2. 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.
3. For example
1. Cheek muscle
Function: to close the jaw
Biological Role: for food
processing (chewing)
Biological Role: (biting) for
protection against threat
4.
5. 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)
8.
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
9. 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
10. 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.
11.
12. Phylogeny
can be summarized in graphic
schemes, or dendrograms, that
depict treelike, branched
connections between groups.
Dendrograms summarize
evolution’s course
13. 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.
14.
15.
16.
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.
17.
18.
19.
20. Denrograms
It 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.
22. A clade is a grouping that includes a common
ancestor and all the descendants (living and
extinct) of that ancestor.
23.
24. 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 clade
Is one that does
not share an
immediate common
ancestors
25. 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
27. Convergence
Is evolutionary change in two or more
lineages such that corresponding features
that were formerly dissimilar become similar
A
BSimilarity
between A and B
evolved from
different lineages
