MSc pupil Ana González visited the collections final month as a part of challenge NorHydro, the place she spent some weeks within the lab working along with her samples. Right here is an account of her expertise:
The problem of figuring out benthic hydrozoans
Hydrozoa is an enchanting however poorly understood group of invertebrates, partially as a result of their identification shouldn’t be at all times a straightforward activity. I’ve been learning benthic hydrozoan communities for over a yr now, specifically these residing within the shallow waters of Mallorca (Spain), and I’ve realized that the variety of kinds and constructions within the group is greater than I had imagined firstly of my research, and their identification is harder than I anticipated. The assemblages of hydrozoans within the Mediterranean are after all very totally different from those that happen in Norway, however one thing that each communities have in frequent is that morphological identification of the animals (i.e. telling which species is current primarily based solely on the traits we are able to observe) is difficult, which is why one of many goals of my go to to the College Museum of Bergen final December was to study a special method (DNA barcoding) that may assist me enhance the identification of my samples in instances when the morphology of the specimens shouldn’t be adequate.
DNA barcoding consists to 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 neighborhood establish specimens that for one cause or the opposite can’t be recognized primarily based on how they give the impression of being. In some teams, reminiscent of many colonial invertebrates, this system has grow to be a key asset as a result of the colonies are sometimes too younger or not reproductive, or the essential 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, relating to DNA barcoding, each step of the method is essential, and being affected person and cautious is crucial.
Getting good ends in the DNA lab is dependent upon a number of elements like not forgetting any step and avoiding contamination so far as attainable, however the work doesn’t finish there: after you have your sequences they need to be cleaned, quality-checked, and at last 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 will help you corroborate the identification of a specimen. When accomplished proper and with a very good database, the DNA barcodes might be helpful to detect variations between hydrozoan assemblages rising in several components of the world or between totally different substrates and ranges of anthropogenic impression, which is what I’m doing in my MSc challenge.
The evaluation of DNA sequences is a strong instrument to check specimens of distinct populations and in some instances animals that apparently belong to the identical species develop into fully totally different (e.g. cryptic species). This isn’t unusual for benthic hydrozoans, which have excessive morphological variety but in addition excessive ranges of plasticity, leading to colonies from totally different species typically being similar to one another after they develop in related substrates. As helpful as DNA analyses are, nevertheless, it is usually essential to contemplate their limitations. For instance, whereas the abundance of every species in a given neighborhood is essential to explain the ecological standing of a habitat, estimating abundance continues to be not at all times attainable from sequence reads in DNA analyses.
Using DNA barcodes in my work shouldn’t be restricted to my present challenge, as I hope my identifications and sequences will assist a bit bit to enhance the databases for future research of hydrozoan communities within the Mediterranean Sea, and perhaps even permit different researchers to check their samples with the species discovered on different components of the world. I believe that wanting intently at every specimen is one of the simplest ways to actually know variation, so each morphology observations and DNA analyses ought to be mixed to acquire good estimates of the variety of a taxon in any locality. For instance, each time the DNA analyses reveal variations in two clades that had been considered the identical species, it’s time to seek for new taxonomic characters that we’d have missed earlier than, and for that cause it is usually essential to have a very good information of the morphology of every species. Each morphological and DNA-based identifications have limitations and benefits so, when you have the chance to make use of each, why select just one?