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