Post on 04-Jul-2015
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Evolutionary Morphology
Part 2 of Chapter 1By Geonyzl Alviola
Function and Biological Role
Function = is restricted to mean the action or property of a part as it works in an organism.
Biological Role = (or just role) refers to how the part is used in the environment during the course of the organism’s life history.
For example
1. Cheek muscle
Function: to close the jaw
Biological Role: for food processing (chewing)
Biological Role: (biting) for protection against threat
For example (one part with several function)
2. quarate bone (in reptiles
Function: to attach the lower jaw to the skull. It also functions to transmit sound waves to the ear.
Biological role: feeding (food procurement) and hearing (detection of enemies or prey)
Example
Function?
Biological Role?
Functions of a part are determined largely in laboratory studies; biological roles are observed in field studies.Inferring biological roles only from laboratory studies can be misleading
Preadaptation
Preadaptation means that a structure or behavior possesses the necessary form and function before (hence pre-) the biological role arises that it eventually serves.
In other words, a preadapted part can do
the job before the job arrives
For example: Bird Feather Story
feathers likely evolved initially in birds (or in theirimmediate ancestors) as insulation to conservebody heat. Like hair in mammals, feathersformed a surface barrier to retard the loss ofbody heat. For warm-blooded birds, featherswere an indispensable energy-conservingfeature. Today, feathers still play a role inthermoregulation; however, for modern birds,flight is the most conspicuous role of feathers.Flight came later in avian evolution.
Phylogeny
can be summarized in graphic schemes, or dendrograms, that depict treelike, branched connections between groups.
Dendrograms summarize evolution’s course
Of Beanstalks and Bushes
1896, Ernst Haeckel wrote The Evolution of Man
Evolution does not proceed up a single ladder, but bushes outward along several simultaneous courses.
Humans share the current evolutionary moment with millions of other species, all with long histories of their own.
All adapted in their own ways to their own environments.
The apparent discreteness of species or groups at the current moment is partly due to their previous divergence.
When followed back into their past, the connectedness of species can be determined. A dendrogram showing lineages in three dimensions (figure 1.22) emphasizes this continuity.
DenrogramsIt is a summarized graphic representation
of the course of evolution or phylogeny
- it is also used to express relative abundance and diversity.
- presented like a branching tree or any form.
Gradual presentation / Abrupt dendogram
A clade is a grouping that includes a common ancestor and all the descendants (living and extinct) of that ancestor.
Monophyletic clade - it includes an ancestor and all its descendants
Paraphyletic clade- one that includes a common ancestor and some but not all, of its descendants.
Polyphyletic cladeIs one that does not share an immediate common ancestors
Parallelism and Convergence
Parallelism is evolutionary change in two or more lineages such that corresponding features undergo equivalent alterations without becoming more or less similar
a b
The ancestor is common in both a and b
Kangaroo ratNorth America
JerboasAfrica and Asia
Convergence
Is evolutionary change in two or more lineages such that corresponding features that were formerly dissimilar become similar
ABSimilarity
between A and B evolved from different lineages
For example
Studying phylogeny
Studying the history of an animal
Tracing its relatives
Associating its resemblance
=======> Paleontology
Paleontology
= study the fossils
= recovery and restoration
= dating the fossils
= stratigraphy
= indexing
= radiometric dating