GEOG 215 Introduction to biogeography

1
GEOG 215Introduction to biogeography

• Instructor
• Ian Hutchinson (RCB 7226)
• Office phone [phone] (campus 23232)
• email ianh_at_sfu.ca
• TA Julie Sabau (jsabau_at_sfu.ca)

2
GEOG 215 - Housekeeping

• Course email geog-215_at_sfu.ca
• Lecture slides and all handouts are posted on the
  course web sitewww.sfu.ca/ianh/geog215/
• Thumbnail booklets available from Student Copy
  Centre Maggie Benson Bldg. (12).
• All readings are from the text (MacDonald, 2003).

3
GEOG 215 - Grades, etc.

• Laboratory assignments 25
• Poster project 25 includes research
  journal 5
• Midterm exam 20
• Final exam 30

4
What is biogeography?

• Biogeography
• the study of the geographical distribution of
  organisms, their habitats (ecological
  biogeography), and the historical and biological
  factors which produced them (historical
  biogeography).

Lincoln , R.J., Boxshall, G.A., and Clark, P.F.
1982. Dictionary of Ecology, Evolution and
Systematics. Cambridge University Press.
5
Goals of biogeography
1. To develop natural laws and concepts that
explain biogeographic processes and account for
the development of biotic distributions. 2. To
provide baseline information on the spatial and
temporal distribution of organisms that can be
used to conserve and manage Earths biotic
resources and heritage.
6
Central questions of biogeography

• What organisms are found where?
• How are these organisms adapted to the local
  environment?
• How have their distributions changed through time?

7
Theres nothing as ROMANTIC as
biogeography Edward Wilson, Emeritus Professor
of Comparative Zoology, Harvard. (quoted by
David Quammen The Song of the Dodo 1996)
8
Is multi-disciplinarityromantic?
Palaeontology
Evolution
9
Is multi-dimensionality romantic?
global local SPACE
Evolving and mobile pieces (life-forms)
Time past
future
Why are the pieces laid out as they are, and how
are their distributions changing?
Changing table-top (environment)
10
Or field work in exotic locations?
Rupununi
11
Biogeography
Present ecological biogeography
observation
ENVIRONMENT BIOTA (climate,
soil, . . .)
experiment
Time
ENVIRONMENT BIOTA (climate,
soil, . . .)
inference
Past historical biogeography
12
GEOG 215 Course themes
Geological history and evolution
Recent and future environmental change
Life forms
Ecological communities and their dynamics
The physical template (climate, soils, landforms)
13
Given the dazzling array of life forms on the
planet, how do we proceed to answer the central
questions
14
Search for an atomic unit
Of what then is biodiversity composed? Since
antiquity biologists have felt a need to posit an
atomic unit by which diversity can be broken
apart, then described, measured, and reassembled
Western science is built on the obsessive
search for atomic units with which abstract laws
and principles can be derived. Scientific
knowledge is written in the vocabulary of atoms,
subatomic particles, molecules, organisms,
ecosystems, and many other units, including
species. The metaconcept holding all the units
together is hierarchy, which presupposes levels
of organization. Wilson, E.O. 1992. The
Diversity of Life, Penguin. p. 35
15
Biological hierarchies
Taxonomic Ecological Trophic order
(etc.) biome top
carnivores
family community
carnivores
genus association
herbivores
species species primary
producers
subspecies
Only in trophic hierarchies where the focus is
energy flow are species not an essential unit
population
individual
16
Some basic terminology

• Taxonomy classification naming of organisms
  taxis (Gr.) order
• Systematics includes evolutionary relationships
  of organisms
• Ecology how organisms interact and are affected
  by their environment
• Trophic how energy flows in an ecological
  community

17
Towards a scientific taxonomy

• Folk taxonomy
• Inuit in one district of Arctic Canada have 100
  names for local birds.
• 2. Tzeltal-language speakers in Chiapas have
  1100 names for local plants.

