Search results for "Study"
showing 10 items of 15483 documents
Novel subpopulations in date palm (Phoenix dactylifera) identified by population-wide organellar genome sequencing
2019
Background The date palm is one of the oldest cultivated fruit trees. The tree can withstand high temperatures and low water and the fruit can be stored dry offering nutrition across the year. The first region of cultivation is believed to be near modern day Iraq, however, where and if the date palm was domesticated is still a topic of debate. Recent studies of chloroplast and genomic DNA revealed two major subpopulations of cultivars centered in both the Eastern range of date palm cultivation including Arabian Peninsula, Iraq and parts of South Asia, and the Western range, including North Africa. Results To better understand the origins of date palm cultivation we sequenced and analyzed ov…
Population and reproductive dynamics of the polychaete Pygospio elegans in a boreal estuary complex
2016
Pygospio elegans is an opportunistic, wide-spread spionid polychaete that reproduces asexually via fragmentation and can produce benthic and pelagic larvae, hence combining different developmental modes in one species. We documented the density, size distribution, and reproductive activity of P. elegans at four sites in the Danish Isefjord-Roskilde Fjord estuary complex, where all modes of reproduction were reported. We compared population dynamics of this species to environmental parameters such as salinity, temperature, and sediment characteristics (grain size, sorting, porosity, water content, organic content, C/N). We observed that new cohorts—resulting either from sexual or asexual rep…
Phenotypic plasticity in growth and fecundity induced by strong population fluctuations affects reproductive traits of female fish
2016
Fish are known for their high phenotypic plasticity in life-history traits in relation to environmental variability, and this is particularly pronounced among salmonids in the Northern Hemisphere. Resource limitation leads to trade-offs in phenotypic plasticity between life-history traits related to the reproduction, growth, and survival of individual fish, which have consequences for the age and size distributions of populations, as well as their dynamics and productivity. We studied the effect of plasticity in growth and fecundity of vendace females on their reproductive traits using a series of long-term incubation experiments. The wild parental fish originated from four separate populat…
Spatio-temporal dynamics of density-dependent dispersal during a population colonisation
2019
Predicting population colonisations requires understanding how spatio‐temporal changes in density affect dispersal. Density can inform on fitness prospects, acting as a cue for either habitat quality, or competition over resources. However, when escaping competition, high local density should only increase emigration if lower‐density patches are available elsewhere. Few empirical studies on dispersal have considered the effects of density at the local and landscape scale simultaneously. To explore this, we analyze 5 years of individual‐based data from an experimental introduction of wild guppies Poecilia reticulata. Natal dispersal showed a decrease in local density dependence as density at…
Males do not always switch females when presented with a better reproductive option
2014
8 pages; International audience; Paired individuals are expected to leave their current partner for newly encountered ones of higher quality. In such cases, animals should therefore be able to compare the quality of their current partner to the quality of a new prospective mate next to the couple. We tested this prediction in Gammarus pulex, an amphipod species where paired males have been described to switch females before copulation. Contrary to expectations, a majority of males remained paired to their current female when presented to an unpaired female of higher quality. In fact, males did not seem to compare the quality of the 2 females before switching. They rather based their decisio…
Communal nesting in the garden dormouse (Eliomys quercinus)
2017
Communal nesting has been described in many rodents including some dormouse species. In this study, we report the existence of this reproductive strategy in the garden dormouse Eliomys quercinus. Data was recorded by checking natural nests and nest-boxes from 2003 to 2013 in SE Spain. Pups and adults dormice found in nests were captured and marked. Overall, 198 nests were found: 161 (81.31%) were singular nests and 37 (18.69%) were communal nests. Communal nests were composed by different combinations of one up to three females together with one up to three different size litters. The number of communal nests varied from year to year in accordance with the number of singular nests and no se…
Size-assortative pairing in Gammarus pulex (Crustacea: Amphipoda): a test of the prudent choice hypothesis.
2010
6 pages; International audience; Positive assortative mating is a widespread phenomenon in the animal kingdom. Several hypotheses have been proposed to explain this reproductive pattern in natural populations, but growing evidence suggests that assortative mating most often results from sexual mating preferences. Recently, conditiondependent mate choice in the face of costly competition for mates has been proposed to explain assortative mating in natural populations. Variation in competitive ability may generate variation in both the strength and the direction of mate preference, resulting in assortative mating with respect to individual quality if low-quality competitors are less choosy, o…
Comment on “Global distribution of earthworm diversity”
2021
Phillips et al . (Reports, 25 October 2019, p. 480) incorrectly conclude that tropical earthworm communities are less diverse and abundant than temperate communities. This result is an artifact generated by some low-quality datasets, lower sampling intensity in the tropics, different patterns in richness-area relationships, the occurrence of invasive species in managed soils, and a focus on local rather than regional richness.
A high-quality genome assembly from short and long reads for the non-biting midge Chironomus riparius (Diptera)
2020
AbstractBackgroundChironomus riparius is of great importance as a study species in various fields like ecotoxicology, molecular genetics, developmental biology and ecology. However, only a fragmented draft genome exists to date, hindering the recent rush of population genomic studies in this species.FindingsMaking use of 50 NGS datasets, we present a hybrid genome assembly from short and long sequence reads that make C. riparius’ genome one of the most contiguous Dipteran genomes published, the first complete mitochondrial genome of the species and the respective recombination rate as one of the first insect recombination rates at all.ConclusionsThe genome and associated resources will be h…
Long-term fitness consequences of high yolk androgen levels: sons pay the costs
2012
Summary 1. Early growth conditions, for example hormonal environment during embryonic development, may have long-lasting effects on behaviour and phenotype, with subsequent fitness consequences. Yolk androgens have been shown to affect various offspring traits in the short-term, but fitness consequences for either offspring or parents, a prerequisite for studying the adaptiveness of this maternal effect, are poorly known in the wild. 2. We experimentally elevated yolk androgen levels of whole clutches in a wild population of collared flycatchers (Ficedula albicollis) and investigated the long-term effects of yolk androgens on offspring local recruitment, parental return rate, and timing and…