Biodiversity

Energy availability determines numbers co-existing species given area.

More evapotranspiration - more species- productivity hypothesis- more energy, productive more food 

More solar radiation tropics- more evapotranspiration

Increase latitude- polar regions- start to decrease evapotranspiration

Diversity often declines when add resources- community

Acquatic- algal blooms 
Algal bloom rapid increase population of algae freshwater systems

Harmful algal blooms (habs) known as red tides - involve toxic or harmful phytoplankton 

fish die- offs 

Plant communities - N fertilisation reduce diversity

Community Exclusion - dominance aka Gause's law 
two species competing same resources cannot coexist at same time- when one has slightest advantage it will dominate 

comes under energy-species richness hypothesis 

AVAILABILTIY HIGH TEMPERATURE DICTATES NUMBER CO-EXISTING SPECIES GIVEN AREA

Physiological response organism to temperature 

Low temperature = reduce population growth , lower survival 

Explnation origin: intuiative feeling warmer habitats easier places make a living than cold

View goes back - earliest naturalists 
Currie (1991) 'benign conditions permit more species'

Claimed underlyng cause latitudinal richness

Tmperature limiting factor only - North

Distribution of fainfal the limiting factor most of the World

 8% world driven by water- global database biodiversity 

HETEROGENEITY CREATES MORE HABITATS

General increase in environmental heterogeneity as move to tropics 

Heterogeneity refers to uneven distrubtion various concentrations species within area

Accommodate great amount species

Organisims finely subdivide landscape- unique suitable habitats = more species coexist landscape without competition  - NICHE PARTITIONING 

 Species start - help each other some ways = more species

Plotted species distribution of frogs related with treets- monotonic relationship 

more trees = more birds 

Reptitles there is no correlation -with trees

Hypothesis only applies amphibians - little support 
probably due to 3rd climatic factor that correlate with tree and amphibian diversity

- latitudinal pattens diversity - marked in oceans- despite little variation haterogeneity 

Little support idea heterogeneity explains latitudinal patterns-  diversity 

Argentinian - Eduardo Rapoport 

Geographic range mammals decreases as move poles- tropics

Rapoport rule - biogeographic principle - as latitude falls down (descends) a decrease in the geographical extent of both animal & plant species can be  observed

Tropical species narrow distribution not really spread across world

Most of the species around the world- narrow distrubtion

The rule explains the greater diversity of species in the tropics in the sense that latitudinal gradients in species diversity had identical data of exceptions - therefore had same underlying cause

Narrow ranges in the tropics- facilitate more species - coexist 

Normally altitudinal ranges are higher at higher altitudes and for wide ocean gradients 

Rapoport role is ecogeographical rule states that latitudinal ranges of plants & animals are generally smaller at lower latitudes than higher latitudes.

Places located at high latitudes (far from equator) receive less sunlight than places at low latitudes (close to equator) 
most sunlight received equator - making this area v warm 
Rainforests receive lots of rin. temperature stays warm all year round
Tropical rainforest- thousands species- animals, plants, fungi & microbes.

Areas rainforests plants densely packed - 

Rapoport's rule ecogeographical rule- LATIUDINAL RANGES of plants and animals smaller atlower latitudes than at high latitudes

The increase in species richness or biodiversity that occurs from the poles to the tropics, often referred to as the latitudinal diversity gradient (LDG)

LDG one of most widely recognised patterns- ecology 

Most sprecies narrow range
Low latitude species have smaller ranges than high latitude species

Tropical species narrow distribution not really spread across world, mot of species around world- narrow distribution

Taxa low latitude (tropics) - narrow range, low env tolerance, many species with narrow niches, niche packing 
Taxa high latitudes ---> wide range and env tolerance FEW SPECIES WTH WIDE NICHES

3 explanations climatic variability - greather high latitudes 
a) require broad niche to survive in the north 
the tropics if you drop one degree = massive diff 
b) Glaciation - high disperal species repopulate north - large geographic range 
c) lack of competition in polar regions Tropics: competition = restricted habitat
Small niches- more highly evolved with fine adaptations
Poles less competition (limited env factors = broad niches-  struggle

Traits that charecterise species-rich tropics:

(a)Long evolutionary history (more generations) with relatively stable existence (lack of glaciation) So.. long evolutionary history = plants produce more, give more to the environment - tropical region constant tropical region species reproduce & grow faster- die faster- adds humus when they decay to soil  Biodiversity - very complex definition-  clear latitudinal pattern- most packed polars
Debate has not ended more hypotheses

Biodiversity encompasses all levels of natural variation from molecular and genetic levels, to species level, and beyond to variation at the landscape level.

Host of global patterns of spatial variation in biodiversity have been explored, the most prominent and intensively studied being latitudinal gradients of species richness.

