Search results for "Parasitism"

Convergent Loss of Chemoreceptors across Independent Origins of Slave-Making in Ants

2022

The evolution of an obligate parasitic lifestyle often leads to the reduction of morphological and physiological traits, which may be accompanied by loss of genes and functions. Slave-maker ants are social parasites that exploit the work force of closely related ant species for social behaviours such as brood care and foraging. Recent divergence between these social parasites and their hosts enables comparative studies of gene family evolution. We sequenced the genomes of eight ant species, representing three independent origins of ant slavery. During the evolution of eusociality, chemoreceptor genes multiplied due to the importance of chemical communication in societies. We investigated ev…

A stoichiometric perspective on host-parasite interactions

2013

The role of local adaptation in the relationship between an endangered root hemiparasite Euphrasia rostkoviana, and its host, Agrostis capillaris

1999

We experimentally studied the role of local adaptation and the co-evolutionary relationship between an annual, endangered root hemiparasite Euphrasia rostkoviana and its main host Agrostis capillaris. According to our hypothesis, the existence of local adaptation in hemiparasites should be observable in better hemiparasite performance when attached to A. capillaris hosts originating from Euphrasia populations. After one month of growth, the height and the number of leaves of hemiparasites were not affected by the origin of their hosts. The differences in growth were due to between population effects. The situation remained constant after three months. Hemiparasite biomass was not affected b…

Population structure of a parasitic plant and its perennial host

2002

Characterization of host and parasite population genetic structure and estimation of gene flow among populations are essential for the understanding of parasite local adaptation and coevolutionary interactions between hosts and parasites. We examined two aspects of population structure in a parasitic plant, the greater dodder (Cuscuta europaea) and its host plant, the stinging nettle (Urtica dioica), using allozyme data from 12 host and eight parasite populations. First, we examined whether hosts exposed to parasitism in the past contain higher levels of genetic variation. Second, we examined whether host and parasite populations differ in terms of population structure and if their populati…

Differences in parasite susceptibility and costs of resistance between naturally exposed and unexposed host populations

2009

It is generally assumed that resistance to parasitism entails costs. Consequently, hosts evolving in the absence of parasites are predicted to invest less in costly resistance mechanisms than hosts consistently exposed to parasites. This prediction has, however, rarely been tested in natural populations. We studied the susceptibility of three naïve, three parasitized and one recently isolated Asellus aquaticus isopod populations to an acanthocephalan parasite. We found that parasitized populations, with the exception of the isopod population sympatric with the parasite strain used, were less susceptible to the parasite than the naïve populations. Exposed but uninfected (resistant) isopods f…

Host manipulation by parasites : adaptation to enhance transmission?

2005

Otto Seppälä tutki väitöskirjassaan loisten kykyä manipuloida isäntiään mahdollisena strategiana tehostaa loisten siirtymistä uusiin isäntäyksilöihin. Monien loisten on havaittu vaikuttavan mm. isäntiensä käyttäytymiseen ja ulkonäköön. Erityisesti ravintoketjuissa saaliseläimistä saalistajiin kulkeutuvilla loisilla isännän manipulointia on yleisesti pidetty loisten evolutiivisena sopeumana altistaa isännät saalistajille ja täten tehostaa loisten siirtymistä elinkierrossa eteenpäin. Manipulaatioteoriaa on kuitenkin vain harvoin testattu kriittisesti selvittämällä saalistuskokein loisten aiheuttamien käyttäytymismuutosten vaikutusta isäntien saalistusalttiuteen.Seppälä selvitti useiden eri ka…

Sperm quality, secondary sexual characters and parasitism in roach (Rutilus rutilus L.)

2004

According to sperm competition models, a male spawning in a disfavoured role should have spermatozoa with higher velocity but shorter longevity compared with a male spawning in a favoured role. Moreover, immunosuppressive androgens are needed to produce both secondary sexual characters and sperm cells. The ‘sperm protection’ hypothesis suggests that the immunosuppressive action of androgens has evolved to protect haploid spermatozoa, which are antigenic, from autoimmune attacks. Therefore, a male with high sexual ornamentation may be more susceptible to diseases but may possess better quality ejaculate than his less ornamented rival. We studied sexual ornamentation (breeding tubercles), eja…

Supplementary material 1 from: Lefort M, Wratten S, Cusumano A, Varennes Y, Boyer S (2017) Disentangling higher trophic level interactions in the cab…

2018

OSR aphid mummy collection. Sampling location and size / Amplification success of mummies' DNA extracts by Illumina sequencing.

Supplementary material 3 from: Lefort M, Wratten S, Cusumano A, Varennes Y, Boyer S (2017) Disentangling higher trophic level interactions in the cab…

2018

Exploratory statistics addressing sequencing depth per country and MOTU rarefaction.

Supplementary material 2 from: Lefort M, Wratten S, Cusumano A, Varennes Y, Boyer S (2017) Disentangling higher trophic level interactions in the cab…

2018

Supporting Information 2