Transcript Document

WALLACE RESOURCE LIBRARY
Lecture 02 – Evolution and Biodiversity in
Madagascar
This is an ‘example’ of a lecture that is given to A level students as part of their
academic lecture series whilst on their expedition.
It has been produced for the exclusive use of the lecturer conducting the series
and is solely intended for educational purposes.
Most of the material comes from Operation Wallacea sources and any other
material that has been used has been credited (as far as is possible) to the
appropriate author wherever possible.
This lecture is only to be used for EDUCATIONAL purposes.
WALLACE RESOURCE LIBRARY
Lecture 02 – Evolution and Biodiversity in
Madagascar
Madagascar -An extraordinary Island
Lecture 2: Biodiversity, biogeography and evolution of wildlife in
Madagascar
Summary
•
•
•
•
Introduction
Madagascar’s biodiversity
The Biogeography of Madagascar
Evolution of wildlife on Madagascar
Introduction
• 400km of the east coast of Africa – In the Indian Ocean with the Mozambique
Channel separating the island from Africa.
• The island is just bigger than France - 581,540 sq km – 4th largest island in the
world – nearly 1000 miles long (north to south).
• About 165 million years Madagascar (with India attached) broke away from
Africa and drifted Southeastwards.
• India eventually broke away leaving Madagascar isolated with all its ‘stowaway’
animals.
• Humans arrived about 2000 years ago – present population is probably above
19 million.
Madagascar’s Biodiversity
•
•
•
•
Can we define ‘biodiversity?
What is a species?
How can we measure biodiversity?
Is biodiversity important?
Biological Diversity
‘ Biodiversity includes all the different plant, animal ,
fungus and microorganism species worldwide, the genes
they contain, and the ecosystems of which they form a
part.‘
‘ Biodiversity is NOT just about the number of different
species. It is also represents the degree of nature’s
variety. Biodiversity takes into account the number of
individuals and in how many places they can be found.’
Biological Diversity
Biological diversity occurs at the level of:
• Genetic diversity within species
• Species diversity within an ecosystem
• Ecosystem diversity within a region
www.nhm.ac.uk
Biological Diversity
Different ecosystems
Genetic biodiversity in mosquitos
www.greenfacts.org/en/biodiversity/figt
ableboxes/1012-richness.htm
http://
What is a species and what is it based on?
A species is often defined as a group of organisms capable of
interbreeding (naturally) and producing fertile offspring.
• Morphological Species (Wiley 1978)
• Based on visible characteristics
• Easy to measure, most useful in practice
• Not most biologically relevant
• Biological Species (Mayr 1942)
• Based on reproductive isolation
• Testable – in theory
• Are hybrids fertile?
• Evolutionary Species (Cracraft 1983)
• Based on evolutionary relationships
Field Study Council
How many species are there?
A quick quiz – answer on a sheet of paper.
1. A scientist (Erwin 1982) counted the number of beetle species in one
species of tree in Panama (1200) – he used this to estimate how many
species there were in the world - how many species did he estimate?
• 30 – 50 million
2. Another scientists (Raven 1983) said there are twice as many species in
the tropics than in temperate regions – what was his estimate?
• 3 million
3. In June 2001 two organisations (Species 2000 and Integrated Taxonomic
Information System) decided to work out together to create the catalogue
of life. By 2007 how many named species were in the catalogue?
• 1 008 965 species (this is now 1,740,330 in 2010)
4. Many scientists say that this represents what % of the actual total
number of species?
• 10%
How many species are there?
5. The UK Biodiversity Action Plan has made a list of species for the world and
UK – if they estimate above 3 490 700 for the world – how many do they
estimate for the UK?
• 123 568
6. Rank the following for the greatest number of species for each group – ( 1
is for highest number of species)
Protoctista Vertebrates Plants Fungi Invertebrates Bacteria
•Bacteria
•Vertebrates
•Fungi
•Protoctista
•Plants
•Invertebrates
7.
4000+
33700+
70000+
80000+
293000+
1280000+
We have ignored viruses? (should we? Is it worth it?) They suspect there
are millions of different types – how many have been described so far?
• 5,000+
How many species are there?
8. The agreed estimates for the total number of species varies greatly – the
IUCN Red data List (1996) suggests between 5 million and (upper figure)
???? Million. Many scientists believe the figure to be much much higher.
• 10 million
9. Suggest a couple of reasons why the estimates differ so much?
• Difficult to see and find, defining a species, difficult to identify,
based on estimates, how they are measured.
10.Which country had the highest extinction rate for animal and plant
species (IUCN 2007)?
• United States of America – 236 animals and 30 plants
What does this tell us about estimating biodiversity?
How do you measure biodiversity?
