Midterm 1 Flashcards
Biogeography
- The study of the past and present geographic distributions of plants and animals and other organisms including the environmental and evolutionary forces that produce those distributions
- Essentially, why a biological individual lives where it lives
When did biogeography develop as a discipline?
The 18th century.
Linnaeus, 1735
- Began to describe and name the animals and plants of the world
- He recorded the type of environment each species was found and where it was found (geographic location)
- Conflict emerging in his work between the words of the bible and the changing characteristics over time –not consistent with a single event/act of God
George Buffon, 1761
- Identified similar environments could be found in different regions of the world but they contained different groupings of organisms of the same species
- Began to identify that mammals found in North America were also found in Eurasia and he hypothesized that they could have once travelled between the two continents
Captain, James Cook (1772-1775)
- Collected thousands of species of plants
- Identified differences based on separations by landscape barriers, water, and climatic differences
- That there were more species (greater diversity) closer to the equator and few species and less diversity toward the poles
Dr. Joseph Hooker, 1843
- Dr. Joseph Hooker returned from New Zealand, Australia, Tasmania and South America with a collection of specimens.
- Noticed that the same plant families were found on different continents
- He concluded that the distance separating these continents was too great for long-distance dispersal, therefore, the southern land areas were once joined (vicariancebiogeographers)
What is a variance event?
- A process in which two or more populations of the same (but geographically separated and non-interbreeding) species become less similar to each other over time
- Differences evolve due to mutation or survival advantages of different traits in differing environments, and eventually become they become so different that they are considered a distinct species
Charles Darwin (19th Century)
- began to realize that species were not as unchanging as people thought
- Came to suggest that organisms were related to one another by evolution
- Darwin recognized that animals and plants produce far more offspring than would be needed to simply replace the breeding pair
- Therefore, there must be competition for survival
- natural selection. Offspring with more favourable characteristics lived longer
Alfred Wallace(January 1823 –November 1913)
- Thought along the same lines as Darwin
- The ideas of natural selection were published by both Darwin and Wallace –the evidence of evolution
- Darwin’s publication “On the Origin of Species” was laid out logically and persuasively and became popular
- Charles Darwin and Alfred Wallace disagreed on the importance of the geological breakup of landmasses in generating biogeographic disjunctions in the Southern Hemisphere (dispersalists)
Adolf Engler (1879)
was the first botanist to make a world map, showing the distributions of regional floras
Zoogeography
began to develop in the 19th century onward, mapping warm-blooded mammal distributions throughout the world
Leon Croizat
- created panbiogeography
- species of very different geographic patterns share similar geographic patterns
- different species have very different dispersal patterns
- shared patterns are not likely to have arisen from long distance dispersal
Panbiogeography
plots distributions of a particular taxon or group of taxa on maps and connects the disjunct distribution areas or collection localities together with lines called tracks
Linking Geography and Evolutionary History
- The only explanation for repeated patterns…is that taxa once had much larger distributions before geologic events
- The over time, events split the once continuous ranges
- Most speciation occurred following vicariance events
Vicariance Biogeography
- developed following panbiogeography
- Dispersal events were rare and unimportant
- All speciation arose from the splitting of once continuous ranges through geological events
- Climactic changes as well as geologic changes can create biogeographic barriers and produce vicariance events
Modern Biogeography
-Modern biogeography began to look at the connectivity of earth continents through time, that may have at one point, been one large continental mass
What is an ecosystem?
- A community of living organisms in conjunction with the nonliving components of their environment, interacting as a system
- These biotic and abiotic components are regarded as linked together through nutrient cycles and energy flows
Ecology
- Derived from “oikos” (Greek) meaning ‘home’
- the scientific study of the interactions between organisms and their environment
Environment
all factors outside the organism that influence it
Factors are either
- abiotic (physical and chemical)
- biotic (other organisms)
Proximal
- patterns explained by the present environment
- Eg. How did the weather (eg. rain) this summer influence plant growth in the region?
Ultimate
- patterns explained by the past environment (i.e. ecological experiences of ancestors through evolution)
- Eg. How has the climate over the past 1000 years influenced the plant species present in the region?
Ecology deals with three levels
- Individuals
- Populations
- Communities
Evolutionary Ecology
–individuals are the units of evolution
-Assumes: specializations imposed by evolutionary history