BIOS104 Threats to biodiversity

What are the 5 big threats to biodiversity?

• Habitat destruction

• climate change

• over exploitation

• invasive alien species

• infectious diseases

What are the three forms of habitat disruption?

• Habitat destruction

• habitat degradation

• habitat disturbance

What are examples and impacts of habitat destruction?

• urban, industrial, agricultural

• reduced population sizes

  fragmentation - indirect impact

  Initial increase in fragmentation then decrease → amount of resources are less, smaller population sizes

  also increasingly difficult to migrate between fragments

What are examples of habitat degradation?

• pollution

• pesticides

• fertiliser

• acid rain

What are examples of habitat disturbance?

• subset of population affected

• minor individual effects

• cumulative damage

  e.g. fin of diver clips coral reef

What effect does deforestation have on precipitation?

As it increases, annual precipitation decreases

• by 2100 we expect 8-10% reduction in precipitation

What are neonicitinoids?

a class of pesticide - neurotoxin

What is an example of neonicitinoid?

Imidacloprid

What are the characteristics of imidacloprid?

• systemic - applied throughout entire plant body

• more potent than naturally occurring pesticides

• environmentally persistent

What are the impacts of insecticides on insects?

They are a major driver of the decline of insects globally

→ bumble bee nests significantly smaller

What is the problem with self-regulation if companies producing insecticides?

There is a conflict of interest as they want them to be seen as safe

What are examples of over-exploitation?

• mega fauna - through hunting

• Cetaceans

• Fisheries

• Medicine- aesthetic reasons, industrial materials

How does exploitation raise prices?

The more rare something is, the more expensive it becomes

e.g. ivory from elephants

What does a tipping point refer to in terms of exploitation ?

Point after exploitation where it becomes unsustainable- tips a system into a new state that we can’t return from

→ decreases in abundance, can’t increase productivity

• even if exploitation decreases again, productivity can’t increase

What are the climate impacts on biodiversity?

• individual/population → phenotypic plasticity + evolution

• Population/species → migration, range shifts

• Communities → species-level selection - current vs. immigrant turnover

• ecosystem

What is phenotypic plasticity?

individual level effect - adapt physiology to suit the environment

What is an example of adaptive phenotypic plasticity?

Great tit

→ earlier egg laying date due to warming

What is an example of evolutionary adaptation in animals to climate change?

Brown owls - underlying genetic change as frequency of brown owls changes

What is an evolutionary adaptation in a population of plants?

after drought, flowering time became much earlier

→ drove genetic change in population

What is a functional trait?

A specific activity carried out by part of a whole or by the whole self

What is the problem with small populations?

• chance effects and population size

• demographic uncertainty

• genetic problems

• inbreeding/genetic impoverishment

• loss of evolutionary potential

How do the current extinction rate compare to those in the background?

Current/future rates 100-1000x greater than background

How can we quantify global diversity?

• extrapolation

• Macro-ecological patterns

• diversity ratios

• taxonomic patterns

When should diversity ratios be used?

Allow estimation of global diversity in a poorly characterized group, from accurate biodiversity estimates in two taxonomic groups at a local scale

How do we calculate diversity ratios?

• calculate ratio

• extrapolate unknown diversity

How can we use higher taxonomy to estimate global diversity?

Use shape of curve to estimate the total number

What does the line on a species against area graph mean?

The slope for all organisms is about 0.25

• roughly speaking if you reduce the area to 10% of its original size you might expect to lose 50% of the species

What is the criteria of a diversity hotspot?

• at least 1,500 species of vascular plants (>0.5% of the world’s vascular plants as endemics)

• It has to have lost at least 70% of its original habitat

What can be found in biodiversity hotspots?

• high levels of biodiversity

• high endemism

What is the argue for prioritisation of hotspots as a resource?

• save most species at the least cost

• set conservation priorities

Is there more species richness with more or less nitrogen deposits?

With less nitrogen deposition

What is endemism?

Species unique to a specific geographical location

How do we calculate extinction rates?

• Observed extinction/opportunity for extinction

• multiply by a million to get extinctions per million species years