Biodiversity loss and Conservation : Causes of Extinction


Biodiversity loss and Conservation

Extinction is the evolutionary equivalent of the proverbial adage that “death and taxes are inevitable.” Evolutionary biologists are certain that, just as every person will eventually pass away, every species will eventually go extinct. In reality, according to the fossil record, 99.9% of all species that have ever existed on earth have perished.When it came to conservation forty years ago, preserving biological diversity meant preventing the extinction of threatened species. These efforts were largely eclipsed by forestry, soil and water conservation, fish and game management, and other related fields. With so many species now in danger and the notion that biological variety includes genes, ecosystems, and other biological entities, conservation biology has emerged as the crisis discipline devoted to preserving life on Earth, which is, perhaps, the most important issue of our time. Conservation biology is the applied science of maintaining the earth’s biological diversity.



Causes of Extinction

There is a quick increase in biodiversity which took place just after the latest mass extinction but before getting the total survey of that increased biodiversity, extinction began and now it is increasing day by day.

Causes of biodiversity loss and extinction can be of two types-

A. Ecological

B. Anthropogenic

A.Ecological Causes

  • Richness & Geographical Distribution –If spp. are distributed over wide geographical region, naturally they have more population. The spp. those who have limited distribution and population, have more chances of getting extinct; e.g. tropical spp.
  • Patchy Distribution – small & patchy population have more chances of extinction.
  • Body Vigor & Trophic state – higher the body vigor, lesser the chances of survival. As a result, top consumers have more possibility of getting extinct.
  • Ability – rare spp. have less ability to colonize. which is why they are vulnerable for extinction.
  • Environmental Factors – fluctuation in climatic factor such as food supply can threaten any species.
  • Environmental Pressure – smaller population may face genetic failure or genetic variability may decrease. Offspring become more homozygous as a result their resistant capability drops & they slowly become unable to sustain.
  • Calamities – Volcanic eruption, Earthquake, Forest fire, Firing (accidental, willful, etc.), Hurricane, Glaciation, Landslide etc.

B.Anthropogenic Causes 

(habitat & pollinator destruction, exploitation, overgrazing, plant introduction without controlled use of fertilizers, pesticides, pollution etc.)

  • Habitat destruction: Tropical rain forest are being destroyed at a rate of 50 acre/min. so far, 40% has already been destroyed. Agricultural land accretion & human settlement caused the filling of most wetlands
  • Exploitation: Too much extraction of forest resources & wild-lives.
  • Overgrazing: which is done By farms & wild animals.
  • Damage to pollinators: Birds, insects being destroyed by traps, poisons etc. resulting in nonviable seeds.
  • Pollution: Via organisations, Industries, elements, metals, isotopes etc.
  • Mining activities: Which can destroy habitats & species directly.

Anthropogenic Pressure on Biodiversity

This is directly proportional to population increase, world population gets doubled in every 30 years. in Bangladesh, population in 1950 was 50 million and now it is more than 160 million. So all amenities (settlement, urbanization, industrialization.) of human life has increased by same magnitude & are always at a cost of Biodiversity loss.

Biodiversity Loss rate Determination

  • Counting lost spp. in the past, studying fossil records, etc. current extinction rate is 20 spp./200 yrs
  • 90% of habitat area destruction brings around 50% spp. loss. in the next 20 years, 2-25% spp. loss will occur. In the next 25 years, 1-10% spp. will be lost because of forest area destruction.
  • Estimated rate of ‘threatened’ taxa provide useful information on rate of Biodiversity Extinction.

IUCN takes care about making Red Data List between 1986 & 1990 threatened animal spp. This number increased by 30% ,threatened plants are now 163 spp. An assumption can be made that in the next 200-300 years around ½ of total birds & mammals will be extinct. ½ of total plant spp. might get lost in next  3000 yrs.

References & Other Links

(This article is completely based on lecture by Dr. Mohammad Azmal Hossain Bhuiyan, Professor, Department of Botany, University of Dhaka.

Some info have been added by the author, any mistake, error, misinformation and other related things found in this article are only author’s to blame)

Written by

Syed Nasif Elias Faruqui, B.S. (Hons), Department of Botany, University of Dhaka

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About Sumaya Islam

A bioscience enthusiast on her way to explore the diversified alleys of lives. Email: Sha0hrin@gmail.com Minimum monthly resolution: publish(1),Share(1)

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