Lecture notes of the first part of the Evolutionary Developmental Biology course. This course is part of the first-year Biomedical Sciences curriculum at the Vrije Universiteit Amsterdam. Note: these notes were written based on online lectures (due to COVID-19), so the content might be different th...
To interpret and understand organismal adaptation to environmental conditions
To explain the diversity of life: the variety of organisms, their characteristics, and their
changes over time
Charles Darwin (1859) the origin of species:
Evolution is change in the heritable characteristics of biological populations over successive
generations.
Natural selection:
1. Variation in reproductive success
2. Variation in the trait of interest
3. Correlation between the trait and reproductive success
4. The trait is heritable
Survival of the fittest
- Typological thinking the “normal” or average condition is the most important aspect to
consider
- Population thinking understanding the variation in a population
Heritable traits with standing genetic variation and possibly subject to selection in humans:
- Trade-offs, random processes, mismatches, evolutionary constraints
- Claims of adaptation need examination, which can be difficult in humans
Determining if something is adaptive:
1. Observing natural selection experimental evolution in microorganisms, nematodes or
insects
2. Perturbing the trait move a trait away from its optimum
3. Trait is produced only when it serves a function
Most of these tests are not possible in humans model organisms
Tree thinking:
Understanding the position of a species or a trait in a phylogenetic tree expresses the relationship
among organisms and their evolutionary history.
,Lecture 2 – Story of our ancestors (Straalen & Roelofs 1)
Homo sapiens (knowledgeable man):
- Kingdom: animalia
- Phylum: chordata
- Subphylum: vertebrata
- Class: mammalia
- Order: primates
- Family: hominidae no tail, remarkably long periods of nursing and adolescence, sexual
dimorphism
- Subfamily: homininae bipedalism, brain size, family structure and sexuality
- Genus: homo
Anagenesis: gradual evolution of a species
The African rain forest gave to savannah (10 Mya) a new ecological niche:
Terrestrial instead of arboreal lifestyle demanded adaptation all old fossil hominins are found in
(East) Africa
Species to remember:
- Australopithecus afarensis
- Lived in Africa, ~3.5 Mya
- Ancestor of all Homo species
- Mosaic of ancestral and derived traits
- Homo erectus
- Lived in Africa and Asia, ~1.5 Mya
- African H. erectus ancestor of H. sapiens
- Homo neanderthalensis
- Lived in Europe and Asia, 600 Kya – 30 Kya
- Similarities to H. sapiens; extinct sister clade
1. Group of organisms that can produce fertile offspring
- Hybridizations between closely related species possible
2. DNA sequence similarity
3. Behaviour
4. Ecological niche
5. Morphology
- Completeness and number of specimens found important
- Variation within species versus variation between species
, Australopithecus:
- Not all humanlike traits evolved at the same time
- Apomorphic (derived) vs. plesiomorphic (ancestral)
- Skull shape and brain volume largely plesiomorphic
- The dental arcade changed from U-shaped to parabolic and became shorter
- Reduction in canine teeth size in australopithecines, but still significant sexual dimorphism
- Strong dimorphism in body size gradually disappeared6 species (4.2-2.5 Mya)
- Gradual evolution of various humanlike traits in subsequent species
- Two lineages diverged from Australopithecus
- Paranthropus (2.5-1.4 Mya), characterized by robust and muscular bodies with apelike
features of the head evolutionary dead end
- Homo (2.8 Mya - now) Homo habilis (2.8-1.4 Mya)
Lucy:
Australopithecus afarensis (3.2 Mya) excavated in 1974 in Ethiopia.
- Most complete Australopithecus fossil at that time
- First to display characteristics of bipedalism and a small brain
- Settled “brain first” versus “bipedalism first” debate
Evolution of the brain of genus Homo habilis:
Use and manufacturing of stone tools:
- Understand fracture mechanics of available stones
- Sensorimotor control over force and accuracy to strike off flakes
- Spatial understanding of where to strike
Homo rudolfensis an alternative “first” Homo species
- First appeared 2 Mya
- More humanlike features of the head
- Debated if it is a separate species or part of Homo habilis
- Few fossils remains found
Species concept problematic in genus Homo
Homo erectus (2 Mya – 108.000 Ya):
- All traits related to bipedalism well developed
- Efficient long-distance runners
- Evolution of less body hair and dark skin colour
- Brain volume (600-1000 cc) still apelike skull features
- Evolution of larger brains started ~800.000 Ya
- First species associated with hunting large animals; more sophisticated stone tool making
- First human species to migrate out of Africa
- Morphologically very diverse
Modes of speciation:
Reproductive isolation followed by local adaptation or genetic drift over time.
1. Sympatric speciation side-by-side evolution
2. Allopatric speciation a group separates and occupies a
new area
3. Parapatric speciation origin of a new species on the
border of the distribution range due to local adaptation
Voordelen van het kopen van samenvattingen bij Stuvia op een rij:
Verzekerd van kwaliteit door reviews
Stuvia-klanten hebben meer dan 700.000 samenvattingen beoordeeld. Zo weet je zeker dat je de beste documenten koopt!
Snel en makkelijk kopen
Je betaalt supersnel en eenmalig met iDeal, creditcard of Stuvia-tegoed voor de samenvatting. Zonder lidmaatschap.
Focus op de essentie
Samenvattingen worden geschreven voor en door anderen. Daarom zijn de samenvattingen altijd betrouwbaar en actueel. Zo kom je snel tot de kern!
Veelgestelde vragen
Wat krijg ik als ik dit document koop?
Je krijgt een PDF, die direct beschikbaar is na je aankoop. Het gekochte document is altijd, overal en oneindig toegankelijk via je profiel.
Tevredenheidsgarantie: hoe werkt dat?
Onze tevredenheidsgarantie zorgt ervoor dat je altijd een studiedocument vindt dat goed bij je past. Je vult een formulier in en onze klantenservice regelt de rest.
Van wie koop ik deze samenvatting?
Stuvia is een marktplaats, je koop dit document dus niet van ons, maar van verkoper rbe239. Stuvia faciliteert de betaling aan de verkoper.
Zit ik meteen vast aan een abonnement?
Nee, je koopt alleen deze samenvatting voor €4,99. Je zit daarna nergens aan vast.
