Question

1. Discuss the situation of the prairie chickens in Illinois in terms of population genetics: What were the effects of habitat loss & fragmentation on the gene pool of the state population of birds? How did genetic drift & changes in gene flow affect the remaining populations? What were the consequences of these factors on the reproductive success of these birds? How was the genetic variation restored in these remnant populations and what was the outcome?

Answer 1

The prairie chicken and its population across the state of Illinois suffered as the prairie grassland system was changed over time to wheat, hay and alfalfa and gradually it led to cultivation of the corn and the soybean. There was a time when the chicken lived in around 20 million acres of prairie land but due to the loss of habitat their population has drastically declined and changed. Today the population has changed to around only 100 to 200. The lack of habitat and decline in the genetic biodiversity has led to the prairie population declined. The fragmentation of the gene pool has led to its diminishing and reduced population and led to loss of genetic variation. This was followed by a population bottleneck which led to sharp reduction in the population size.

The genetic drift and gene flow affected the remaining population in a way that its number reduced and they had very low genetic variability. The heterozygosity declined extensively and hence this also led to short term survival. They are now endangered species and due to their small size, there is very limited genetic diversity and hence with the genetic drift and flow, it has impacted the population that has remained after the size has shrink.

The consequence of these factors on the reproductive success of these birds are:-

1. Limited genetic variability due to the shrinking size of the population and hence it has impacted the whole of the gene pool.
2. They are at risk of being completely eliminated and wiped off of their population if they encounter or suffer from a disease or any sort of natural disaster.
3. Low number of the birds leads to a lot of problem with inbreeding.

The genetic variation was restored through well organized conservation and inbreeding programs. The translocation of the small and isolated population to a different place for breeding can help in reversing the effects of genetic drift and hence introduce more genetic diversity. The introduction of genetic variation and new alleles can help in introduction of genetic difference in the species.