Nature or nurture

February 8, 2019

The way in which living things are given their formal Latin names is systematic in so much as the first part of the name signifies the group of organisms reckoned to be very similar or somehow related in evolutionary terms. The second part of the name is descriptive, usually of colour, shape, size, aroma, growing habit etc. The traditional way of classifying living things relied on careful observation, perhaps dissection. Anatomy and even behaviour may contribute to the academic process of classification. That approach has served us well since Linnaeus. (The binomial system was developed by Carl Linnaeus 1707 – 1778), a Swedish botanist, physician, and zoologist who formalised the modern system of naming organisms).

The two part name signifies that the organism belongs to a particular species. In recent years a new tool has been brought to bear on determining whether two individuals are of the same or a different species or share some commonality in their evolution and share a close relationship meriting their inclusion in the same grouping. That new tool is genomics. Individual organisms are compared at the level of their DNA. I believe that this technique has been a great help in classifying the thousands of species of trees in the world, many of which have been found in tropical forests relatively recently.

Using genetic analysis will no doubt shed more light on more common species such as dandelions and brambles whose two word Latin names are elaborated a little further by adding agg to signify that what we call a dandelion or a bramble are in fact aggregates of many tens or hundreds of sub-species.

So perhaps the answers to all these classification issues will simply come down to analysing and comparing genetic material, resources permitting.

 

Hold on there – not so fast. There is at least one further issue that complicates and fascinates in this situation for me. When we see two individuals in the wild that look as though they may be different species (but perhaps similar species) could there be something more at play - something else that determines the appearance, physiology or behaviour of two individuals.

 

I have heard Nature v Nurture arguments since the 1960s. No doubt the same arguments occurred for decades or centuries before I became aware. There was probably a time when the nature of the beast was thought to determine all life outcomes. The debate has moved to the balance between the effects of nature and nurture. It becomes a messy discussion involving opinions, beliefs, anecdotes and science. Here is a small piece of observational science to ponder. I write this after reading an article in my local Beekeepers’ Magazine (*)

Picture the scene. The action takes place on a frame of wax in the brood chamber of a honeybee hive. The worker bees have cleaned an area of cells ready for the queen to lay her eggs. The queen can choose to lay an unfertilised egg which will develop into a drone (male) with only one set of chromosomes which come from the queen (mother). So the drone has no father (but it does have a grandfather – the queen’s father).

That is fascinating enough but here are two more points of interest. When the virgin queen took her mating flight she mated with many males and received sperm from (typically) a dozen different males. She stores the sperm for use throughout her useful laying life. Consequently the female bees (workers) in her colony are all sisters or half sisters.

Here is the nature v nurture bit. Imagine that the queen is concentrating on producing females at the moment and so is laying fertilised eggs, one per cell, each egg with two sets of chromosomes all destined to become females.

Suppose that in adjacent cells the queen lays eggs fertilised with the same sperm. On the face of it these adjacent cells will produce identical sisters, genetically identical. In other words nature (genetics) will yield clones destined to develop into workers, who baring accidents will perform the same functions in the hive and have very similar lives.

The colony has sensed that they need to make a new or additional queen. One of those cells destined to produce a worker bee is chosen and when the egg hatches into a larva extra rich food (royal jelly) is placed in the cell. The cell is enlarged with wax to accommodate the extra food and allow for the larva to grow and once the cell is sealed undergo metamorphosis into a new queen.

The egg that became a worker will have a number of roles within the colony performing functions that change as she ages. She will live for about six weeks during the busy summer. What began as her identical sister has through nurturing become a virgin queen, larger than a worker and when successfully mated, capable of heading a colony of up to 60000 bees. She has developed an ovipositor but also retains the ability to sting to death a rival queen. Baring accidents she will live for 2-3 years. Her sister, the worker develops a sting used to defend the colony.

No question about it nurture has determined these outcomes for two genetically identical bees. The genes define all that the individual bee could become and nurture determines what part of that potential is realised.

 

* Fred Ayers – Lune Valley Community Beekeepers. Reporting on work by Dr Paul Hurd and Prof. Rysard Maleska.

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