Long recognised that the number of species in most taxonomic groups is lowest in the poles and increases towards the tropics.

Some exceptions to this, in that seabirds are more diverse towards the poles, and thought that free-living microbes are cosmopolitan.

Four hypothesis explain why there are more species in the tropics than the poles: (a) the energy-species hypothesis: the availability of resources and climate dictates number co-existing species in given area (i.e. more available energy tropics); (b) The heterogeneity hypothesis, suggests a general increase in heterogeneity as move towards the tropics; (c) Rapoport’s Rule, suggests that the geographic range of species decreases as move poles – tropics; and (d) a combination of them all.
In general, two traits characterise the species rich tropics: long evolutionary history + stable existence, and constantly high temperatures. 

Variety life on earth not spread evenly- concentrated v special places

WHY IS THIS IMPORTANT?

difference niches and areas in the world

- in tropics more life, the distribution f species gives us inside into conservation

biodiversity - knowing this can priortise areas for conservation 

Amphibian species rchness & intensity of three factors threatening global amphibian diversity- projected year 2080  climate change, land use change how itll be distributed 

http://go.nature.com/2oiQrB8

Land-use processes in Amazon threatening global tropical diversity 

have the tools to understand this- remote sensing helped famalan since researcher cannot undertake etensive ground coverage investigation

Find texts add more- read Fernando publicartions 

Learning Objectives

On completion of this module you should be able to:

üDescribe temporal and spatial patterns of terrestrial diversity and discuss the underlying causes of such patterns. ü üDiscuss the main current threats to biodiversity. ü üCritically discuss the rationale for preservation of species and ecosystems. ü üOutline the criteria that can be used to identify species and areas of high conservation importance. ü üGive examples of species and habitat conservation.

Use socratic method to learn this course! 

üWhat can we say about this phenomenon? üWell, what are your assumptions? üAnd what do you base your reasoning on? PAR phenomenon assumption reasoning step back try to look at assumptions, see problem as a whole, do this achieve high in test inshAllah

Generally refers to variety and variability of life on earth

Biodiversity encompasses all levels of natural variation from molecular and genetic levels, to species level and beyong to variation at the landscape level

Biodiveristy simplest measure - species richness

VAST GLOBAL BIODIVERSITY (speciesl evel) 

5-to-30 million species animals   and plants on earth (< 10%   described) 

estimated 2b 1.5mil species funghi need to know this better
Molecular tools reveal vast   diversity microbes  (>10,000   genetically distinct prokaryotes   in handful of soil) 

The flowering plants most diverse group of land plants- 416 families 

WATCH YOUTUBE VIDEO MAKE NOTES 

https://www.youtube.com/watch?v=7tgNamjTRkk

Lectures this week:

1.Global patterns of diversity – why are there more species in the tropics than the poles? 2.Local patterns of diversity – what are the drivers of local diversity? 3.Temporal patterns of diversity (succession): How does diversity change over time? 

Lectures this week:

1.Global patterns of diversity – why are there more species in the tropics than the poles? 2.Local patterns of diversity – what are the drivers of local diversity? 3.Temporal patterns of diversity (succession): How does diversity change over time? 

Latitudinal patterns diversity

Species more packed in tropics

Polar regions Antarctica less species

much more diversity in latitudinal parts of world than longitudinal 

most intensive and prominent studies are latitudinal gradients of species richness

LONG RECOGNISED THAT NUMBER OF SPECIES IN MOST TAXONOMIC GROUPS IS LOWEST IN THE POLES AND INCREASES TOWARDS THE TROPICS 

Huston 1994

Latitudinal patterns diversity

Species more packed in tropics

Polar regions Antarctica less species

much more diversity in latitudinal parts of world than longitudinal 

most intensive and prominent studies are latitudinal gradients of species richness

LONG RECOGNISED THAT NUMBER OF SPECIES IN MOST TAXONOMIC GROUPS IS LOWEST IN THE POLES AND INCREASES TOWARDS THE TROPICS 

Huston 1994

BUT reverse latitudinal patterns exist

a) seabirds- greatest abundance and diversity at high latitudes ( high productive or nothern oceans)

Antarctic- 17 species flightless penguins

Sub-Arctic - 22 species non-migratory Auks, Murrs, Puffins

(b) Mammals

Ecological Diversity in South American Mammals: Their Geographical Distribution Shows Variable Associations with Phylogenetic Diversity and Does Not Follow the Latitudinal Richness Gradient.

(c) Lichens – maximal diversity in dry/cold regions and Boreal forest

  Abundance of free-living microbes (< 1mm) so large that their dispersal is rarely (if ever) restricted by geographical barriers

 Some one third of the global diversity of soil protozoa present within single patch of grassland in Scotland.

The hyptheses mentioned explain why so many more species in the tropics than poles