The biochemistry of cell communication (Introduction)

by David Turell , Monday, September 05, 2016, 22:26 (3000 days ago) @ David Turell

This article says exactly what I noted earlier about innate immunity and Tasmanian devils:-https://www.newscientist.com/article/2104275-superfast-evolution-could-save-tasmanian-devils-from-extinction/-
"Devil facial tumour disease is a transmissible cancer that was first observed in Tasmanian devils in 1996. They usually contract the disease by biting a tumour on an infected animal. Initially, the fatality rate was reportedly almost 100 per cent.-"This high mortality rate has seen the total devil population decline by 80 per cent - and locally the figure can touch 95 per cent. This led to fears of rapid extinction, but some devil populations seem to be doing better than disease models would predict.-"To understand why, Menna Jones at the University of Tasmania, Australia, and her colleagues recently analysed the genomes of almost 300 devils from three separate regions in Tasmania.-"The researchers compared genetic samples taken from the three devil populations before and after the cancer arrived in each area. Populations affected by the disease differed from pre-disease ones in two regions of the genome - both with known links to cancer and immunity. This hints that genetic resistance to the cancer has spread through the devil populations, which might explain why numbers are defying expectations in disease-struck areas.-"“These gene variants would have been around before, but there was no evolutionary advantage to them being at high frequency,” says Katherine Belov at the University of Sydney. “Since the arrival of this new disease, the animals without these variants would have been dying, leading to an increase in the frequency of these protective variants.” (my bold)-"Given the prevalence of the genetic changes in devil populations today - and what is known about their reproductive behaviour - the study authors estimate that resistance spread through the population over just four to six generations. “It's as if extreme mortality has led to extreme evolutionary selection pressure,” says Jones. “It has happened a lot faster than we expected.'”-Comment: What humans 'expect' is not necessarily what will happen. Only factual information counts.