EVOLUTION Flashcards
how did Linneus play a part in evolution
classified plants and animals into hierarchey system e.g. Homo sapiens, by looking at characteristics :
- Vertebrates - invertebrates = backbone or not
- Types of mammals = give birth placental / aplacental
explain Darwin contribution to the evolution theory
- went to med school - later pursude natural science
- Fact of evolution was known before him
- He explained WHY it was happening
explain Edmonstone contribution to the evolution theory
- indirectly contributed to Darwin’s work in evolution
- skills in taxidermy due to tasks given by enslaver (e.g. hunting)
- Teaches Darwin taxidermy while hanging out with him - proved valuable during Darwin’s research trips, e.g. HMS Beagle
- Darwin respected Edmonstone and considered him his intellectual equal
explain the HMS Beagle research trip
- British royal navy vessel
- Made navigation better
- 5 year voyage – supposed to be 2
- Darwin collect samples of different specimens from places – develop a picture of the world wide distribution of variation
explain Erasmus Darwin contribution to the evolution theory
- Charles’ Grandfather
- Physican + botanist
- Wrote about the idea of evolution in a book before Darwin published his book
explain Comte de Buffon contribution to the evolution theory
- proposed that animals migrate and change in response to their environments
- argued that animals in the ‘New World’ were inferior to those in the ‘Old World’ (Europe, Asia, and Africa) - believed that the American environment were harsher and less favorable - lead to smaller, weaker, and less diverse animals
explain Jean baptiste Lamarck contribution to the evolution theory
- wrote The Natural History of Invertebrate Animals
- believed organisms could acquire traits during their lifetime based on use and disuse and pass these traits on to their offspring e.g. giraffes stretch their necks to feed off trees – generations later their necks gradually grow
explain Georges cuvier contribution to the evolution theory
- organized the animal kingdom based on anatomical and physiological characteristics
- theory of catastrophism - earths features are shaped by natural disasters which caused mass extinctions of species - after which new species would appear
explain Charles lyell contribution to the evolution theory
- theory of uniformitarianism - geological processes have been occurring in the same way throughout Earth’s history
- principles pf geology book - Darwin took a copy on HMS beagle
- threat suggested Earth was much older than previously thought (around 300 million years) - though we now know it to be closer to 4.5 billion years
explain Thomas Malthus contribution to the evolution theory
- Essays on the principle of population book - explored the relationship between population growth + resources (especially food)
- Malthusian catastrophe = eventually there will be not enough food to feed the population
7 people that contributed to Darwins evolution theory
Edmonstone
Erasmus Darwin
Comte de Buffon
Jean baptiste Lamarck
Georges cuvier
Charles lyell
Thomas Malthus
4 fundamental observations that Darwin made about the natural world that helped him develop the theory of evolution
- Mechanism – Variability
- individuals within a population vary in their traits e.g. morphology and behaviour - Mechanism – Inheritance
- Recognises organisms inherit characteristics from parents - Mechanism – Offspring Numbers
- organisms produce more offspring than can survive to adulthood - Mechanism – Competition
- competition among individuals for limited resources such as food, shelter, and mates
explain Natural selection
- If the ability to survive + reproduce is linked to traits that are passed down, then new traits that help organisms to have these will become more common over time
- Darwin didn’t publish books until 1859 – origin of species
example of sexual selection
- Male peacocks have large, colorful tail feathers - make them more visible to predators + slow them down when flying BUT it provides a significant advantage in reproduction (indicators of good health / genetic quality)
- Asymmetry of investment - Sperm are “cheap” to produce - can produce many offspring - eggs are “expensive” - require more resources to produce and care for the offspring
2 mechanisms by which sexual selection operates
Female choice
Male-male competition
explain female choice in sexual selection
- females often choose mates based on specific traits that refelct the quality or fitness of a potential partner
- e.g. zebra finch - males with brighter beaks (due to a diet rich in carotenoids) are considered healthier - signal good nutrition and overall well-being - 90% of females preferred males with brighter faces
explain male-male competition in sexual selection
- males compete with each other for access to females
- e.g. elephant seals - males fight for control over land territories where females gather to breed to gain exclusive reproductive access to all the females on that beach
- 90% of male elephant seals die without reproducing, while a small number of successful males are able to father 80-100 offspring
- leads to sexual dimorphism - male = 4x size of females because larger males are more successful
example of 3 vestigial characteristics as a result of evolutionary change
- pythons (leftover legs) - small, vestigial leg bones - remnants from when their ancestors were four-legged reptiles - no longer serve the function of movement
- Whale pelvic bones - remnants from their ancestors who walked on land - once supported legs, but as whales adapted to a fully aquatic life, legs were no longer needed
- vestigial gene (GLO) - glucose -> vitamin C - there but does not work due to mutations (leftover from ancestors that could make their own) - has to get from diet instead - risk of developing scurvy if don’t get enough
example of an evolutionary change achieved by remodelling in humans
testes
- Original position of testes = parallel to belly button
- has to migrate to normal position for better temp for sperm – leads to weakness in abdominal wall – more probable to hernea
**they come from fish testes – consequence of evolutionary history
example of an experiment that tested an hypothesis of adaptation by natural selection
kestrels
- Lay just under 6 eggs per nest - is this optimal? -tested whether increasing or decreasing the number of eggs would improve the kestrels’ lifetime reproductive success
- found parents with larger clutch sizes (8 eggs) fledged more chicks (6.99 chicks) than those with average (6 eggs) or reduced (4 eggs) clutch sizes
- BUT larger clutch sizes reduced parent survival rates - only 43% of parents with enlarged clutches (8 eggs) survived
- Parents with average clutch sizes (6 eggs) had the highest lifetime reproductive success therefore is optimal
- kestrels have evolved to lay around 6 eggs per nest - balance between maximizing the number of chicks they can raise + ensuring the parents survive long enough to continue reproducing
