Extinction and Biodiversity Loss

Question 1

How many Earths were needed to sustain the human population in 2020

Answer 1

1.6

Question 2

If current trends continue, what will be the impact on vertebrates?

Answer 2

There will be a 67% loss of populations in 2020 compared to 1970

Question 3

How many species are there?

Answer 3

Estimates provided by ecologists range from 3-100 million, however the most plausible range is 3-30 milllion

Question 4

What is the number of living species currently known and how are they distributed?

Answer 4

Roughly 1.6M, arthropods account for >50% of all monographed species diversity

Question 5

Discuss the idea that 5% of the worlds species are found in the UK

Answer 5

hugely overestimated because the British biota is much better known against the world average and only a small proportion of these species are endemic to the UK

Question 6

What are the scales of extinction processes

Answer 6

1. Global extinction
2. Extinction in the wild
3. Regional extinction
4. Local extinction
5. Ecological extinction
6. Economic extinction

Question 7

What percent of the worlds species have gone extinct? cite

Answer 7

99.9% have gone extinct (Raup,1991)

Question 8

Post-human drivers of extinction?

Answer 8

Habitat loss
 Habitat Fragmentation
 Pollution
 Climate change
 Overharvesting
 Invasive species

Question 9

Describe the Island equilibrium theory

Answer 9

As the number of species on a island increase, the rate of immigration decreases and the rate of extinctions increase until the two line cross and settle at an equilibrium

Question 10

What effects the immigration and extinction rates of an island

Answer 10

The island’s distance from the mainland and it’s size

Question 11

Describe how an island’s distance from the mainland can effect the island equilibrium

Answer 11

Immigration rates will be higher on closer islands due to the ease of access

Question 12

Describe how an island’s size can effect the island equilibrium

Answer 12

Large islands have more resources so the rate of extinction is low

Question 13

How many recorded extinction have there been in the last 400 years, and how have they been distributed?

Answer 13

There have been 724 recorded animal extinctions in the last 400 years, about half were of island species. At least 90% of the bird species that have become extinct in that period were island-dwellers.

Question 14

What makes island species so vulnerable to extinction?

Answer 14

Endemism
Rarity
Insularity
Invasive species

Question 15

Why are contemporary extinctions not as high as predicted

Answer 15

Conservation efforts, surviving in managed landscapes such as agricultural and secondary forest and extinction debt

Question 16

What is extinction debt

Answer 16

The idea that apecies can initially survive habitat change but will later become extinct without any further habitat modification e.g a long living tree who’s seeds can no longer root, but the tree remains alive for a long time

Question 17

How are most extinction rates inferred?

Answer 17

Through species-area relationship equatons

Question 18

What is the discrepancy between predictions made by species-area relationship equations and recorded extinction rates

Answer 18

more species are left after a given loss of habitat than the number of species predicted to remain, based on SARS

Question 19

What is EAR

Answer 19

Endemics–area relationship,

Question 20

Why is there a discrepancy between predictions made by species-area relationship equations and recorded extinction rates

Answer 20

The area required to remove the last individual of a species (extinction) is larger, than the sample area needed to encounter the first individual of a species, irrespective of species distribution and spatial scale.

Question 21

Give an example of when SARS has been inaccurate

Answer 21

The pre-Colombian extent of the Atlantic forest (~1 mill km2) had been reduced to ~8% of its original forest cover by 1990. Currently only 4 species are considered to be virtually extinct, but three of these have been “rediscovered” recently. The predicted number of extinctions was roughly 341

Question 22

What are the estimations for co-extinction and who found them

Answer 22

Using nomographic method based on mean host specificity (number of host species per affiliate species), there are and estimated 6300 affiliate species which are “coendangered” with host species currently listed as endangered. (Koh et al. 2004)

Question 23

What is the old background extinction rate and who gave the estimate

Answer 23

Raup (1978) based on a large number of cohorts of marine invertebrate fossil genera estimated that 9% of all species went extinct every 10^6 yrs ≈ 0.2 species/yr

Question 24

What are the current extinction rates and who gave the estimate

Answer 24

Current rate: Wilson (1989, 1992) based on a

perhaps conservative tropical deforestation rate of 0.7%– 1.8 yr–1 estimated 17,500 – 27,000 species extinct/yr

Question 25

Why is it difficult to declare an organism extinct

Answer 25

Probability of detection: small populations may persist
undetected in remote areas
A time lag of up to 50 yrs without “rediscovery” records is often required before a species can be declared terminally extinct (e.g. Ivory-billed woodpeckers; Reported sightings but no conclusive evidence for an extant population.
Difficult to name species that have become extinct recently because it is hard to say with conviction that a species is extinct (e.g. Bermuda petrel thought to be extinct for almost 3 centuries but rediscovered)
Interference from ex-situ conservation measures
Very few arthropod species recorded as extinct; biases in the records for more charismatic organisms

Question 26

What are the issues with species-area predictions

Answer 26

Does not consider patterns of habitat fragmentation;
Does not consider the effects of habitat insularization on different groups of organisms across a range of habitat tolerance to the intervening matrix;
Many habitat types surrounding remnants of primary
habitat are semi-permeable to dispersal;
Does not consider differential uses of secondary habitats e.g. second-growth matrix around forest isolates in continental areas;

Question 27

Who is the main criticizer of SARS

Answer 27

He and Hubbelll 2011

Question 28

What is habitat loss?

