Laurence Hurst (Educator)

Laurence Hurst (Educator)

I am the Professor of Evolutionary Genetics at The University of Bath. I have won prizes for both teaching and research. I especially enjoy giving talks in schools.

Location Bath, UK

Activity

  • See my answer - hope this helps

  • Dear Jacqueline, mutations start out rare (low frequency) but can increase in frequency. While there exists the new mutation and the original form then there will be variation with a population. If however the new mutation becomes the version all individuals have then it will be a fixed difference. If we compare this species to another species in which the...

  • My pleasure

  • If a mutation occurs in junk it is still a mutation, but likely to be a neutral mutation - one with no effects on fitness. I hope that helps. @DrusillaWinters

  • I am glad you are enjoying it!

  • Regarding data sharing, all sequence data that evolutionary biologists generate is freely available in worldwide resources such as NCBI. It is standard practice to release the information the second it is generated or when the first scientific paper on the subject is published. I pay to have DNA sequenced but never to access deposited data.

    @AndyHurley

  • One notion of a species is the "biological species concept" that emphasises the lack of interbreeding. In fruit flies (well studied in terms of speciation), the first genetic changes cause only partial hybrid breakdown - in the "hybrids" the males are more affected than the females. And naturally we have no idea about reproduction between fossil "species" -...

  • @JonBird Notice also that not all evolution is owing to selection - as we saw in the introductory sessions, most sequence evolution in the human genome is likely to be neutral or effectively neutral.

  • There is evidence from the Framingham heart study data for ongoing natural selection in humans. There is evidence for selection on cholesterol metabolism and blood pressure, both of which may relate to present day diets.

  • We do tend to use standard units. We tend to write in powers as well. The convention when we can't write a power properly is to use the ^ symbol i.e. 4.5 x 10^9 is the age of the earth in years. The units we use tend to go with the question. Depending on the discussion we often calculate in tens of thousands of years (out of Africa ~ 80 thousand), millions...

  • There is no one number but in part that is because speciation can occur by many mechanisms. In plants changes in chromosome number lead to new species instantaneously - new plant species pop up by this mechanism in real time (there is for example one being traced in North Wales which seems to date to the late 1960s if I recall). Conversely, knowledge of...

  • If I understand you correctly, I think you are talking about convergent evolution - the same or similar "answer", derived independently. If so then yes, there are loads of examples. An eye-like structure has evolved multiple times - ours is like the octopus simple eye but theirs is actually better as it doesn't have a central blind spot. Insects evolved a...

  • There are indeed different ways of asking how common two strings of anything are, DNA being an example. One question is to ask, assuming a position in DNA aligns between two species, what is the probability that the bases are the same. The second is to ask, if I pick a random base pair in one species, what is the probability it will align with a base in the...

  • Wafa - the soot deposits didn't make the new mutations. Rather the soot provided the conditions favouring a mutation if it occurred (or already existed).

  • Why we often discuss the peppered moth data is that Kettlewell actually studied the process of selection in action - he put out his moth trap and recorded the rates of the black and white versions of the moth over many years and was lucky enough to see dramatic changes - note these are different forms of individuals in the same species, not different species...

  • For the purposes of evolutionary change we just consider mutations that can be transmitted - ie those in germline @JonBird

  • @JonBird Any mutation inherited and seen in the fertilised egg - which is just a single cell with one copy of each chromosome from mum and one from dad - will be seen in all subsequent cells be they somatic or germline. Any mutations not so inherited will be particular to that individual but can be transmitted to offspring if the mutation occurs of germline...

  • Some have - am I am delighted to say that some have and have understood the logical inevitability that DNA->mutation-> changes in mutation frequency and have jettisoned their old beliefs.

  • Many plants survived the recent ice age in so called "refugia". As the temperature warmed up they slowly spread towards the poles as the ice retreated. No doubt some seeds and microorganisms persisted also under the ice (microorganisms have an amazing ability to persist), but for the most part the trends we see are of species recolonising from the refugia as...

  • With our new genetic tools we can indeed now see evolution happening in real time - Darwin never could.

  • Caterpillars are by definition the stage prior to butterflies and moths - so if you known the number of these you know the number of species with caterpillars.

