BIOL1007 Lecture Notes - Lecture 25: Iucn Red List, Coextinction, Numbat
25% mammals, 41% amphibians
○
IUCN Red list has 20000 species at risk of extinction
-
Should be only 1spp every few years
○
Rate of extinction 100000x higher than background rates
-
The Extinction Crisis
Recent mammal extinctions
-
Lost 18 species in the last 200 years
-
19 of 60 rodents extinct/endangered
○
Non-flying mammals in the critical weight range have suffered most
-
Most had disappeared by the 1930s
-
e.g. Numbat - endangered, distribution has contracted significantly
-
In Aus
Multidisciplinary field of research
-
Targets specific problems and questions
-
e.g. endangered species management, reserve design, ecological economics, restoration
ecology, ecosystem conservation, environmental ethics, environmental law, environmental
business, conservation journalism/marketing, eco-arts
-
Not just a scientific question, need to take a broader perspective e.g. natural sciences, social
sciences and humanities
-
Paradigms for Conservation Biology
Effect of small numbers on a population's persistence
○
Occurs in all pops, strongest effects in small pops
□
May result in loss of some alleles and the fixation or rise to 100% frequency
of other alleles
□
Decreases genetic variation
□
Genetic drift - whereby allele frequencies of a pop change over generations due to
chance (sampling error)
▪
Ie. Stochastic influences (demographic and environmental, genetic drift, inbreeding
depression)
○
How or why is it small is NOT the issue
○
Small population (cost of being small)
-
Why the population has declined to low numbers, what might be causing it and how to
reverse the decline
○
Diagnose the causes of declines and treat them
○
Declining pop (reason it's small)
-
Paradigms of conservation biology
Identifying the risks associated with these paradigms means you can reduce the problem
-
To describe problems and understand processes causing range of declines
-
To predict impacts of threats - can start to prioritise urgent actions
-
To develop solutions
-
Aims of conservation biology
The Evil quartet - Alien species, Overhunting, Habitat loss,
Coextinction
The evil quartet of extinction forces (drivers of extinction)
L25 - Conservation
Monday, 30 October 2017
9:04 AM
mod 4 - ecology and ecosystems Page 1
Coextinction
The evil quartet of extinction forces (drivers of extinction)
Alien
species
Spent about 1 bill managing pest animals
•
3.5 bill managing weed
•
200-100 years ago with europeans
○
e.g. cattle, sheep ,goats, pigs, buffalo, donkey, deer all feral
○
Major pests
○
New invaders brought new megafauna
•
Cats, rats, mice arrived with early explorers
○
Rabbits, hare, foxes released
○
New microfauna
•
e.g. fireants - dangerous to humans, eliminate other species, flood areas they
enter
•
Aus has 56 introduced/exotic vertebrates
-
NZ has more non-native plants than native
-
Acclimatisation societies e.g. introduce rabbits to make it more European,
for comfort and familiarity
○
Ornamentals
○
Agricultural
○
Domestics
○
Biological control e.g. cane toads to control weevil
○
Deliberate introductions
•
Trade routes
○
Ease of global travel
○
Poor quarantine
○
Human traffic
•
Native invaders can escape to new places across the country
•
"tens rule"
○
1 in 10 plant and animal species brought into a region will escape to appear
in the wild
○
1 in 10 of those escaped species will become naturalised
○
1 in 10 of these will become invasive
○
So unlikely for species to thrive when move into a new place
○
Success rate for invaders and moving through landscape
•
Maximise or enable high reproduction
▪
Enable great ecological dispersal
▪
Enable species to be greatly ecologically flexible
▪
Invasive species, Opportunist species which can deal with disturbance, tend
to…
○
Predicting who might invade
•
Invasion
-
pest animals sometimes deliberately introduced
•
Feral animals - fox, rabbit, cat, pig, goat, donkey, camel, water buffalo
•
20 mammals 25 birds, several amphibians, 30 freshwater fish
○
Feral species in Aus
•
Experiments - supplementation or removal, to test impact of invasive species
•
Impact of introduced animals
-
Competes with native cats
○
Local fauna naïve to it
○
Predation on everything
○
Linked to 12 extinctions and threats to mammals, birds, reptiles,
amphibians
○
Fox distributions limited by and facilitated by rabbit distribution -
continental scale, habitat scale in forests
○
Need to think of flow on effects
○
Still potential for reinvasion after removal
e.g. Red Fox
•
mod 4 - ecology and ecosystems Page 2
Document Summary
Iucn red list has 20000 species at risk of extinction. Rate of extinction 100000x higher than background rates. Lost 18 species in the last 200 years. Non-flying mammals in the critical weight range have suffered most. Most had disappeared by the 1930s e. g. numbat - endangered, distribution has contracted significantly. Targets specific problems and questions e. g. endangered species management, reserve design, ecological economics, restoration ecology, ecosystem conservation, environmental ethics, environmental law, environmental business, conservation journalism/marketing, eco-arts. Not just a scientific question, need to take a broader perspective e. g. natural sciences, social sciences and humanities. Effect of small numbers on a population"s persistence. Stochastic influences (demographic and environmental, genetic drift, inbreeding depression) Genetic drift - whereby allele frequencies of a pop change over generations due to chance (sampling error) Occurs in all pops, strongest effects in small pops. May result in loss of some alleles and the fixation or rise to 100% frequency of other alleles.