Download - Biogeo
Prepared by:
Lhea Joy BaylonLianell MaesaCha Villania
COMPARATIVE BIOGEOGRAPHY
• Biogeography can be a powerful
tool to explore data on the
diversity, phylogeny, and
distribution of organisms, to
reveal the biological and
geographical history of Earth.
COMPARATIVE BIOGEOGRAPHY
• Uses the naturally hierarchical phylogenetic
relationships of clades to discover the biotic
area relationships among local and global
biogeographic regions.
• Approach offers a comprehensive empirical
framework for discovering and deciphering
of life on Earth.
• To introduce comparative
biogeography, we differentiate
between the two types of
biogeographic investigation that it
encompasses: systematic
biogeography and evolutionary
biogeography.
Systematic Biogeography
• is the study of biotic area relationships and their classification and distribution.
• For example, the distribution and relationships of numerous taxa may be expressed in a hierarchy as Eastern South America (Africa, India), meaning that organisms in Africa have their closest relatives in India and that together they are in turn related to organisms in eastern South America. Examples include such diverse taxa as vascular plants, fishes, birds, and dinosaurs.
Evolutionary Biogeography
• is the proposal of evolutionary
mechanisms responsible for organismal
distributions.
• Possible mechanisms responsible for the
distribution of organisms related as in the
area homolog Eastern South America
(Africa, India) include widespread taxa
disrupted by continental break-up or
individual episodes of long distance
movement, to name just two.
BIOGEOGRAPHIC DISTRIBUTION
• The idea that the ranges of species was due to their spreading from a point of origination had several precursors before Darwin developed it in 1837
• Buffon (father of zoogeography) in 1779– Similar species occupy the same position in
different ecologies– Proposed that a fauna was the product of the
conditions of the district where it originated
• Peter Simon Pallas (German zoologist)– Similar forms were often connected by a
graded chain of intermediate forms
• Leopold von Butch– Drew the logical conclusion that varieties
become segregated species
• J G Gmelin (botanist) in 1747– First to have suggested that species
were independently created all over the world
• Joseph Hooker– Species could spread beyond their
allocated domain• Charles Darwin–Held to be important on islands, but also
where rivers, mountains and other impediments prevented species split into separate breeding populations from back-crossing
• Mayr–Darwin prevaricated on its importance,
and eventually also accepted the possibility of “sympatric” speciation – speciation due to a move into new ecological or behavioural niches
• Alexander von Humboldt (1805), EAW Zimmerman (1778) and CF Willdenow (1798)– Species had spread from a central
point, the landing site of the Ark• Alfred Russel Wallace (1855)– Published the principle that species are
always found close in space and time to an allied species that precedes it in the geologic record
• Wallace did his work in the Amazon region and the Malay Archipelago, while Darwin’s own observations twenty years earlier had been in Galapagos Archipelago and the plains of Patagonia during the Beagle voyage
• Darwin was spurred into publication of his ideas when Wallace, not knowing of Darwin’s views, sent him a paper on the topic in 1858
• Darwin had just suffered the death of his son Charles, and his grief, he passed it on to Lyell and Hooker, with whom he had previously discussed his views who submitted it to the Linnean Society of London with extracts of Darwin’s unpublished 1844 Essay on Natural Selection and a letter wrote to Asa Gray in the United States on 5 September 1857
• It is clear that Wallace and Darwin independently discovered biogeography, and are due the joint credit they now are imputed.
Biogeographic Distributions
• I. Three important principles: How do these principles support descent with modification?• A. Environment cannot
account for either similarity or dissimilarity, since similar environments can harbor entirely different species groups
• B. "Affinity" (=similarity) of groups on the same continent (or sea) is closer than between continents (or seas)
• C. Geographical barriers usually divide these different groups, and there is a correlation between degree of difference and rate of migration or ability to disperse across the barriers