Association ◽  
Swimming Velocity ◽  
Sperm Function ◽  
Sperm Length ◽  
Atp Content ◽  
Number Of Individuals ◽  
The Relationship ◽  
Sperm Traits

The relationship between sperm energetics and sperm function is poorly known, but is central to our understanding of the evolution of sperm traits. The aim of this study was to examine how sperm morphology and ATP content affect sperm swimming velocity in the zebra finch Taeniopygia guttata . We exploited the high inter-male variation in this species and created extra experimental power by increasing the number of individuals with very long or short sperm through artificial selection. We found a pronounced quadratic relationship between total sperm length and swimming velocity, with velocity increasing with length up to a point, but declining in the very longest sperm. We also found an unexpected negative association between midpiece length and ATP content: sperm with a short midpiece generally contained the highest concentration of ATP. Low intracellular ATP is therefore unlikely to explain reduced swimming velocity among the very longest sperm (which tend to have a shorter midpiece).

scholarly journals No Evidence for Pre-Copulatory Sexual Selection on Sperm Length in a Passerine Bird

PLoS ONE ◽  
2012 ◽  
Vol 7 (2) ◽  
pp. e32611 ◽  
Author(s):  
Jan T. Lifjeld ◽  
Terje Laskemoen ◽  
Oddmund Kleven ◽  
A. Tiril M. Pedersen ◽  
Helene M. Lampe ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Passerine Bird ◽  
Sperm Length

Postcopulatory sexual selection is associated with accelerated evolution of sperm morphology

Evolution ◽  
2015 ◽  
Vol 69 (4) ◽  
pp. 1044-1052 ◽  
Author(s):  
Melissah Rowe ◽  
Tomáš Albrecht ◽  
Emily R. A. Cramer ◽  
Arild Johnsen ◽  
Terje Laskemoen ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Sperm Morphology ◽  
Postcopulatory Sexual Selection ◽  
Accelerated Evolution

scholarly journals Selection on sperm morphology under relaxed sperm competition in a wild passerine bird

2008 ◽  
Vol 5 (1) ◽  
pp. 58-61 ◽  
Author(s):  
Sara Calhim ◽  
Helene M Lampe ◽  
Tore Slagsvold ◽  
Tim R Birkhead
Keyword(s):  
Sexual Selection ◽  
Sperm Competition ◽  
Sperm Morphology ◽  
Reproductive Traits ◽  
Female Preference ◽  
Passerine Bird ◽  
High Heritability ◽  
Individual Consistency ◽  
Sperm Size

Theories regarding the role of sexual selection on the evolution of sperm traits are based on an association between pre-copulatory (e.g. female preference) and post-copulatory (e.g. ejaculate quality) male reproductive traits. In tests of these hypotheses, sperm morphology has rarely been used, despite its high heritability and intra-individual consistency. We found evidence of selection for longer sperm through positive phenotypic associations between sperm size and the two major female preference traits in the pied flycatcher, Ficedula hypoleuca . Our results support the sexually selected sperm hypothesis in a species under low sperm competition and demonstrate that natural and pre-copulatory sexual selection forces should not be overlooked in studies of intraspecific sperm morphology evolution.

scholarly journals Sperm form and function: what do we know about the role of sexual selection?

Reproduction ◽  
2018 ◽  
Vol 155 (5) ◽  
pp. R229-R243 ◽  
Author(s):  
Stefan Lüpold ◽  
Scott Pitnick
Keyword(s):  
Sexual Selection ◽  
Sperm Morphology ◽  
Swimming Velocity ◽  
Secondary Sexual Traits ◽  
Form And Function ◽  
Biophysical Studies ◽  
Evolutionary Context ◽  
Sexual Selection Theory ◽  
And Function

Sperm morphological variation has attracted considerable interest and generated a wealth of predominantly descriptive studies over the past three centuries. Yet, apart from biophysical studies linking sperm morphology to swimming velocity, surprisingly little is known about the adaptive significance of sperm form and the selective processes underlying its tremendous diversification throughout the animal kingdom. Here, we first discuss the challenges of examining sperm morphology in an evolutionary context and why our understanding of it is far from complete. Then, we review empirical evidence for how sexual selection theory applies to the evolution of sperm form and function, including putative secondary sexual traits borne by sperm.

scholarly journals Estimation of the propensity for sexual selection in a cyclical parthenogen

2020 ◽  
Author(s):  
David Duneau ◽  
Florian Altermatt ◽  
Jean-Baptiste Ferdy ◽  
Frida Ben-Ami ◽  
Dieter Ebert
Keyword(s):  
Sexual Selection ◽  
Sexual Reproduction ◽  
Sperm Competition ◽  
Indirect Evidence ◽  
Sperm Length ◽  
Cyclical Parthenogenesis ◽  
Single Female ◽  
Sexual Process ◽  
Different Populations ◽  
Firm Evidence

AbstractCyclical parthenogenesis is a widespread reproductive strategy in which organisms go through one or multiple rounds of clonal reproduction before sexual reproduction. Because sexual reproduction is typically less common than parthenogenesis in populations of the planktonic cladoceran Daphnia magna, it is not frequently studied. Here we examine the sexual process of D. magna and its relation to sexual selection in Daphnia rockpool populations by observing natural mating in these shallow habitats where sex generally occurs throughout the summer. Although microsatellite markers were found to reveal no evidence of disassortative mating or, thus, of inbreeding avoidance, body length and infection status did reveal assortative mating, suggesting sexual selection to act. When two males mated with a single female, the larger male was observed to remain longer, possibly giving it an advantage in sperm competition. Indirect evidence points at the brood pouch as the likely site of fertilization and thus, sperm competition. Sperm length was as variable within ejaculates as it was among males from different populations. Our data provide firm evidence that sexual selection is present in this species, most likely manifesting itself through a combination of female choice and male–male competition.

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