Melanistic Tigers

GS 3: Environment and Biodiversity: Diversifying the genetic pool

Why is it in the news?

• Melanistic tigers, also known as pseudo-melanistic or black tigers, are a rare colour variant of Bengal tigers. Recently, a tigress from Maharashtra’s Tadoba-Andhari Tiger Reserve was moved to Similipal Tiger Reserve in Odisha, traveling 800 km to diversify the genetic pool of Similipal’s tiger population.
• Odisha has a unique concentration of melanistic tigers, which led the state government to take steps against inbreeding, contributing to the appearance of these unusual black-coated tigers.

Appearance and Historical Significance of Pseudo-Melanistic Tigers

• Pseudo-melanistic tigers have a coat that appears mostly black, with white and orange stripes peeking through, creating an inverse look compared to typical tigers.
• Historically, black tigers were considered mythical until the late 1700s, when artist James Forbes documented one in a watercolour painting. For over two centuries, sightings remained rare until 1970, when a black-striped cub was born at the Oklahoma City Zoo but was sadly killed by its mother.
• A major confirmation came in the 1990s when poachers in New Delhi were found with a rare tiger pelt. The latest recorded sighting of a black tiger was in Similipal in 2017-18.

Genetic Cause of Pseudo-Melanism

• The dark coat pattern in pseudo-melanistic tigers is a result of a mutation in the Taqpep gene, which causes their stripes to spread widely across the orange or tawny base, giving an almost fully black appearance.
• This mutation is exceedingly rare outside Similipal, with only a few captive black tigers existing in Nandankanan Zoological Park in Bhubaneswar and Arignar Anna Zoological Park in Chennai, both descended from Similipal’s population.

The Taqpep Gene and Related Species

• In 2021, a study by the National Centre for Biological Sciences (NCBS) in Bengaluru identified the Taqpep gene mutation as the cause behind the unique colour patterns in melanistic tigers.
• This same gene influences stripe and spot patterns in other species, such as tabby cats and king cheetahs with darker or blotchier markings.
• In melanistic tigers, the mutation involves changing Cytosine (C) to Thymine (T) at position 1360, and it appears in about 60% of Similipal’s tiger cubs, showing a high likelihood of passing on this trait.

Why the Mutation is Prevalent in Similipal

• Similipal’s high population of melanistic tigers can be attributed to the isolation of its tigers from other groups, resulting in inbreeding within a limited gene pool.
• According to the All Odisha Tiger Estimation (AOTE-2023-24), 30 tigers reside in Odisha, with 27 in Similipal, including at least 13 pseudo-melanistic adults (seven females and six males). No other wild habitat globally has such a high concentration of these tigers.
• Genetic studies and simulations suggest that the high mutation rate in Similipal results from inbreeding and genetic drift—a process where certain genes become more common or vanish in isolated populations purely by chance, rather than due to adaptation.

Air Quality Index (AQI)

GS 3: Environment and Biodiversity: Air Pollution

Why is it in the news?

• The Air Quality Index (AQI), introduced by the central government in 2014 as part of the Swachh Bharat campaign, simplifies pollution data to make it easily understandable for the public.
• Designed to raise awareness, AQI combines data from various pollutants into a single value, helping people gauge the air quality and understand necessary health precautions.
• Developed in collaboration with IIT Kanpur and an expert group comprising medical professionals, environmental experts, and advocacy groups, the AQI uses a color-coded system to denote different pollution levels.

Delhi’s Post-Diwali Air Quality

• On the day after Diwali, November 1, 2024, Delhi’s AQI reached approximately 351, placing it in the “very poor” category. Despite a firecracker ban, several violations occurred across the city, leading to a spike in pollution.
• Seasonal factors like cooler, denser winter air, road dust, vehicular emissions, and stubble burning in nearby states Punjab and Haryana further contributed to the drop in air quality—a common occurrence in Delhi during this period.

Comparing This Year’s AQI to Last Year

• The 24-hour average AQI in Delhi for both Diwali and pre-Diwali days was worse than the last two years. However, stronger wind speeds on the morning after Diwali helped disperse pollutants, preventing AQI from rising to levels observed in previous years.
• The post-Diwali AQI on November 1 averaged at 339, an improvement from 358 recorded on November 13, 2023. Favourable meteorological conditions, particularly wind speeds reaching 10 kmph, helped reduce the pollution load.

Understanding the AQI and Its Calculation

• The AQI consolidates data from multiple pollutants, such as PM 10, PM 2.5, Nitrogen Dioxide, Ozone, and Carbon Monoxide, into a single value with an associated colour code. This makes it easier to convey the overall air quality level to the public.
• The calculation of AQI involves assessing these pollutants, each weighted by its health impact. The pollutant with the worst weight determines the composite AQI, producing one colour and one number to represent the overall air impact.
• Numerous monitoring stations nationwide collect this data, which is then processed to provide the AQI.

