Chapter 43 - Conservation Biology

threats to biodiversity

• HUMANS

• high rate of species extinction is due to ecosystem degradation by humans

3 Levels (Components) of Biodiversity

1. genetic diversity

2. species diversity

3. ecosystem diversitt

Loss of genetic diversity

genetic diversity is comprised (made up of) genetic variation within a population and between populations

• losing genetic variation in either of these → losing genetic diversity

• ex. Sakinaw Lake sockeye salmon

  • population declined from 5,000 (in 1980) to 0 (in 2007)

species diversity

variety of species in an ecosystem or throughout he biosphere

• conservation biologists are concerned about species loss due to alarming stats regarding extinction and biodiversity

• animals at risk globally:

  • 12% of birds

  • 20% of mammals

  • 32% of amphibitans

COSEWIC

Committee on Status of Endangered Wildlife in Canada

• meets twice a year to assess the status of wildlife species at risk of extinction

• members are wildlife biology experts

• was created un the Species at Risk Act (SARA)

  • makes recommendations to the minster about species who should be added to SARA

COSEWIC definition of Endangered, Threatened, and Exirpated species

• endangered - wildlife species facing imminent extirpation or extinction

• threatened - wildlife species that is likely to become endangered if nothing is done to reverse the factors leading to its extirpation or extinction

• exirpated - wildlife species that no longer exists in the wild in canada, but exists somewhere else

Yangtze River Dolphin

declared functionally extinct in 2006, sighting reported in 2016

Steller’s sea cow

• close relative of manatees

• found in Bering Sea

• grew to 11m long

• first found in 1741 by Europeans

• hunted to extinction in 1768

Thylacine/ Tasmanian TIger

marsupial “wolf” last seen in the wild in 1932

Dodo

• first found by europeans on Mauritius around 1600

• extinct 80-110 years later

Eskimo Curlew

• at one point, was one of the most common shorebirds in North AMerica

• flocks migrated from South America → Prairies → breeding grounds in Alaska and Northern Canada

• 2 million birds harvested annually in the 19th century

• may now be extinct

Passenger Pigeon

• estimated population 3-5 billion

• may have been the most abundant bird ever

• extinct in 1914

  • Martha, the last known Passenger pigeon died in 1914

Mountain Gorilla

• our closest living relatives

• threatened with extinction

• only 620 left in 1989

  • 1063-1080 in 2026

Bonobo (Pan paniscus)

98.4% DNA similarity with Humans

• 15,000-20,000 left in the wild

• endangered because of bush meat trade and habitat loss

Southern Resident Killer Whales

endangered, primarily due to loss of their primary prey, chinook and chum salmon

• at the center of the controversy over the expansion of the Transmountain pipeline that will increase oil tanker traffic in Salish Sea

• 74 left in 2025

Ecosystem Diversity and how human activity is affecting it

variety of ecosystems in the biosphere

• human activity is reducing ecosystem diversity

• more than 50% of wetlands in the contiguous United States have been drained and converted to other ecosystems, which contributes to flooding

Benefits of species and Genetic diversity

in the US, 25% of prescriptions contain substances from plants

• ex. rosy periwinkle contains alkaloids that inibit cancer growth

Ecosystem Services

encompass all the processes through which natural ecosystems and their species help sustain human life

• ex.

  • purification of air and water

  • detoxification and decomposition of wastes

  • cycling of nutrients

  • moderation of weather extremes

Wetlands and Ecosystem Services

wetlands help to prevent flooding and remove pollutants

Cattail harvesting and Ecosystem Services

• Cattails provide ecosystem services

  • capture nutrients like phosphorus and heavy materials

  • can be harvested to produce biofuels (with zero carbon footprint) that replace fossil fuels

3 Main threats to Biodiversity

1. habitat destruction

2. introduced species

3. overexploitation

Habitat loss

• habitat loss due to humans is the greatest threat to biodiversity

• in almost all cases, habitat fragmentation and destruction lead to loss of biodiversity

• ex. tallgrass praries in Manitoba occupy <0.1% of its original area

• ex. about 93% of coral reefs have been damaged by humans activities

Introduced species

• moved by Humans from native locations to new geographic regions

• without their native predators, parasites, and pathogens, they may spread rapidly

• introduced species that gain a foothold in a new habitat usually disrupt the community

Lake Victoria Cichlids

Introduction of Nile Perch lead to extinction of 200 out of 300 cichlid species in Lake Victoria

Invasive carp in North America

common carp in the minnow family Cyprinidae is native to Eurasia, but they are ecological vandals

• destroy aquatic vegetation, release sequestered nutrients, outcompete native species, and make water more turbid and less productive

Zebra Mussels

Dreissenid (zebra) mussels are native to lakes in southern Russia

• accidentally introduced into eastern North America in the 1980s and spread rapidly across the United States and Canada

  • reached Lake Winnipeg in 2013

• they radically alter the aquatic ecosystem

Exploitation

human harvesting of wild plants or animals at rates that surpass the ability of populations of those species to rebound

• ex. overexploitation by the fishing industry has greatly reduced populations of some fish like bluefin tuna and and sharks

Shark finning

when sharks are harvested for their fins only, while the remainings are discarded

Concept proposed by marine ecologist Daniel Pauly (UBC)

• large declines in ecosystems are masked by where the baseline is set

• notable in fisheries, where fishery scientists fail to set the correct baseline

2 main approaches of Population conservation

1. small-population approach

2. declining-population approach

The extinction vortex

process where a small population declines further due to positive-feedback loops, eventually leading to extinction

why are small populations at risk of an extinction vortex

because they are prone to positive-feedback loops that accelerate population decline

what is the key factor driving the extinction vortex

loss of genetic variation which reduces the population’s ability to adapt

Case Study - the greater Prairie chicken