Errors have occurred in the development of living organisms from time to time. As bodies experience growth, they are presented to a whole new level of errors in their development. These errors could either be gene-mediated or environmentally induced. A good example of an environmentally induced error is the thermal effect on the development of insects. When maggots are collected from a corpse and maintained under a known environmental condition until pupation, they exhibit changing development habits.
When the temperature is chilled at 3°C, the development of the maggots is seemingly ‘arrested’ without increasing mortality and provided the number of larvae is low, and mass maggot heating is absent (Byrd & Castner, 2009). Therefore, the thermal environment of insects all the way from collection to deposition should be put into the record to ensure accurate estimation of development unless the maggots are exposed to conditions aimed at stopping development. However, it should also be noted that the time of collection and maintenance could also result in a development error for the maggots.
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Gene-mediated errors in insects come as a result of changes in chromosome numbers or differences in banding patterns. When an insect experiences monosomy (when a cell has only one chromosome of a pair of chromosomes) it results in the size reduction disorder. The insect's growth is arrested as it grows small. In the case of a trisomy (when a cell has an extra copy of a chromosome making the number of chromosomes three), it results in the clear wing disorder. Duplication of a chromosome leads to a duplication disorder where the insect is seen to have two heads and additional body segments. The deletion of a small part of the large sex chromosome, on the other hand, results in the unsegmented disorder, where the insect appears to have a small body and no segments.
Developmental Symbiosis
Developmental symbiosis refers to the growth of individual organisms that live in close proximity depending on one another for certain benefits to boost their growth. Symbiosis can be either a mechanism of adaptation or a mechanism of protection. Avice & Ayala (2007) say that the acquisition of a strong symbiotic association between living things benefits them in that they get to share their metabolic capacities. Avice & Ayala (2007) further state that this kind of co-relation has been on the rise in the animal kingdom as most animals have diversified on the basis of symbiotic associations acquired in their early stages.
On the other end, Gilbert (2016) addresses symbiosis as a mechanism of protection. He highlights the way the embryo protects itself before establishing a functional immune system. The embryo at its early stages has got no protection mechanism by itself so it results in forming symbiotic relationship with other organisms (Gilbert, 2016). Here, this discussion takes a deeper look at the symbiotic development of embryos as Gilbert (2016) observes.
In using the example of the ‘Palaeon’ embryo, Gilbert (2016) shows how this embryo benefits from its symbiotic association with ‘Alteromonas’. He takes two samples of the ‘Palaeon’ embryo- one which is bacteria free and the other which is inoculated with ‘Alteromonas’. In observing, the bacteria free embryo dies where else the treated one survives. This shows how the young embryo benefits from its symbiotic association with bacteria. The shrimp embryo receives protection against pathogens at its tender stages through developmental symbiosis with bacteria before it can to protect itself.
However, it should be noted that developmental symbiosis poses a great threat to organisms that do not have a strong metabolic component. This organisms fall at risk of being depleted by organisms that they share a symbiotic relationship with.
References
Avise, J. C. & Ayala, J. (2007). In the Light of Evolution: Adaptation and complex design . Washington, D.C: National Academic Press.
Byrd, J. H. & Castner, J. L. (2009). Forensic Entomology: The Utility of Arthropods in legal investigation . Boca Raton, Florida: CRC Press.
Gilbert, S. F. (2016). Developmental Biology 10e Online: Developmental Symbiosis as Protection. Retrieved from http://10e.devbio.com/article.php?id=208.
