Chapter 19- Reporting Flashcards
Who wrote the conditions of existence?
George Cuvier and Charles Bell
● Adaptation through differences
● concentrated on the species distinctions that enable each species to adjust to its surroundings
Conditions of existence
Who wrote the unity of type?
Geoffroy St. Hilaire and Richard Owen
- is critical and secondary to that is evolution
(adaptation) - basic structural agreement that is
present in organisms of the same class and is not influenced by their living styles
Unity of type
- Homologies of embryo and larval structure serves as evidences
Descent with modification
provide the basis for anterior-posterior
axis specification throughout the animal kingdom
Hox genes
demonstrated that the human
HOXB4 gene could mimic the function of its
Drosophila homologue, deformed, when introduced into Dfd-deficient Drosophila embryos
Malicki et al. (1992)
postulated that the Hox gene
expression pattern defines the development of all animals, and that the pattern of Hox gene expression is constant for all phyla
Slack et al. (1993)
They have cataloged four critical
ways in which variation in Hox expression patterns might lead
to evolutionary change.
Gellon and McGinnis (1998)
Four critical ways in which variation in Hox expression patterns might lead
to evolutionary change.
- Changes in the Hox protein-responsive elements of downstream genes
- Changes in Hox gene transcription patterns within a portion of the body
- Changes in Hox gene transcription patterns between portions of the body
- Changes in the number of Hox gene
expressed in the imaginal disc
of the third thoracic segment (wing or haltere are derived)
Ultrabithorax gene (Ubx)
is critical for providing the
proximal-distal axis of the appendages.
Distal-less (Dll) gene
What gene is responsible why snakes are limbless?
HoxC-6 and HoxC-8
is needed both for the polarity of
the limb and for maintenance of the apical ectodermal ridge (AER). Python hindlimb buds lack the AER.
Sonic hedgehog
single hox gene complex per haploid
genome.
Invertebrates
chelicerates possess unique characteristics where their head and
thorax are fused known as __________________
cephalothorax
organisms that have two (2) body
segments, mainly: cephalothorax and abdomen. They have no antennae but have six pairs of appendages. e.g. spiders, scorpions, horseshoe crabs
Chelicerates
arose from neural folds through
the attraction of the neural plate with the
presumptive epidermis
neural cell crest
is a longitudinal ciliated groove
on the ventral wall of the pharynx which produces mucus to gather food particles.
Endostyle
is a pharyngeal organ of uro- chordates,
cephalochordates, and primitive vertebrates. This organ has iodine-concentrating and iodine metabolism activities, and therefore the
endostyle is considered to be homologous to the follicle of these.
Thyroid gland
it is used for specifying dorsal-ventral
polarity, which is used by mammals to activate
inflammatory proteins
Dorsal-cactus pathway
This pathway involves the activation of cell
constituents to perform cellular metabolic processes. A ligand binding to its receptor conforming a signal to channel the secondary messengers inside the cell that gives another signal for the cell to perform a metabolic activity
Tyrosine-Kinase Pathway
Three processes to alter development:
- Dissociation (heterochrony & Allometry)
- Duplication and Divergence
- Co-option
An embryo can change in one region without the other altering through mutation or environmental disruption
Dissociation
these changes can
occur together
spatial and temporal changes
- involve the space /environment in changes
spatial
the factors change from one time to in
certain period of time
Temporal
Change in the proportional time of two
developmental mechanisms that pass down from one generation to another (relative to the ancestors)
Heterochrony
Two types of heterochrony
- paedomorphosis
- peramorphosis
type of heterochrony that is child shape
paedomorphosis
type of heterochrony that is ‘beyond-shape’ accelerated and early development
peramorphosis
changes in a gene’s capacity to cause
or induce the response to the hormones that cause transformation or the metamorphosis to occur
gene mutation
abnormal development
of the cells based on time
heterochronic expression
● Different parts different growth rate
● Important to the body plan growth
- due to different development or growth
rate of the structure formed so it aid on
body plan or the actual outcome of the
organism structure that ultimately give
benefits to the organism
Allometry
- formation of unnecessary / other structures
Duplication
give the formulated structure new roles (One
of the copies can maintain the original role while the others are free to mutate and diverge functionally.)
Divergence
● No structure/components have singular
purpose/roles
● Structure or components can be used in many ways
● pre-existing units can be co-opted (recruited) for new functions.
Co-option
procedure wherein an already-existing
unit or the organism protein or genes is repurposed for a new application and function.
- Found in molecular and morphological level
Co-opted
A phenomenon in which multiple biological trait evolve together and how other structures change in response to the change of a single structure
Correlated progression
A chemical messenger that is released by a cell to signal itself or other cells.
Ligands
A protein that are inside or outside of the cell
that receives signals and give a response
Receptors A
Three types of Developmental Constraints
● Physical Constraints
● Morphogenetic Constraints
● Phyletic Constraints
physical factors that limit the formation of
mechanisms of an organism. These factors are Laws of diffusion, hydraulics, and physical support.
- Elasticity and tensile strengths of tissue
Physical constraints
is the development of normal
structures that is controlled by the growth,
differentiation, and movement of cells, and tissues.
morphogenetic
- It involves morphogenetic construction rules such as the reaction- diffusion model that explain why some morphologies are forbidden
Morphogenetic constraints
- Historical restrictions based on the genetics of an organism’s development.
- Once a structure comes to be generated by inductive interactions, it is difficult to start over again.
Phyletic constraints
- biological structures that have lost a major
ancestral formation and are usually drastically reduced in size.
vestigial
Evolutionary modifications of cytoplasmic
determinants in mollusc embryos can give
rise to new types of larvae that still
metamorphose into molluscs.
cytoplasmic determinants
The formation of new body plans is inhibited by the need for global sequences of induction during this stage.
- Before and after this stage, there are many inductive events but almost all of them occur within discrete modules
Neurula stage
development appears to be buffered so that slight abnormalities of genotype or slight perturbations of the environment will not lead to the formation of abnormal phenotypes
Canalization (Buffer systems of development)
- protein that binds to a set of signal transduction molecules that are inherently unstable.
- provides a way to resist fluctuation due to slight mutation or environmental change
Heat shock protein Hsp90
It has been one of the greatest
intellectual achievements of biology. By merging the traditions of Darwin and Mendel, evolution within a species could be explained: Diversity within a population arose from the random production of mutations, and the environment acted to select the most fit phenotypes.
Modern synthesis
The supposition that all
evolutionary changes occur gradually was debated by Darwin and his friends
gradualism
some major assumptions that have now been called into question
- gradualism
- extrapolation of microevolution to macroevolution
- specificity of phenotype from genotype
- lack of genetic similarity in disparate organisms
The idea that accumulations of
small mutations result in changes leading to new species has also been criticized
Extrapolation of microevolution to
macroevolution
