MSc scholar Ana González visited the collections final month as a part of venture NorHydro, the place she spent some weeks within the lab working together with her samples. Right here is an account of her expertise:
The problem of figuring out benthic hydrozoans
Hydrozoa is a captivating however poorly understood group of invertebrates, partly as a result of their identification just isn’t all the time a simple process. I’ve been learning benthic hydrozoan communities for over a 12 months now, specifically these dwelling within the shallow waters of Mallorca (Spain), and I’ve realized that the variety of kinds and buildings within the group is greater than I had imagined in the beginning of my research, and their identification is harder than I anticipated. The assemblages of hydrozoans within the Mediterranean are in fact very totally different from those that happen in Norway, however one thing that each communities have in widespread is that morphological identification of the animals (i.e. telling which species is current based mostly solely on the traits we will observe) is difficult, which is why one of many goals of my go to to the College Museum of Bergen final December was to be taught a unique method (DNA barcoding) that may assist me enhance the identification of my samples in instances when the morphology of the specimens just isn’t ok.
A number of the morphological characters which can be used to determine benthic hydrozoans. On the left aspect a member of Campanulariidae, with a stolonal colony, and on the suitable aspect Monotheca obliqua with an erect colony.
DNA barcoding consists find a brief DNA sequence (the barcode) that’s related for all members of 1 species however totally different from all different species. It’s a comparatively latest instrument that –amongst different issues– has helped the scientific group determine specimens that for one purpose or the opposite can’t be recognized based mostly on how they appear. In some teams, resembling many colonial invertebrates, this system has change into a key asset as a result of the colonies are sometimes too younger or not reproductive, or the vital characters for identifications could also be discovered solely in a single stage of the life cycle and never in others. For this go to I had the prospect to convey all my samples from Mallorca to Bergen and I set to extracting the DNA of chosen specimens, amplifying two totally different barcode genes (COI and 16S), and acquiring clear sequences for them. I found that, in the case of DNA barcoding, each step of the method is vital, and being affected person and cautious is important.
Me on the DNA lab, working the electrophoresis for my samples.
Getting good ends in the DNA lab is determined by a number of components like not forgetting any step and avoiding contamination so far as doable, however the work doesn’t finish there: after you have your sequences they must be cleaned, quality-checked, and eventually in contrast with others. Because of this having a whole and reliable database of DNA barcodes is critical, particularly if you wish to use the sequence that can assist you corroborate the identification of a specimen. When completed proper and with a great database, the DNA barcodes might be helpful to detect variations between hydrozoan assemblages rising in several elements of the world or between totally different substrates and ranges of anthropogenic impression, which is what I’m doing in my MSc venture.
Left: Clytia sp rising on the marine plant Posidonia oceanica. Heart: A polyp of Halecium sp, one of the troublesome genera of Hydrozoa to determine based mostly solely in morphology, particularly when the colony just isn’t reproductive. Proper: Eudendrium sp., present in harbours in Mallorca in excessive abundances.
The evaluation of DNA sequences is a strong instrument to match specimens of distinct populations and in some instances animals that apparently belong to the identical species change into utterly totally different (e.g. cryptic species). This isn’t unusual for benthic hydrozoans, which have excessive morphological variety but additionally excessive ranges of plasticity, leading to colonies from totally different species generally being similar to one another once they develop in related substrates. As helpful as DNA analyses are, nevertheless, it is usually vital to think about their limitations. For instance, whereas the abundance of every species in a given group is vital to explain the ecological standing of a habitat, estimating abundance continues to be not all the time doable from sequence reads in DNA analyses.
Many cryptic species have been found in Aglaopheniidae because of the mix of DNA barcoding and morphological evaluation
Using DNA barcodes in my work just isn’t restricted to my present venture, as I hope my identifications and sequences will assist somewhat bit to enhance the databases for future research of hydrozoan communities within the Mediterranean Sea, and perhaps even enable different researchers to match their samples with the species discovered on different elements of the world. I feel that wanting intently at every specimen is one of the best ways to really know variation, so each morphology observations and DNA analyses needs to be mixed to acquire good estimates of the variety of a taxon in any locality. For instance, every time the DNA analyses reveal variations in two clades that had been regarded as the identical species, it’s time to seek for new taxonomic characters that we’d have missed earlier than, and for that purpose it is usually vital to have a great data of the morphology of every species. Each morphological and DNA-based identifications have limitations and benefits so, when you’ve got the chance to make use of each, why select just one?
Ana