Search results for "Systematics"
showing 10 items of 6702 documents
PCR survey ofXenoturbella bockiHox genes
2007
Xenoturbella bocki has recently been identified as one of the most basal deuterostomes, although an even more basal phylogenetic position cannot be ruled out. Here we report on a polymerase chain reaction survey of partial Hox homeobox sequences of X. bocki. Surprisingly, we did not find evidence for more than five Hox genes, one clear labial/PG1 ortholog, one posterior gene most similar to the PG9/10 genes of Ambulacraria, and three central group genes whose precise assignment to a specific paralog group remains open. We furthermore report on a re-evaluation of the available published evidence of Hox genes in other basal deuterostomes.
Tracing the origin of the compensasome: evolutionary history of DEAH helicase and MYST acetyltransferase gene families.
2001
Dosage compensation in Drosophila is mediated by a complex of proteins and RNAs called the "compensasome." Two of the genes that encode proteins of the complex, maleless (mle) and males-absent-on-the-first (mof), respectively, belong to the DEAH helicase and MYST acetyltransferase gene families. We performed comprehensive phylogenetic and structural analyses to determine the evolutionary histories of these two gene families and thus to better understand the origin of the compensasome. All of the members of the DEAH and MYST families of the completely sequenced Saccharomyces cerevisiae and Caenorhabditis elegans genomes, as well as those so far (June 2000) found in Drosophila melanogaster (f…
Intraspecific variation in mating behaviour does not cause sexual isolation between Drosophila virilis strains
2005
There is increasing evidence that mate recognition systems vary within species. We studied the courtship rituals of five Drosophila virilis strains to investigate this intraspecific variation. Males that actively and persistently courted the female without paying much attention to the female's behaviour were the most successful at copulating. Intraspecific variation in mating rituals was high, but not as high as at the species level and it was not high enough to cause sexual isolation between the strains. The differences in courtship interactions of the strains reflected their geographical origin. Males from one of the strains did not produce audible song during their courtship, but still m…
Optimum and Maximum Host Sizes at Parasitism for the Endoparasitoid <I>Hyposoter didymator</I> (Hymenoptera: Ichneumonidae) Differ Greatl…
2007
Host size is considered a reliable indicator of host quality and an important determinant of parasitoid fitness. Koinobiont parasitoids attack hosts that continue feeding and growing during parasitism. In contrast with hemolymph-feeding koinobionts, tissue-feeding koinobionts face not only a minimum host size for successful development but also a maximum host size, because consumption of the entire host is often necessary for successful egression. Here we study interactions between a generalist tissue-feeding larval endoparasitoid, Hyposoter didymator Thunberg (Hymenoptera: Ichneumonidae) and two of its natural hosts, Spodoptera exigua Hübner and Chrysodeixis chalcites Esper (Lepidoptera: N…
An improved high yield method to obtain microsatellite genotypes from red deer antlers up to 200 years old.
2013
Analysis of DNA from older samples, such as museum specimen, is a promising approach to studying genetics of populations and ecological processes across several generations. Here, we present a method for extracting high quality nuclear DNA for microsatellite analysis from antlers of red deer (Cervus elaphus). The genotyping of individuals was based on nine microsatellite loci. Because the amount of DNA found in antlers was high, we could reduce the amount of sample and chemicals used and shorten the decalcification time in comparison to other methods. Using these methods, we obtained genotypes from antlers up to 200 years old.
Unconditional adoption rules out the need for parent–offspring recognition in a single‐brooded colonial seabird
2021
Parent–offspring recognition (POR) is fundamental in colonial birds when the potential intermingling of chicks is higher due to the large number and proximity of nests. In species with isolated nests, where chick presence in the nest is strong contextual evidence of kinship, there might be circumstances when the parent might doubt the identity of the chick, but not enough to reject it. Olfactory-based recognition of conspecifics and nest sites in birds has gained strong evidence suggesting a potential role of olfaction in POR. Despite that, there are no studies testing it. We used Scopoli's shearwater (Calonectris diomedea) as model colonial single-brooded species with a developed olfactory…
Globin genes are present in Ciona intestinalis.
2003
The key position of the Ciona intestinalis basal to the vertebrate phylogenetic tree brings up the question of which respiratory proteins are used by the tunicate to facilitate oxygen transport and storage. The publication of the Ciona draft genome sequence suggests that globin genes are completely missing and that-like some molluscs and arthropods-the sea squirt uses hemocyanin instead of hemoglobin for respiration. However, we report here the presence and expression of at least four distinct globin gene/protein sequences in Ciona. This finding is in agreement with the ancestral phylogeny of the vertebrate globins. Moreover, it seems likely that the Ciona hemocyanin-like sequences have enz…
Early evolution of metazoan serine/threonine and tyrosine kinases: identification of selected kinases in marine sponges.
1997
The phylum Porifera (sponges) was the first to diverge from the common ancestor of the Metazoa. In this study, six cDNAs coding for protein-serine/threonine kinases (PS/TKs) are presented; they have been isolated from libraries obtained from the demosponges Geodia cydonium and Suberites domuncula and from the calcareous sponge Sycon raphanus. Sequence alignments of the catalytic domains revealed that two major families of PS/TK, the "conventional" (Ca(2+)-dependent) protein kinase C (PKC), the cPKC subfamily, as well as the "novel" (Ca(2+)-independent) PKC (nPKC), form two separate clusters. In each cluster, the sequence from S. raphanus diverges first. To approach the question about the or…
Courtship song and immune function in the field cricket Gryllus bimaculatus
2003
It has been assumed that sexual ornaments have evolved to reveal males’ health and vigour for females. Choosy females may indirectly use ornaments as an indicator of the presence and effectiveness of genes for resistance against parasites. In this study we tested whether females of the Mediterranean field cricket, Gryllus bimaculatus, can use courtship song as a cue for choosing males with high immunocompetence, measured as encapsulation rate of nylon implants and lytic activity of haemolymph. We found that female crickets preferred courtship songs from males with a high encapsulation rate. Female crickets also had a tendency to prefer courtship songs with high tick rate and long high-frequ…
Biomineralizations: insights and prospects from crustaceans.
2011
19 pages; International audience; For growing, crustaceans have to molt cyclically because of the presence of a rigid exoskeleton. Most of the crustaceans harden their cuticle not only by sclerotization, like all the arthropods, but also by calcification. All the physiology of crustaceans, including the calcification process, is then linked to molting cycles. This means for these animals to find regularly a source of calcium ions quickly available just after ecdysis. The sources of calcium used are diverse, ranging from the environment where the animals live to endogenous calcium deposits cyclically elaborated by some of them. As a result, crustaceans are submitted to an important and energ…