Answer 28

The destruction of a habitat inhabited by an organism

Question 29

What is fragmentation?

Answer 29

process whereby a large continuous area of habitat is both reduced in area and divided into smaller fragments where original populations are divided into smaller subpopulations; produces a series of remnant vegetation patches surrounded by a matrix of different vegetation and/or land use.

Question 30

What are the effects of fragmentation?

Answer 30

• Initial exclusion
• Barriers and isolation
• Crowding effect
• Reduction in total and effective
population size
• Stochastic loss (genetic drift)
• Loss to inbreeding depression
• Truncation of the habitat matrix
• Intrusion of edges (Edge Effects)
• Biological invasions

Question 31

Why does fragmentation cause loss to inbreeding depression?

Answer 31

A genetic bottleneck occurs, decreasing the genetic variability of the isolate population, which increases the chances of offspring inheriting deleterious recessive genes normally suppressed by heterozygosity

Question 32

Define edge effect?

Answer 32

The result of the interaction between two adjacent ecosystems separated by an abrupt transition

Question 33

Describe the process of edge effect

Answer 33

As patches become smaller their ratio of edge to interior increases disproportionately
Small habitats have less or no
interior (or core) habitat
In small fragments, ecosystem
dynamics are probably driven
predominantly by external rather
than internal forces

Question 34

What are some abioitc edge effects, who described them?

Answer 34

The climate in crops and pastures tends to be dryer and temperature fluctuates more steeply due to more sun being able to hit the ground an reradiate. In forests the climate is cooler, moister and more uniform. A gradient is formed between these two microclimates which can effect the biomass (Murcia 1995)

Question 35

Negative effect of edge effect

Answer 35

(b) More fragmented landscapes contain more
edge for a given amount of habitat;
(c) Negative edge effects due to adverse species
interactions;
(d) Negative edge effects due to unfavourable
microclimatic conditions.

Question 36

Example of increased predation due to edge effect, and cite

Answer 36

Experimental quail nests were positioned at various distances away from the forest edge. There was a negative e correlation between distance from the forest edge and the percentage of predation (Wilcove, 195)

Question 37

When is edge effect a good thing

Answer 37

They support ecotonal species such as Lantana canescens, a rare tropical shrub native to the ecotone between pine and hardwood forests of Miami-Dade County, Florida, U.S.A. (Possley et al. 2008)
Many species require more than one type of habitat
If habitat amount is held constant, increasing fragmentation per se actually implies smaller distances between patches.

Question 38

What is a mesopredator

Answer 38

middle predators who’s numbers are often limited by apex predators

Question 39

What is a keystone species

Answer 39

species (and some would argue processes) that have
a disproportionate effect on the persistence of all other species. (e.g. extinction, large changes in density); exert strong control on community structure not by large numbers but by their ecological roles, or niches.

Question 40

How does fragmentation effect mesopredators

Answer 40

Small fragments can not support large predators. Consequently mesopredators numbers will increase which will have a negative effect on their prey population

Question 41

What benefits do keystone predators bring to an ecosystem

Answer 41

Feed on competitive dominants
Can enhance local species diversity
Prevent competitive exclusion among prey

Question 42

Explain sea-otters keystone role in maintaining biodiversity on the Pacific coast of North America

Answer 42

Sea otters feed on sea urchin. When the otters declined in the 20th century through fur
trapping and removal by fishermen, sea urchin
populations skyrocketed and grazed heavily on
macroscopic algae and kelp. Some kelp forests were destroyed which in turn lowered the diversity of other plants and animals in that habitat. Reintroduction of sea otters reversed this situation, and kelp beds recovered.

Question 43

What category of keystone species are there

Answer 43

Predator
Plant
Prey
Link
Modifier

Question 44

What are the effects removing a keystone predator

Answer 44

Increase in one or several predators/ consumers/
competitors, which subsequently extirpates several
prey/competitor species (sea otters)

Question 45

What are the effects removing a keystone prey

Answer 45

Other species more sensitive to predation may

become extinct; predator populations may crash

Question 46

What are the effects removing a keystone plant

Answer 46

Extirpation of dependent animals, potentially including

pollinators and seed dispersers

Question 47

What are the effects removing a keystone link

Answer 47

Failure of reproduction and recruitment in certain

plants, with potential subsequent losses

Question 48

What are the effects removing a keystone modifier

Answer 48

Loss of structures/materials that affect habitat type and
energy flow; disappearance of species dependent on
particular successional habitats and resources

Question 49

How many species are threatened by invasive species

Answer 49

42% threatened or endangered species are primarily at risk from invasive species

Question 50

Where is the small Asian mongoose from?

Answer 50

South and Southest Asia

Question 51

How did it become an invasive species

Answer 51

Introduced to the Pacific Islands and Caribbean to control rats, but became a failed biological control

Question 52

What damage has the small asian mongoose done?

Answer 52

The extinction of the Jamaican petrel and “ rice rate