Evolutionary Theory 1 Flashcards
What is evolution?
- change in organisms over generational time - a change in allele frequencies over time
- ongoing biological process
- change in traits of phenotype
- changes in genotype do not always result in changes in phenotype
- genetic/genotype level
phenotype
- observable trait or characteristic
- physical traits like eye colour, but also things like blood type or hormone levels
- behavioural traits are also phenotypes that are shaped by evolution
- controlled only in part by genotype
genotype
- genetic component that determines a characteristic (genes/alleles)
- genetic change may not result in phenotypic change
microevolution
genetic changes within populations that may cause populations of a species to vary in trait frequencies (eg. lactase persistence)
macroevolution
genetic changes in populations over larger spans of time that may result in the appearance of new species
how do we know about evolution?
scientific method
what does misconceptions and distrust in science create
misconceptions and distrust in evolutionary research
scientific method
- evidence based
- with new evidence ideas are re-evaluated
- often quantitative
- observe and test to understand the world, NOT prove a scenario
- a cycle or series of procedures used in scientific research to gain knowledge and stimulate new information/discoveries
- OBSERVATIONS AND TESTS
- must me repeatable and reproducible
what is the cycle of the scientific method
observation
observe directly or take cues from previous research
hypothesis
- testable explanation of observations
- written as a statement that, if untrue, may be disproven by evidence obtained during data collection
- null hypothesis (claim that effect being studied does not exist)
- alternate hypothesis (opposing theory to null hypothesis, tested to disprove null hypothesis)
data collection
- process of acquiring new information or evidence
- feasibility versus strength of data field or laboratory based
- two types of data: quantitative and qualitative
analysis of information
various methods and models
interpretation
- did the hypothesis explain the observation
- is there evidence and data to support hypothesis, does it accept/reject the null/alternate hypothesis
scientific theory
- proposed explanations of robust relationships between natural phenomena that collectively help explain patterns in the natural world
- when a hypothesis stands up to repeated testing
- ex. germ theory, evolutionary theory
self-correcting
- can be altered over time with further experimentation and new technologies
biological anthropology as a science
- reliance on the scientific method
- interpreted in evolutionary framework
biological anthropology as a social science
- people cannot be divorced from their social and cultural context
- importance of the biocultural perspective
Plato on evolutionary theory
- eidos or ‘theory of forms’
- ideal and imperfect worlds
- perfect forms and imperfect manifestations
Aristotle on evolutionary theory
- system of classifications
- gradation of species in terms of “complexity”
- ladder increasing towards perfection
plotinus on evolutionary theory
- a single higher transcendent ‘one’
- everything exists in a state of greater or less perfection
view from greek philosophy of evolutionary theory
- have a ‘proper’ place in natures
- fixity of species and uniformity; species are unchanging, variation either undesired or unimportant
scala naturae
- ladder of life, great chain of being
- integrating greek philosophy and christian ideas (midieval europe)
Al-Jahiz view on evolutionary theory
- translation of Aristotle
- struggle for existence
Ibn Khaldun on evolutionary theory
- muqaddimah
- different stages of development; abiotic components - plants - animals
- noted similarities and discussed possibility of relationship between primates and humans
the scientific revolution
- early 17th century europe
- increasingly questioning the nature of the world
- made observations that led to questioning of earlier ideas
- discovery of the new world, earth is round, earth revolves around the sun and solar system, physics, new scientific instruments
- laying groundwork for development of scientific method and seeking to explain for natural phenomena
John Ray
- pastor, naturalist
- classification according to observation
- definition of species through reproductive isolation
carolus linnaeus
- taxonomy: description and classifications of life forms
- binomial nomenclature and the systema naturae; standardized genus and species names
- type specimen for our species
carolus linnaeus system of classification
- systema naturae; inclusive hierarchical system, general to specific, taxa (units representing different levels of grouping)
georges-louis leclerc, comte de buffon
- regional variation in plants and animals
- environmental factors as agents of change
- greater age of the earth; how could all this variation have arisen in a short time period?
James ussher
- biblical scholar; chronology
- calculated age of the earth; october 23rd, 4004BC
Erasmus darwin
- idea of a common ancestor
- expanses of time
- competition for resources and role of the environment
- zoonomia or ‘the laws of organic life’; “the strongest and most active animal should propagate the species, which should thence become improved”
jean-baptiste lamarck
- increasing complexity > environment pushing organism to perfection
- proposed a mechanism for evolution
- inheritance of acquired characteristics; use-disuse theory, a trait acquired by an animal during its lifetime can be passed on to offspring
james hutton
- Uniformitarianism; the continuity of geological processes
- gradualism; slow and steady change
georges cuvier
- extinction; fossils from extinct life forms
- castastrophism; fixity of species
charles lyell
- principles of geology
- Consolidated the theory of uniformitarianism; geological processed have remained consistent, rate of processes are constant, so the earth is very old
- defining geological epochs with fossils
thomas malthus
- an essay on the principle of population
- populations can increase in size indefinitely without limits in place; i.e. subsistence, diseases
- population increases limited by resource availability; if population exceed food resources - catastrophe
- improvement in conditions>increase in population>competition
orgins of evolutionary theory
by early 19th century
- deep time and geological processes
- relationship between environment and variation
- change between generations
- competition for resources
- BUT, no valid mechanism for change between generations or production of variation
charles darwin
- darwin and wedgood families; intellectual circles
- University of edinburgh (medicine) ; not for doctor
- university of cambridge (theology); appreciation for natural history
- joined scientific expedition on the HMS beagle; naturalist and gentlemans companion, documentation and chronicling of natural features
route of HMS beagle
sailed aroung tip of south america, coast of chile, galapagos islands off the western coast of ecuador
HMS beagle
observations
- fossils bear similarities to living species
- huge diversity in living forms
- many parts of the world (galapagos islands)
galapagos islands
observations
- some variation in traits in close otherwise similar animals
darwin’s finches
- each island has its own type of finch
- varied beak size, shape variation, diet
- brought finches back to UK
- explored variation with ornithologist John Gould after return to england
- facilitate resource exploitation in different niches (difference sized seeds etc.)
- had a common mainland ancestor; modified in different island habitats, minimised competition for resources
- observations were curcual to development of idea of evolution due to natural selection
evolution by natural selection
when Darwin returned from voyage in 1836, integrated;
- ideas of evolution
- the ideas of thomar malthus about competition for resources
- his observations in the galapagos
- theorized natural selection as a mechanism for evolutioon
natural selection
- the process by which some organisms with features that enable them to adapt to the environment preferentially survive and reproduce; results in increase in the frequency of those beneficial features in the population
- can also remove deleterious traits
elements of natural selection
- variation exists in all populations
- traits are inherited through reporduction
- there are limited resources, and therefore competition for those resources
