Human Origins Flashcards
(38 cards)
What is the nature of science?
To present a picture of the world based on reliable empirical evidence. It is not completely static.
What is a theory?
A hypothesis that has been proven to be not wrong, but not 100% true (because science is never 100% true).
What is Evolution? How does it apply to humans?
Evolution is the change in genetic constitution through various mechanisms of a population or groups within a population. Humans and other primates evolved from a common ancestor.
What is an Allele?
An allele is one of two or more versions of a DNA sequence at a given genomic location.
What are the six mechanisms of evolution?
Origin of genetic variation, variation within populations, Genetic drift, Natural selection, Speciation, Micro-macro evolution.
Explain the origin of variation, mutation:
Single base pair alterations. Occurs when there insertions, deletions, and rearrangement of genetic material. Also changes in ploidy (number of chromosomes).
Cost/benefit of mutation?
May have no effect on, increase, or decrease survival depending on where the change occurs. In this respect, mutations are random.
Explain the origin of variation Sexual selection
Variation in reproduction and mating success. Some populations are more successful than others due to male competition, female choice, sexual conflict - peacock spiders are an example.
Explain mechanism of change genetic drift:
There are variations within a population-occurs faster in smaller populations. Random changes in allele frequency (genotypes) occur over a course of generations
Explain mechanism of change natural selection:
The different traits of an individual within a population that allow them to reach sexual maturity, therefore passing this trait to the next generation. Eg Darwin’s Finches.
What is sexual dimorphism?
apparent physical differences between male and female - causes male competition.
What is sexual conflict?
A male shows behaviour that increases the chance of fertilization with a cost to the female.
Explain kin selection:
Cooperation arises in groups where individuals are related, because the survival of another of your kin is survival of your own genetics. Increases inclusive fitness. eg meerkat looking out for predators while the group eats.
What is inclusive fitness?
The fitness of yourself and the group.
What is the phylogenetic species concept?
Phenotypically and genotypically distinguishable populations - an irreducible group whose members are descended form a common ancestor. They possess a combination of defining or derived traits.
What is the biological species concept?
Group of actually or potentially interbreeding populations that are reproductively isolated.
What is speciation?
It is the basis for biodiversity. The process of cladogenesis (branching) in evolution associated with some isolating mechanisms between populations which diverge.
Explain genetic flow:
the transfer of genetic material from one population to another. If the rate is high enough, two populations will have equivalent allele frequencies and will be considered a single effective population.
How are species classified?
By their unique genetic history.
What is macro evolutin?
Big change eg trees, that does not result in speciation.
What is a phylogenetic tree?
A branching diagram that shows the relationship among various biological species.
Represents a timeline.
Branch points indicate where a single lineage evolved into distinct new ones.
What is a cladogram?
Based on evolutionary relationships between species. The closer they are on a cladogram, the closer the two species are genetically. The nodes represent common ancestors, and there is no indication of time.
What is the difference between the cladogram and the phylogenetic tree?
There is no indication of when the splits occur on a cladogram.
What does the trajectory of human evolution rely heavily on?
Fossils records and accurate dating of fossils.
