GEOG 215 Introduction to biogeography Instructor Ian Hutchinson

GEOG 215 Introduction to biogeography Instructor Ian Hutchinson (RCB 7226) Office phone: 778. 782. 3232 (campus: 23232) email: ianh@sfu. ca TA: Julie Sabau (jsabau@sfu. ca)

GEOG 215 - Housekeeping • Course email: geog-215@sfu. ca • Lecture slides and all handouts are posted on the course web site: www. sfu. ca/~ianh/geog 215/ • “Thumbnail” booklets available from Student Copy Centre [Maggie Benson Bldg. ] (~$12). • All readings are from the text (Mac. Donald, 2003).

GEOG 215 - Grades, etc. • Laboratory assignments: 25% • Poster project: 25% includes research journal: 5% • Midterm exam: 20% • Final exam: 30%

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.

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 Earth’s biotic resources and heritage.

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?

“There’s nothing as ROMANTIC as biogeography” Edward Wilson, Emeritus Professor of Comparative Zoology, Harvard. (quoted by David Quammen: “The Song of the Dodo” [1996])

Climatology Geology Is multidisciplinarity romantic? Pedology Biogeography Ecology Palaeontology Evolution

Is multi-dimensionality romantic? Evolving and mobile pieces global (life-forms) Time: past future Why are the pieces laid out as they are, and how are their distributions changing? Changing table-top (environment) local SPACE

Or field work in exotic locations? Rupununi

Biogeography Present = ecological biogeography observation ENVIRONMENT BIOTA (climate, soil, . . . ) experiment Time ENVIRONMENT (climate, soil, . . . ) inference Past = historical biogeography BIOTA

GEOG 215: Course themes Geological history and evolution Recent and future environmental change Life forms The physical template (climate, soils, landforms) Ecological communities and their dynamics

Given the dazzling array of life forms on the planet, how do we proceed to answer the “central questions”

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

Biological hierarchies Taxonomic order (etc. ) Ecological biome family community genus association species subspecies population individual species Trophic top carnivores herbivores primary producers Only in trophic hierarchies where the focus is energy flow are species not an essential unit

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

Towards a scientific taxonomy Folk taxonomy: 1. Inuit in one district of Arctic Canada have 100 names for local birds. 2. 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.

Taxonomy in the “Classical World” Aristotle (384– 322 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. Aristotle’s ideas held sway (in Europe) until the 17 th century.

Early modern taxonomy John Ray (1627– 1705) 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).

Linnean taxonomy Formalized species descriptions based on diagnostic traits Hierarchy based on groupings of species and genera, not splitting of larger classes Carl Linnaeus (1707 -1778) (aka Carl von Linné and Carolus Linnaeus) Latin binomials (Genus, species) [following the Swiss botanist Bauhin {1560 -1634}] replace long Latin descriptions (e. g. Sturnella magna = ‘big lark’)

Linnean taxonomy: Eng: eastern meadowlark Sp: pradero tortilla-con-chile, Fr: sturnelle des prés Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Aves (birds) Order: Passeriformes (perching birds) Family: Fringillidae (finches) Genus: Sturnella Image: Delbert Rust Species: Sturnella magna (Linnaeus, 1758) Subspecies: Up to 17 subspecies recognized (indicates local variation)

Linnean taxonomy: diagnostic morphologies of related species 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? Sturnella magna S. neglecta Images: http: //birds. cornell. edu/crows/mlarkdiff. htm

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.

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

“Species” in folk vs. scientific taxonomies underdifferentiated Birds (Inuit) 102 birds Plants (Tzeltal) sample of 200 plants 1: 1 overdifferentiated 4 98 0 82 68 50 (2 names) under-differentiated = fewer names for organisms than species recognized by science; 1: 1 = correspondence; over-differentiated = more names, etc. (mainly cultivated plants; e. g. four varieties of beans)

Intra-specific variation in domesticated plants and animals Brassica oleracea Canis familiaris

Intra-specific variation in snow geese Eng: “greater” Inuit: k(h)anguk “lesser” Eng: blue goose Inuit: khavik separate species? or just morpho-colour phases of the same species?

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)

Images: http: //evolution. berkeley. edu/evosite/evo 101/ Meadowlarks western eastern • 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.

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?

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.

Does DNA “barcoding” solve the problem? • Mitochondrial DNA indicates the genetic similarity between organisms and can be used to establish an evolutionary time frame; • mt. DNA 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.

How much variation in mt. DNA is there in a taxon? Cytochrome c oxidase Within species subunit I (COI) gene Within genus moths 0. 25% 6. 5% birds 0. 4% 7. 9% ~20 x

Images: http: //evolution. berkeley. edu/evosite/evo 101/ DNA barcodes: meadowlarks • mt. DNA 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

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

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.

How does a palaeontologist assign a species name to a fossil? Evidence: shell or bone beds ……. . tracks or burrows. Taxon named from: Morphology -- yes (hominid fossils illustrate difficulties) Breeding behaviour -- no mt. DNA -- yes (if DNA is preserved in the specimen )

Naming fossils: South African hominids Australopithecus robustus? Australopithecus africanus? Paranthropus crassidens? or are they all Paranthropus robustus? Images: http: //www. modernhumanorigins. com/robustus. html

The Homo floresiensis controversy: A new human species or just a local population (individual? ) of Homo sapiens? How much morphovariation should a paleontologist allow? See: Hopkin, M. 2006; Will the hobbit argument ever be resolved? Nature, 25 August; doi: 10. 1038/news 060821

“Mr T”: a composite specimen of Triceratops in AMNH Constructed from 14 dinosaur skeletons; undoubtedly derived from several different species

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.

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 mt. DNA analysis kit that will return a species name for every organism encountered on a walk in the woods.

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”

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 subspecies.

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

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.

Protecting sub-species: hybrids Florida panther [Puma (Felis) concolor coryi] § 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