Sources Irving, L. 1953. The naming of birds
by Nunamiut Eskimo. Arctic, 6, 35-43. Berlin, B.
1966. Folk taxonomies and Biological
Classification. Science, 154, 273-275.
18
Taxonomy in the Classical World
Aristotle (384322 BC ). formulated two
classifications, genos and eidos. Genos referred
to broad categories of animals, (e.g. reptiles),
while eidos were animals in a genos. Aristotle's
system was intentionally hierarchical with
mammals placed at the top of the hierarchy.
Aristotles ideas held sway (in Europe) until the
17th century.
19
Early modern taxonomy
John Ray (16271705) introduced the term species,
which he defined (following plant and animal
breeders) as a group of organisms capable of
interbreeding and producing fertile offspring.
His taxonomy used multiple morphological
characters to classify species (e.g. flowers,
seeds, fruits and roots for plants).
20
Linnean taxonomy
Formalized species descriptions based on
diagnostic traits
Hierarchy based on groupings of species and
genera, not splitting of larger classes
Latin binomials (Genus, species) following the
Swiss botanist Bauhin 1560-1634 replace long
Latin descriptions (e.g. Sturnella magna big
lark)
Carl Linnaeus (1707-1778) (aka Carl von Linné
and Carolus Linnaeus)
21
Linnean taxonomyEng eastern meadowlark Sp
pradero tortilla-con-chile, Fr sturnelle des
prés
Kingdom Animalia       Phylum Chordata 
        Subphylum Vertebrata 
           Class Aves (birds)               Orde
r Passeriformes (perching birds) 
                 Family Fringillidae
(finches)  Genus
Sturnella                        Species
Sturnella magna 
(Linnaeus, 1758) Subspecies Up to 17
subspecies recognized (indicates local variation)
Image Delbert Rust
22
Linnean taxonomy diagnostic morphologies of
related species
Sturnella magna S. neglecta

• Eastern meadowlarks (Sturnella magna) can be
  distinguished from western meadowlarks (S.
  neglecta) by the white (as opposed to yellow)
  feathers behind the lower mandible. Or can they?

Images http//birds.cornell.edu/crows/mlarkdiff.h
tm
23
Why did Linnaeus base his classification on
species? Are species real?

1. There is general agreement amongst disparate
   human groups as to what constitutes separate
   sorts of organisms, based on differential
   morphology, and
2. Like begets like - intermediate forms are rare.

24
The importance of the species concept
The species concept is crucial to the study of
biodiversity. It is the grail of systematic
biology. Not to have a natural unit such as the
species would be to abandon a large part of
biology into free fall. .. Without natural
species, ecosystems could be analyzed only in the
broadest terms, using crude and shifting
descriptions of the organisms that compose
them. Wilson, E.O. 1992. The Diversity of
Life. Penguin. p. 36
25
Species in folk vs. scientific taxonomies
under- 11
over- differentiated
differentiated
Birds (Inuit) 102 birds 4 (2 names) 98 0
Plants (Tzeltal)sample of 200 plants 82 68 50
under-differentiated fewer names for organisms
than species recognized by science 11
correspondence over-differentiated more names,
etc. (mainly cultivated plants e.g. four
varieties of beans)
26
Intra-specific variation in domesticated plants
and animals
Brassica oleracea
Canis familiaris
27
Intra-specific variation in snow geese
Eng greater Inuit k(h)anguk
Eng blue goose Inuit khavik
lesser
separate species? or just morpho-colour phases
of the same species?

28
(No Transcript)
29
Difficulties in defining species strictly on
morphological traits led to the adoption of the
biological species concept.
Species are groups of actually (or potentially)
interbreeding natural populations which are
reproductively isolated from other such groups.
Ernst Mayr (1953)
(apply this to previous examples)
30
Meadowlarks
Images http//evolution.berkeley.edu/evosite/evo1
01/

• Western and eastern meadowlarks are almost
  identical in appearance.
• Their geographical ranges overlap, but their
  distinct songs prevent inter-breeding.
• The species are maintained by sexual signaling.

31
Merits of the biological species concept

• Emphasises the critical importance of
  evolutionary descent,
• Emphasises that species act as discrete breeding
  groups - they breed true to type.
• Provides a testable hypothesis - can they produce
  viable offspring?

32
Drawbacks of the biological species concept

• Some organisms that are morphologically
  distinct can interbreed (bad species e.g.
  pines)
• We have knowledge of the breeding behaviour of
  only a tiny proportion of the living species on
  Earth.
• Impossible to apply to extinct species
  interbreeding cannot be directly observed.

33
Does DNA barcodingsolve the problem?

• Mitochondrial DNA indicates the genetic
  similarity between organisms and can be used to
  establish an evolutionary time frame
• mtDNA is passed on from mother to offspring. If
  the mutation rate is known, the ancestry of the
  lineage can be estimated (e.g. Mitochondrial
  Eve lived about 140 000 years ago)
• Many copies per cell a single gene is all that
  is required for barcoding plants or animals.

