Can we track animal migration by eDNA?

Is it possible to track migration by molecular genetic techniques?

DNA technology immensely applicable in relatively all biological science. The scientist can use molecular genetic research tools independently in their respective fields.

DNA technology is applicable in disease diagnosis, identification of an individual, paternity verification, genomic research, microbial identification and fossils identification. 

Molecular genetic revolutionaries microbial genetics with its advantages over traditional microbiology practices. Read the article on microbial genetics here, 

Microbial genetics: A rapid advancement in microbiology

“A seasonal movement of an organism from one place to another place is called as migration”. The process of migration is very crucial for survival and reproduction of eukaryotes.

We can understand the behaviour of an organism by tracking their migration pattern. This information can help us to protect the organism and their migration route.

For tracking migration patterns,  “eDNA” gives some crucial information about the organism. eDNA is an environmental DNA – excretion material, feathers, hair, nail, outer skin and blood or saliva are the major source of eDNA.

A sample is collected from the observation site and DNA is extracted from the sample. Tracking migration by DNA analysis is an accurate method because it gives us the exact information of a particular animal from the population. 

Let us understand the entire process of animal tracking with the help of a simple example. 

A tiger is walking in the jungle. He started his journey from Point A . He first reached on one side of a dense jungle at point B, where he takes some rest and rubbed his back with the tree, see figure.

Now the tiger walks to another side of the jungle in search of food and reached point C. At point C, he left behind some excreted material and runs toward his prey on the riverside at point D, he eats his prey and migrates to the river and drink some water at Point E.

We can collect eDNA sample from each site for analysis of migration pattern. Hair sample from site  A and B, faeces sample from site C, saliva or hair sample from site D and faeces or hair sample from site E are collected. DNA is extracted from each sample.

Sequence specific primers are used for amplification of eDNA sample. After amplification, the sample is analyzed on agarose gel electrophoresis. 

Read more about the chemical used in agarose gel electrophoresis (EtBr, electrophoresis buffer, Bromophenol blue) and the process of electrophoresis in our series of Gel Electrophoresis.

If DNA bands are matches for all the samples, we can conclude that the samples are from the same animal and we can create migration graph based on the data.

Further, the sample can be sent for sequence analysis. Next-generation sequencing helps in understanding sequence homology by comparing each sequence with another. 

Now we can create a migration route and calculate distance travelled by an animal as well.

Fish excretes in water. They shed off their outer gelatinous layer in water. DNA can be extracted from water (sea water or fresh water based on the study).

 Advance tools of bioinformatics and sequencing help us to identify each fish based on their DNA data. If we want to understand the migration route of the fish then the Similar experiment we can perform on another side of the sea or the river.

By doing this we can understand the migration of some specific fish population. Senior research associate Mark Stoeckle reported fish migration by executing this method.

Tracking using electronic track belt is an easy technique but we cannot track the entire population of an animal. Additionally, it has limited battery life so if an animal is migrated out from our Range, it is difficult to track them back.

Scientists are now applying DNA typing method for tracking great human migration. Humans were migrated to each any every corner of the world from where they were originated. 

For more detail on DNA typing and DNA fingerprinting read the article: DNA Fingerprinting.

The African subcontinent is the origin of the human race. By collecting fossil DNA, scientists are trying to create a migration map of the human.

Further, fossil DNA can give information regarding the age of that particular fossil. We can compare DNA sequences of fossil’s with our ancestor and can estimate the age of that fossil.   

Tracking avian migration is possible by the same eDNA method. By taking excretion sample and feather sample from the site of observation, we can create an avian migration map. 

Read next article: What is DNA replication?

eDNA is actually a good source of unknown information. Even a soil sample, water sample or any decomposed animal body is a source of eDNA. We can identify fungi, bacteria and other microbes from the site of sample collection.

If we want to know how many types of bacteria are grown on a decomposed body of an animal, we can collect eDNA from the decomposed animal and analyze it. Further metagenomics analysis helps in gathering information. 

For more detail on metagenomics read the article: Microbial genetics: A rapid advancement in microbiology 

We can conserve endangered species by studying the migration pattern of birds and other animals. We can conserve their habitats as well.

Industrial revolution results in climatic and environmental damage. The migration pattern of animal, bird and other aquatic eukaryotes are greatly influenced by human interference.

We have to preserve migration routes of other organisms because animal, bird and other eukaryote follow the unique path of their migration which affects their breeding pattern.

Different types of molecular genetic techniques can be used for analysis of migration pattern. SNP (single nucleotide polymorphism), SSCP ( simple sequence conformation polymorphism), VNTR (variable numbers of tandem repeats) and STR ( short tandem repeats) are some of the important molecular techniques which help in species identification and tracking of migration.

Environmental safety is becoming one of the major challenges in the upcoming years. We have to develop new strategies for preserving our climate and environment, may be eDNA will play an essential role in environmental safety in the future as well.

Story written and covered by- Tushar Chauhan

Reviewed by- Binal Tailor