Transcript Adaptive morphology - Autecology

Adaptive or Functional
morphology - Autecology
What is the origin of our
morphologies or how do
structures work
• (Palaeo)Autecology: study of the life
modes of organisms and the relationship
between individuals and the
environments. It focusses on the
growth and shapes of organisms ad on
the correspondence of morphology to
both life strategy and habitats.
Aims:
• To define the function of a particular
anatomical form
• To describe how organimsms reached
their present forms.
Phases:
(1) God’s luck: Divine designer
(2) B. G. Cuvier: the founder of
comparative anatomy
(law of correlation parts)
(3) C. Darwin
• Adaptation: accordance
between an organism and the
environment or it is the fitness of an
organism to its environment
Anatomical form =
Morphology
Influential factors
• Our morphology (adaptation to
environmental needs) is interrelation of
the following factors :
1) the genome; 2) the development of
body plan (isometric growth vs.
allometric growth)
Growth strategy: the
development of body plan
• Marginal accretion: adding on discrete
growth layers to their skeletons as
they get larger; leaves "growth lines"
• Addition: discrete new parts added or
intercalated, with little change
afterward
• Adding body segments
Serial addition
• in colonial organisms: the parts
replicated are comparable to entire
other organisms
Molting
• each growth stage or instar is entirely new
hard part material; allows for radical
transformation between growth stages
(extreme in advanced
insects); leaves
discrete size classes
representing age
classes.
Continous modification
• Bone tissue remodelled throughout
ontogeny.
Influential factors
3) the function of the organism; 4) the
organism’s behaviour
Investigative methods
• Structure can be compared directly
with modern, working counterparts
(homologues, analogues).
• Paradigm approach: one function can be
tested against the efficiency of a
mathematical or physical model for the
working structure
• Application of various experimental
techniques where physical models are
subjected to simulated encironments.
1. Experimental palaeoautecology
2. Computer simulation
Procedure
Each structure has to be describe.
Described structures are compered one
to another and to the environment.
Function and morfology for each
structure has to be define.
 Connection between structural
performance and fitness to morphology.
Analogues and homologues
• The morphology ad function of a modern
structure is compared with an assumed
counterpart in an extinct or fossils organism.
• Homologous structures, like wings of birds or
lungs of the vertebrates, have evolved once.
• Analogous structures: evolved at different
times from different structures (wings in
birds, in insects…
Analogues and homologues
• Could exist does exist?
• Certain morpholohy repeats over Life
evolution: Some adaptations are
mechanically advantageous and easy to
produce developmentally
Convergation
• Different lineages of organisms can
independently develop some of the same
features, even though ancestors were
quite different (e.g., streamlining in
sharks, tunas, ichthyosaurs & dolphins;
cactus-like form in separate lineages of
plant; etc.).
How this method works in the
field?
• We have to define the adaptation or the
structure we pick up for study, then make a
list with all organisms that show this
adaptation or have this structure –
Theoretical and traditional morphology
• Try to go far in the past to see who was the
first organism that showed this adaptation or
had this structure - phylogenetic lineages in
order to see wh this adaptation/structure
arose
• Ancestor and descendants form a
lineage (historical line). If the same
basic adaptations are selected for and
elaborated over time, this is called a
trend. (e.g., longer and longer legs for
fast running; longer and longer necks
for browsing in trees, etc.)
• If a new adaptation (or loss of
competitor group) occurs, many
different variations from a common
ancestral population might survive (new
or unoccupied "niches" in environment).
Over a geologically short period time, a
common ancestor can radiate into many
different descendant lineages
Paradigm approach
• The aim to bring scientific methodology
to functional studies
• First we have to postulate one or more
bilogical functions for a particular
structure
• Secondly for each function an ideal
model or paradigm has to be designed
Case study: gastropods
• We study the following prameters:
shell’s shapes, aperture’s shape; apex,
number of whorl, ornamentation…
Shapes
• Ratio between measurable parameters
define the shape of shells.
