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 their

immediate ancestors) as insulation to conserve body heat. Like hair in mammals, feathers formed a surface barrier to retard the loss of body heat. For warm-blooded birds, feathers were an indispensable energy-conserving feature. Today, feathers still play a role in thermoregulation; 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