• by measuring organisms in the field (such as the work carried out by Operation Wallacea).
• by using formulae such as:
• Simpson index (A level)
D=1 - [ Σ(n/N)2 ]
(n = number of individuals of a species, N = total number of all species)
• Shannon-Wiener index H’=Σpiln(pi)
(pi = proportion of the species)
These formulae help to ‘quantify’ biodiversity but there is NO one formulae that truly
represents a figure for biodiversity.
Some useful terms:
Species richness is the number of species in a given area.
Species evenness is a measure of the relative abundance of the different species making up
the richness of an area.
Madagascar biodiversity facts
• Madagascar is a biodiversity HOTSPOT (Myers 1988) – an area that holds
especially high numbers of endemic species.
• There are 34 world biodiversity hotspots but they only cover 2.3% of the
Earth’s land surface.
• Madagascar and its neighboring island groups have an astounding total of eight
plant families, four bird families, and five primate families that live nowhere
else on Earth.
• Madagascar’s more than 50 lemur species are the island’s charismatic
worldwide ambassadors for conservation, although, tragically, 15 more species
have been driven to extinction since humans arrived.
• Over half of the world’s chameleon species are found on Madagascar.
• The natural vegetation of this particular ‘hotspot island’ is very diverse.
NHM
Madagascar - Species numbers and endemism
Taxonomic
Group
Species
Endemic
Species
Percent
Endemism
Plants
13,000
11,600
89.2
Mammals
155
144
92.9
Birds
310
181
58.4
Reptiles
384
367
95.6
Amphibians
230
229
99.6
Freshwater
Fishes
164
97
59.1
How do you think this compares to India and the UK?
Madagascar - Species numbers and endemism
Taxonomic Group
Species
Endemic Species
Percent Endemism
Plants
13,000
15,000
11,600
4950
89.2
33
Mammals
155
350
144
44
92.9
12.5
Birds
310
1224
181
55
58.4
0.04
Reptiles
384
408
367
187
95.6
45
Amphibians
230
197
Scottish229
Crossbill 110
99.6
56
Freshwater Fishes
164
2546
59.1
1.1
97
284
How do you think this compares to India and the UK? India in RED
UK – only has 1 endemic bird and 16 endemic freshwater fish !!!
Image - RSPB
Unique flora and fauna in Madagascar
As many as 90% of the species are endemic to Madagascar
Taken at the Durrell –
Jersey 2011
Your thoughts!
Summary ideas from the 2010 International Year of Biodiversity.
Biogeography of
Madagascar
Madagascar has THREE broad
ecosystem types –
1.Dry forests in the north
2.Humid forests in the east
3.Spiny forests in the south
http://www.cbd.int/ts32/ts32-chap-10.shtml
WWF ecosystems of Madagascar
Madagascar
Madagascar
Madagascar
Madagascar
Madagascar
Madagascar
dry deciduous forests (AT0202)
lowland forests (AT0117)
subhumid forests (AT0118)
spiny thickets (AT1311)
succulent woodlands (AT1312)
mangroves (AT1404)
Operation Wallacea research sites:
Mahamavo - dry deciduous forests (AT0202)
Ifotaka - spiny thickets (AT1311)
Evolution of wildlife in Madagascar
Evolution of wildlife in Madagascar
Why is the Wildlife of Madagascar so different?
Working in groups of 3 or 4 - Match the 10 pairs of cards together
(Evolution Challenge) – e.g. pair a definition/picture with a KEYWORD –
then briefly discuss within your group how the wildlife of Madagascar
might have evolved (the cards are clues!).
Why is Madagascan wildlife so different?
Endemic
Fossils
Darwin and
Wallace
Native to or confined to a certain region.
Giant lemur (skull )- 2,000 – 26,000
years ago – 200kg. Gorilla sized.
Dates:
Wallace - (1823 - 1913)
Darwin - (1809 -1882)
Why is Madagascan wildlife so different?
Isolation by
continental drift
Allopatric
speciation
Speciation following
geographical isolation of
subpopulations of the
species.
Variation
Gene Pool
The variety of life on
Earth at all its levels,
from genes to
ecosystems.
All the genes in a
particular population at
a particular time.
Evolution
An overall change of a population’s
gene pool over time through
processes such as mutation and
natural selection.
Natural Selection
A process that explains how organisms with traits and
characteristics that are beneficial to survive in their
environment are passed down to future generations
while less adapted dwindle/shrink.
Fitness
The success of an individual (or
allele or genotype in a
population) in surviving and
reproducing.
Summary
•
•
•
•
Introduction
Madagascar’s biodiversity
The Biogeography of Madagascar
Evolution of wildlife on Madagascar