BIOLOGIA TEMA 5 Y 6 4ºESO
theori about origin of life
Theory of spontaneous generation (Aristotle)
–Formerly it was believed that decomposing organic matter produced living beings spontaneously
Theory of prebiotic synthesis (Alexander O, John H)
–Life arose from inorganic matter
Panspermia theory
–Proposed by SvanteArrhenius
–Suggests that life came to earth from another planet–It does not solve the question posed by the origin of the first living being
Present-day hypothesis
–Possible appearance of living beings in deep-sea hydrothermal vents
the theories of evolution
Lamarckism or transformism
–Proposed by Jean Baptiste de Monet, Chevalier de Lamarck, en 1809
–Is the theory of inheritance of acquired traits
–Principles
•Environmental conditions vary over time
•Changes create new needs (the need creates the organ)
•New habits emerge
•Modifications are passed on to offspring
Darwinism
–Proposed by Charles Darwin andAlfred Russell Wallacein 1859
–Theory of evolution by natural selection
–Principles
•There are small variations in individuals of the same species
•There is a struggle for survival in the habitat where they live
•Some variations are more successful (natural selection)
•The species changes
Neo-Darwinism orsynthetic theory
–It arises as a result of genetic research produced in the 20th century
–Changes in species occur by
•Mutations: changes in the genetic sequence of DNA, harmful or neutral
•Sexual reproduction: combinations of genes different from those of the parents
•Genetic recombination: new combinations of genes in meiosis and in the fertilization of sexual reproduction
Neutralism
–Created by Motto Kimura
–Living beings evolve by mutations
–Defend that there is no natural selection
Theory of punctuated equilibrium
–Proposed by Niles EldredgeandStephen Jay Gould
–Evolution is not slow andalways gradual; instead, inmany cases, new speciesare formed rapidly
Endosymbiosis
–Proposed by Lynn Margulis
–Explain the evolution of the eukaryotic cell from prokaryotic cells
•Primordial protoeukaryote: digested prokaryotes
•Among the survivors there would be two types–Effective in respiration: originated the mitochondria–Effective in photosynthesis: they originated chloroplasts
Evolutionary developmental biology
–Some body changes in species are due to mutations in a small group of Hoxgenes
evidences of evolution
Anatomical and morphological evidence
–Homologous organs
–Analogous organs
–Vestigial organs
Fossil evidence
–Fossils show that many different organisms existed on Earth
–Evolutionary series show gradual changes in species
Embryological evidence
–Embryonic development (ontogeny) is a summary of evolution (phylogeny)
Biogeographicalevidence
–Organisms with a common origin evolve in different species if they are geographically separated
Molecular evidence
–The more similar the biomolecules of various living things are, the closer their evolutionary relationship –Example: chlorophyll
Other evidence
–Coevolution between species
•Mutualism•Parasitism•Mimesis•Domestication
•Temporally sequence of the stratum
process of hominization
The Hominization process consists of evolutionary transformation of hominoids into Hominids. It is a process that has occurred in the hominoid-line since its divergence from the last common hominoid ancestor shared with any living ape.
Human evolution
–The hominization process has spanned 6 million years
–Australopithecus
•Australopithecus afarensis
•Australopithecus africanus
–Homo
•Homo habilis
•Homo erectus
•Homo sapiens neanderthalensis
•Homo sapiens sapiens
1.Environmental factors
–Characteristics of the environment that affect living beings
–Types of factors
•Abiotic: biotope
•Biotic: biocoenosis
Limiting abiotic factors
–Part of the biotope
–They define the living conditions
–Types of factors
•Terrestrial environment: temperature, humidity, relief, availability of water, light, nutrients
•Aquatic environment: depth, light, pressure, water movement, oxygen concentration, temperature, salinity
–Ecological valence
•Range of values of abiotic factors in which a species can live
•Optimal: ideal environmental conditions for a species
•Adaptations: allow a species to adapt to the environment
•Eurioicspecies: large tolerance ranges–Example: eurytherm
•Stenoicspecies: small tolerance ranges
–Example: stenohaline
2. Know the concepts of adaptation, limiting factor and tolerance limit
Adaptation is a process that allow a species to adapt to the environment. They produce changes in populations over time: they are the engine of evolution. Thanks to adaptations, species survive. It can be Anatomical (morphological), Physiological or Ethological (behavioural).
Limiting factor: Part of the biotope that define the living conditions that can be: Terrestrial environment: temperature, humidity, relief, availability of water, light, nutrients.
Aquatic environment: depth, light, pressure, water movement, oxygen concentration, temperature, salinity
Tolerance limits consist of the the upper and lower limits of a particular environmental condition which allows a certain species to survive. Environmental conditions can include the amount of water, temperature, light, or the availability of other resources.
3.Population–>Group of organisms of the same species that live in the same territory and can reproduce with each other
Ecotone–>Transition between two communities of an ecosystem
Community orbiocoenosis–> Living things that make up an ecosystem. It includes the populations of all species in an ecosystem
4.Intraspecific relationships
–Between individuals of the same species
•Colony
–Organisms attached to a substrate, attached to each other
•Family
–Individuals with a high degree of kinship
•Social
–Many individuals live in large groups and divide the work to benefit the whole
•Gregarious
–Individuals united for defense, mobility, etc.
Interspecific relationships
–Neutral
–Beneficial: Mutualism Symbiosis Commensalism
–Detrimental: Predation Herbivory Parasitism
Competition Amensalism