Midterm 2 Flashcards
Species Variability
Each species has its own morphological variability, and we can group those variabilities into three categories: Ontogenetic, Genetic, Nongenetic
Ontogentic
variability in the result of the organism growth during its lifetime.
three stages, juvenile, adult, gerontic
genetic variability
has to do with the genetic structure of the specimen, it can either be continuous or discontinuous
Nongenetic
primarily induced by ecological factors, example: suprapopulations in bivalves, they was was no space to grow so they squished each other and as a resulted, the morphology changed.
ontogenetic trajectory
growth can be plotted to track morphological change; put it on a chart and measure the changes; empirical analysis
types of ontogentic variability
Isometric: organism shape remains the same during the ontogeny. (Just an increase in size)
Anisometric: organism shape changes (shape changes through time and if we plot the different values of 2 parameters then we will see that they are aligned according with a curved line, this parameters show what changes)
5 growth strategies in ontogenetic variability
Accretion- adding identical layers to its body in concentric form; ex: bivalve
Addition- added layers one segment at a time ex: echinoderms and radiolarians
Molting- As the organism grows the hard body part doesn’t grow with it, organism breaks out of the carapace and there is a “detachment line” ex; trilobites.
Modification- relative size of the bones makes us change ex: vertebrates
Mixed- more than one growth pattern happens in one organism; cephalopods (accretion addition and modification)
continuous variability
type of genetic variability that occurs continuously in the whole population of the species and cannot be explained by external/environmental factors
discontinuous variability
rare case, common in cases of differentiated sexes where there is changes without any transition between them.
example: planktic foraminifers (dexitral (left) vs. sinistral (right) coiling)
sexual dimorphism
female and male within the species are easily distinguishable and there is a sharp gap between the morphologies but it is harder to find these differences in fossil species.
agglutinant foraminifera
case of non genetic variability, this organism builds its tests with things in the environment, so the variability is environmental rather than genetic
Biases of paleontological (fossil) record
Fossilization bias- organisms destroyed/not part of the fossil record so none or fragmentary tests remain
Areal bias- fossils could be spread out but only one part of the fossil basin is collected due to funding limitations
sampling bias- only one portion of a layer is continuously sampled
Holotype
specimen designated to be the representative of the species, and is chosen by the author. It will have all the characteristics of the species (the best specimen of the species)
Paratype
the rest of the specimens from the biological population after the holotype has been chosen, chosen by the author
neotype
if the holotype was destroyed, a new one must be chosen after the original is proven to be destroyed
how do you select a holotype
it is a subjective method of choosing.
lectotype
species was described but the author did not select a holotype. This occurs to fossils that were described before the type classification was made in the 19th century
paralectotype
remaining specimens after the lectotype selection
type locality vs. type level
type locality- finding a species in a geographical location on earth
type level- finding a species somewhere in the geological timeframe of the earth
Textilaria Americana
example of author not naming a holotype, a lectotype being chosen then the original samples being rediscovered
Morphospecies
Species defined by their morophology. Essential question: how do we know see the differences between individual species when there are some overlap.
need for specialists in morphospecies
specialists are needed when you cannot tell the morphological differences of a specimen
the differences between biology, paleontology and genetics
Biology- Species can reproduce with themselves, but cant cross breed
Genetics- Species is defined as the isolation genetic code
Paleontology- Species is defined in relation to time, where the species came about and so forth. Centered on the evolution in space and time.
how do the 3 sciences deal with the mechanisms that create new species
- paleontology: deals with the effects of the these mechanisms
- biology and genetics: deals with the process of the mechanisms
process of classification of evolutionary process
morphology- grouped by common ancestry
polyphyly- grouped by morphology
paraphyly- grouped partly by common ancestry, only reflect the evolutionary process partly
systems of classification
essentialism/typological- organisms are grouped together based on morphoplogy ex: linean classification system
nominalism- the classification of groups and the organisms that exist in nature are just a product of the human mind. Theory never really used, put forth by Lamarck
empiricism- taking into account all morphological changes of an species, but could not explain how these morphologies came to be.
evolutionary classification- Charles Dariwn; it is possible to recognize the ancestral descent
holotype syndrome
specialists only illustrate speciments that resemble the holotype, neotype and lectotype and results in little new added info to get more information about the specimen.
type series
classifications that take into account the evolutionary process of the specimens
subspecies level
proposed by Charles Darwin, a level below species and therefore and formalizing the species heterogeneity
pioneers in the 3 branches of science
Ernest W. Mayr- biology
Theodosius G. Dobzhansky- genetics
George G. Simpson- paleontology
composite paleontological species
characteristics:
1. Monophyletic
2. morphological variability
3. morphologically heterogenous and discontinuous entity
4. has a developmental history that is traceable
5. existence can be tested
speciation and extinction
speciation- start of species evolution
extinction- end of the species
stratigraphic range
the interval between speciation and extinction
infraspecific categories
individuals of species clustered to form group populations
Allopatric
isolated populations
sympatric
when two or more populations area of distribution overlap over a certain geological time period
gradualism
Darwin’s theory of evolution, changes in species happening slowly over time; this happens when the parental species co-exist with the daughter species resulted in a variety of species
phyletic transition
when the emergence of the daughter species coincides with the extinction of the parent species
Monophly
grouping species according to the direct ancestor-descendant relationships
Polyphyly
formation of groups inconsistent with the ancestor-descendant relationships.
Paraphyly
includes only a part of the descendant species from a common ancestor.
evolutionary classification
started with Darwinism, it groups species in lineages not genuses. Grouped based on common ancestory and achievements in the evolutionary process.
why use lineages in evolutionary classification
lineage shows how unrelated organisms from separate ancestors evolved to look the same way
difference between linean and evolutionary classification
linean groups on morphological similarities while evolutionary classification groups based on common ancestry
typological classification has axiomatic character, while evolutionary classification is scientific
are lineages equal/identical
No, species can develop more than others, some will develop to a certain point and then stop
types of lineage
directional- continuous evolution between two or more features resulting in monophyletic-linear succession of species
branched- occurrence of at least one feature that creates a divergence
iterative- repetitive evolution of one or a group of features which leads to descendant species that considerably resemble each other and evolved from one common ancestor
condensed- fast evolution, with differences in morphology with the ancestral species, but little variability within the species
what are the dominant elements in life forms on earth
carbon, oxygen, hydrogen, nitrogen, sulphur, phosphorus
petroleum composition
???
living matter molecular composition theory
the proof life formed in aquatic regions, because the human body is 70-90% made out of water.