Height > Width
Width > Height
Aperture shapes
Moonlike
Rounded
Kiddney-like
Apex
• α<300
α=150-1800
α= 60-900
Number of whorls
n<4
n = 6 – 10
n > 10
Ornamentation on the last whorl
Smooth surface
Growth line
Costa
Costa
Case study: gastropods
• We study, also: axis of coiling;
expansion rate (W), Distance from the
generating curve (D), Translation rate
(T)
Mathematical model, X-ray image and
real mode help us to measure the
parametersl
W
D
T
Mathematical model
• The variation in the form of planispirally
coiled cephalopods summarized by varying
expansion rate (W) and distance of aperture
from axi (D)
W
Paradigma ‘s bad characteristics
• Structural constrains: usually special
puropese for each structure! Not
necessary
• Evolutionary heritage: an organism can
build a new anatomical feature only out
of the raw materials that were
furnished by its ancestor.
• Pleiotropy: single gene has many
independent phenotypic manifestation.
• Ecophenotypic
• Organisms of the same species may look
substantially different depending on
their environment, e.g. Scleractinian
corals in different energy regimes.
• There may be no selective advantage
whatsoever (human chin)
• Not every feature is optimally designed
• The correlation between structure and
function is not perfect
Computer simulation
Adaptation
• How well an organism is fitted to its
environment?
• Size as an adaptation
• What do you think: are large organisms
better adatped than small ones?
• Giants are particularities of the certain
groups of organisms. Is it simply chance,
or are there biomechanical reasons?
• Why do some groups
never produce
giants?
• Does evolution
always go from small
to large? Cope’s law
• How long does it
take for large size
to evolve?
• What is better: to
be giant or to be
dwarf?
Biomechanical reasons or
constraints
• Mechanical postulates are adopted for
analysis of organisms.
• Investigations are directed towards:
• Toughness of the matter and
architectural pattern
• Energy and power: Prey and mandible
• Motion: swimming, flying, propulsion
Biomechanial reasons
Why so few giants?
• Arthopods would suffer the cost of moulting
dozen of times
• Filter-feeding habitis of brachiopods, most
molluscs, bryozoans, graptolites, some
echinoderms because exposed cilia cannot
sustain a large organism.
• Mechanical constrains in shells: weight of
shell and the amount of calcium carbonate to
be extracted from the sea-water tend to
prevent huge size.
Time necessary for development
of giants – Evolution of large size
Triassic (Norian) – Prosauropodi
(Plateosurus), 5m = body length
Liassic – Melanosaurus
12 m = length,
weight = 10 t
Time necessary for development
of giants
• Bathonian – Kimeridge – the largest
dinosaurs up to 30 m in length, weight =
80 t
Advantage and disadvantage
of large size
1. Improved ability to capture a prey or escape
from predators
2. Greater reproductivity success
3. Increased intelligence
4. Better stamina
5. Expanded size range of possible food items
6. Decreased annual mortality
7. Extended individual longevity
8. Increased heat retention per unit volume
Advantage and disadvantage
of large size
• Greater proneness to extinction
1. expression of specialization: need for
large amounts of food and, need for
particular environmental conditions
2. small population sizes i.e. small gene
pools)
Heterochrony
• Changes in the developmental rates of
an organism
• Result: set of growth strategies that
produce significant morphological
changes between parent and daughter
populations.
Paedomorphosis
• change in which the adult of a derived
organism resembles a juvenile of the
ancestor.
Peramorphosis
A juvenile of a derived organism
resembles an adult of the ancestor.
Ancestor
Descedant
Sexual Dimorphism
• Male and female organisms of the same
species differ a lot.
How do we distinguish
dimorphismsin fossils?
• Analogy with living relatives
• Ratios of presumed females to males
(differentiation in size, shapes...)
• Taphonomic variability: post mortem
distortion