L6 - Microevolution Flashcards
What scale is microevolution on?
It is evolution on a small scale, within a single population. It means narrowing our focus to one branch of the tree of life
What is a single population?
For animals, a population is a group of organisms that interbreed with each other - that is, they all share a gene pool.
How do you detect microevolution?
A change in gene frequency in a population. A group of organisms that share a common gene pool
What are the mechanisms?
Mutation, Migration, Genetic drift, Natural selection
What are classification levels?
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
What are the different Kingdoms?
Eukaryota ; Fungi, Animalia, Plantae, Protista. Prokaryota ; Bacteria, Archaea
What is a species?
A species is often defined as a group of individuals that actually or potentially interbreed in nature. In this sense, a species is the biggest gene pool possible under natural conditions. For example, these happy face spiders look different, but since they can interbreed, they are considered the same species.
What is speciation?
A lineage-splitting event that produces two or more separate species. Branching points on a phylogeny tree represent past speciation events
What is geographic (allopatric) isolation?
Common way for the process of speciation to begin. Rivers change course, mountains rise, continents drift. Continuous population is divided into two or more smaller populations. Populations are prevented from interbreeding by geographic isolation.
What causes a reduction in gene flow - large range?
Where population extends over a broad geographic range, and mating throughout the population is not random. Reduced gene flow, but not total isolation. Selective pressures at opposite ends of the range would alter gene frequencies in groups at edges.
What causes a reduction in gene flow - other ‘barriers’?
Natural selection, sexual selection, or even genetic drift can create barriers. Lack of ‘fit’ between sexual organs. For example, The satin bowerbird builds a channel between upright sticks, and decorates with bright blue objects, while the MacGregor’s bowerbird builds a tall tower of sticks and decorates with bits of charcoal
What is the recent african origin (RAO) model?
The ancestors of all modern humans originated in East Africa and that, around 100,000 years ago, some modern humans left the african continent and subsequently colonised the entire world, displacing previously established human species such as Neanderthals in Europe.
What are some of the problems with species?
Criteria of ‘interbreeding individuals cannot be easily applied to organisms that reproduce only or mainly asexually. Also, many plants, and some animals, form hybrids in nature
When did the first humans come?
100,000 yrs ago
When did the first cats come?
42 million yrs ago
When did the first dinosaurs come?
230 million
When did the first life come?
3.6 billion yrs ago
