Search results for "Variation"

Disentangling structural genomic and behavioural barriers in a sea of connectivity

2019

18 pages, 4 tables, 3 figures.-- This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited

Infection, specificity and host manipulation of Australapatemon sp. (Trematoda, Strigeidae) in two sympatric species of leeches (Hirudinea)

2017

SUMMARYFactors that drive parasite specificity and differences in infection dynamics among alternative host species are important for ecology and evolution of host–parasite interactions, but still often poorly known in natural systems. Here, we investigated spatiotemporal dynamics of infection, host susceptibility and parasite-induced changes in host phenotype in a rarely explored host–parasite system, theAustralapatemonsp. trematode infecting two sympatric species of freshwater leeches,Erpobdella octoculataandHelobdella stagnalis. We show significant variation in infection abundance between the host species in both space and time. Using experimental infections, we also show that most of th…

Variable crab camouflage patterns defeat search image formation.

2021

Understanding what maintains the broad spectrum of variation in animal phenotypes and how this influences survival is a key question in biology. Frequency dependent selection – where predators temporarily focus on one morph at the expense of others by forming a “search image” – can help explain this phenomenon. However, past work has never tested real prey colour patterns, and rarely considered the role of different types of camouflage. Using a novel citizen science computer experiment that presented crab “prey” to humans against natural backgrounds in specific sequences, we were able to test a range of key hypotheses concerning the interactions between predator learning, camouflage and mor…

Strong signature of selection in seeder populations but not in resprouters of the fynbos heathErica coccinea(Ericaceae)

2016

A higher frequency of natural selection is expected in populations of organisms with shorter generation times. In fire-prone ecosystems, populations of seeder plants behave as functionally semelparous populations, with short generation times compared to populations of resprouter plants, which are truly iteroparous. Therefore, a stronger signature of natural selection should be detected in seeder populations, favoured by their shorter generation times and higher rates of population turnover. Here we test this idea in Erica coccinea from the Cape Floristic Region, which is dimorphic for post-fire regeneration mode. We measured three floral traits supposedly subject to natural selection in see…

Seasonal genetic variation associated with population dynamics of a poecilogonous polychaete worm

2017

Poecilogonous species show variation in developmental mode, with larvae that differ both morphologically and ecologically. The spionid polychaete Pygospio elegans shows variation in developmental mode not only between populations, but also seasonally within populations. We investigated the consequences of this developmental polymorphism on the spatial and seasonal genetic structure of P. elegans at four sites in the Danish Isefjord‐Roskilde‐Fjord estuary at six time points, from March 2014 until February 2015. We found genetic differentiation between our sampling sites as well as seasonal differentiation at two of the sites. The seasonal genetic shift correlated with the appearance of new s…

2016

Most large mammals have constantly been exposed to anthropogenic influence over decades or even centuries. Because of their long generation times and lack of sampling material, inferences of past population genetic dynamics, including anthropogenic impacts, have only relied on the analysis of the structure of extant populations. Here, we investigate for the first time the change in the genetic constitution of a natural red deer population over two centuries, using up to 200-year-old antlers (30 generations) stored in trophy collections. To the best of our knowledge, this is the oldest DNA source ever used for microsatellite population genetic analyses. We demonstrate that government policy …

Molecular phylogeography ofThymus herba-barona(Lamiaceae): Insight into the evolutionary history of the flora of the western Mediterranean islands

2011

Thymus herba-barona is endemic to Majorca, Corsica, and Sardinia. In order to gain insight into its evolutionary history, we examined the genetic diversity and phylogeography of the species using sequences of the trnT-trnL intergenic spacer from 106 individuals belonging to 15 populations. We detected high within-species genetic diversity and strong among- population differentiation, but no evidence for phylogeographic structure. A haplotype network supported the occurrence of three main clades, the ancestral one being geographically restricted to the Gennargentu massif in Sardinia, while the two derived ones were relatively widespread. Coalescent-based analyses indicated deep divergence ti…

Selection for multicomponent mimicry: equal feature salience and variation in preferred traits

2016

When should multiple traits on Batesian mimics be selected to resemble corresponding traits on model species? Here, we explore two possibilities. First, features of equal salience to predators may be used to categorize prey, selecting for multicomponent mimicry. Second, if different predators use single yet different traits to categorize prey, multicomponent mimicry may still be selected. We studied how blue tits categorized rewarding and unrewarding artificial prey items that are differentiated by a combination of two color dimensions. Many birds used both color dimensions to make decisions, and overall, the population selected for multicomponent mimicry. However, a subset of birds used on…

Karyotype variability and inter-population genomic differences in freshwater ostracods (Crustacea) showing geographical parthenogenesis

2018

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…

Variation in the COI gene of the freshwater pearl mussel Margaritifera margaritifera from River Vuokkijoki

2017

The freshwater pearl mussel Margaritifera margaritifera L. is one of the most endangered freshwater mussels in the world. Effective conservation of threatened species requires not only ecological, but also genetic information from the target species and populations. Since low genetic diversity can reduce the ability of a species to adapt to environmental changes, maintaining genetic diversity has been identified as one of the key elements in successful conservation programs. We examined genetic variation of the freshwater pearl mussel from the River Vuokkijoki, Karelia, Russia. We sequenced a fragment of the cytochrome c oxidase subunit I gene (COI) from 22 individuals and compared the data…