34
How much variation in mtDNA is there in a taxon?
Cytochrome c oxidase subunit I (COI) gene Within species Within genus
moths 0.25 6.5
birds 0.4 7.9
20x
35
DNA barcodes meadowlarks
Images http//evolution.berkeley.edu/evosite/evo1
01/

• mtDNA sequencing indicates that the eastern
  meadowlark (remember the 17 subspecies) consists
  of two cryptic i.e. difficult to
  differentiate species. COI divergence between
  the two 4.8.

Hebert et al., 2004, Pub. Lib. of Science,
Biology, vol 2 issue 9
36
DNA barcodes skippers

• Neotropical skipper butterfly (Astraptes
  fulgerator)
• First described in 1775
• Ranges from south Texas-northern Mexico to
  Argentina
• Is it one species or are there many cryptic
  species?

Hebert et al., 2004, Proc. Nat. Acad. Sci., 101,
14812-14817
37
DNA barcodes skippers

• Single gene tested from adults reared from
  caterpillars in laboratory.
• 10 species identified based on significant
  differences in COI gene. Matched to caterpillar
  colour patterns and food plants.

Hebert et al., 2004, Proc. Nat. Acad. Sci., 101,
14812-14817.
38
How does a palaeontologist assign a species name
to a fossil?
U
Evidence shell or bone beds .. tracks or
burrows. Taxon named from Morphology -- yes
(hominid fossils illustrate difficulties)
Breeding behaviour -- no mtDNA -- yes (if DNA
is preserved in the specimen )

39
Naming fossilsSouth African hominids
Australopithecusrobustus?
Australopithecusafricanus?
Paranthropus crassidens?
or are they all Paranthropus robustus?
Images http//www.modernhumanorigins.com/robustus
.html
40
The Homo floresiensis controversy A new human
species or just a local population (individual?)
of Homo sapiens? How much morpho-variation should
a paleontologist allow?
See Hopkin, M. 2006 Will the hobbit argument
ever be resolved? Nature, 25 August
doi10.1038/news060821
41
Mr T a composite specimen of Triceratops in
AMNH
Constructed from 14 dinosaur skeletons
undoubtedly derived from several different
species
42
Species definition in use today

• Organisms that share at least one diagnostic
  morphological trait that can interbreed freely
  under natural conditions, and whose direct
  ancestors or descendants can be traced in the
  fossil record.

43
Naming species in the field
Biogeographers and field biologists recognize the
superiority of the biological species concept,
but base their field identifications almost
entirely on diagnostic morphological criteria.
The DNA barcode project envisages that by the
end of this century everyone will own a mini
mtDNA analysis kit that will return a species
name for every organism encountered on a walk in
the woods.
44
Continuing problems what is a sub-species?
A sub-species is a geographical race that has
distinctive traits which interbreeds with other
subspecies where their ranges overlap.
sub-species are recognized according to
whatever traits taxonomists choose to study
45
Designating sub-species
Thousands of geographical races possible because
in most species thousands of genes in operation,
and many segregated populations! The sub-species
(as a formal concept) is therefore now
essentially abandoned, but some organisms covered
by the Species-At-Risk Act (Canada) and
Endangered Species Act (U.S.) are sub-species.
46
Protecting sub-species island populations
Q What is the most endangered mammal in
Canada? A M. vancouverensis?, or
M. caligata vancouverensis?
See also VI ermine (Mustela erminae anguinae)
VI water shrew (Sorex palustris
brooksi) VI wolverine (Gulo gulo
vancouverensis)
genetic analysis suggests the latter i.e. that
the Vancouver Island marmot is a darker phase of
the relatively common hoary marmot of the mainland
47
Protecting sub-species local populations
Cutthroat Trout Oncorhynchus clarkii

• The most widespread and diverse trout species in
  the western hemisphere
• 15 sub-species in North America as a result of
  genetic isolation (one recently extinct)
• Many of the subspecies are protected
• Rocky Mountain cutthroat O.c. virginalis,
  pictured is but one example.

48
Protecting sub-species hybrids

• Restricted to Everglades of southern Florida
• The subspecies is now a hybrid of a population of
  native North American cougars and South
  American panthers released into the wild

Florida pantherPuma (Felis) concolor coryi