Lecture 1

Biodiversity is in decline worldwide

Aims to understand

Outlie of lecture

1992 Biodiversity defenition

Since then a number of related conventions have arisen. There is now several different conventions

Following on from those, the way that the industry works (conservation has become an industry) - follwing the summit in 1992 there are annual conferences of the parties (COP) meetings. These are the same people that attended the origional earth summit (members of the UN). Used to see how we are doing and if anything needs to be done better. Since 1992 there has been a hole series of the COPs. 2002 was the 6th COP at the Hague. This was the first time to set targets. What was the target that they set?

In 2011 they had nother get together (COP) this time at a town called Aichi in Japan. Recognised that they missed the last target so they set new targets. These were known as the Aichi targets, which are to be met by 2020. Now have a series of goals. 2010 was the year of biodiversity. 2010-2020 is the UN decade of biodiversity.

What is the Nagoya Protocol (adoptedat Nagoya Japan in OCT 2010)

Sources of biodiversity data needed to meet targets. How do we know what the state of the world is in terms of biodiversity?

Distribution and abundance

Souces of biodiversity data on vital rates is much scarcer and harder to come by

Uses of biodiversity data

IUCN red list

What is the effectiveness of listing under the US endagered species act

The other thing we can do with this sort of data is?

E.g impacts of climate change on European birds (huntley et al 2008 PLoS One) combine EBCC census data with climate data.

Predicting future changes continued

Thomas et al 2004 Nature

Extinction

There are grwoing suggestions that we are currently enering a 6th major extinction event

Lecture 2

Widespread concern that we are entering a sixth global mass extinction event. But in the past 500 years, only 1200 species have been recorded as going extinct.
Reasons for the mismatch between recorded recent extnctions and predicted future extinctions
1. Least important but worth knowing about: Time-lags in recording and designating species as extinct.

2. Unrecorded extinctions

No obvious decrease in rate on those pacific islands up to late 20th century e.g new zealand: extinction rate after arrival of Polynesians very simular to that after arrival of Europeans

We shouldnt think this is a phenomenon that is restricted to the pacific islands, there have been simular losses closer to home

Not just islands that are affected

Third reason for mismatch.
3. Extinction rates strongly depend on the interval over which they're calculated

How can we predict future extinction rates? There are three main approaches.
1. Species area estimates
Based on established relationships between land area and species richness.

How reliable is this method generally?

Why is extinction debt largely a sampling artefact?

Mendenhall et al 2014 questioned why these models are always used on islands.

2. Estimation from empirical data on actual extinctions

Stuart Pimm et al, 2006 suggested that globally, recent extinctions of birds are 100 times higher than this, and predicted that they will rise to 1500 times higher by the end of the 21st century. This is an alarming prediction

3. Estimation from Red Lists of threatened species

How long will it take us until 75% of species have gone extinct if the rate at which species move along this conveyor belt continues. 75% is what we consider as a mass extinction.

Or they could prove unduly optomistic

Hawaiian honeycreepers case study

In 1827 Culex pipens introduced onto Maui by British sailors from a whaler ship (The wellington) was returning from the sub antarctic from an unsuccessful whaling trip. Common practice was that they had barrels on board that contained fresh water that the crew could drink. Over the voyage the water would go off due to bacteria. Whenever they could, when they passed land they would stop off and empty the foul water and fill up with clean water. The wellington did this at Maui (Hawaiian islands).

What happened to the birds on Hawaii?

Generally over the last 12000 years since the and of the placeothene, weve seen mass extinction of mega herbivores on continents, seen 20% of birds dissappearing from pacific islands and probably simular rates of extinction on other islands areound the globe. We have predictions possibly as low as 24o years for us to lose 75% of species even from continental landmasses - this might be unduly pessimistic or optomistic. Overall it looks like following the end of the last series of ice ages we are now an era which we can define geologically, officially we are currently in the holoscene (era following the last ice age). Unofficially we are now in a whole new geological era called the Anthropocene era.

Even if humans disappeared tomorrow - someone who comes along to the earth in a million years, when the earth has been reduced to an a layer of stuff it will have evidence of our activities.

Lecture 3

Rarity is a perfectly natural phenomenon. All natural communities contain some rare species.

Speckled wood butterfly have been spreading northward over the last 20 or so years. Known from data collected from butterfly monitoring scheme. People walk along transects throughout the UK and count number of individuals seen along transect.

Distribution and abundance are related

This is supported by fossil evidence

Consequences of relationship between distribution and abundance

Why does this occur? If we induce a reduction in population size, why does it induce a reduction in the range?
This occurs because species are not evenly distributed through their ranges. What ever occurs on the outer edge is no good for species. As you move in towards the core of the distribution, conditions improve and the ideal conditions are somewhere within the core of distribution. Not necessarily the geographical dead center. If conditions improve then survival is likely to be higher and the reproductive rate is likely to be higher. A combination of survival and reproduction results in little r. r=instantaneous rate of population growth will reach its maximum somewhere within the core of the distribution where conditions are as good as they ever get (r=0). Moving away, conditions aren't ideal but they are still good (r>0) and population in this area tends to expand. Move even further away (r<0) because conditions arent good enough for pop growth to be higher than 0. In this range, individuals either dying too quick or reproducing too slow for population to persist.

