0000000000118164
AUTHOR
Koen Martens
Karyotype variability and inter-population genomic differences in freshwater ostracods (Crustacea) showing geographical parthenogenesis
Transitions from sexual to asexual reproduction are often associated with polyploidy and increased chromosomal plasticity in asexuals. We investigated chromosomes in the freshwater ostracod species Eucypris virens (Jurine, 1820), where sexual, asexual and mixed populations can be found. Our initial karyotyping of multiple populations from Europe and North Africa, both sexual and asexual, revealed a striking variability in chromosome numbers. This would suggest that chromosomal changes are likely to be accelerated in asexuals because the constraints of meiosis are removed. Hence, we employed comparative genomic hybridization (CGH) within and among sexual and asexual populations to get insigh…
Images are not and should not ever be type specimens: a rebuttal to GarraffoniFreitas.
Note. This original form of this rebuttal was submitted to Science on 3 March 2017 (limited to 300 words as per Science editorial policy) but rejected on 13 March 2017. Herein, we elaborate on our original Science submission in order to more fully address the issue without the length limitations. This rebuttal is followed by the list of the signatories who supported our original submission.
An updated checklist of Recent ostracods (Crustacea: Ostracoda) from inland waters of Sicily and adjacent small islands with notes on their distribution and ecology
Because of its position in the middle of the Mediterranea Sea and a complex geological history that has promoted repeated waves of biological colonization, Sicily (Southern Italy) is of particular interest from a biogeographical perspective. A number of previous investigations, dating back as far as the end of the 19th century, have contributed to gather information about the occurrence of Recent non-marine ostracods in Sicily, making this region one of the most intensively studied areas of the Central Mediterranean. Published data on ostracod distributions have been integrated through an extensive field survey on mainland Sicily and surrounding small islands and archipelagos. Altogether, 2…
Two celebrations and the Sustainable Development Goals
No Abstract
The distribution of sexual reproduction of the geographic parthenogenEucypris virens(Crustacea: Ostracoda) matches environmental gradients in a temporary lake
Niche segregation may prevent competitive exclusion and promote local coexistence. This typically results in the occupation of different habitats. In the freshwater ostracod Eucypris virens (Jurine, 1820), the distribution of sexual and parthenogenetic populations in the temporary Lake Caracuel, central Spain, was not homogeneous. Parthenogens were found everywhere including the littoral, whereas sexuals were restricted to the centre. We investigated the hypothesis that spatial distribution responded to ecological differences. We studied the ecological significance of this segregation by linking environmental data to male presence, sexual fraction, ploidy, and genetic structure of our model…
Exceptional cryptic diversity and multiple origins of parthenogenesis in a freshwater ostracod.
The persistence of asexual reproduction in many taxa depends on a balance between the origin of new asexual lineages and the extinction of old ones. This turnover determines the diversity of extant asexual populations and so influences the interaction between sexual and asexual modes of reproduction. Species with mixed reproduction, like the freshwater ostracod (Crustacea) morphospecies Eucypris virens, are a good model to examine these dynamics. This species is also a geographic parthenogen, in which sexual females and males co-exist with asexual females in the circum-Mediterranean area only, whereas asexual females occur all over Europe. A molecular phylogeny of E. virens based on the mit…
Distribution of recent ostracods in inland waters of Sicily (Southern Italy)
From 2003 to 2005, freshwater ostracods were sampled in 67 water bodies of mainland Sicily (Provinces of Agrigento, Caltanisetta, Catania, Enna, Palermo, Messina, Ragusa, Siracusa and Trapani) located from sea level up to 1300 m a.s.l. This survey took into account streams, springs, wells, but especially temporary and ephemeral habitats (e.g., flooded meadows, temporary ponds). The aim of this research was to give the first comprehensive picture of the regional ostracod fauna and establish relationships between the distribution of ostracod species and some habitat features. Altogether, 21 ostracod taxa belonging to five families (Candonidae, Ilyocyprididae, Cyprididae, Notodromadidae, and L…
Mate recognition as a reproductive barrier in sexual and parthenogenetic Eucypris virens (Crustacea, Ostracoda)
Mate selection is one of the motors of evolution and of particular importance in the case of organisms in which sexual and parthenogenetic populations coexist. Sexual populations of the ostracod species complex Eucypris virens are often mixed with parthenogenetic ones. A powerful mate selection mechanism must exist to avoid time, energy and sperm loss, for the maintenance and success of sexual reproduction in these mixed populations. There are four types of E. virens individuals: males (diploid), sexual females (diploid) and asexual females (parthenogenetic and either di- or triploid). From one parthenogenetic population and two populations with males of E. virens, we sampled early stage ju…
A (very) brief vademecum on biological nomenclature
This editorial is aimed at explaining why the editors of Hydrobiologia are so concerned with biological nomenclature and why we ask our authors the utmost precision when referring to species in their papers... In these lines, we want to show that this is not just an old fashion formalism, but a necessity to correctly and univocally identify the biological subjects that are the basis of the research published in ecology-related journals.
Extreme tolerance to environmental stress of sexual and parthenogenetic resting eggs ofEucypris virens(Crustacea, Ostracoda)
Summary 1. The freshwater ostracod (Ostracoda), Eucypris virens, is commonly found in European temporary pools, where its long-term persistence completely relies on the build-up of resting egg banks. Extreme tolerance of dormant eggs and seeds is widely assumed, but freshwater ostracod eggs are relatively poorly studied. The study of ostracod resting eggs is of particular relevance as it may yield the key to understanding the distribution of the sexes in many species capable of both sexual and asexual reproduction. 2. We assessed the tolerance of dried resting eggs produced by females originating from three populations with males and three all-female E. virens populations. Hatching time and…
Linking present environment and the segregation of reproductive modes (geographical parthenogenesis) in Eucypris virens (Crustacea: Ostracoda)
Aim Geographical parthenogenesis – in which parthenogenetic populations are more widely distributed than sexually reproducing populations – is observed in many plant and animal species. Many hypotheses have been proposed to account for this biogeographical pattern, and these often invoke historical processes such as the influence of glaciation. However, there are relatively few empirical studies of the contemporary factors associated with geographical parthenogenesis. The aim of this study was to understand its causes by linking contemporary environmental gradients with reproductive modes in the freshwater ostracod Eucypris virens. Location Europe and North Africa. Methods We sampled popula…
Preface: Emerging trends in aquatic ecology III
Humans have never faced such major threats to their homes as they are experiencing now. Despite several global initiatives to ameliorate environmental problems, to preserve biodiversity and to alleviate poverty, these major threats are far from being resolved. According to a recent survey conducted by Ripple et al. (2017) and signed by 15,364 scientists of 184 countries, several indicators of environmental health are still worsening significantly. For example, along with the continuing increase of atmospheric CO2 and global temperatures (the threats best known by the general public as ‘‘climate change’’), there are still steep increases in atmospheric concentrations of methane and nitrous o…