  • Dear Jon, as it happens the expert on these moths (Mike Majerus) was the best many at my wedding. I've never seen anyone seriously questioning the data from Kettlewell. The coupling to the blackening of the trees seems very well resolved. There is a replicate experiment going on in Eastern Europe at present as there the trees remain dark - and the moths...

  • the strength of selection is indeed dependent on the extent of differential survival.

  • The environment doesn't cause the mutation. Mutations happen all the time in all genes. Occasionally these are beneficial in the new environment. To see the difference consider this analogy. I move to a country where the petrol for my car is slightly different. I could work out what the problem is, go into the engine fix the one bit that needs fixing and...

  • Dear Jon, To a first approximation of the allele is neutral it stands a 50:50 chance of going up or down in frequency. The other question we ask is what is the probability it will by chance go from rare (one copy only) to being so common everyone has the new version. This probability is 1/2N, where N is the number of individuals in the population. As the...

  • Wafa - we share a common ancestor with all other species. Our common ancestor with chimps we think was about 6 million years ago. It was neither chimp nor human as neither then existed. Our common ancestor with mice was about 100 million years ago and was neither mouse nor human.

  • Dear John, For multicellular species like us (but not like plants), we divide our cells in the embryo into those that will make up the body (soma) and those that will be so called germline - the cells that will go on to makes eggs and sperm. Only mutations that happen in the germline cells and their progenitors will be transmitted to sons and daughters. So...

  • Dear John, These questions are more in the land of chemistry than biology. But we know a few things - RNAs (single strand of nucleic acid - like one half of the ladder) tend to bend back on themselves and make so called "stem-loop" structures. You get mutual base pairing in the stem parts of the structures. So base-pairing per se is probably just a chemical...

  • Dear Lorraine, the idea for the course was to support teachers at all levels but also pupils at secondary/High school and above. You are right that this level is too high for primary students.

    We have produced full lessons and all resources for teachers of year 6 (10-11 year olds) that you can find...

  • Dear Clemence - the idea for the course was to support teachers at all levels but also pupils at secondary/High school and above. You are right that this level is too high for primary students.

    We have produced full lessons and all resources for teachers of year 6 (10-11 year olds) that you can find...

  • Most mutations are indeed bad for us, but a few can be advantageous - see the section on selection and adaptation

  • @WafaAbdelkreem Indeed - because of the nature of DNA, mutations are transmitted well from parents to offspring and then on to their offspring.

  • Dear Wafa, It is important to distinguish "physiological adaptation" and "genetic adaptation". If I simply move to higher altitude or somewhere cold my body adjusts its physiology. This can include making more or fewer red blood cells. This is physiological adaptation. This is not evolutionary or genetical change - the raised levels of red blood cells will...

  • Organisms are responding to life it cities. Can you see this article?

    https://www.nationalgeographic.com/news/2018/05/urban-living-drives-evolution-in-surprising-way/

  • Epigenetics refers to variation that is explained by changes to the DNA that aren't owing to the sort of mutation we have looked at. For example, a C in DNA can have another chemical group - a methyl group - attached to it. If this occurs sometimes it stops a gene from turning on. So differences between genetically identical cells in your body are often...

  • It depends on what you mean by "cause'. We know the genetic basis of the white and black forms - it is indeed two different versions of the same gene (and if you have both the black and the white version of the gene the moth is black - we say black is "dominant" over white. However, this just defines two different types. If you want to know why one is more...

  • In short the strength of selection is dependent on the extent of differential survival in the population associated with the trait. Lets go to a case of black moths/mice on a black background versus a white version on the same background. You can imagine a case where there are very few predators about - if so the advantage of being camouflaged is small and...

  • Indeed, the movement of species around the globe often causes major effects when the invading species take over.

  • The simple answer is yes. One of the first breakthroughs in this regard was the discovery of the genetic basis of how organisms behave over the 24 hours of the day. Mutations in the period gene in flies were showed to be inherit and affect how different flies behave differently. Twin studies in humans show a genetic component to many behaviours e.g....

  • Continue!

  • Dear Wafa
    Just bear with the genetics. If you understand DNA you will understand how evolution works. Let me know if you have any issues.

  • Our resources are here. They are made for year 6 and work very well during in school tests:

    https://people.bath.ac.uk/bssldh/LaurenceDHurst/Outreach.html

    I'd be interested to hear your thoughts.