Impact of Pollutants PM 2.5 and PM 10

• Small particulate matter, particularly PM 2.5, poses significant health risks due to its size.
• These particles, around 3% the diameter of a human hair, can bypass the nose and throat and enter the respiratory and circulatory systems, causing respiratory issues, reduced visibility, and even chronic diseases like asthma, bronchitis, and cardiovascular ailments.
• Given their minuscule size, PM 2.5 particles are detectable only through an electron microscope.

How AQI Guides Government Policies

• The AQI influences regional government policies to manage air quality. In Delhi, the Graded Response Action Plan (GRAP) provides emergency measures for reducing pollution in Delhi-NCR.
• Depending on AQI levels, GRAP may enforce bans on coal and firewood use in eateries, restrictions on diesel generator usage (except for essential services), and increased parking fees to discourage private vehicle use.
• These actions aim to prevent further deterioration of air quality, especially during critical periods like winter and post-Diwali.

Discovery of a Black Hole Triple System

GS 3: Science and Technology: Black hole

Why is it in the news?

• A groundbreaking study has revealed the first known “black hole triple” system, located approximately 8,000 light-years from Earth.
• This system consists of a central black hole that is currently consuming a small star that is spiralling closely around it, as well as a more distant star that appears to orbit the black hole but is actually much farther away.
• This discovery has sparked discussions about the processes involved in black hole formation.

About Black holes

• Black holes are regions in space where gravitational pull is so intense that not even light can escape. Typically, astronomers believe that black holes form when massive stars undergo supernova explosions at the end of their life cycles. However, this triple system suggests an alternative and gentler formation process.
• The study, titled “The black hole low-mass X-ray binary V404 Cygni is part of a wide triple,” was conducted by researchers from the California Institute of Technology and the Massachusetts Institute of Technology and published in Nature

Characteristics of the Triple System

• Previously, most black holes discovered have been part of binary systems, consisting of a black hole and a secondary celestial object, such as another star or a black hole.
• The newly identified black hole triple features one star orbiting the black hole every 6.5 days and a more distant star that takes about 70,000 years to complete its orbit. This system is situated in the constellation Cygnus and contains one of the oldest known black holes, V404 Cygni, which is nine times the mass of our Sun.

Formation Insights: ‘Failed Supernova’

• The Study hypothesize that the presence of two stars around V404 Cygni suggests that this black hole did not form from a traditional supernova explosion, which typically ejects surrounding stars during the process.
• Instead, they propose that the black hole was created through “direct collapse,” where the star collapses inward after exhausting its nuclear fuel without producing an explosive event.
• The researchers described this phenomenon as a “failed supernova,” explaining that the gravitational collapse occurs too rapidly for a supernova to initiate, resulting in an implosion that does not expel matter.
• However, the dynamics of the black hole triple system indicate that it will not retain all three members indefinitely, as V404 Cygni continues to consume the nearer star. This observation implies that some previously identified binary systems may have once existed as triples, with the black hole eventually devouring one of its companions.

Bibek Debroy, PM’s Economic Advisory Council Chairman, Passed Away

GS 4: Ethics/Miscellaneous : Personalities

About the news

• Bibek Debroy, a noted author, economist, and Padma Shri awardee, passed away recently (on 1^st Nov) at the age of 69. He had served as the Prime Minister’s Economic Advisory Council Chairman since 2017 and was a member of NITI Aayog until mid-2019.
• Beyond economics, Debroy was a Sanskrit scholar who translated significant texts, including the Bhagavad Gita and the Mahabharata, and was working on translating the Puranas.
• Prime Minister Narendra Modi described him as a “towering scholar” whose work left an indelible mark on India’s intellectual landscape.

Early Years and Career

• Debroy studied at Ramakrishna Mission School, Presidency College, Delhi School of Economics, and Trinity College, Cambridge.
• He began his career teaching at Presidency College and held various positions, including at the Gokhale Institute of Economics and Politics and the Indian Institute of Foreign Trade.
• His notable role as director of the Rajiv Gandhi Institute for Contemporary Studies (RGICS) saw the publication of a report that controversially named Gujarat as India’s top state for economic freedom, igniting debate on the state’s development model.
• After stints at the Punjab Haryana Delhi Chamber of Commerce and Industry and the Centre for Policy Research, Debroy joined NITI Aayog in 2014, where he continued to contribute significantly to economic discourse. His ability to simplify complex economic issues made him a prolific and thought-provoking commentator in the media.