So how does the outer edge persist?

If humans then come along with shotgun or whatever and start killing individuals in source area and reduce population size, there is now enough territory to go around.

How can reducing the range result in a decrease in abundance even in protected areas?

Case study: New Zealand Takahe Porphyrio hochstetten. New Zealand mainly 2 islands. On the south island there is a species of bird the Takahe which was once abundant on the south island. Had a related but separate species on the North island.

Other examples include:

Red kite in the UK

How do rare species go extinct?

Deterministic processes occur when?

What are Stochastic processes?

Intrinsic stochastic process

Intrinsic stochastic process

Very rough rule of thumb

How does all of this come together to effect the likelihood that a species will go extinct?

Case study of how small populations go extinct: Heath Hen

In 1916 there were very stong gales, fire destroyed breeding habitat, harsh winter, heavy protection by Goshawks, population reduced to 150; inbreeding depression.

Extinction vortex can be avoided: Mauritius kestrel Falco punctatus

What happebned as a result of all these factors?

Carl 'There are no hopeless cases. Only expensive cases and people who give up hope.'

Lecture 4

Increasing recognition of ecosystem services provided by biodiversity

Climatic regulation - one of the biggest services. Can see the effects of losses of biodiversity on climate by looking at the destruction of tropical forests.

Another large scale thing biodiversity does is hydrological regulation. So as well as regulating the climate it also regulates the water cycle.

Pollination

But how much biodiversity do we need? OR what is the relationship between species richness and ecosystem functioning?

Would it be more efficient to have fewer species - if we only had the species that pollinate most efficiently?

So, how do we understand how the relationship between species richness and ecosystem functioning?

There are a number of predictions we might have to what the relationship might look like.
1) As we increase species richness the system performs better but only up to a point. After this point adding more species doesn't add much in terms of functionality.
2) Bit like popping rivets out of a sheet of metal. At first have redundancy so not much happens, then get to critical threshold to which redundancy drops very quickly but to a new stable level, lower level of ecosystem functioning but it is stable.
3) Might be that there is no predicatble relationship between species richness and ecosystem functioning (idiosyncrasy). Need evidence to be able to which of these patterns real experimental ecosystems actually conform to.

Data support positive relationship, with some evidence of redundancy. Cardinale, Sankaran et al 2006. In each case the X axis shows an increase in species richness and Y shows some measure of ecosystem functioning. On first one we have plant species richness in out experimental grassland and total plant cover. It goes up to a point and then tends to level off.

If rather than plant cover, we look at net primary productivity, we find a similar relationship. It goes up at first with increasing number of species and then levels off.

If we look at the biomass of microbes within the soil, the more species of plants we have, the more species of microbes we have but notice there are only 3 data points. So the straight line is simply the shortest distance between 3 data points which isn't convincing in understanding overall relationship.

This one looks at the number of mycorrhizal fungal species in the soil in these experimental grasslands in relation to shoot biomass. Looks at mycorrhiza in soil and biomass of green plants above the soil and the more species of mycorrhiza there are in the soil, the better the plants are growing but only up to a point.

Looking at CO2 flux, this is a measure of how much energy the system is capturing through photosynthesis and then is using for respiration. The more species there are, the greater flux there is but there is so much noise around the data. So not very informative.

Might interpret this one as a decrease in functioning but it isn't. We have the number of consumer species (herbivores) and the biomass of plants. So the increase in ecosystem functioning here is an increase in herbivory and an increase in herbivory would lead to a reduction in the biomass of palnts. So this is also an increase in ecosystem functioning, there is no evidence of ecosystem redundancy here.

In at least half of the above graphs, there is strong evidence of redundancy, why?

Why should ecosystem functioning increase as species richness increases? Cardinale et al 2007 produced paper on the possible mechanisms.
1. Sampling

2. Species complimentary

3. Positive interactions

If we are interested for biodiversity for what it does for us and what it will provide, then does this redundancy mean that there are lots of spare species and we can afford to lose maybe lots of species without paying any real penalty in terms of ecosystem goods, service and functioning?

All data were collected over short period of time - single growing system.

Loss of Pleistocene megafauna ( huge herbivores used to trundle around that disappeared after the end of the Pleistocene era). If we look at parts of world where those species used to occur,. There is a recurrent pattern.

There are other examples. Species redundancy might be a feature of ecosystems, so we can lose species without much happening. But we all know examples of where loss of species can have catastrophic effects on ecosystem functioning. One good example that is often cited is Barro Colorado Island (Terborgh, 1988)

A similar thing happened in Venezuela

Example of a totally different system. In Alaksa there was overhunting of sea otters.

Finally plant and pollinators

Two opposing sets of evidence. Rather than think of ecosystem functioning lets look at an aspect of their function e.g they stability. Does the stability of ecosystems vary with species richness? Are species rich ecosystems in some way more vulnerable?

The simultaneous occurrence of these two opposing views depending on how you think about it was called what?

Why was it called Mays paradox?

Evidence to support this idea comes from experimental grasslands

What they found supports what we expect from this division of stability into constancy and resilience. What were the results?

Why in terms of the behavior of food webs, complex systems should be more stable. The idea that species rich systems are less stable was prevalent up until 1990's. We have no gone back to a view similar to 1970's.

Example to explain this:

Conclusion