Bio 5 Flashcards
Natural vs artificial selection
Neither can alter phenotypes pf an organism during its lifetime, only of individuals yet to be born and both can create a new species by varying a populations gene pool. But natural selection is a random process that takes longer since it involves accumulation of mutations. Artificial selection is directive and faster since it selects a specific trait and creates a new species if two organisms breed successfully
What is the hardy wineburg equilibrium
Its A state where a population has no changes to their gene pool and frequency of alleles are constant. In order to be in the equilibrium a species must achieve random mating, no mutations, no migration and no genetic drift. All genotypes must reproduce with equal success and so populations are rarely in the equilibrium for long. The idea helps us to recognize when a species is changing.
Evolution
The change in a species gene pool over time. It is the processes that transformed life from their earliest beginnings to today. Misconceptions about evolution are that it tends to perfection, grants animals what they need, involves animals trying to adapt, and has yet to complete the evolutionary tree. Gradualism is the idea that evolution involves gradual changes. Convergent evolution is when diverse species develop similar adaptations and divergent evolution is when diverse species seperates from a common ancestor. Coevolution is the evolutionary changes in one species in response to evolutionary changes in another. Polyploidy can prevent populations from interbreeding. Allopatric speciation is speciation that follows a period of geographic isolation and sympatric speciation is speciation that does not. Humans influence speciation since urbanization leads to fragmentation. Structures that serve similar purposes but evolved independently are analogous structures.
Two main ideas that existed before darwin
Before darwin two main ideas existed about earth. One said Earth was young so processes like erosion had not enough time to change the earths. James Hutton challenged this by studying rates of erosion and sedimentation. He concluded that it would takes millions of years, leading him to support uniformatarianism. Charles Lyell, the father of geology, expanded on huttons ideas and wrote a book that provided more evidence for uniformatarianism. The other idea said that life was immutable. It was challenged by Cuiver, who compared bones of elephants and fossils of mammoths and found that they were different species, and lamarck, who made a hypothesis stating that organisms evolved by their use of certain body parts and can pass this traits to the next generation. He was correct to suggest that species evolved in response to their environment and pass the traits on.
Darwin
Darwin published Origin of Species but took a long time to do so because the theory would be controversial so he wanted as much evidence as possible. The book proposed a theory of how organisms evolve. It said that natural selection was the way that nature favours the reproductive success of certain individuals. Healthy populations make more offspring than can survive. Darwin classified animals based on phylogeny.
What is microevolution
Small changes in allele frequencies and phenotypic ratios
Types of natural selection
Stabilizing is most common, disruptive is the most likely to lead to speciation and directional.
What does sexual selection do
Select traits that enhance mating success
What is sexual dimorphism
When the two genders look way different
What is genetic drift
Random change in the genetic makeup of a population
