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Notes all colleges evolution biology 2021
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Lecture 1: HistoryTinbergen’s 4 questions
1.What is it for?
2.How did it develop during the lifetime of an
individual?
3. How did it evolve over the history of the
species?
4. How does it work?
Practical applications of evolutionary biology:
Fisheries Biology
● Genetic consequences of selective harvesting
● Genetic consequences of hatcheries
Evolutionary impact assessment: framework for quantifying the effects of harvest-induced evolution
on the utility generated by fish stocks.
Conservation Biology:
‘’Conservation biology is the study of the conservation of nature and of Earth's biodiversity with the
aim of protecting species, their habitats, and ecosystems from excessive rates of extinction and the
erosion of biotic interactions’’
● Identification of evolutionary significant units (ESUs)
● Avoidance of inbreeding depression in captivity
● Avoiding the loss of adaptive variation (adaptive rescue)
● Identification of minimal population size for viability
● Predicting the response to global change
Human Health
● Evolution of pathogens and antibiotic resistance
● Understanding gene function through comparative study
● Tracing the origin and spread of infectious diseases (covid)
● Detection of nucleotide changes responsible for genetic
disorders
● Long-term consequences of medical intervention
Primary goals of evolutionary biology
1. Pattern: evolutionary history
2. Process: understanding of the mechanisms that drive the change
3. Utility: Application of knowledge to understand the genetic underpinnings of biological
diversity & solve practical problems in life sciences
What is evolution?
● Descent with modification
● Changes in the properties of populations that transcend the lifetime of a single individual
● Changes in allele frequency over time
Key ingredients:
1. Change that is heritable across generations
2. A property of populations, not individuals
All evolving systems must have:
Populations, variation and hereditary similarity (offspring resemble parents)
,Aristotle (384-322 BC)
Living organisms arranged in the Great Chain of Being:
plants→lower animals→humans→spiritual beings
Ussher (1664)
Calculated age Earth: 5,668 years old
Linnaeus (1707-1778)
Modern system of taxonomy: based on similarity; hierarchical relationships organisms
Lamarck (1809)
First articulated the theory of evolution
● Organisms continually arise by spontaneous generation
● ‘Nervous fluid’ acts to move each species up the Great Chain of Being
○ No extinction, just continuous change
● Organisms develop adaptations to changing environment through the use and disuse of
organs (heavy use attracts more ‘nervous fluid’)
● Acquired characteristics are inherited
Problems
1. No evidence of spontaneous generation & plenty for extinction
2. No evidence of an innate drive toward complexity
3. No evidence of inheritance of acquired characteristics (the way Lamarck intended)
Geology: new concept of the age of the Earth (Charles Lyell)
Extends back through vast time periods
The processes at work today have been the same throughout the entire history of the Earth
=Uniformitarianism
Darwin (1809-1882)
Before Darwin:
● Orthodoxy: species fixed, designed by God
● Variation = imperfection
● Young Earth
Obeservations voyage of the Beagle
● Same things in different places (anteaters)
● Recent fossils closely related to existing species
● Adjacent layers in fossil record contain similar organisms
● Closely related species that occupy different ecological settings tend to have different
characters (Galapagos finches beaks)
● Populations that are physically isolated tend to differ
Observations from domestic animals:
● High levels of variability within a species
● Variants can pass these characteristics to offspring
○ Idea of heredity, mechanisms were not known)
Malthus (1766-1834)
Essay on the Principle of Populations 1798
● Populations reproduce exponentially
● Natural populations have a large capacity to reproduce, if left unchecked: increase faster than
we can produce food to feed them
, ● Many more organisms are born than can possibly survive
○ Favourable variations would tend to be preserved, and unfavourable ones to be
destroyed. The result would be the formation of a new species
Darwin: As ~, and as, there is a frequently recurring struggle for existence, it follows that any being,
if it vary however slightly in a manner profitable to itself, will have a better chance of surviving, and
thus be naturally selected
Wallace (1823-1913) co discoverer natural selection
this self-acting process would necessarily improve the race, because in every generation the inferior
would inevitably be killed off and the superior would remain – that is, the fittest would survive
Darwin’s 4 theories of evolution
1. Evolution has occurred. Species evolve over time, all species derive from very different
species living in the past. (Pattern)
2. The primary cause of evolutionary change is natural selection.Species change over time
because bearers of different traits have different probabilities of contributing offspring to the
next generation. (Process)
3. Splitting of single species into two or more species has occurred. Darwin postulated that all
life originated with one or a few species. Because many species exist today, there must have
been a process whereby one species can split into at least two species.
All species have common ancestors
4. Evolutionary change is gradual. Evolution occurs by the gradual transformation of populations
over long periods of time ( rather than by a species changing instantaneously into something
different.
Elements of evolution by natural selection
● Many more individuals are born than survive (COMPETITION).
● Individuals vary in traits directly related to their ability to survive and reproduce (VARIATION).
● These advantageous traits passed on to offspring (HERITABILITY).
● Repeat:
○ This process is over long periods of time (ITERATION).
VRAAG OP TENTAMEN: differential reproductive success, variation, heritability
Misconceptions
Evolution ≠ in response to wants/needs, but in response to differences in survival & reproduction
Mutations ≠ in response to needs of organism, but random (at least with respect to benefits)
Te veel mutaties ook nadelig
Biology’s law
Evolution by natural selection – a necessary outcome of differential survival and reproduction,
provided the characteristics that caused those differences are heritable.
● A mechanism, as mechanical as any physical law.
● Acts on individuals, but only populations evolve.
● Opportunistic, not goal seeking – backward-looking, not anticipatory.
● Not the only mechanism of evolution.
Evidence for evolution
1. Homology (of the vertebrate limb)
Comparative anatomy: same skeletal elements appear in very different species, only makes sense as
a process of descent with modification
Similarity between species that is not functionally necessary.
Homology: ‘’the state of having the same or similar relation, relative position, or structure’’
Analogy: ‘’similarity of function & superficial resemblance of structures that have different origins’’
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